import * as JitsiConferenceEvents from '../../JitsiConferenceEvents';
import SpeakerStats from './SpeakerStats';

/**
 * A collection for tracking speaker stats. Attaches listeners
 * to the conference to automatically update on tracked events.
 */
export default class SpeakerStatsCollector {
    /**
     * Initializes a new SpeakerStatsCollector instance.
     *
     * @constructor
     * @param {JitsiConference} conference - The conference to track.
     * @returns {void}
     */
    constructor(conference) {
        this.stats = {
            users: {

                // userId: SpeakerStats
            },
            dominantSpeakerId: null
        };

        const userId = conference.myUserId();

        this.stats.users[userId] = new SpeakerStats(userId, null, true);

        conference.addEventListener(
            JitsiConferenceEvents.DOMINANT_SPEAKER_CHANGED,
            this._onDominantSpeaker.bind(this));
        conference.addEventListener(
            JitsiConferenceEvents.USER_JOINED,
            this._onUserJoin.bind(this));
        conference.addEventListener(
            JitsiConferenceEvents.USER_LEFT,
            this._onUserLeave.bind(this));
        conference.addEventListener(
            JitsiConferenceEvents.DISPLAY_NAME_CHANGED,
            this._onDisplayNameChange.bind(this));
    }

    /**
     * Reacts to dominant speaker change events by changing its speaker stats
     * models to reflect the current dominant speaker.
     *
     * @param {string} dominantSpeakerId - The user id of the new
     * dominant speaker.
     * @returns {void}
     * @private
     */
    _onDominantSpeaker(dominantSpeakerId) {
        const oldDominantSpeaker
            = this.stats.users[this.stats.dominantSpeakerId];
        const newDominantSpaker = this.stats.users[dominantSpeakerId];

        oldDominantSpeaker && oldDominantSpeaker.setIsDominantSpeaker(false);
        newDominantSpaker && newDominantSpaker.setIsDominantSpeaker(true);
        this.stats.dominantSpeakerId = dominantSpeakerId;
    }

    /**
     * Reacts to user join events by creating a new SpeakerStats model.
     *
     * @param {string} userId - The user id of the new user.
     * @param {JitsiParticipant} - The JitsiParticipant model for the new user.
     * @returns {void}
     * @private
     */
    _onUserJoin(userId, participant) {
        let savedUser = this.stats.users[userId];

        if (!savedUser) {
            savedUser = this.stats.users[userId]
                = new SpeakerStats(userId, participant.getDisplayName());
        }
    }

    /**
     * Reacts to user leave events by updating the associated user's
     * SpeakerStats model.
     *
     * @param {string} userId - The user id of the user that left.
     * @returns {void}
     * @private
     */
    _onUserLeave(userId) {
        const savedUser = this.stats.users[userId];

        if (savedUser) {
            savedUser.markAsHasLeft();
        }
    }

    /**
     * Reacts to user name change events by updating the last known name
     * tracked in the associated SpeakerStats model.
     *
     * @param {string} userId - The user id of the user that left.
     * @returns {void}
     * @private
     */
    _onDisplayNameChange(userId, newName) {
        const savedUser = this.stats.users[userId];

        if (savedUser) {
            savedUser.setDisplayName(newName);
        }
    }

    /**
     * Return a copy of the tracked SpeakerStats models.
     *
     * @returns {Object} The keys are the user ids and the values are the
     * associated user's SpeakerStats model.
     * @private
     */
    getStats() {
        return this.stats.users;
    }
}