import Vue from 'vue';
import _ from 'lodash';

import http from '../services/http';
import utils from '../services/utils';
import stub from '../stubs/song';
import favoriteStore from './favorite';
import userStore from './user';
import albumStore from './album';
import artistStore from './artist';

export default {
    stub,
    albums: [],
    cache: {},

    state: {
        /**
         * All songs in the store
         *
         * @type {Array}
         */
        songs: [stub],

        /**
         * The recently played songs **in the current session**
         *
         * @type {Array}
         */
        recent: [],
    },

    /**
     * Init the store.
     *
     * @param  {Array.<Object>} albums The array of albums to extract our songs from
     */
    init(albums) {
        // Iterate through the albums. With each, add its songs into our master song list.
        this.state.songs = albums.reduce((songs, album) => {
            // While doing so, we populate some other information into the songs as well.
            album.songs.forEach(song => {
                song.fmtLength = utils.secondsToHis(song.length);

                // Manually set these additional properties to be reactive
                Vue.set(song, 'playCount', 0);
                Vue.set(song, 'album', album);
                Vue.set(song, 'liked', false);
                Vue.set(song, 'lyrics', null);
                Vue.set(song, 'playbackState', 'stopped');

                // Cache the song, so that byId() is faster
                this.cache[song.id] = song;
            });

            return songs.concat(album.songs);
        }, []);
    },

    /**
     * Initializes the interaction (like/play count) information.
     *
     * @param  {Array.<Object>} interactions The array of interactions of the current user
     */
    initInteractions(interactions) {
        favoriteStore.clear();

        interactions.forEach(interaction => {
            var song = this.byId(interaction.song_id);

            if (!song) {
                return;
            }

            song.liked = interaction.liked;
            song.playCount = interaction.play_count;
            song.album.playCount += song.playCount;
            song.album.artist.playCount += song.playCount;

            if (song.liked) {
                favoriteStore.add(song);
            }
        });
    },

    /**
     * Get the total duration of some songs.
     *
     * @param {Array.<Object>}  songs
     * @param {Boolean}         toHis Whether to convert the duration into H:i:s format
     *
     * @return {Float|String}
     */
    getLength(songs, toHis) {
        var duration = songs.reduce((length, song) => length + song.length, 0);

        if (toHis) {
            return utils.secondsToHis(duration);
        }

        return duration;
    },

    /**
     * Get all songs.
     *
     * @return {Array.<Object>}
     */
    all() {
        return this.state.songs;
    },

    /**
     * Get a song by its ID.
     *
     * @param  {String} id
     *
     * @return {Object}
     */
    byId(id) {
        return this.cache[id];
    },

    /**
     * Get songs by their IDs.
     *
     * @param  {Array.<String>} ids
     *
     * @return {Array.<Object>}
     */
    byIds(ids) {
        return ids.map(id => this.byId(id));
    },

    /**
     * Increase a play count for a song.
     *
     * @param {Object} song
     * @param {?Function} cb
     */
    registerPlay(song, cb = null) {
        var oldCount = song.playCount;

        http.post('interaction/play', { song: song.id }, response => {
            // Use the data from the server to make sure we don't miss a play from another device.
            song.playCount = response.data.play_count;
            song.album.playCount += song.playCount - oldCount;
            song.album.artist.playCount += song.playCount - oldCount;

            if (cb) {
                cb();
            }
        });
    },

    /**
     * Add a song into the "recently played" list.
     *
     * @param {Object}
     */
    addRecent(song) {
        // First we make sure that there's no duplicate.
        this.state.recent = _.without(this.state.recent, song);

        // Then we prepend the song into the list.
        this.state.recent.unshift(song);
    },

    /**
     * Get extra song information (lyrics, artist info, album info).
     *
     * @param  {Object}     song
     * @param  {?Function}  cb
     */
    getInfo(song, cb = null) {
        // Check if the song's info has been retrieved before.
        if (song.infoRetrieved) {
            if (cb) {
                cb();
            }

            return;
        }

        http.get(`${song.id}/info`, response => {
            var data = response.data;

            song.lyrics = data.lyrics;

            // If the artist image is not in a nice form, don't use it.
            if (data.artist_info && typeof data.artist_info.image !== 'string') {
                data.artist_info.image = null;
            }

            song.album.artist.info = data.artist_info;

            // Set the artist image on the client side to the retrieved image from server.
            if (data.artist_info.image) {
                song.album.artist.image = data.artist_info.image;
            }

            // Convert the duration into i:s
            if (data.album_info && data.album_info.tracks) {
                data.album_info.tracks.forEach(track => track.fmtLength = utils.secondsToHis(track.length));
            }

            // If the album cover is not in a nice form, don't use it.
            if (data.album_info && typeof data.album_info.image !== 'string') {
                data.album_info.image = null;
            }

            song.album.info = data.album_info;

            // Set the album on the client side to the retrieved image from server.
            if (data.album_info.cover) {
                song.album.cover = data.album_info.cover;
            }

            song.infoRetrieved = true;

            if (cb) {
                cb();
            }
        });
    },

    /**
     * Scrobble a song (using Last.fm).
     *
     * @param  {Object}     song
     * @param  {?Function}  cb
     */
    scrobble(song, cb = null) {
        if (!window.useLastfm || !userStore.current().preferences.lastfm_session_key) {
            return;
        }

        http.post(`${song.id}/scrobble/${song.playStartTime}`, () => {
            if (cb) {
                cb();
            }
        });
    },

    /**
     * Update song data.
     *
     * @param  {Array.<Object>} songs     An array of song
     * @param  {Object}         data
     * @param  {?Function}      successCb
     * @param  {?Function}      errorCb
     */
    update(songs, data, successCb = null, errorCb = null) {
        if (!userStore.current().is_admin) {
            return;
        }

        http.put('songs', {
            data,
            songs: _.pluck(songs, 'id'),
        }, response => {
            response.data.forEach(song => {
               this.syncUpdatedSong(song);
            });

            if (successCb) {
                successCb();
            }
        }, () => {
            if (errorCb) {
                errorCb();
            }
        });
    },

    /**
     * Sync an updated song into our current library.
     *
     * This is one of the most ugly functions I've written, if not the worst itself.
     * Sorry, future me.
     * Sorry guys.
     * Forgive me.
     *
     * @param  {Object} updatedSong The updated song, with albums and whatnot.
     *
     * @return {?Object}             The updated song.
     */
    syncUpdatedSong(updatedSong) {
        // Cases:
        // 1. Album doesn't change (and then, artist doesn't either)
        // 2. Album changes (note that a new album might have been created) and
        //      2.a. Artist remains the same.
        //      2.b. Artist changes as well. Note that an artist might have been created.

        // Find the original song,
        var originalSong = this.byId(updatedSong.id);

        if (!originalSong) {
            return;
        }

        // and keep track of original album/artist.
        var originalAlbumId = originalSong.album.id;
        var originalArtistId = originalSong.album.artist.id;

        // First, we update the title and the lyrics
        originalSong.title = updatedSong.title;
        originalSong.lyrics = updatedSong.lyrics;

        if (updatedSong.album.id === originalAlbumId) { // case 1
            // Nothing to do
        } else { // case 2
            // First, remove it from its old album
            albumStore.removeSongsFromAlbum(originalSong.album, originalSong);

            var existingAlbum = albumStore.byId(updatedSong.album.id);
            var newAlbumCreated = !existingAlbum;

            if (!newAlbumCreated) {
                // The song changed to an existing album. We now add it to such album.
                albumStore.addSongsIntoAlbum(existingAlbum, originalSong);
            } else {
                // A new album was created. We:
                // - Add the new album into our collection
                // - Add the song into it
                albumStore.addSongsIntoAlbum(updatedSong.album, originalSong);
                albumStore.append(updatedSong.album);
            }

            if (updatedSong.album.artist.id === originalArtistId) { // case 2.a
                // Same artist, but what if the album is new?
                if (newAlbumCreated) {
                    artistStore.addAlbumsIntoArtist(artistStore.byId(originalArtistId), updatedSong.album);
                }
            } else { // case 2.b
                // The artist changes.
                var existingArtist = artistStore.byId(updatedSong.album.artist.id);

                if (!existingArtist) {
                    // New artist created. We:
                    // - Add the album into it, because now it MUST BE a new album
                    // (there's no "new artist with existing album" in our system).
                    // - Add the new artist into our collection
                    artistStore.addAlbumsIntoArtist(updatedSong.album.artist, updatedSong.album);
                    artistStore.append(updatedSong.album.artist);
                }
            }

            // As a last step, we purify our library of empty albums/artists.
            if (albumStore.isAlbumEmpty(albumStore.byId(originalAlbumId))) {
                albumStore.remove(albumStore.byId(originalAlbumId));
            }

            if (artistStore.isArtistEmpty(artistStore.byId(originalArtistId))) {
                artistStore.remove(artistStore.byId(originalArtistId));
            }

            // Now we make sure the next call to info() get the refreshed, correct info.
            originalSong.infoRetrieved = false;
        }

        return originalSong;
    },

    /**
     * Get the last n recently played songs.
     *
     * @param  {Number} n
     *
     * @return {Array.<Object>}
     */
    getRecent(n = 10) {
        return _.take(this.state.recent, n);
    },

    /**
     * Get top n most-played songs.
     *
     * @param  {Number} n
     *
     * @return {Array.<Object>}
     */
    getMostPlayed(n = 10) {
        var songs = _.take(_.sortByOrder(this.state.songs, 'playCount', 'desc'), n);

        // Remove those with playCount=0
        _.remove(songs, song => !song.playCount);

        return songs;
    },
};