/**
 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */

import { Platform } from '@angular/cdk/platform';
import { Inject, Injectable, Optional } from '@angular/core';

import { NxDateAdapter } from './date-adapter';
import { NX_DATE_LOCALE } from './date-token';

// TODO(mmalerba): Remove when we no longer support safari 9.
/** Whether the browser supports the Intl API. */
const SUPPORTS_INTL_API = typeof Intl !== 'undefined';

/** The default month names to use if Intl API is not available. */
const DEFAULT_MONTH_NAMES = {
    long: ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'],
    short: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'],
    narrow: ['J', 'F', 'M', 'A', 'M', 'J', 'J', 'A', 'S', 'O', 'N', 'D'],
};

/** The default date names to use if Intl API is not available. */
const DEFAULT_DATE_NAMES = range(31, i => String(i + 1));

/** The default day of the week names to use if Intl API is not available. */
const DEFAULT_DAY_OF_WEEK_NAMES = {
    long: ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'],
    short: ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'],
    narrow: ['S', 'M', 'T', 'W', 'T', 'F', 'S'],
};

/**
 * Matches strings that have the form of a valid RFC 3339 string
 * (https://tools.ietf.org/html/rfc3339). Note that the string may not actually be a valid date
 * because the regex will match strings an with out of bounds month, date, etc.
 */
const ISO_8601_REGEX = /^\d{4}-\d{2}-\d{2}(?:T\d{2}:\d{2}:\d{2}(?:\.\d+)?(?:Z|(?:\+|-)\d{2}:\d{2})?)?$/;

/** Creates an array and fills it with values. */
function range<T>(length: number, valueFunction: (index: number) => T): T[] {
    const valuesArray = Array(length);
    for (let i = 0; i < length; i++) {
        valuesArray[i] = valueFunction(i);
    }
    return valuesArray;
}

/**
 * Adapts the native JS Date for use with cdk-based components that work with dates.
 * @docs-private
 */
@Injectable()
export class NxNativeDateAdapter extends NxDateAdapter<Date> {
    /** Whether to clamp the date between 1 and 9999 to avoid IE and Edge errors. */
    private readonly _clampDate: boolean;

    /**
     * Whether to use `timeZone: 'utc'` with `Intl.DateTimeFormat` when formatting dates.
     * Without this `Intl.DateTimeFormat` sometimes chooses the wrong timeZone, which can throw off
     * the result. (e.g. in the en-US locale `new Date(1800, 7, 14).toLocaleDateString()`
     * will produce `'8/13/1800'`.
     *
     * TODO(mmalerba): drop this variable. It's not being used in the code right now. We're now
     * getting the string representation of a Date object from it's utc representation. We're keeping
     * it here for sometime, just for precaution, in case we decide to revert some of these changes
     * though.
     */
    useUtcForDisplay = true;

    constructor(@Optional() @Inject(NX_DATE_LOCALE) dateLocale: string | null, platform: Platform) {
        super();
        super.setLocale(dateLocale || 'en-US');

        // IE does its own time zone correction, so we disable this on IE.
        this.useUtcForDisplay = !platform.TRIDENT;
        this._clampDate = platform.TRIDENT || platform.EDGE;
    }

    getYear(date: Date): number {
        return date.getFullYear();
    }

    getMonth(date: Date): number {
        return date.getMonth();
    }

    getDate(date: Date): number {
        return date.getDate();
    }

    getDayOfWeek(date: Date): number {
        return date.getDay();
    }

    getMonthNames(style: 'long' | 'short' | 'narrow'): string[] {
        if (SUPPORTS_INTL_API) {
            const dtf = new Intl.DateTimeFormat(this.locale, { month: style, timeZone: 'utc' });
            return range(12, i => this._stripDirectionalityCharacters(this._format(dtf, new Date(2017, i, 1))));
        }
        return DEFAULT_MONTH_NAMES[style];
    }

    getDateNames(): string[] {
        if (SUPPORTS_INTL_API) {
            const dtf = new Intl.DateTimeFormat(this.locale, { day: 'numeric', timeZone: 'utc' });
            return range(31, i => this._stripDirectionalityCharacters(this._format(dtf, new Date(2017, 0, i + 1))));
        }
        return DEFAULT_DATE_NAMES;
    }

    getDayOfWeekNames(style: 'long' | 'short' | 'narrow'): string[] {
        if (SUPPORTS_INTL_API) {
            const dtf = new Intl.DateTimeFormat(this.locale, { weekday: style, timeZone: 'utc' });
            return range(7, i => this._stripDirectionalityCharacters(this._format(dtf, new Date(2017, 0, i + 1))));
        }
        return DEFAULT_DAY_OF_WEEK_NAMES[style];
    }

    getYearName(date: Date): string {
        if (SUPPORTS_INTL_API) {
            const dtf = new Intl.DateTimeFormat(this.locale, { year: 'numeric', timeZone: 'utc' });
            return this._stripDirectionalityCharacters(this._format(dtf, date));
        }
        return String(this.getYear(date));
    }

    getFirstDayOfWeek(): number {
        // We can't tell using native JS Date what the first day of the week is, we default to Sunday.
        return 0;
    }

    getNumDaysInMonth(date: Date): number {
        return this.getDate(this._createDateWithOverflow(this.getYear(date), this.getMonth(date) + 1, 0));
    }

    clone(date: Date): Date {
        return this.createDate(this.getYear(date), this.getMonth(date), this.getDate(date));
    }

    createDate(year: number, month: number, date: number): Date {
        // Check for invalid month and date (except upper bound on date which we have to check after
        // creating the Date).
        if (month < 0 || month > 11) {
            throw Error(`Invalid month index "${month}". Month index has to be between 0 and 11.`);
        }

        if (date < 1) {
            throw Error(`Invalid date "${date}". Date has to be greater than 0.`);
        }

        const result = this._createDateWithOverflow(year, month, date);
        // Check that the date wasn't above the upper bound for the month, causing the month to overflow
        if (result.getMonth() !== month) {
            throw Error(`Invalid date "${date}" for month with index "${month}".`);
        }

        return result;
    }

    today(): Date {
        return new Date();
    }

    parse(value: any): Date | null {
        // We have no way using the native JS Date to set the parse format or locale, so we ignore these
        // parameters.
        if (typeof value === 'number') {
            return new Date(value);
        }
        return value ? new Date(Date.parse(value)) : null;
    }

    format(date: Date, displayFormat: object): string {
        if (!this.isValid(date)) {
            throw Error('NxNativeDateAdapter: Cannot format invalid date.');
        }

        if (SUPPORTS_INTL_API) {
            // On IE and Edge the i18n API will throw a hard error that can crash the entire app
            // if we attempt to format a date whose year is less than 1 or greater than 9999.
            if (this._clampDate && (date.getFullYear() < 1 || date.getFullYear() > 9999)) {
                date = this.clone(date);
                date.setFullYear(Math.max(1, Math.min(9999, date.getFullYear())));
            }

            displayFormat = { ...displayFormat, timeZone: 'utc' };

            const dtf = new Intl.DateTimeFormat(this.locale, displayFormat);
            return this._stripDirectionalityCharacters(this._format(dtf, date));
        }
        return this._stripDirectionalityCharacters(date.toDateString());
    }

    addCalendarYears(date: Date, years: number): Date {
        return this.addCalendarMonths(date, years * 12);
    }

    addCalendarMonths(date: Date, months: number): Date {
        let newDate = this._createDateWithOverflow(this.getYear(date), this.getMonth(date) + months, this.getDate(date));

        // It's possible to wind up in the wrong month if the original month has more days than the new
        // month. In this case we want to go to the last day of the desired month.
        // Note: the additional + 12 % 12 ensures we end up with a positive number, since JS % doesn't
        // guarantee this.
        if (this.getMonth(newDate) !== (((this.getMonth(date) + months) % 12) + 12) % 12) {
            newDate = this._createDateWithOverflow(this.getYear(newDate), this.getMonth(newDate), 0);
        }

        return newDate;
    }

    addCalendarDays(date: Date, days: number): Date {
        return this._createDateWithOverflow(this.getYear(date), this.getMonth(date), this.getDate(date) + days);
    }

    toIso8601(date: Date): string {
        return [date.getUTCFullYear(), this._2digit(date.getUTCMonth() + 1), this._2digit(date.getUTCDate())].join('-');
    }

    /**
     * Returns the given value if given a valid Date or null. Deserializes valid ISO 8601 strings
     * (https://www.ietf.org/rfc/rfc3339.txt) into valid Dates and empty string into null. Returns an
     * invalid date for all other values.
     */
    deserialize(value: any): Date | null {
        if (typeof value === 'string') {
            if (!value) {
                return null;
            }
            // The `Date` constructor accepts formats other than ISO 8601, so we need to make sure the
            // string is the right format first.
            if (ISO_8601_REGEX.test(value)) {
                const date = new Date(value);
                if (this.isValid(date)) {
                    return date;
                }
            }
        }
        return super.deserialize(value);
    }

    isDateInstance(obj: any) {
        return obj instanceof Date;
    }

    isValid(date: Date) {
        return !isNaN(date.getTime());
    }

    invalid(): Date {
        return new Date(NaN);
    }

    /** Creates a date but allows the month and date to overflow. */
    private _createDateWithOverflow(year: number, month: number, date: number) {
        const result = new Date(year, month, date);

        // We need to correct for the fact that JS native Date treats years in range [0, 99] as
        // abbreviations for 19xx.
        if (year >= 0 && year < 100) {
            result.setFullYear(this.getYear(result) - 1900);
        }
        return result;
    }

    /**
     * Pads a number to make it two digits.
     * @param n The number to pad.
     * @returns The padded number.
     */
    private _2digit(n: number) {
        return ('00' + n).slice(-2);
    }

    /**
     * Strip out unicode LTR and RTL characters. Edge and IE insert these into formatted dates while
     * other browsers do not. We remove them to make output consistent and because they interfere with
     * date parsing.
     * @param str The string to strip direction characters from.
     * @returns The stripped string.
     */
    private _stripDirectionalityCharacters(str: string) {
        return str.replace(/[\u200e\u200f]/g, '');
    }

    /**
     * When converting Date object to string, javascript built-in functions may return wrong
     * results because it applies its internal DST rules. The DST rules around the world change
     * very frequently, and the current valid rule is not always valid in previous years though.
     * We work around this problem building a new Date object which has its internal UTC
     * representation with the local date and time.
     * @param dtf Intl.DateTimeFormat object, containg the desired string format. It must have timeZone set to 'utc' to work fine.
     * @param date Date from which we want to get the string representation according to dtf.
     * @returns A Date object with its UTC representation based on the passed in date info.
     */
    private _format(dtf: Intl.DateTimeFormat, date: Date) {
        const d = new Date(
            Date.UTC(date.getFullYear(), date.getMonth(), date.getDate(), date.getHours(), date.getMinutes(), date.getSeconds(), date.getMilliseconds()),
        );
        return dtf.format(d);
    }
}
