/* global module */
'use strict';

/**
 * Class representing the API
 */
var SpotifyWebApi = (function() {
    var _baseUri = 'https://api.spotify.com/v1';
    var _accessToken = null;
    var _promiseImplementation = null;

    var WrapPromiseWithAbort = function(promise, onAbort) {
        promise.abort = onAbort;
        return promise;
    };

    var _promiseProvider = function(promiseFunction, onAbort) {
        var returnedPromise;
        if (_promiseImplementation !== null) {
            var deferred = _promiseImplementation.defer();
            promiseFunction(
                function(resolvedResult) {
                    deferred.resolve(resolvedResult);
                },
                function(rejectedResult) {
                    deferred.reject(rejectedResult);
                }
            );
            returnedPromise = deferred.promise;
        } else {
            if (window.Promise) {
                returnedPromise = new window.Promise(promiseFunction);
            }
        }

        if (returnedPromise) {
            return new WrapPromiseWithAbort(returnedPromise, onAbort);
        } else {
            return null;
        }
    };

    var _extend = function() {
        var args = Array.prototype.slice.call(arguments);
        var target = args[0];
        var objects = args.slice(1);
        target = target || {};
        objects.forEach(function(object) {
            for (var j in object) {
                if (object.hasOwnProperty(j)) {
                    target[j] = object[j];
                }
            }
        });
        return target;
    };

    var _buildUrl = function(url, parameters) {
        var qs = '';
        for (var key in parameters) {
            if (parameters.hasOwnProperty(key)) {
                var value = parameters[key];
                qs += encodeURIComponent(key) + '=' + encodeURIComponent(value) + '&';
            }
        }
        if (qs.length > 0) {
            // chop off last '&'
            qs = qs.substring(0, qs.length - 1);
            url = url + '?' + qs;
        }
        return url;
    };

    var _performRequest = function(requestData, callback) {
        var req = new XMLHttpRequest();

        var promiseFunction = function(resolve, reject) {
            function success(data) {
                if (resolve) {
                    resolve(data);
                }
                if (callback) {
                    callback(null, data);
                }
            }

            function failure() {
                if (reject) {
                    reject(req);
                }
                if (callback) {
                    callback(req, null);
                }
            }

            var type = requestData.type || 'GET';
            req.open(type, _buildUrl(requestData.url, requestData.params));
            if (_accessToken) {
                req.setRequestHeader('Authorization', 'Bearer ' + _accessToken);
            }
            if (requestData.contentType) {
                req.setRequestHeader('Content-Type', requestData.contentType)
            }

            req.onreadystatechange = function() {
                if (req.readyState === 4) {
                    var data = null;
                    try {
                        data = req.responseText ? JSON.parse(req.responseText) : '';
                    } catch (e) {
                        console.error(e);
                    }

                    if (req.status >= 200 && req.status < 300) {
                        success(data);
                    } else {
                        failure();
                    }
                }
            };

            if (type === 'GET') {
                req.send(null);
            } else {
                var postData = null
                if (requestData.postData) {
                    postData = requestData.contentType === 'image/jpeg' ? requestData.postData : JSON.stringify(requestData.postData)
                }
                req.send(postData);
            }
        };

        if (callback) {
            promiseFunction();
            return null;
        } else {
            return _promiseProvider(promiseFunction, function() {
                req.abort();
            });
        }
    };

    var _checkParamsAndPerformRequest = function(requestData, options, callback, optionsAlwaysExtendParams) {
        var opt = {};
        var cb = null;

        if (typeof options === 'object') {
            opt = options;
            cb = callback;
        } else if (typeof options === 'function') {
            cb = options;
        }

        // options extend postData, if any. Otherwise they extend parameters sent in the url
        var type = requestData.type || 'GET';
        if (type !== 'GET' && requestData.postData && !optionsAlwaysExtendParams) {
            requestData.postData = _extend(requestData.postData, opt);
        } else {
            requestData.params = _extend(requestData.params, opt);
        }
        return _performRequest(requestData, cb);
    };

    /**
     * Creates an instance of the wrapper
     * @constructor
     */
    var Constr = function() {};

    Constr.prototype = {
        constructor: SpotifyWebApi
    };

    /**
     * Fetches a resource through a generic GET request.
     *
     * @param {string} url The URL to be fetched
     * @param {function(Object,Object)} callback An optional callback
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getGeneric = function(url, callback) {
        var requestData = {
            url: url
        };
        return _checkParamsAndPerformRequest(requestData, callback);
    };

    /**
     * Fetches information about the current user.
     * See [Get Current User's Profile](https://developer.spotify.com/web-api/get-current-users-profile/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getMe = function(options, callback) {
        var requestData = {
            url: _baseUri + '/me'
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Fetches current user's saved tracks.
     * See [Get Current User's Saved Tracks](https://developer.spotify.com/web-api/get-users-saved-tracks/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getMySavedTracks = function(options, callback) {
        var requestData = {
            url: _baseUri + '/me/tracks'
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Adds a list of tracks to the current user's saved tracks.
     * See [Save Tracks for Current User](https://developer.spotify.com/web-api/save-tracks-user/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Array<string>} trackIds The ids of the tracks. If you know their Spotify URI it is easy
     * to find their track id (e.g. spotify:track:<here_is_the_track_id>)
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.addToMySavedTracks = function(trackIds, options, callback) {
        var requestData = {
            url: _baseUri + '/me/tracks',
            type: 'PUT',
            postData: trackIds
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Remove a list of tracks from the current user's saved tracks.
     * See [Remove Tracks for Current User](https://developer.spotify.com/web-api/remove-tracks-user/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Array<string>} trackIds The ids of the tracks. If you know their Spotify URI it is easy
     * to find their track id (e.g. spotify:track:<here_is_the_track_id>)
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.removeFromMySavedTracks = function(trackIds, options, callback) {
        var requestData = {
            url: _baseUri + '/me/tracks',
            type: 'DELETE',
            postData: trackIds
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Checks if the current user's saved tracks contains a certain list of tracks.
     * See [Check Current User's Saved Tracks](https://developer.spotify.com/web-api/check-users-saved-tracks/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Array<string>} trackIds The ids of the tracks. If you know their Spotify URI it is easy
     * to find their track id (e.g. spotify:track:<here_is_the_track_id>)
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.containsMySavedTracks = function(trackIds, options, callback) {
        var requestData = {
            url: _baseUri + '/me/tracks/contains',
            params: { ids: trackIds.join(',') }
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Get a list of the albums saved in the current Spotify user's "Your Music" library.
     * See [Get Current User's Saved Albums](https://developer.spotify.com/web-api/get-users-saved-albums/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getMySavedAlbums = function(options, callback) {
        var requestData = {
            url: _baseUri + '/me/albums'
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Save one or more albums to the current user's "Your Music" library.
     * See [Save Albums for Current User](https://developer.spotify.com/web-api/save-albums-user/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Array<string>} albumIds The ids of the albums. If you know their Spotify URI, it is easy
     * to find their album id (e.g. spotify:album:<here_is_the_album_id>)
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.addToMySavedAlbums = function(albumIds, options, callback) {
        var requestData = {
            url: _baseUri + '/me/albums',
            type: 'PUT',
            postData: albumIds
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Remove one or more albums from the current user's "Your Music" library.
     * See [Remove Albums for Current User](https://developer.spotify.com/web-api/remove-albums-user/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Array<string>} albumIds The ids of the albums. If you know their Spotify URI, it is easy
     * to find their album id (e.g. spotify:album:<here_is_the_album_id>)
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.removeFromMySavedAlbums = function(albumIds, options, callback) {
        var requestData = {
            url: _baseUri + '/me/albums',
            type: 'DELETE',
            postData: albumIds
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Check if one or more albums is already saved in the current Spotify user's "Your Music" library.
     * See [Check User's Saved Albums](https://developer.spotify.com/web-api/check-users-saved-albums/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Array<string>} albumIds The ids of the albums. If you know their Spotify URI, it is easy
     * to find their album id (e.g. spotify:album:<here_is_the_album_id>)
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.containsMySavedAlbums = function(albumIds, options, callback) {
        var requestData = {
            url: _baseUri + '/me/albums/contains',
            params: { ids: albumIds.join(',') }
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Get the current user’s top artists based on calculated affinity.
     * See [Get a User’s Top Artists](https://developer.spotify.com/web-api/get-users-top-artists-and-tracks/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getMyTopArtists = function(options, callback) {
        var requestData = {
            url: _baseUri + '/me/top/artists'
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Get the current user’s top tracks based on calculated affinity.
     * See [Get a User’s Top Tracks](https://developer.spotify.com/web-api/get-users-top-artists-and-tracks/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getMyTopTracks = function(options, callback) {
        var requestData = {
            url: _baseUri + '/me/top/tracks'
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Get tracks from the current user’s recently played tracks.
     * See [Get Current User’s Recently Played Tracks](https://developer.spotify.com/web-api/web-api-personalization-endpoints/get-recently-played/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getMyRecentlyPlayedTracks = function(options, callback) {
        var requestData = {
            url: _baseUri + '/me/player/recently-played'
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Adds the current user as a follower of one or more other Spotify users.
     * See [Follow Artists or Users](https://developer.spotify.com/web-api/follow-artists-users/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Array<string>} userIds The ids of the users. If you know their Spotify URI it is easy
     * to find their user id (e.g. spotify:user:<here_is_the_user_id>)
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is an empty value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.followUsers = function(userIds, callback) {
        var requestData = {
            url: _baseUri + '/me/following/',
            type: 'PUT',
            params: {
                ids: userIds.join(','),
                type: 'user'
            }
        };
        return _checkParamsAndPerformRequest(requestData, callback);
    };

    /**
     * Adds the current user as a follower of one or more artists.
     * See [Follow Artists or Users](https://developer.spotify.com/web-api/follow-artists-users/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Array<string>} artistIds The ids of the artists. If you know their Spotify URI it is easy
     * to find their artist id (e.g. spotify:artist:<here_is_the_artist_id>)
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is an empty value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.followArtists = function(artistIds, callback) {
        var requestData = {
            url: _baseUri + '/me/following/',
            type: 'PUT',
            params: {
                ids: artistIds.join(','),
                type: 'artist'
            }
        };
        return _checkParamsAndPerformRequest(requestData, callback);
    };

    /**
     * Add the current user as a follower of one playlist.
     * See [Follow a Playlist](https://developer.spotify.com/web-api/follow-playlist/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} playlistId The id of the playlist. If you know the Spotify URI it is easy
     * to find the playlist id (e.g. spotify:user:xxxx:playlist:<here_is_the_playlist_id>)
     * @param {Object} options A JSON object with options that can be passed. For instance,
     * whether you want the playlist to be followed privately ({public: false})
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is an empty value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.followPlaylist = function(playlistId, options, callback) {
        var requestData = {
            url: _baseUri + '/playlists/' + playlistId + '/followers',
            type: 'PUT',
            postData: {}
        };

        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Removes the current user as a follower of one or more other Spotify users.
     * See [Unfollow Artists or Users](https://developer.spotify.com/web-api/unfollow-artists-users/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Array<string>} userIds The ids of the users. If you know their Spotify URI it is easy
     * to find their user id (e.g. spotify:user:<here_is_the_user_id>)
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is an empty value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.unfollowUsers = function(userIds, callback) {
        var requestData = {
            url: _baseUri + '/me/following/',
            type: 'DELETE',
            params: {
                ids: userIds.join(','),
                type: 'user'
            }
        };
        return _checkParamsAndPerformRequest(requestData, callback);
    };

    /**
     * Removes the current user as a follower of one or more artists.
     * See [Unfollow Artists or Users](https://developer.spotify.com/web-api/unfollow-artists-users/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Array<string>} artistIds The ids of the artists. If you know their Spotify URI it is easy
     * to find their artist id (e.g. spotify:artist:<here_is_the_artist_id>)
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is an empty value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.unfollowArtists = function(artistIds, callback) {
        var requestData = {
            url: _baseUri + '/me/following/',
            type: 'DELETE',
            params: {
                ids: artistIds.join(','),
                type: 'artist'
            }
        };
        return _checkParamsAndPerformRequest(requestData, callback);
    };

    /**
     * Remove the current user as a follower of one playlist.
     * See [Unfollow a Playlist](https://developer.spotify.com/web-api/unfollow-playlist/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} playlistId The id of the playlist. If you know the Spotify URI it is easy
     * to find the playlist id (e.g. spotify:user:xxxx:playlist:<here_is_the_playlist_id>)
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is an empty value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.unfollowPlaylist = function(playlistId, callback) {
        var requestData = {
            url: _baseUri + '/playlists/' + playlistId + '/followers',
            type: 'DELETE'
        };
        return _checkParamsAndPerformRequest(requestData, callback);
    };

    /**
     * Checks to see if the current user is following one or more other Spotify users.
     * See [Check if Current User Follows Users or Artists](https://developer.spotify.com/web-api/check-current-user-follows/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Array<string>} userIds The ids of the users. If you know their Spotify URI it is easy
     * to find their user id (e.g. spotify:user:<here_is_the_user_id>)
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is an array of boolean values that indicate
     * whether the user is following the users sent in the request.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.isFollowingUsers = function(userIds, callback) {
        var requestData = {
            url: _baseUri + '/me/following/contains',
            type: 'GET',
            params: {
                ids: userIds.join(','),
                type: 'user'
            }
        };
        return _checkParamsAndPerformRequest(requestData, callback);
    };

    /**
     * Checks to see if the current user is following one or more artists.
     * See [Check if Current User Follows](https://developer.spotify.com/web-api/check-current-user-follows/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Array<string>} artistIds The ids of the artists. If you know their Spotify URI it is easy
     * to find their artist id (e.g. spotify:artist:<here_is_the_artist_id>)
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is an array of boolean values that indicate
     * whether the user is following the artists sent in the request.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.isFollowingArtists = function(artistIds, callback) {
        var requestData = {
            url: _baseUri + '/me/following/contains',
            type: 'GET',
            params: {
                ids: artistIds.join(','),
                type: 'artist'
            }
        };
        return _checkParamsAndPerformRequest(requestData, callback);
    };

    /**
     * Check to see if one or more Spotify users are following a specified playlist.
     * See [Check if Users Follow a Playlist](https://developer.spotify.com/web-api/check-user-following-playlist/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} playlistId The id of the playlist. If you know the Spotify URI it is easy
     * to find the playlist id (e.g. spotify:user:xxxx:playlist:<here_is_the_playlist_id>)
     * @param {Array<string>} userIds The ids of the users. If you know their Spotify URI it is easy
     * to find their user id (e.g. spotify:user:<here_is_the_user_id>)
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is an array of boolean values that indicate
     * whether the users are following the playlist sent in the request.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.areFollowingPlaylist = function(playlistId, userIds, callback) {
        var requestData = {
            url: _baseUri + '/playlists/' + playlistId + '/followers/contains',
            type: 'GET',
            params: {
                ids: userIds.join(',')
            }
        };
        return _checkParamsAndPerformRequest(requestData, callback);
    };

    /**
     * Get the current user's followed artists.
     * See [Get User's Followed Artists](https://developer.spotify.com/web-api/get-followed-artists/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Object} [options] Options, being after and limit.
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is an object with a paged object containing
     * artists.
     * @returns {Promise|undefined} A promise that if successful, resolves to an object containing a paging object which contains
     * artists objects. Not returned if a callback is given.
     */
    Constr.prototype.getFollowedArtists = function(options, callback) {
        var requestData = {
            url: _baseUri + '/me/following',
            type: 'GET',
            params: {
                type: 'artist'
            }
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Fetches information about a specific user.
     * See [Get a User's Profile](https://developer.spotify.com/web-api/get-users-profile/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} userId The id of the user. If you know the Spotify URI it is easy
     * to find the id (e.g. spotify:user:<here_is_the_id>)
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getUser = function(userId, options, callback) {
        var requestData = {
            url: _baseUri + '/users/' + encodeURIComponent(userId)
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Fetches a list of the current user's playlists.
     * See [Get a List of a User's Playlists](https://developer.spotify.com/web-api/get-list-users-playlists/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} userId An optional id of the user. If you know the Spotify URI it is easy
     * to find the id (e.g. spotify:user:<here_is_the_id>). If not provided, the id of the user that granted
     * the permissions will be used.
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getUserPlaylists = function(userId, options, callback) {
        var requestData;
        if (typeof userId === 'string') {
            requestData = {
                url: _baseUri + '/users/' + encodeURIComponent(userId) + '/playlists'
            };
        } else {
            requestData = {
                url: _baseUri + '/me/playlists'
            };
            callback = options;
            options = userId;
        }
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Fetches a specific playlist.
     * See [Get a Playlist](https://developer.spotify.com/web-api/get-playlist/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} playlistId The id of the playlist. If you know the Spotify URI it is easy
     * to find the playlist id (e.g. spotify:user:xxxx:playlist:<here_is_the_playlist_id>)
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getPlaylist = function(playlistId, options, callback) {
        var requestData = {
            url: _baseUri + '/playlists/' + playlistId
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Fetches the tracks from a specific playlist.
     * See [Get a Playlist's Tracks](https://developer.spotify.com/web-api/get-playlists-tracks/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} playlistId The id of the playlist. If you know the Spotify URI it is easy
     * to find the playlist id (e.g. spotify:user:xxxx:playlist:<here_is_the_playlist_id>)
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getPlaylistTracks = function(playlistId, options, callback) {
        var requestData = {
            url: _baseUri + '/playlists/' + playlistId + '/tracks'
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Creates a playlist and stores it in the current user's library.
     * See [Create a Playlist](https://developer.spotify.com/web-api/create-playlist/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} userId The id of the user. If you know the Spotify URI it is easy
     * to find the id (e.g. spotify:user:<here_is_the_id>)
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.createPlaylist = function(userId, options, callback) {
        var requestData = {
            url: _baseUri + '/users/' + encodeURIComponent(userId) + '/playlists',
            type: 'POST',
            postData: options
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Change a playlist's name and public/private state
     * See [Change a Playlist's Details](https://developer.spotify.com/web-api/change-playlist-details/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} playlistId The id of the playlist. If you know the Spotify URI it is easy
     * to find the playlist id (e.g. spotify:user:xxxx:playlist:<here_is_the_playlist_id>)
     * @param {Object} data A JSON object with the data to update. E.g. {name: 'A new name', public: true}
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.changePlaylistDetails = function(playlistId, data, callback) {
        var requestData = {
            url: _baseUri + '/playlists/' + playlistId,
            type: 'PUT',
            postData: data
        };
        return _checkParamsAndPerformRequest(requestData, data, callback);
    };

    /**
     * Add tracks to a playlist.
     * See [Add Tracks to a Playlist](https://developer.spotify.com/web-api/add-tracks-to-playlist/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} playlistId The id of the playlist. If you know the Spotify URI it is easy
     * to find the playlist id (e.g. spotify:user:xxxx:playlist:<here_is_the_playlist_id>)
     * @param {Array<string>} uris An array of Spotify URIs for the tracks
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.addTracksToPlaylist = function(playlistId, uris, options, callback) {
        var requestData = {
            url: _baseUri + '/playlists/' + playlistId + '/tracks',
            type: 'POST',
            postData: {
                uris: uris
            }
        };
        return _checkParamsAndPerformRequest(requestData, options, callback, true);
    };

    /**
     * Replace the tracks of a playlist
     * See [Replace a Playlist's Tracks](https://developer.spotify.com/web-api/replace-playlists-tracks/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} playlistId The id of the playlist. If you know the Spotify URI it is easy
     * to find the playlist id (e.g. spotify:user:xxxx:playlist:<here_is_the_playlist_id>)
     * @param {Array<string>} uris An array of Spotify URIs for the tracks
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.replaceTracksInPlaylist = function(playlistId, uris, callback) {
        var requestData = {
            url: _baseUri + '/playlists/' + playlistId + '/tracks',
            type: 'PUT',
            postData: { uris: uris }
        };
        return _checkParamsAndPerformRequest(requestData, {}, callback);
    };

    /**
     * Reorder tracks in a playlist
     * See [Reorder a Playlist’s Tracks](https://developer.spotify.com/web-api/reorder-playlists-tracks/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} playlistId The id of the playlist. If you know the Spotify URI it is easy
     * to find the playlist id (e.g. spotify:user:xxxx:playlist:<here_is_the_playlist_id>)
     * @param {number} rangeStart The position of the first track to be reordered.
     * @param {number} insertBefore The position where the tracks should be inserted. To reorder the tracks to
     * the end of the playlist, simply set insert_before to the position after the last track.
     * @param {Object} options An object with optional parameters (range_length, snapshot_id)
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.reorderTracksInPlaylist = function(playlistId, rangeStart, insertBefore, options, callback) {
        /* eslint-disable camelcase */
        var requestData = {
            url: _baseUri + '/playlists/' + playlistId + '/tracks',
            type: 'PUT',
            postData: {
                range_start: rangeStart,
                insert_before: insertBefore
            }
        };
        /* eslint-enable camelcase */
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Remove tracks from a playlist
     * See [Remove Tracks from a Playlist](https://developer.spotify.com/web-api/remove-tracks-playlist/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} playlistId The id of the playlist. If you know the Spotify URI it is easy
     * to find the playlist id (e.g. spotify:user:xxxx:playlist:<here_is_the_playlist_id>)
     * @param {Array<Object>} uris An array of tracks to be removed. Each element of the array can be either a
     * string, in which case it is treated as a URI, or an object containing the properties `uri` (which is a
     * string) and `positions` (which is an array of integers).
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.removeTracksFromPlaylist = function(playlistId, uris, callback) {
        var dataToBeSent = uris.map(function(uri) {
            if (typeof uri === 'string') {
                return { uri: uri };
            } else {
                return uri;
            }
        });

        var requestData = {
            url: _baseUri + '/playlists/' + playlistId + '/tracks',
            type: 'DELETE',
            postData: { tracks: dataToBeSent }
        };
        return _checkParamsAndPerformRequest(requestData, {}, callback);
    };

    /**
     * Remove tracks from a playlist, specifying a snapshot id.
     * See [Remove Tracks from a Playlist](https://developer.spotify.com/web-api/remove-tracks-playlist/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} playlistId The id of the playlist. If you know the Spotify URI it is easy
     * to find the playlist id (e.g. spotify:user:xxxx:playlist:<here_is_the_playlist_id>)
     * @param {Array<Object>} uris An array of tracks to be removed. Each element of the array can be either a
     * string, in which case it is treated as a URI, or an object containing the properties `uri` (which is a
     * string) and `positions` (which is an array of integers).
     * @param {string} snapshotId The playlist's snapshot ID against which you want to make the changes
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.removeTracksFromPlaylistWithSnapshotId = function(playlistId, uris, snapshotId, callback) {
        var dataToBeSent = uris.map(function(uri) {
            if (typeof uri === 'string') {
                return { uri: uri };
            } else {
                return uri;
            }
        });
        /* eslint-disable camelcase */
        var requestData = {
            url: _baseUri + '/playlists/' + playlistId + '/tracks',
            type: 'DELETE',
            postData: {
                tracks: dataToBeSent,
                snapshot_id: snapshotId
            }
        };
        /* eslint-enable camelcase */
        return _checkParamsAndPerformRequest(requestData, {}, callback);
    };

    /**
     * Remove tracks from a playlist, specifying the positions of the tracks to be removed.
     * See [Remove Tracks from a Playlist](https://developer.spotify.com/web-api/remove-tracks-playlist/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} playlistId The id of the playlist. If you know the Spotify URI it is easy
     * to find the playlist id (e.g. spotify:user:xxxx:playlist:<here_is_the_playlist_id>)
     * @param {Array<number>} positions array of integers containing the positions of the tracks to remove
     * from the playlist.
     * @param {string} snapshotId The playlist's snapshot ID against which you want to make the changes
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.removeTracksFromPlaylistInPositions = function(playlistId, positions, snapshotId, callback) {
        /* eslint-disable camelcase */
        var requestData = {
            url: _baseUri + '/playlists/' + playlistId + '/tracks',
            type: 'DELETE',
            postData: {
                positions: positions,
                snapshot_id: snapshotId
            }
        };
        /* eslint-enable camelcase */
        return _checkParamsAndPerformRequest(requestData, {}, callback);
    };

    /**
     * Upload a custom playlist cover image.
     * See [Upload A Custom Playlist Cover Image](https://developer.spotify.com/web-api/upload-a-custom-playlist-cover-image/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} playlistId The id of the playlist. If you know the Spotify URI it is easy
     * to find the playlist id (e.g. spotify:user:xxxx:playlist:<here_is_the_playlist_id>)
     * @param {string} imageData Base64 encoded JPEG image data, maximum payload size is 256 KB.
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.uploadCustomPlaylistCoverImage = function(playlistId, imageData, callback) {
        var requestData = {
            url: _baseUri + '/playlists/' + playlistId + '/images',
            type: 'PUT',
            postData: imageData.replace(/^data:image\/jpeg;base64,/, ''),
            contentType: 'image/jpeg'
        };
        return _checkParamsAndPerformRequest(requestData, {}, callback);
    };

    /**
     * Fetches an album from the Spotify catalog.
     * See [Get an Album](https://developer.spotify.com/web-api/get-album/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} albumId The id of the album. If you know the Spotify URI it is easy
     * to find the album id (e.g. spotify:album:<here_is_the_album_id>)
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getAlbum = function(albumId, options, callback) {
        var requestData = {
            url: _baseUri + '/albums/' + albumId
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Fetches the tracks of an album from the Spotify catalog.
     * See [Get an Album's Tracks](https://developer.spotify.com/web-api/get-albums-tracks/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} albumId The id of the album. If you know the Spotify URI it is easy
     * to find the album id (e.g. spotify:album:<here_is_the_album_id>)
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getAlbumTracks = function(albumId, options, callback) {
        var requestData = {
            url: _baseUri + '/albums/' + albumId + '/tracks'
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Fetches multiple albums from the Spotify catalog.
     * See [Get Several Albums](https://developer.spotify.com/web-api/get-several-albums/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Array<string>} albumIds The ids of the albums. If you know their Spotify URI it is easy
     * to find their album id (e.g. spotify:album:<here_is_the_album_id>)
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getAlbums = function(albumIds, options, callback) {
        var requestData = {
            url: _baseUri + '/albums/',
            params: { ids: albumIds.join(',') }
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Fetches a track from the Spotify catalog.
     * See [Get a Track](https://developer.spotify.com/web-api/get-track/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} trackId The id of the track. If you know the Spotify URI it is easy
     * to find the track id (e.g. spotify:track:<here_is_the_track_id>)
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getTrack = function(trackId, options, callback) {
        var requestData = {};
        requestData.url = _baseUri + '/tracks/' + trackId;
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Fetches multiple tracks from the Spotify catalog.
     * See [Get Several Tracks](https://developer.spotify.com/web-api/get-several-tracks/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Array<string>} trackIds The ids of the tracks. If you know their Spotify URI it is easy
     * to find their track id (e.g. spotify:track:<here_is_the_track_id>)
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getTracks = function(trackIds, options, callback) {
        var requestData = {
            url: _baseUri + '/tracks/',
            params: { ids: trackIds.join(',') }
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Fetches an artist from the Spotify catalog.
     * See [Get an Artist](https://developer.spotify.com/web-api/get-artist/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} artistId The id of the artist. If you know the Spotify URI it is easy
     * to find the artist id (e.g. spotify:artist:<here_is_the_artist_id>)
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getArtist = function(artistId, options, callback) {
        var requestData = {
            url: _baseUri + '/artists/' + artistId
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Fetches multiple artists from the Spotify catalog.
     * See [Get Several Artists](https://developer.spotify.com/web-api/get-several-artists/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Array<string>} artistIds The ids of the artists. If you know their Spotify URI it is easy
     * to find their artist id (e.g. spotify:artist:<here_is_the_artist_id>)
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getArtists = function(artistIds, options, callback) {
        var requestData = {
            url: _baseUri + '/artists/',
            params: { ids: artistIds.join(',') }
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Fetches the albums of an artist from the Spotify catalog.
     * See [Get an Artist's Albums](https://developer.spotify.com/web-api/get-artists-albums/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} artistId The id of the artist. If you know the Spotify URI it is easy
     * to find the artist id (e.g. spotify:artist:<here_is_the_artist_id>)
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getArtistAlbums = function(artistId, options, callback) {
        var requestData = {
            url: _baseUri + '/artists/' + artistId + '/albums'
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Fetches a list of top tracks of an artist from the Spotify catalog, for a specific country.
     * See [Get an Artist's Top Tracks](https://developer.spotify.com/web-api/get-artists-top-tracks/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} artistId The id of the artist. If you know the Spotify URI it is easy
     * to find the artist id (e.g. spotify:artist:<here_is_the_artist_id>)
     * @param {string} countryId The id of the country (e.g. ES for Spain or US for United States)
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getArtistTopTracks = function(artistId, countryId, options, callback) {
        var requestData = {
            url: _baseUri + '/artists/' + artistId + '/top-tracks',
            params: { country: countryId }
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Fetches a list of artists related with a given one from the Spotify catalog.
     * See [Get an Artist's Related Artists](https://developer.spotify.com/web-api/get-related-artists/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} artistId The id of the artist. If you know the Spotify URI it is easy
     * to find the artist id (e.g. spotify:artist:<here_is_the_artist_id>)
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getArtistRelatedArtists = function(artistId, options, callback) {
        var requestData = {
            url: _baseUri + '/artists/' + artistId + '/related-artists'
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Fetches a list of Spotify featured playlists (shown, for example, on a Spotify player's "Browse" tab).
     * See [Get a List of Featured Playlists](https://developer.spotify.com/web-api/get-list-featured-playlists/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getFeaturedPlaylists = function(options, callback) {
        var requestData = {
            url: _baseUri + '/browse/featured-playlists'
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Fetches a list of new album releases featured in Spotify (shown, for example, on a Spotify player's "Browse" tab).
     * See [Get a List of New Releases](https://developer.spotify.com/web-api/get-list-new-releases/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getNewReleases = function(options, callback) {
        var requestData = {
            url: _baseUri + '/browse/new-releases'
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Get a list of categories used to tag items in Spotify (on, for example, the Spotify player's "Browse" tab).
     * See [Get a List of Categories](https://developer.spotify.com/web-api/get-list-categories/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getCategories = function(options, callback) {
        var requestData = {
            url: _baseUri + '/browse/categories'
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Get a single category used to tag items in Spotify (on, for example, the Spotify player's "Browse" tab).
     * See [Get a Category](https://developer.spotify.com/web-api/get-category/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} categoryId The id of the category. These can be found with the getCategories function
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getCategory = function(categoryId, options, callback) {
        var requestData = {
            url: _baseUri + '/browse/categories/' + categoryId
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Get a list of Spotify playlists tagged with a particular category.
     * See [Get a Category's Playlists](https://developer.spotify.com/web-api/get-categorys-playlists/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} categoryId The id of the category. These can be found with the getCategories function
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getCategoryPlaylists = function(categoryId, options, callback) {
        var requestData = {
            url: _baseUri + '/browse/categories/' + categoryId + '/playlists'
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Get Spotify catalog information about artists, albums, tracks or playlists that match a keyword string.
     * See [Search for an Item](https://developer.spotify.com/web-api/search-item/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} query The search query
     * @param {Array<string>} types An array of item types to search across.
     * Valid types are: 'album', 'artist', 'playlist', and 'track'.
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.search = function(query, types, options, callback) {
        var requestData = {
            url: _baseUri + '/search/',
            params: {
                q: query,
                type: types.join(',')
            }
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Fetches albums from the Spotify catalog according to a query.
     * See [Search for an Item](https://developer.spotify.com/web-api/search-item/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} query The search query
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.searchAlbums = function(query, options, callback) {
        return this.search(query, ['album'], options, callback);
    };

    /**
     * Fetches artists from the Spotify catalog according to a query.
     * See [Search for an Item](https://developer.spotify.com/web-api/search-item/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} query The search query
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.searchArtists = function(query, options, callback) {
        return this.search(query, ['artist'], options, callback);
    };

    /**
     * Fetches tracks from the Spotify catalog according to a query.
     * See [Search for an Item](https://developer.spotify.com/web-api/search-item/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} query The search query
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.searchTracks = function(query, options, callback) {
        return this.search(query, ['track'], options, callback);
    };

    /**
     * Fetches playlists from the Spotify catalog according to a query.
     * See [Search for an Item](https://developer.spotify.com/web-api/search-item/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} query The search query
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.searchPlaylists = function(query, options, callback) {
        return this.search(query, ['playlist'], options, callback);
    };

    /**
     * Get audio features for a single track identified by its unique Spotify ID.
     * See [Get Audio Features for a Track](https://developer.spotify.com/web-api/get-audio-features/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} trackId The id of the track. If you know the Spotify URI it is easy
     * to find the track id (e.g. spotify:track:<here_is_the_track_id>)
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getAudioFeaturesForTrack = function(trackId, callback) {
        var requestData = {};
        requestData.url = _baseUri + '/audio-features/' + trackId;
        return _checkParamsAndPerformRequest(requestData, {}, callback);
    };

    /**
     * Get audio features for multiple tracks based on their Spotify IDs.
     * See [Get Audio Features for Several Tracks](https://developer.spotify.com/web-api/get-several-audio-features/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Array<string>} trackIds The ids of the tracks. If you know their Spotify URI it is easy
     * to find their track id (e.g. spotify:track:<here_is_the_track_id>)
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getAudioFeaturesForTracks = function(trackIds, callback) {
        var requestData = {
            url: _baseUri + '/audio-features',
            params: { ids: trackIds }
        };
        return _checkParamsAndPerformRequest(requestData, {}, callback);
    };

    /**
     * Get audio analysis for a single track identified by its unique Spotify ID.
     * See [Get Audio Analysis for a Track](https://developer.spotify.com/web-api/get-audio-analysis/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {string} trackId The id of the track. If you know the Spotify URI it is easy
     * to find the track id (e.g. spotify:track:<here_is_the_track_id>)
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getAudioAnalysisForTrack = function(trackId, callback) {
        var requestData = {};
        requestData.url = _baseUri + '/audio-analysis/' + trackId;
        return _checkParamsAndPerformRequest(requestData, {}, callback);
    };

    /**
     * Create a playlist-style listening experience based on seed artists, tracks and genres.
     * See [Get Recommendations Based on Seeds](https://developer.spotify.com/web-api/get-recommendations/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Object} options A JSON object with options that can be passed
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getRecommendations = function(options, callback) {
        var requestData = {
            url: _baseUri + '/recommendations'
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Retrieve a list of available genres seed parameter values for recommendations.
     * See [Available Genre Seeds](https://developer.spotify.com/web-api/get-recommendations/#available-genre-seeds) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getAvailableGenreSeeds = function(callback) {
        var requestData = {
            url: _baseUri + '/recommendations/available-genre-seeds'
        };
        return _checkParamsAndPerformRequest(requestData, {}, callback);
    };

    /**
     * Get information about a user’s available devices.
     * See [Get a User’s Available Devices](https://developer.spotify.com/web-api/get-a-users-available-devices/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getMyDevices = function(callback) {
        var requestData = {
            url: _baseUri + '/me/player/devices'
        };
        return _checkParamsAndPerformRequest(requestData, {}, callback);
    };

    /**
     * Get information about the user’s current playback state, including track, track progress, and active device.
     * See [Get Information About The User’s Current Playback](https://developer.spotify.com/web-api/get-information-about-the-users-current-playback/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Object} options A JSON object with options that can be passed.
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getMyCurrentPlaybackState = function(options, callback) {
        var requestData = {
            url: _baseUri + '/me/player'
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Get the object currently being played on the user’s Spotify account.
     * See [Get the User’s Currently Playing Track](https://developer.spotify.com/web-api/get-the-users-currently-playing-track/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Object} options A JSON object with options that can be passed.
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getMyCurrentPlayingTrack = function(options, callback) {
        var requestData = {
            url: _baseUri + '/me/player/currently-playing'
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Transfer playback to a new device and determine if it should start playing.
     * See [Transfer a User’s Playback](https://developer.spotify.com/web-api/transfer-a-users-playback/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Array<string>} deviceIds A JSON array containing the ID of the device on which playback should be started/transferred.
     * @param {Object} options A JSON object with options that can be passed.
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.transferMyPlayback = function(deviceIds, options, callback) {
        var postData = options || {};
        postData.device_ids = deviceIds;
        var requestData = {
            type: 'PUT',
            url: _baseUri + '/me/player',
            postData: postData
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Start a new context or resume current playback on the user’s active device.
     * See [Start/Resume a User’s Playback](https://developer.spotify.com/web-api/start-a-users-playback/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Object} options A JSON object with options that can be passed.
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.play = function(options, callback) {
        options = options || {};
        var params = 'device_id' in options ? { device_id: options.device_id } : null;
        var postData = {};
        ['context_uri', 'uris', 'offset', 'position_ms'].forEach(function(field) {
            if (field in options) {
                postData[field] = options[field];
            }
        });
        var requestData = {
            type: 'PUT',
            url: _baseUri + '/me/player/play',
            params: params,
            postData: postData
        };

        // need to clear options so it doesn't add all of them to the query params
        var newOptions = typeof options === 'function' ? options : {};
        return _checkParamsAndPerformRequest(requestData, newOptions, callback);
    };

    /**
     * Pause playback on the user’s account.
     * See [Pause a User’s Playback](https://developer.spotify.com/web-api/pause-a-users-playback/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Object} options A JSON object with options that can be passed.
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.pause = function(options, callback) {
        options = options || {};
        var params = 'device_id' in options ? { device_id: options.device_id } : null;
        var requestData = {
            type: 'PUT',
            url: _baseUri + '/me/player/pause',
            params: params
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Skips to next track in the user’s queue.
     * See [Skip User’s Playback To Next Track](https://developer.spotify.com/web-api/skip-users-playback-to-next-track/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Object} options A JSON object with options that can be passed.
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.skipToNext = function(options, callback) {
        options = options || {};
        var params = 'device_id' in options ? { device_id: options.device_id } : null;
        var requestData = {
            type: 'POST',
            url: _baseUri + '/me/player/next',
            params: params
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Skips to previous track in the user’s queue.
     * Note that this will ALWAYS skip to the previous track, regardless of the current track’s progress.
     * Returning to the start of the current track should be performed using `.seek()`
     * See [Skip User’s Playback To Previous Track](https://developer.spotify.com/web-api/skip-users-playback-to-next-track/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {Object} options A JSON object with options that can be passed.
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.skipToPrevious = function(options, callback) {
        options = options || {};
        var params = 'device_id' in options ? { device_id: options.device_id } : null;
        var requestData = {
            type: 'POST',
            url: _baseUri + '/me/player/previous',
            params: params
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Seeks to the given position in the user’s currently playing track.
     * See [Seek To Position In Currently Playing Track](https://developer.spotify.com/web-api/seek-to-position-in-currently-playing-track/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {number} position_ms The position in milliseconds to seek to. Must be a positive number.
     * @param {Object} options A JSON object with options that can be passed.
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.seek = function(position_ms, options, callback) {
        options = options || {};
        var params = {
            position_ms: position_ms
        };
        if ('device_id' in options) {
            params.device_id = options.device_id;
        }
        var requestData = {
            type: 'PUT',
            url: _baseUri + '/me/player/seek',
            params: params
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Set the repeat mode for the user’s playback. Options are repeat-track, repeat-context, and off.
     * See [Set Repeat Mode On User’s Playback](https://developer.spotify.com/web-api/set-repeat-mode-on-users-playback/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {String} state A string set to 'track', 'context' or 'off'.
     * @param {Object} options A JSON object with options that can be passed.
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.setRepeat = function(state, options, callback) {
        options = options || {};
        var params = {
            state: state
        };
        if ('device_id' in options) {
            params.device_id = options.device_id;
        }
        var requestData = {
            type: 'PUT',
            url: _baseUri + '/me/player/repeat',
            params: params
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Set the volume for the user’s current playback device.
     * See [Set Volume For User’s Playback](https://developer.spotify.com/web-api/set-volume-for-users-playback/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {number} volume_percent The volume to set. Must be a value from 0 to 100 inclusive.
     * @param {Object} options A JSON object with options that can be passed.
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.setVolume = function(volume_percent, options, callback) {
        options = options || {};
        var params = {
            volume_percent: volume_percent
        };
        if ('device_id' in options) {
            params.device_id = options.device_id;
        }
        var requestData = {
            type: 'PUT',
            url: _baseUri + '/me/player/volume',
            params: params
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Toggle shuffle on or off for user’s playback.
     * See [Toggle Shuffle For User’s Playback](https://developer.spotify.com/web-api/toggle-shuffle-for-users-playback/) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @param {bool} state Whether or not to shuffle user's playback.
     * @param {Object} options A JSON object with options that can be passed.
     * @param {function(Object,Object)} callback An optional callback that receives 2 parameters. The first
     * one is the error object (null if no error), and the second is the value if the request succeeded.
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.setShuffle = function(state, options, callback) {
        options = options || {};
        var params = {
            state: state
        };
        if ('device_id' in options) {
            params.device_id = options.device_id;
        }
        var requestData = {
            type: 'PUT',
            url: _baseUri + '/me/player/shuffle',
            params: params
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    };

    /**
     * Gets the user's playing queue
     *
     * See [Get the User's Queue](https://developer.spotify.com/documentation/web-api/reference/#/operations/get-queue) on
     * the Spotify Developer site for more information about the endpoint.
     *
     * @return {Object} Null if a callback is provided, a `Promise` object otherwise
     */
    Constr.prototype.getMyCurrentQueue = function(options, callback) {
        var requestData = {
            url: _baseUri + '/me/player/queue'
        };
        return _checkParamsAndPerformRequest(requestData, options, callback);
    }

    /**
     * Gets the access token in use.
     *
     * @return {string} accessToken The access token
     */
    Constr.prototype.getAccessToken = function() {
        return _accessToken;
    };

    /**
     * Sets the access token to be used.
     * See [the Authorization Guide](https://developer.spotify.com/web-api/authorization-guide/) on
     * the Spotify Developer site for more information about obtaining an access token.
     *
     * @param {string} accessToken The access token
     * @return {void}
     */
    Constr.prototype.setAccessToken = function(accessToken) {
        _accessToken = accessToken;
    };

    /**
     * Sets an implementation of Promises/A+ to be used. E.g. Q, when.
     * See [Conformant Implementations](https://github.com/promises-aplus/promises-spec/blob/master/implementations.md)
     * for a list of some available options
     *
     * @param {Object} PromiseImplementation A Promises/A+ valid implementation
     * @throws {Error} If the implementation being set doesn't conform with Promises/A+
     * @return {void}
     */
    Constr.prototype.setPromiseImplementation = function(PromiseImplementation) {
        var valid = false;
        try {
            var p = new PromiseImplementation(function(resolve) {
                resolve();
            });
            if (typeof p.then === 'function' && typeof p.catch === 'function') {
                valid = true;
            }
        } catch (e) {
            console.error(e);
        }
        if (valid) {
            _promiseImplementation = PromiseImplementation;
        } else {
            throw new Error('Unsupported implementation of Promises/A+');
        }
    };

    return Constr;
})();

if (typeof module === 'object' && typeof module.exports === 'object') {
    module.exports = SpotifyWebApi;
}