const logger = require("jitsi-meet-logger").getLogger(__filename);

/**
 * Implements API class that embeds Jitsi Meet in external applications.
 */

var postisInit = require("postis");

/**
 * The minimum width for the Jitsi Meet frame
 * @type {number}
 */
var MIN_WIDTH = 790;

/**
 * The minimum height for the Jitsi Meet frame
 * @type {number}
 */
var MIN_HEIGHT = 300;

/**
 * Last id of api object
 * @type {number}
 */
var id = 0;

/**
 * Maps the names of the commands expected by the API with the name of the
 * commands expected by jitsi-meet
 */
var commands = {
    "displayName": "display-name",
    "toggleAudio": "toggle-audio",
    "toggleVideo": "toggle-video",
    "toggleFilmStrip": "toggle-film-strip",
    "toggleChat": "toggle-chat",
    "toggleContactList": "toggle-contact-list",
    "toggleShareScreen": "toggle-share-screen",
    "hangup": "video-hangup",
    "email": "email",
    "avatarUrl": "avatar-url"
};

/**
 * Maps the names of the events expected by the API with the name of the
 * events expected by jitsi-meet
 */
var events = {
    "incomingMessage": "incoming-message",
    "outgoingMessage": "outgoing-message",
    "displayNameChange": "display-name-change",
    "participantJoined": "participant-joined",
    "participantLeft": "participant-left",
    "videoConferenceJoined": "video-conference-joined",
    "videoConferenceLeft": "video-conference-left",
    "readyToClose": "video-ready-to-close"
};

/**
 * Sends the passed object to Jitsi Meet
 * @param postis {Postis object} the postis instance that is going to be used
 * to send the message
 * @param object the object to be sent
 * - method {sting}
 * - params {object}
 */
function sendMessage(postis, object) {
    postis.send(object);
}

/**
 * Adds given number to the numberOfParticipants property of given APIInstance.
 * @param {JitsiMeetExternalAPI} APIInstance the instance of the
 * JitsiMeetExternalAPI
 * @param {int} number - the number of participants to be added to
 * numberOfParticipants property (this parameter can be negative number if the
 * numberOfParticipants should be decreased).
 */
function changeParticipantNumber(APIInstance, number) {
    APIInstance.numberOfParticipants += number;
}

/**
 * Generates array with URL params based on the passed config object that will
 * be used for the Jitsi Meet URL generation.
 *
 * @param config {object} the config object.
 * @returns {Array<string>} the array with URL param strings.
 */
function configToURLParamsArray(config) {
    const params = [];

    for (const key in config) {
        try {
            params.push(key + '='
                + encodeURIComponent(JSON.stringify(config[key])));
        } catch (e) {
            console.warn(`Error encoding ${key}: ${e}`);
        }
    }
    return params;
}

/**
 * Constructs new API instance. Creates iframe element that loads
 * Jitsi Meet.
 * @param domain the domain name of the server that hosts the conference
 * @param room_name the name of the room to join
 * @param width width of the iframe
 * @param height height of the iframe
 * @param parent_node the node that will contain the iframe
 * @param configOverwrite object containing configuration options defined in
 * config.js to be overridden.
 * @param interfaceConfigOverwrite object containing configuration options
 * defined in interface_config.js to be overridden.
 * @param noSsl if the value is true https won't be used
 * @param {string} [jwt] the JWT token if needed by jitsi-meet for
 * authentication.
 * @constructor
 */
function JitsiMeetExternalAPI(domain, room_name, width, height, parentNode,
    configOverwrite, interfaceConfigOverwrite, noSsl, jwt) {
    if (!width || width < MIN_WIDTH)
        width = MIN_WIDTH;
    if (!height || height < MIN_HEIGHT)
        height = MIN_HEIGHT;

    this.parentNode = null;
    if (parentNode) {
        this.parentNode = parentNode;
    } else {
        var scriptTag = document.scripts[document.scripts.length - 1];
        this.parentNode = scriptTag.parentNode;
    }

    this.iframeHolder =
        this.parentNode.appendChild(document.createElement("div"));
    this.iframeHolder.id = "jitsiConference" + id;
    if(width)
        this.iframeHolder.style.width = width + "px";
    if(height)
        this.iframeHolder.style.height = height + "px";
    this.frameName = "jitsiConferenceFrame" + id;
    this.url = (noSsl) ? "http" : "https" +"://" + domain + "/";
    if(room_name)
        this.url += room_name;

    if (jwt) {
        this.url += '?jwt=' + jwt;
    }

    this.url += "#jitsi_meet_external_api_id=" + id;

    const configURLParams = configToURLParamsArray(configOverwrite);
    if (configURLParams.length) {
        this.url += '&config.' + configURLParams.join('&config.');
    }

    const interfaceConfigURLParams
        = configToURLParamsArray(interfaceConfigOverwrite);
    if (interfaceConfigURLParams.length) {
        this.url += '&interfaceConfig.'
            + interfaceConfigURLParams.join('&interfaceConfig.');
    }

    this.frame = document.createElement("iframe");
    this.frame.src = this.url;
    this.frame.name = this.frameName;
    this.frame.id = this.frameName;
    this.frame.width = "100%";
    this.frame.height = "100%";
    this.frame.setAttribute("allowFullScreen","true");
    this.frame = this.iframeHolder.appendChild(this.frame);
    this.postis = postisInit({
        window: this.frame.contentWindow,
        scope: "jitsi_meet_external_api_" + id
    });

    this.eventHandlers = {};

    // Map<{string} event_name, {boolean} postis_listener_added>
    this.postisListeners = {};

    this.numberOfParticipants = 1;
    this._setupListeners();

    id++;
}

/**
 * Executes command. The available commands are:
 * displayName - sets the display name of the local participant to the value
 * passed in the arguments array.
 * toggleAudio - mutes / unmutes audio with no arguments
 * toggleVideo - mutes / unmutes video with no arguments
 * filmStrip - hides / shows the film strip with no arguments
 * If the command doesn't require any arguments the parameter should be set
 * to empty array or it may be omitted.
 * @param name the name of the command
 * @param arguments array of arguments
 */
JitsiMeetExternalAPI.prototype.executeCommand
= function(name, ...argumentsList) {
    if(!(name in commands)) {
        logger.error("Not supported command name.");
        return;
    }
    sendMessage(this.postis, {method: commands[name], params: argumentsList});
};

/**
 * Executes commands. The available commands are:
 * displayName - sets the display name of the local participant to the value
 * passed in the arguments array.
 * toggleAudio - mutes / unmutes audio. no arguments
 * toggleVideo - mutes / unmutes video. no arguments
 * filmStrip - hides / shows the film strip. no arguments
 * toggleChat - hides / shows chat. no arguments.
 * toggleContactList - hides / shows contact list. no arguments.
 * toggleShareScreen - starts / stops screen sharing. no arguments.
 * @param object the object with commands to be executed. The keys of the
 * object are the commands that will be executed and the values are the
 * arguments for the command.
 */
JitsiMeetExternalAPI.prototype.executeCommands = function(object) {
    for(var key in object)
        this.executeCommand(key, object[key]);
};

/**
 * Adds event listeners to Meet Jitsi. The object key should be the name of
 * the event and value - the listener.
 * Currently we support the following
 * events:
 * incomingMessage - receives event notifications about incoming
 * messages. The listener will receive object with the following structure:
 * {{
 *  "from": from,//JID of the user that sent the message
 *  "nick": nick,//the nickname of the user that sent the message
 *  "message": txt//the text of the message
 * }}
 * outgoingMessage - receives event notifications about outgoing
 * messages. The listener will receive object with the following structure:
 * {{
 *  "message": txt//the text of the message
 * }}
 * displayNameChanged - receives event notifications about display name
 * change. The listener will receive object with the following structure:
 * {{
 * jid: jid,//the JID of the participant that changed his display name
 * displayname: displayName //the new display name
 * }}
 * participantJoined - receives event notifications about new participant.
 * The listener will receive object with the following structure:
 * {{
 * jid: jid //the jid of the participant
 * }}
 * participantLeft - receives event notifications about the participant that
 * left the room.
 * The listener will receive object with the following structure:
 * {{
 * jid: jid //the jid of the participant
 * }}
 * video-conference-joined - receives event notifications about the local user
 * has successfully joined the video conference.
 * The listener will receive object with the following structure:
 * {{
 * roomName: room //the room name of the conference
 * }}
 * video-conference-left - receives event notifications about the local user
 * has left the video conference.
 * The listener will receive object with the following structure:
 * {{
 * roomName: room //the room name of the conference
 * }}
 * readyToClose - all hangup operations are completed and Jitsi Meet is ready
 * to be disposed.
 * @param object
 */
JitsiMeetExternalAPI.prototype.addEventListeners = function(object) {
    for(var i in object)
        this.addEventListener(i, object[i]);
};

/**
 * Adds event listeners to Meet Jitsi. Currently we support the following
 * events:
 * incomingMessage - receives event notifications about incoming
 * messages. The listener will receive object with the following structure:
 * {{
 *  "from": from,//JID of the user that sent the message
 *  "nick": nick,//the nickname of the user that sent the message
 *  "message": txt//the text of the message
 * }}
 * outgoingMessage - receives event notifications about outgoing
 * messages. The listener will receive object with the following structure:
 * {{
 *  "message": txt//the text of the message
 * }}
 * displayNameChanged - receives event notifications about display name
 * change. The listener will receive object with the following structure:
 * {{
 * jid: jid,//the JID of the participant that changed his display name
 * displayname: displayName //the new display name
 * }}
 * participantJoined - receives event notifications about new participant.
 * The listener will receive object with the following structure:
 * {{
 * jid: jid //the jid of the participant
 * }}
 * participantLeft - receives event notifications about participant the that
 * left the room.
 * The listener will receive object with the following structure:
 * {{
 * jid: jid //the jid of the participant
 * }}
 * video-conference-joined - receives event notifications fired when the local
 * user has joined the video conference.
 * The listener will receive object with the following structure:
 * {{
 * roomName: room //the room name of the conference
 * }}
 * video-conference-left - receives event notifications fired when the local
 * user has joined the video conference.
 * The listener will receive object with the following structure:
 * {{
 * roomName: room //the room name of the conference
 * }}
 * @param event the name of the event
 * @param listener the listener
 */
JitsiMeetExternalAPI.prototype.addEventListener = function(event, listener) {
    if(!(event in events)) {
        logger.error("Not supported event name.");
        return;
    }
    // We cannot remove listeners from postis that's why we are handling the
    // callback that way.
    if(!this.postisListeners[event]) {
        this.postis.listen(events[event], function(data) {
            if((event in this.eventHandlers) &&
                typeof this.eventHandlers[event] === "function")
                this.eventHandlers[event].call(null, data);
        }.bind(this));
        this.postisListeners[event] = true;
    }
    this.eventHandlers[event] = listener;
};

/**
 * Removes event listener.
 * @param event the name of the event.
 */
JitsiMeetExternalAPI.prototype.removeEventListener = function(event) {
    if(!(event in this.eventHandlers))
    {
        logger.error("The event " + event + " is not registered.");
        return;
    }
    delete this.eventHandlers[event];
};

/**
 * Removes event listeners.
 * @param events array with the names of the events.
 */
JitsiMeetExternalAPI.prototype.removeEventListeners = function(events) {
    for(var i = 0; i < events.length; i++)
        this.removeEventListener(events[i]);
};

/**
 * Returns the number of participants in the conference.
 * NOTE: the local participant is included.
 * @returns {int} the number of participants in the conference.
 */
JitsiMeetExternalAPI.prototype.getNumberOfParticipants = function() {
    return this.numberOfParticipants;
};

/**
 * Setups listeners that are used internally for JitsiMeetExternalAPI.
 */
JitsiMeetExternalAPI.prototype._setupListeners = function() {
    this.postis.listen("participant-joined",
        changeParticipantNumber.bind(null, this, 1));
    this.postis.listen("participant-left",
        changeParticipantNumber.bind(null, this, -1));
};

/**
 * Removes the listeners and removes the Jitsi Meet frame.
 */
JitsiMeetExternalAPI.prototype.dispose = function() {
    this.postis.destroy();
    var frame = document.getElementById(this.frameName);
    if(frame)
        frame.src = 'about:blank';
    var self = this;
    window.setTimeout(function () {
        self.iframeHolder.removeChild(self.frame);
        self.iframeHolder.parentNode.removeChild(self.iframeHolder);
    }, 10);
};

module.exports = JitsiMeetExternalAPI;