import logging from "./logging";
import { getItem } from "./storage";

export const GatewayErrors = {
    BAD_PAYLOAD: 4001,
    BAD_AUTH: 4002,
    AUTHENTICATION_TIMEOUT: 4003,
    NO_PING: 4004,
    FLOODING: 4005,
    ALREADY_AUTHENTICATED: 4006,
    PAYLOAD_TOO_LARGE: 4007,
    TOO_MANY_SESSIONS: 4008,
}; 

export const GatewayPayloadType = {
    Hello: 0,
    Authenticate: 1,
    Ready: 2,
    Ping: 3,

    ChannelCreate: 110,
    ChannelUpdate: 111,
    ChannelDelete: 112,

    MessageCreate: 120,
    MessageUpdate: 121,
    MessageDelete: 122,
}

export const GatewayEventType = {
    ...GatewayPayloadType,

    Open: -5,
    Close: -4,
    BadAuth: -3,
}

const log = logging.logger("Gateway", true);

export default {
    ws: null,
    authenticated: false,
    open: false,
    heartbeatInterval: null,
    user: null,
    channels: null,
    reconnectDelay: 400,
    reconnectTimeout: null,
    handlers: new Map(),
    disableReconnect: false,
    init(token) {
        if (!token) {
            log("no auth token, skipping connection");
            this.dispatch(GatewayEventType.BadAuth, 0);
            return false;
        }
        log(`connecting to gateway - gatewayBase: ${getItem("gatewayBase")}`);
        this.ws = new WebSocket(getItem("gatewayBase"));
        this.ws.onopen = () => {
            if (this.reconnectTimeout) {
                clearTimeout(this.reconnectTimeout);
            }
            this.disableReconnect = false;
            this.open = true;
            this.dispatch(GatewayEventType.Open, null);
            log("open");
        };
        this.ws.onmessage = (event) => {
            const payload = JSON.parse(event.data);

            switch (payload.t) {
                case GatewayPayloadType.Hello: {
                    this.send({
                        t: GatewayPayloadType.Authenticate,
                        d: token
                    });

                    this.heartbeatInterval = setInterval(() => {
                        this.send({
                            t: GatewayPayloadType.Ping,
                            d: 0
                        });
                    }, payload.d.pingInterval);

                    log("hello");
                    break;
                }
                case GatewayPayloadType.Ready: {
                    this.user = payload.d.user;
                    this.channels = payload.d.channels;

                    this.reconnectDelay = 400;

                    log("ready");
                    break;
                }
            }

            this.dispatch(payload.t, payload.d);
        };
        this.ws.onclose = ({ code }) => {
            this.authenticated = false;
            this.user = null;
            this.channels = null;
            this.open = false;
            if (this.heartbeatInterval) {
                clearInterval(this.heartbeatInterval);
            }

            if (code === GatewayErrors.BAD_AUTH) {
                this.dispatch(GatewayEventType.BadAuth, 1);
                if (this.reconnectTimeout)
                    clearTimeout(this.reconnectTimeout);
            } else if (this.disableReconnect) {
                if (this.reconnectTimeout)
                    clearTimeout(this.reconnectTimeout);
            } else {
                if (this.reconnectDelay < 60000) {
                    this.reconnectDelay *= 2;
                }
                this.reconnectTimeout = setTimeout(() => {
                    this.init(token);
                }, this.reconnectDelay);
            }

            this.dispatch(GatewayEventType.Close, code);

            log("close");
        };
        this.ws.onerror = (e) => {
            log("websocket: onerror", e);
        };

        return true;
    },
    send(data) {
        return this.ws.send(JSON.stringify(data));
    },
    dispatch(event, payload) {
        const eventHandlers = this.handlers.get(event);
        if (!eventHandlers)
            return;

        eventHandlers.forEach((e) => {
            e(payload);
        });
    },
    subscribe(event, handler) {
        if (!this.handlers.get(event)) {
            this.handlers.set(event, new Set());
        }

        this.handlers.get(event).add(handler);
        return handler; // can later be used for unsubscribe()
    },
    unsubscribe(event, handler) {
        const eventHandlers = this.handlers.get(event);
        if (!eventHandlers)
            return;

        eventHandlers.delete(handler);

        if (eventHandlers.size < 1) {
            this.handlers.delete(event);
        }
    },
    close() {
        this.disableReconnect = true;
        if (this.ws)
            this.ws.close();
    }
};