/** @odoo-module **/

import { debounce } from "@bus/workers/websocket_worker_utils";

/**
 * Type of events that can be sent from the worker to its clients.
 *
 * @typedef { 'connect' | 'reconnect' | 'disconnect' | 'reconnecting' | 'notification' | 'initialized' } WorkerEvent
 */

/**
 * Type of action that can be sent from the client to the worker.
 *
 * @typedef {'add_channel' | 'delete_channel' | 'force_update_channels' | 'initialize_connection' | 'send' | 'leave' | 'stop' | 'start'} WorkerAction
 */

export const WEBSOCKET_CLOSE_CODES = Object.freeze({
    CLEAN: 1000,
    GOING_AWAY: 1001,
    PROTOCOL_ERROR: 1002,
    INCORRECT_DATA: 1003,
    ABNORMAL_CLOSURE: 1006,
    INCONSISTENT_DATA: 1007,
    MESSAGE_VIOLATING_POLICY: 1008,
    MESSAGE_TOO_BIG: 1009,
    EXTENSION_NEGOTIATION_FAILED: 1010,
    SERVER_ERROR: 1011,
    RESTART: 1012,
    TRY_LATER: 1013,
    BAD_GATEWAY: 1014,
    SESSION_EXPIRED: 4001,
    KEEP_ALIVE_TIMEOUT: 4002,
    RECONNECTING: 4003,
});
// Should be incremented on every worker update in order to force
// update of the worker in browser cache.
export const WORKER_VERSION = "1.0.7";
const MAXIMUM_RECONNECT_DELAY = 60000;

/**
 * This class regroups the logic necessary in order for the
 * SharedWorker/Worker to work. Indeed, Safari and some minor browsers
 * do not support SharedWorker. In order to solve this issue, a Worker
 * is used in this case. The logic is almost the same than the one used
 * for SharedWorker and this class implements it.
 */
export class WebsocketWorker {
    INITIAL_RECONNECT_DELAY = 1000;
    RECONNECT_JITTER = 1000;

    constructor() {
        // Timestamp of start of most recent bus service sender
        this.newestStartTs = undefined;
        this.websocketURL = "";
        this.currentUID = null;
        this.currentDB = null;
        this.isWaitingForNewUID = true;
        this.channelsByClient = new Map();
        this.connectRetryDelay = this.INITIAL_RECONNECT_DELAY;
        this.connectTimeout = null;
        this.debugModeByClient = new Map();
        this.isDebug = false;
        this.isReconnecting = false;
        this.lastChannelSubscription = null;
        this.lastNotificationId = 0;
        this.messageWaitQueue = [];
        this._forceUpdateChannels = debounce(this._forceUpdateChannels, 300);
        this._updateChannels = debounce(this._updateChannels, 0);

        this._onWebsocketClose = this._onWebsocketClose.bind(this);
        this._onWebsocketError = this._onWebsocketError.bind(this);
        this._onWebsocketMessage = this._onWebsocketMessage.bind(this);
        this._onWebsocketOpen = this._onWebsocketOpen.bind(this);
    }

    //--------------------------------------------------------------------------
    // Public
    //--------------------------------------------------------------------------

    /**
     * Send the message to all the clients that are connected to the
     * worker.
     *
     * @param {WorkerEvent} type Event to broadcast to connected
     * clients.
     * @param {Object} data
     */
    broadcast(type, data) {
        for (const client of this.channelsByClient.keys()) {
            client.postMessage({ type, data });
        }
    }

    /**
     * Register a client handled by this worker.
     *
     * @param {MessagePort} messagePort
     */
    registerClient(messagePort) {
        messagePort.onmessage = (ev) => {
            this._onClientMessage(messagePort, ev.data);
        };
        this.channelsByClient.set(messagePort, []);
    }

    /**
     * Send message to the given client.
     *
     * @param {number} client
     * @param {WorkerEvent} type
     * @param {Object} data
     */
    sendToClient(client, type, data) {
        client.postMessage({ type, data });
    }

    //--------------------------------------------------------------------------
    // PRIVATE
    //--------------------------------------------------------------------------

    /**
     * Called when a message is posted to the worker by a client (i.e. a
     * MessagePort connected to this worker).
     *
     * @param {MessagePort} client
     * @param {Object} message
     * @param {WorkerAction} [message.action]
     * Action to execute.
     * @param {Object|undefined} [message.data] Data required by the
     * action.
     */
    _onClientMessage(client, { action, data }) {
        switch (action) {
            case "send":
                return this._sendToServer(data);
            case "start":
                return this._start();
            case "stop":
                return this._stop();
            case "leave":
                return this._unregisterClient(client);
            case "add_channel":
                return this._addChannel(client, data);
            case "delete_channel":
                return this._deleteChannel(client, data);
            case "force_update_channels":
                return this._forceUpdateChannels();
            case "initialize_connection":
                return this._initializeConnection(client, data);
        }
    }

    /**
     * Add a channel for the given client. If this channel is not yet
     * known, update the subscription on the server.
     *
     * @param {MessagePort} client
     * @param {string} channel
     */
    _addChannel(client, channel) {
        const clientChannels = this.channelsByClient.get(client);
        if (!clientChannels.includes(channel)) {
            clientChannels.push(channel);
            this.channelsByClient.set(client, clientChannels);
            this._updateChannels();
        }
    }

    /**
     * Remove a channel for the given client. If this channel is not
     * used anymore, update the subscription on the server.
     *
     * @param {MessagePort} client
     * @param {string} channel
     */
    _deleteChannel(client, channel) {
        const clientChannels = this.channelsByClient.get(client);
        if (!clientChannels) {
            return;
        }
        const channelIndex = clientChannels.indexOf(channel);
        if (channelIndex !== -1) {
            clientChannels.splice(channelIndex, 1);
            this._updateChannels();
        }
    }

    /**
     * Update the channels on the server side even if the channels on
     * the client side are the same than the last time we subscribed.
     */
    _forceUpdateChannels() {
        this._updateChannels({ force: true });
    }

    /**
     * Remove the given client from this worker client list as well as
     * its channels. If some of its channels are not used anymore,
     * update the subscription on the server.
     *
     * @param {MessagePort} client
     */
    _unregisterClient(client) {
        this.channelsByClient.delete(client);
        this.debugModeByClient.delete(client);
        this.isDebug = Object.values(this.debugModeByClient).some(
            (debugValue) => debugValue !== ""
        );
        this._updateChannels();
    }

    /**
     * Initialize a client connection to this worker.
     *
     * @param {Object} param0
     * @param {string} [param0.db] Database name.
     * @param {String} [param0.debug] Current debugging mode for the
     * given client.
     * @param {Number} [param0.lastNotificationId] Last notification id
     * known by the client.
     * @param {String} [param0.websocketURL] URL of the websocket endpoint.
     * @param {Number|false|undefined} [param0.uid] Current user id
     *     - Number: user is logged whether on the frontend/backend.
     *     - false: user is not logged.
     *     - undefined: not available (e.g. livechat support page)
     * @param {Number} param0.startTs Timestamp of start of bus service sender.
     */
    _initializeConnection(client, { db, debug, lastNotificationId, uid, websocketURL, startTs }) {
        if (this.newestStartTs && this.newestStartTs > startTs) {
            this.debugModeByClient[client] = debug;
            this.isDebug = Object.values(this.debugModeByClient).some(
                (debugValue) => debugValue !== ""
            );
            this.sendToClient(client, "initialized");
            return;
        }
        this.newestStartTs = startTs;
        this.websocketURL = websocketURL;
        this.lastNotificationId = lastNotificationId;
        this.debugModeByClient[client] = debug;
        this.isDebug = Object.values(this.debugModeByClient).some(
            (debugValue) => debugValue !== ""
        );
        const isCurrentUserKnown = uid !== undefined;
        if (this.isWaitingForNewUID && isCurrentUserKnown) {
            this.isWaitingForNewUID = false;
            this.currentUID = uid;
        }
        if ((this.currentUID !== uid && isCurrentUserKnown) || this.currentDB !== db) {
            this.currentUID = uid;
            this.currentDB = db;
            if (this.websocket) {
                this.websocket.close(WEBSOCKET_CLOSE_CODES.CLEAN);
            }
            this.channelsByClient.forEach((_, key) => this.channelsByClient.set(key, []));
        }
        this.sendToClient(client, "initialized");
    }

    /**
     * Determine whether or not the websocket associated to this worker
     * is connected.
     *
     * @returns {boolean}
     */
    _isWebsocketConnected() {
        return this.websocket && this.websocket.readyState === 1;
    }

    /**
     * Determine whether or not the websocket associated to this worker
     * is connecting.
     *
     * @returns {boolean}
     */
    _isWebsocketConnecting() {
        return this.websocket && this.websocket.readyState === 0;
    }

    /**
     * Determine whether or not the websocket associated to this worker
     * is in the closing state.
     *
     * @returns {boolean}
     */
    _isWebsocketClosing() {
        return this.websocket && this.websocket.readyState === 2;
    }

    /**
     * Triggered when a connection is closed. If closure was not clean ,
     * try to reconnect after indicating to the clients that the
     * connection was closed.
     *
     * @param {CloseEvent} ev
     * @param {number} code  close code indicating why the connection
     * was closed.
     * @param {string} reason reason indicating why the connection was
     * closed.
     */
    _onWebsocketClose({ code, reason }) {
        if (this.isDebug) {
            console.debug(
                `%c${new Date().toLocaleString()} - [onClose]`,
                "color: #c6e; font-weight: bold;",
                code,
                reason
            );
        }
        this.lastChannelSubscription = null;
        if (this.isReconnecting) {
            // Connection was not established but the close event was
            // triggered anyway. Let the onWebsocketError method handle
            // this case.
            return;
        }
        this.broadcast("disconnect", { code, reason });
        if (code === WEBSOCKET_CLOSE_CODES.CLEAN) {
            // WebSocket was closed on purpose, do not try to reconnect.
            return;
        }
        // WebSocket was not closed cleanly, let's try to reconnect.
        this.broadcast("reconnecting", { closeCode: code });
        this.isReconnecting = true;
        if (code === WEBSOCKET_CLOSE_CODES.KEEP_ALIVE_TIMEOUT) {
            // Don't wait to reconnect on keep alive timeout.
            this.connectRetryDelay = 0;
        }
        if (code === WEBSOCKET_CLOSE_CODES.SESSION_EXPIRED) {
            this.isWaitingForNewUID = true;
        }
        this._retryConnectionWithDelay();
    }

    /**
     * Triggered when a connection failed or failed to established.
     */
    _onWebsocketError() {
        if (this.isDebug) {
            console.debug(
                `%c${new Date().toLocaleString()} - [onError]`,
                "color: #c6e; font-weight: bold;"
            );
        }
        this._retryConnectionWithDelay();
    }

    /**
     * Handle data received from the bus.
     *
     * @param {MessageEvent} messageEv
     */
    _onWebsocketMessage(messageEv) {
        const notifications = JSON.parse(messageEv.data);
        if (this.isDebug) {
            console.debug(
                `%c${new Date().toLocaleString()} - [onMessage]`,
                "color: #c6e; font-weight: bold;",
                notifications
            );
        }
        this.lastNotificationId = notifications[notifications.length - 1].id;
        this.broadcast("notification", notifications);
    }

    /**
     * Triggered on websocket open. Send message that were waiting for
     * the connection to open.
     */
    _onWebsocketOpen() {
        if (this.isDebug) {
            console.debug(
                `%c${new Date().toLocaleString()} - [onOpen]`,
                "color: #c6e; font-weight: bold;"
            );
        }
        this._updateChannels();
        this.messageWaitQueue.forEach((msg) => this.websocket.send(msg));
        this.messageWaitQueue = [];
        this.broadcast(this.isReconnecting ? "reconnect" : "connect");
        this.connectRetryDelay = this.INITIAL_RECONNECT_DELAY;
        this.connectTimeout = null;
        this.isReconnecting = false;
    }

    /**
     * Try to reconnect to the server, an exponential back off is
     * applied to the reconnect attempts.
     */
    _retryConnectionWithDelay() {
        this.connectRetryDelay =
            Math.min(this.connectRetryDelay * 1.5, MAXIMUM_RECONNECT_DELAY) +
            this.RECONNECT_JITTER * Math.random();
        this.connectTimeout = setTimeout(this._start.bind(this), this.connectRetryDelay);
    }

    /**
     * Send a message to the server through the websocket connection.
     * If the websocket is not open, enqueue the message and send it
     * upon the next reconnection.
     *
     * @param {{event_name: string, data: any }} message Message to send to the server.
     */
    _sendToServer(message) {
        const payload = JSON.stringify(message);
        if (!this._isWebsocketConnected()) {
            this.messageWaitQueue.push(payload);
        } else {
            this.websocket.send(payload);
        }
    }

    /**
     * Start the worker by opening a websocket connection.
     */
    _start() {
        if (this._isWebsocketConnected() || this._isWebsocketConnecting()) {
            return;
        }
        if (this.websocket) {
            this.websocket.removeEventListener("open", this._onWebsocketOpen);
            this.websocket.removeEventListener("message", this._onWebsocketMessage);
            this.websocket.removeEventListener("error", this._onWebsocketError);
            this.websocket.removeEventListener("close", this._onWebsocketClose);
        }
        if (this._isWebsocketClosing()) {
            // close event was not triggered and will never be, broadcast the
            // disconnect event for consistency sake.
            this.lastChannelSubscription = null;
            this.broadcast("disconnect", { code: WEBSOCKET_CLOSE_CODES.ABNORMAL_CLOSURE });
        }
        this.websocket = new WebSocket(this.websocketURL);
        this.websocket.addEventListener("open", this._onWebsocketOpen);
        this.websocket.addEventListener("error", this._onWebsocketError);
        this.websocket.addEventListener("message", this._onWebsocketMessage);
        this.websocket.addEventListener("close", this._onWebsocketClose);
    }

    /**
     * Stop the worker.
     */
    _stop() {
        clearTimeout(this.connectTimeout);
        this.connectRetryDelay = this.INITIAL_RECONNECT_DELAY;
        this.isReconnecting = false;
        this.lastChannelSubscription = null;
        if (this.websocket) {
            this.websocket.close();
        }
    }

    /**
     * Update the channel subscription on the server. Ignore if the channels
     * did not change since the last subscription.
     *
     * @param {boolean} force Whether or not we should update the subscription
     * event if the channels haven't change since last subscription.
     */
    _updateChannels({ force = false } = {}) {
        const allTabsChannels = [
            ...new Set([].concat.apply([], [...this.channelsByClient.values()])),
        ].sort();
        const allTabsChannelsString = JSON.stringify(allTabsChannels);
        const shouldUpdateChannelSubscription =
            allTabsChannelsString !== this.lastChannelSubscription;
        if (force || shouldUpdateChannelSubscription) {
            this.lastChannelSubscription = allTabsChannelsString;
            this._sendToServer({
                event_name: "subscribe",
                data: { channels: allTabsChannels, last: this.lastNotificationId },
            });
        }
    }
}
