package eu.kanade.tachiyomi.source.online

import eu.kanade.tachiyomi.network.GET
import eu.kanade.tachiyomi.network.NetworkHelper
import eu.kanade.tachiyomi.network.asObservableSuccess
import eu.kanade.tachiyomi.network.awaitSuccess
import eu.kanade.tachiyomi.network.newCachelessCallWithProgress
import eu.kanade.tachiyomi.source.CatalogueSource
import eu.kanade.tachiyomi.source.model.FilterList
import eu.kanade.tachiyomi.source.model.MangasPage
import eu.kanade.tachiyomi.source.model.Page
import eu.kanade.tachiyomi.source.model.SChapter
import eu.kanade.tachiyomi.source.model.SManga
import okhttp3.Headers
import okhttp3.OkHttpClient
import okhttp3.Request
import okhttp3.Response
import rx.Observable
import tachiyomi.core.common.util.lang.awaitSingle
import uy.kohesive.injekt.injectLazy
import java.net.URI
import java.net.URISyntaxException
import java.security.MessageDigest

/**
 * A simple implementation for sources from a website.
 */
@Suppress("unused")
abstract class HttpSource : CatalogueSource {

    /**
     * Network service.
     */
    protected val network: NetworkHelper by injectLazy()

    /**
     * Base url of the website without the trailing slash, like: http://mysite.com
     */
    abstract val baseUrl: String

    /**
     * Version id used to generate the source id. If the site completely changes and urls are
     * incompatible, you may increase this value and it'll be considered as a new source.
     */
    open val versionId = 1

    /**
     * ID of the source. By default it uses a generated id using the first 16 characters (64 bits)
     * of the MD5 of the string `"${name.lowercase()}/$lang/$versionId"`.
     *
     * The ID is generated by the [generateId] function, which can be reused if needed
     * to generate outdated IDs for cases where the source name or language needs to
     * be changed but migrations can be avoided.
     *
     * Note: the generated ID sets the sign bit to `0`.
     */
    override val id by lazy { generateId(name, lang, versionId) }

    /**
     * Headers used for requests.
     */
    val headers: Headers by lazy { headersBuilder().build() }

    /**
     * Default network client for doing requests.
     */
    open val client: OkHttpClient
        get() = network.client

    /**
     * Generates a unique ID for the source based on the provided [name], [lang] and
     * [versionId]. It will use the first 16 characters (64 bits) of the MD5 of the string
     * `"${name.lowercase()}/$lang/$versionId"`.
     *
     * Note: the generated ID sets the sign bit to `0`.
     *
     * Can be used to generate outdated IDs, such as when the source name or language
     * needs to be changed but migrations can be avoided.
     *
     * @since extensions-lib 1.5
     * @param name [String] the name of the source
     * @param lang [String] the language of the source
     * @param versionId [Int] the version ID of the source
     * @return a unique ID for the source
     */
    @Suppress("MemberVisibilityCanBePrivate")
    protected fun generateId(name: String, lang: String, versionId: Int): Long {
        val key = "${name.lowercase()}/$lang/$versionId"
        val bytes = MessageDigest.getInstance("MD5").digest(key.toByteArray())
        return (0..7).map { bytes[it].toLong() and 0xff shl 8 * (7 - it) }.reduce(Long::or) and Long.MAX_VALUE
    }

    /**
     * Headers builder for requests. Implementations can override this method for custom headers.
     */
    protected open fun headersBuilder() = Headers.Builder().apply {
        add("User-Agent", network.defaultUserAgentProvider())
    }

    /**
     * Visible name of the source.
     */
    override fun toString() = "$name (${lang.uppercase()})"

    /**
     * Returns an observable containing a page with a list of manga. Normally it's not needed to
     * override this method.
     *
     * @param page the page number to retrieve.
     */
    @Deprecated("Use the non-RxJava API instead", replaceWith = ReplaceWith("getPopularManga"))
    override fun fetchPopularManga(page: Int): Observable<MangasPage> {
        return client.newCall(popularMangaRequest(page))
            .asObservableSuccess()
            .map { response ->
                popularMangaParse(response)
            }
    }

    /**
     * Returns the request for the popular manga given the page.
     *
     * @param page the page number to retrieve.
     */
    protected abstract fun popularMangaRequest(page: Int): Request

    /**
     * Parses the response from the site and returns a [MangasPage] object.
     *
     * @param response the response from the site.
     */
    protected abstract fun popularMangaParse(response: Response): MangasPage

    /**
     * Returns an observable containing a page with a list of manga. Normally it's not needed to
     * override this method.
     *
     * @param page the page number to retrieve.
     * @param query the search query.
     * @param filters the list of filters to apply.
     */
    @Deprecated("Use the non-RxJava API instead", replaceWith = ReplaceWith("getSearchManga"))
    override fun fetchSearchManga(
        page: Int,
        query: String,
        filters: FilterList,
    ): Observable<MangasPage> {
        return Observable.defer {
            try {
                client.newCall(searchMangaRequest(page, query, filters)).asObservableSuccess()
            } catch (e: NoClassDefFoundError) {
                // RxJava doesn't handle Errors, which tends to happen during global searches
                // if an old extension using non-existent classes is still around
                throw RuntimeException(e)
            }
        }
            .map { response ->
                searchMangaParse(response)
            }
    }

    /**
     * Returns the request for the search manga given the page.
     *
     * @param page the page number to retrieve.
     * @param query the search query.
     * @param filters the list of filters to apply.
     */
    protected abstract fun searchMangaRequest(
        page: Int,
        query: String,
        filters: FilterList,
    ): Request

    /**
     * Parses the response from the site and returns a [MangasPage] object.
     *
     * @param response the response from the site.
     */
    protected abstract fun searchMangaParse(response: Response): MangasPage

    /**
     * Returns an observable containing a page with a list of latest manga updates.
     *
     * @param page the page number to retrieve.
     */
    @Deprecated("Use the non-RxJava API instead", replaceWith = ReplaceWith("getLatestUpdates"))
    override fun fetchLatestUpdates(page: Int): Observable<MangasPage> {
        return client.newCall(latestUpdatesRequest(page))
            .asObservableSuccess()
            .map { response ->
                latestUpdatesParse(response)
            }
    }

    /**
     * Returns the request for latest manga given the page.
     *
     * @param page the page number to retrieve.
     */
    protected abstract fun latestUpdatesRequest(page: Int): Request

    /**
     * Parses the response from the site and returns a [MangasPage] object.
     *
     * @param response the response from the site.
     */
    protected abstract fun latestUpdatesParse(response: Response): MangasPage

    /**
     * Get the updated details for a manga.
     * Normally it's not needed to override this method.
     *
     * @param manga the manga to update.
     * @return the updated manga.
     */
    @Suppress("DEPRECATION")
    override suspend fun getMangaDetails(manga: SManga): SManga {
        return fetchMangaDetails(manga).awaitSingle()
    }

    @Deprecated("Use the non-RxJava API instead", replaceWith = ReplaceWith("getMangaDetails"))
    override fun fetchMangaDetails(manga: SManga): Observable<SManga> {
        return client.newCall(mangaDetailsRequest(manga))
            .asObservableSuccess()
            .map { response ->
                mangaDetailsParse(response).apply { initialized = true }
            }
    }

    /**
     * Returns the request for the details of a manga. Override only if it's needed to change the
     * url, send different headers or request method like POST.
     *
     * @param manga the manga to be updated.
     */
    open fun mangaDetailsRequest(manga: SManga): Request {
        return GET(baseUrl + manga.url, headers)
    }

    /**
     * Parses the response from the site and returns the details of a manga.
     *
     * @param response the response from the site.
     */
    protected abstract fun mangaDetailsParse(response: Response): SManga

    /**
     * Get all the available chapters for a manga.
     * Normally it's not needed to override this method.
     *
     * @param manga the manga to update.
     * @return the chapters for the manga.
     */
    @Suppress("DEPRECATION")
    override suspend fun getChapterList(manga: SManga): List<SChapter> {
        return fetchChapterList(manga).awaitSingle()
    }

    @Deprecated("Use the non-RxJava API instead", replaceWith = ReplaceWith("getChapterList"))
    override fun fetchChapterList(manga: SManga): Observable<List<SChapter>> {
        return client.newCall(chapterListRequest(manga))
            .asObservableSuccess()
            .map { response ->
                chapterListParse(response)
            }
    }

    /**
     * Returns the request for updating the chapter list. Override only if it's needed to override
     * the url, send different headers or request method like POST.
     *
     * @param manga the manga to look for chapters.
     */
    protected open fun chapterListRequest(manga: SManga): Request {
        return GET(baseUrl + manga.url, headers)
    }

    /**
     * Parses the response from the site and returns a list of chapters.
     *
     * @param response the response from the site.
     */
    protected abstract fun chapterListParse(response: Response): List<SChapter>

    /**
     * Parses the response from the site and returns a SChapter Object.
     *
     * @param response the response from the site.
     */
    protected abstract fun chapterPageParse(response: Response): SChapter

    /**
     * Get the list of pages a chapter has. Pages should be returned
     * in the expected order; the index is ignored.
     *
     * @param chapter the chapter.
     * @return the pages for the chapter.
     */
    @Suppress("DEPRECATION")
    override suspend fun getPageList(chapter: SChapter): List<Page> {
        return fetchPageList(chapter).awaitSingle()
    }

    @Deprecated("Use the non-RxJava API instead", replaceWith = ReplaceWith("getPageList"))
    override fun fetchPageList(chapter: SChapter): Observable<List<Page>> {
        return client.newCall(pageListRequest(chapter))
            .asObservableSuccess()
            .map { response ->
                pageListParse(response)
            }
    }

    /**
     * Returns the request for getting the page list. Override only if it's needed to override the
     * url, send different headers or request method like POST.
     *
     * @param chapter the chapter whose page list has to be fetched.
     */
    protected open fun pageListRequest(chapter: SChapter): Request {
        return GET(baseUrl + chapter.url, headers)
    }

    /**
     * Parses the response from the site and returns a list of pages.
     *
     * @param response the response from the site.
     */
    protected abstract fun pageListParse(response: Response): List<Page>

    /**
     * Returns an observable with the page containing the source url of the image. If there's any
     * error, it will return null instead of throwing an exception.
     *
     * @since extensions-lib 1.5
     * @param page the page whose source image has to be fetched.
     */
    @Suppress("DEPRECATION")
    open suspend fun getImageUrl(page: Page): String {
        return fetchImageUrl(page).awaitSingle()
    }

    @Deprecated("Use the non-RxJava API instead", replaceWith = ReplaceWith("getImageUrl"))
    open fun fetchImageUrl(page: Page): Observable<String> {
        return client.newCall(imageUrlRequest(page))
            .asObservableSuccess()
            .map { imageUrlParse(it) }
    }

    /**
     * Returns the request for getting the url to the source image. Override only if it's needed to
     * override the url, send different headers or request method like POST.
     *
     * @param page the chapter whose page list has to be fetched
     */
    protected open fun imageUrlRequest(page: Page): Request {
        return GET(page.url, headers)
    }

    /**
     * Parses the response from the site and returns the absolute url to the source image.
     *
     * @param response the response from the site.
     */
    protected abstract fun imageUrlParse(response: Response): String

    /**
     * Returns the response of the source image.
     * Typically does not need to be overridden.
     *
     * @since extensions-lib 1.5
     * @param page the page whose source image has to be downloaded.
     */
    open suspend fun getImage(page: Page): Response {
        return client.newCachelessCallWithProgress(imageRequest(page), page)
            .awaitSuccess()
    }

    /**
     * Returns the request for getting the source image. Override only if it's needed to override
     * the url, send different headers or request method like POST.
     *
     * @param page the chapter whose page list has to be fetched
     */
    protected open fun imageRequest(page: Page): Request {
        return GET(page.imageUrl!!, headers)
    }

    /**
     * Assigns the url of the chapter without the scheme and domain. It saves some redundancy from
     * database and the urls could still work after a domain change.
     *
     * @param url the full url to the chapter.
     */
    fun SChapter.setUrlWithoutDomain(url: String) {
        this.url = getUrlWithoutDomain(url)
    }

    /**
     * Assigns the url of the manga without the scheme and domain. It saves some redundancy from
     * database and the urls could still work after a domain change.
     *
     * @param url the full url to the manga.
     */
    fun SManga.setUrlWithoutDomain(url: String) {
        this.url = getUrlWithoutDomain(url)
    }

    /**
     * Returns the url of the given string without the scheme and domain.
     *
     * @param orig the full url.
     */
    private fun getUrlWithoutDomain(orig: String): String {
        return try {
            val uri = URI(orig.replace(" ", "%20"))
            var out = uri.path
            if (uri.query != null) {
                out += "?" + uri.query
            }
            if (uri.fragment != null) {
                out += "#" + uri.fragment
            }
            out
        } catch (e: URISyntaxException) {
            orig
        }
    }

    /**
     * Returns the url of the provided manga
     *
     * @since extensions-lib 1.4
     * @param manga the manga
     * @return url of the manga
     */
    open fun getMangaUrl(manga: SManga): String {
        return mangaDetailsRequest(manga).url.toString()
    }

    /**
     * Returns the url of the provided chapter
     *
     * @since extensions-lib 1.4
     * @param chapter the chapter
     * @return url of the chapter
     */
    open fun getChapterUrl(chapter: SChapter): String {
        return pageListRequest(chapter).url.toString()
    }

    /**
     * Called before inserting a new chapter into database. Use it if you need to override chapter
     * fields, like the title or the chapter number. Do not change anything to [manga].
     *
     * @param chapter the chapter to be added.
     * @param manga the manga of the chapter.
     */
    open fun prepareNewChapter(chapter: SChapter, manga: SManga) {}

    /**
     * Returns the list of filters for the source.
     */
    override fun getFilterList() = FilterList()
}
