/**
 * This implements the webplayer reducers.
 */

// NPM imports
import Immutable from "immutable";

// Local imports
import { createReducer } from "../utils";

// Models
import { stateRecord } from "../models/webplayer";

// Actions
import {
    PLAY_PAUSE,
    STOP_PLAYBACK,
    SET_PLAYLIST,
    PUSH_SONG,
    POP_SONG,
    JUMP_TO_SONG,
    PLAY_PREVIOUS,
    PLAY_NEXT,
    TOGGLE_RANDOM,
    TOGGLE_REPEAT,
    TOGGLE_MUTE,
    SET_VOLUME,
    INVALIDATE_STORE } from "../actions";


/**
 * Initial state
 */

var initialState = new stateRecord();


/**
 * Helper functions
 */

/**
 * Stop playback in reducer helper.
 *
 * @param   state   Current state to update.
 */
function stopPlayback(state) {
    return (
        state
        .set("isPlaying", false)
        .set("currentIndex", 0)
        .set("playlist", new Immutable.List())
    );
}


/**
 * Reducers
 */

export default createReducer(initialState, {
    [PLAY_PAUSE]: (state, payload) => {
        // Force play or pause
        return state.set("isPlaying", payload.isPlaying);
    },
    [STOP_PLAYBACK]: (state) => {
        // Clear the playlist
        return stopPlayback(state);
    },
    [SET_PLAYLIST]: (state, payload) => {
        // Set current playlist, reset playlist index
        return (
            state
            .set("playlist", new Immutable.List(payload.playlist))
            .set("currentIndex", 0)
        );
    },
    [PUSH_SONG]: (state, payload) => {
        // Push song to playlist
        const newPlaylist = state.get("playlist").insert(payload.index, payload.song);
        return state.set("playlist", newPlaylist);
    },
    [POP_SONG]: (state, payload) => {
        // Pop song from playlist
        return state.deleteIn(["playlist", payload.index]);
    },
    [JUMP_TO_SONG]: (state, payload) => {
        // Set current index
        const newCurrentIndex = state.get("playlist").findKey(x => x == payload.song);
        return state.set("currentIndex", newCurrentIndex);
    },
    [PLAY_PREVIOUS]: (state) => {
        const newIndex = state.get("currentIndex") - 1;
        if (newIndex < 0) {
            // If there is an overlow on the left of the playlist, just stop
            // playback
            return stopPlayback(state);
        } else {
            return state.set("currentIndex", newIndex);
        }
    },
    [PLAY_NEXT]: (state) => {
        const newIndex = state.get("currentIndex") + 1;
        if (newIndex > state.get("playlist").size) {
            // If there is an overflow, just stop playback
            return stopPlayback(state);
        } else {
            // Else, play next item
            return state.set("currentIndex", newIndex);
        }
    },
    [TOGGLE_RANDOM]: (state) => {
        return state.set("isRandom", !state.get("isRandom"));
    },
    [TOGGLE_REPEAT]: (state) => {
        return state.set("isRepeat", !state.get("isRepeat"));
    },
    [TOGGLE_MUTE]: (state) => {
        return state.set("isMute", !state.get("isMute"));
    },
    [SET_VOLUME]: (state, payload) => {
        return state.set("volume", payload.volume);
    },
    [INVALIDATE_STORE]: () => {
        return new stateRecord();
    },
});