// @flow

import {
    createStartAudioOnlyEvent,
    createStartMutedConfigurationEvent,
    createSyncTrackStateEvent,
    createTrackMutedEvent,
    sendAnalytics
} from '../../analytics';
import { APP_STATE_CHANGED } from '../../mobile/background';

import { SET_AUDIO_ONLY, setAudioOnly } from '../audio-only';
import { isRoomValid, SET_ROOM } from '../conference';
import JitsiMeetJS from '../lib-jitsi-meet';
import { MiddlewareRegistry } from '../redux';
import { getPropertyValue } from '../settings';
import { setTrackMuted, TRACK_ADDED } from '../tracks';

import { setAudioMuted, setCameraFacingMode, setVideoMuted } from './actions';
import { CAMERA_FACING_MODE, VIDEO_MUTISM_AUTHORITY } from './constants';
import logger from './logger';
import {
    _AUDIO_INITIAL_MEDIA_STATE,
    _VIDEO_INITIAL_MEDIA_STATE
} from './reducer';

/**
 * Implements the entry point of the middleware of the feature base/media.
 *
 * @param {Store} store - The redux store.
 * @returns {Function}
 */
MiddlewareRegistry.register(store => next => action => {
    switch (action.type) {
    case APP_STATE_CHANGED:
        return _appStateChanged(store, next, action);

    case SET_AUDIO_ONLY:
        return _setAudioOnly(store, next, action);

    case SET_ROOM:
        return _setRoom(store, next, action);

    case TRACK_ADDED: {
        const result = next(action);
        const { track } = action;

        track.local && _syncTrackMutedState(store, track);

        return result;
    }
    }

    return next(action);
});

/**
 * Adjusts the video muted state based on the app state.
 *
 * @param {Store} store - The redux store in which the specified {@code action}
 * is being dispatched.
 * @param {Dispatch} next - The redux {@code dispatch} function to dispatch the
 * specified {@code action} to the specified {@code store}.
 * @param {Action} action - The redux action {@code APP_STATE_CHANGED} which is
 * being dispatched in the specified {@code store}.
 * @private
 * @returns {Object} The value returned by {@code next(action)}.
 */
function _appStateChanged({ dispatch }, next, action) {
    const { appState } = action;
    const mute = appState !== 'active'; // Note that 'background' and 'inactive' are treated equal.

    sendAnalytics(createTrackMutedEvent('video', 'background mode', mute));

    dispatch(setVideoMuted(mute, VIDEO_MUTISM_AUTHORITY.BACKGROUND));

    return next(action);
}

/**
 * Adjusts the video muted state based on the audio-only state.
 *
 * @param {Store} store - The redux store in which the specified {@code action}
 * is being dispatched.
 * @param {Dispatch} next - The redux {@code dispatch} function to dispatch the
 * specified {@code action} to the specified {@code store}.
 * @param {Action} action - The redux action {@code SET_AUDIO_ONLY} which is
 * being dispatched in the specified {@code store}.
 * @private
 * @returns {Object} The value returned by {@code next(action)}.
 */
function _setAudioOnly({ dispatch }, next, action) {
    const { audioOnly, ensureVideoTrack } = action;

    sendAnalytics(createTrackMutedEvent('video', 'audio-only mode', audioOnly));

    dispatch(setVideoMuted(audioOnly, VIDEO_MUTISM_AUTHORITY.AUDIO_ONLY, ensureVideoTrack));

    return next(action);
}

/**
 * Notifies the feature base/media that the action {@link SET_ROOM} is being
 * dispatched within a specific redux {@code store}.
 *
 * @param {Store} store - The redux store in which the specified {@code action}
 * is being dispatched.
 * @param {Dispatch} next - The redux {@code dispatch} function to dispatch the
 * specified {@code action} to the specified {@code store}.
 * @param {Action} action - The redux action, {@code SET_ROOM}, which is being
 * dispatched in the specified {@code store}.
 * @private
 * @returns {Object} The new state that is the result of the reduction of the
 * specified {@code action}.
 */
function _setRoom({ dispatch, getState }, next, action) {
    // Figure out the desires/intents i.e. the state of base/media. There are
    // multiple desires/intents ordered by precedence such as server-side
    // config, config overrides in the user-supplied URL, user's own app
    // settings, etc.

    const state = getState();
    const { room } = action;
    const roomIsValid = isRoomValid(room);

    // XXX The configurations/preferences/settings startWithAudioMuted,
    // startWithVideoMuted, and startAudioOnly were introduced for
    // conferences/meetings. So it makes sense for these to not be considered
    // outside of conferences/meetings (e.g. WelcomePage). Later on, though, we
    // introduced a "Video <-> Voice" toggle on the WelcomePage which utilizes
    // startAudioOnly outside of conferences/meetings so that particular
    // configuration/preference/setting employs slightly exclusive logic.
    const mutedSources = {
        // We have startWithAudioMuted and startWithVideoMuted here:
        config: true,
        settings: true,

        // XXX We've already overwritten base/config with urlParams. However,
        // settings are more important than the server-side config.
        // Consequently, we need to read from urlParams anyway:
        urlParams: true,

        // We don't have startWithAudioMuted and startWithVideoMuted here:
        jwt: false
    };
    const audioMuted
        = roomIsValid
            ? Boolean(
                getPropertyValue(state, 'startWithAudioMuted', mutedSources))
            : _AUDIO_INITIAL_MEDIA_STATE.muted;
    const videoMuted
        = roomIsValid
            ? Boolean(
                getPropertyValue(state, 'startWithVideoMuted', mutedSources))
            : _VIDEO_INITIAL_MEDIA_STATE.muted;

    sendAnalytics(
        createStartMutedConfigurationEvent('local', audioMuted, videoMuted));
    logger.log(
        `Start muted: ${audioMuted ? 'audio, ' : ''}${
            videoMuted ? 'video' : ''}`);

    // Unconditionally express the desires/expectations/intents of the app and
    // the user i.e. the state of base/media. Eventually, practice/reality i.e.
    // the state of base/tracks will or will not agree with the desires.
    dispatch(setAudioMuted(audioMuted));
    dispatch(setCameraFacingMode(CAMERA_FACING_MODE.USER));
    dispatch(setVideoMuted(videoMuted));

    // startAudioOnly
    //
    // FIXME Technically, the audio-only feature is owned by base/conference,
    // not base/media so the following should be in base/conference.
    // Practically, I presume it was easier to write the source code here
    // because it looks like startWithAudioMuted and startWithVideoMuted.
    //
    // XXX After the introduction of the "Video <-> Voice" toggle on the
    // WelcomePage, startAudioOnly is utilized even outside of
    // conferences/meetings.
    let audioOnly;

    if (JitsiMeetJS.mediaDevices.supportsVideo()) {
        audioOnly
            = Boolean(
                getPropertyValue(
                    state,
                    'startAudioOnly',
                    /* sources */ {
                        // FIXME Practically, base/config is (really) correct
                        // only if roomIsValid. At the time of this writing,
                        // base/config is overwritten by URL params which leaves
                        // base/config incorrect on the WelcomePage after
                        // leaving a conference which explicitly overwrites
                        // base/config with URL params.
                        config: roomIsValid,

                        // XXX We've already overwritten base/config with
                        // urlParams if roomIsValid. However, settings are more
                        // important than the server-side config. Consequently,
                        // we need to read from urlParams anyway. We also
                        // probably want to read from urlParams when
                        // !roomIsValid.
                        urlParams: true,

                        // The following don't have complications around whether
                        // they are defined or not:
                        jwt: false,
                        settings: true
                    }));
    } else {
        // Default to audio-only if the (execution) environment does not
        // support (sending and/or receiving) video.
        audioOnly = true;
    }

    sendAnalytics(createStartAudioOnlyEvent(audioOnly));
    logger.log(`Start audio only set to ${audioOnly.toString()}`);

    dispatch(setAudioOnly(audioOnly, false));

    return next(action);
}

/**
 * Syncs muted state of local media track with muted state from media state.
 *
 * @param {Store} store - The redux store.
 * @param {Track} track - The local media track.
 * @private
 * @returns {void}
 */
function _syncTrackMutedState({ getState }, track) {
    const state = getState()['features/base/media'];
    const muted = Boolean(state[track.mediaType].muted);

    // XXX If muted state of track when it was added is different from our media
    // muted state, we need to mute track and explicitly modify 'muted' property
    // on track. This is because though TRACK_ADDED action was dispatched it's
    // not yet in redux state and JitsiTrackEvents.TRACK_MUTE_CHANGED may be
    // fired before track gets to state.
    if (track.muted !== muted) {
        sendAnalytics(createSyncTrackStateEvent(track.mediaType, muted));
        logger.log(
            `Sync ${track.mediaType} track muted state to ${
                muted ? 'muted' : 'unmuted'}`);

        track.muted = muted;
        setTrackMuted(track.jitsiTrack, muted);
    }
}