import {
    each,
    map,
    difference,
    union,
    without
} from 'lodash';
import NProgress from 'nprogress';

import http from '../services/http';
import stub from '../stubs/playlist';
import songStore from './song';

export default {
    stub,

    state: {
        playlists: [],
    },

    init(playlists) {
        this.all = playlists;
        each(this.all, this.objectifySongs);
    },

    /**
     * All playlists of the current user.
     *
     * @return {Array.<Object>}
     */
    get all() {
        return this.state.playlists;
    },

    /**
     * Set all playlists.
     *
     * @param  {Array.<Object>} value
     */
    set all(value) {
        this.state.playlists = value;
    },

    /**
     * Objectify all songs in the playlist.
     * (Initially, a playlist only contain the song IDs).
     *
     * @param  {Object} playlist
     */
    objectifySongs(playlist) {
        playlist.songs = songStore.byIds(playlist.songs);
    },

    /**
     * Get all songs in a playlist.
     *
     * @param {Object}
     *
     * return {Array.<Object>}
     */
    getSongs(playlist) {
        return playlist.songs;
    },

    /**
     * Add a playlist/playlists into the store.
     *
     * @param {Array.<Object>|Object} playlists
     */
    add(playlists) {
        this.all = union(this.all, [].concat(playlists));
    },

    /**
     * Remove a playlist/playlists from the store.
     *
     * @param  {Array.<Object>|Object} playlist
     */
    remove(playlists) {
        this.all = difference(this.all, [].concat(playlists));
    },

    /**
     * Create a new playlist, optionally with its songs.
     *
     * @param  {String}         name  Name of the playlist
     * @param  {Array.<Object>} songs An array of song objects
     * @param  {?Function}      cb
     */
    store(name, songs, cb = null) {
        if (songs.length) {
            // Extract the IDs from the song objects.
            songs = map(songs, 'id');
        }

        NProgress.start();

        http.post('playlist', { name, songs }, response => {
            const playlist = response.data;
            playlist.songs = songs;
            this.objectifySongs(playlist);
            this.add(playlist);

            cb && cb();
        });
    },

    /**
     * Delete a playlist.
     *
     * @param  {Object}     playlist
     * @param  {?Function}  cb
     */
    delete(playlist, cb = null) {
        NProgress.start();

        http.delete(`playlist/${playlist.id}`, {}, () => {
            this.remove(playlist);
            cb && cb();
        });
    },

    /**
     * Add songs into a playlist.
     *
     * @param {Object}          playlist
     * @param {Array.<Object>}  songs
     * @param {?Function}       cb
     */
    addSongs(playlist, songs, cb = null) {
        const count = playlist.songs.length;
        playlist.songs = union(playlist.songs, songs);

        if (count === playlist.songs.length) {
            return;
        }

        http.put(`playlist/${playlist.id}/sync`, { songs: map(playlist.songs, 'id') }, () => cb && cb());
    },

    /**
     * Remove songs from a playlist.
     *
     * @param  {Object}         playlist
     * @param  {Array.<Object>} songs
     * @param  {?Function}      cb
     */
    removeSongs(playlist, songs, cb = null) {
        playlist.songs = difference(playlist.songs, songs);

        http.put(`playlist/${playlist.id}/sync`, { songs: map(playlist.songs, 'id') }, () => cb && cb());
    },

    /**
     * Update a playlist (just change its name).
     *
     * @param  {Object}     playlist
     * @param  {?Function}  cb
     */
    update(playlist, cb = null) {
        NProgress.start();

        http.put(`playlist/${playlist.id}`, { name: playlist.name }, () => cb && cb());
    },
};