import { Packet, PacketType } from "../socket.io-parser"
import { on } from "./on"
import { Manager } from "./manager"
import {
    DefaultEventsMap,
    EventNames,
    EventParams,
    EventsMap,
    StrictEventEmitter,
} from "./typed-events"

const debug = require("../debug")("socket.io-client")

export interface SocketOptions {
    /**
     * the authentication payload sent when connecting to the Namespace
     */
    auth: { [key: string]: any } | ((cb: (data: object) => void) => void)
}

/**
 * Internal events.
 * These events can't be emitted by the user.
 */
const RESERVED_EVENTS = Object.freeze({
    connect: 1,
    connect_error: 1,
    disconnect: 1,
    disconnecting: 1,
    // EventEmitter reserved events: https://nodejs.org/api/events.html#events_event_newlistener
    newListener: 1,
    removeListener: 1,
})

interface Flags {
    compress?: boolean
    volatile?: boolean
}

interface SocketReservedEvents {
    connect: () => void
    connect_error: (err: Error) => void
    disconnect: (reason: Socket.DisconnectReason) => void
}

export class Socket<
    ListenEvents extends EventsMap = DefaultEventsMap,
    EmitEvents extends EventsMap = ListenEvents
    > extends StrictEventEmitter<ListenEvents, EmitEvents, SocketReservedEvents> {
    public readonly io: Manager<ListenEvents, EmitEvents>

    public id: string
    public connected: boolean
    public disconnected: boolean

    public auth: { [key: string]: any } | ((cb: (data: object) => void) => void)
    public receiveBuffer: Array<ReadonlyArray<any>> = [];
    public sendBuffer: Array<Packet> = [];

    private readonly nsp: string

    private ids: number = 0;
    private acks: object = {};
    private flags: Flags = {};
    private subs?: Array<VoidFunction>
    private _anyListeners: Array<(...args: any[]) => void>

    /**
     * `Socket` constructor.
     *
     * @public
     */
    constructor(io: Manager, nsp: string, opts?: Partial<SocketOptions>) {
        super()
        this.io = io
        this.nsp = nsp
        this.ids = 0
        this.acks = {}
        this.receiveBuffer = []
        this.sendBuffer = []
        this.connected = false
        this.disconnected = true
        this.flags = {}
        if (opts && opts.auth) {
            this.auth = opts.auth
        }
        if (this.io._autoConnect) this.open()
    }

    /**
     * Subscribe to open, close and packet events
     *
     * @private
     */
    private subEvents(): void {
        if (this.subs) return

        const io = this.io
        this.subs = [
            on(io, "open", this.onopen.bind(this)),
            on(io, "packet", this.onpacket.bind(this)),
            on(io, "error", this.onerror.bind(this)),
            on(io, "close", this.onclose.bind(this)),
        ]
    }

    /**
     * Whether the Socket will try to reconnect when its Manager connects or reconnects
     */
    public get active(): boolean {
        return !!this.subs
    }

    /**
     * "Opens" the socket.
     *
     * @public
     */
    public connect(): this {
        if (this.connected) return this

        this.subEvents()
        if (!this.io["_reconnecting"]) this.io.open() // ensure open
        if ("open" === this.io._readyState) this.onopen()
        return this
    }

    /**
     * Alias for connect()
     */
    public open(): this {
        return this.connect()
    }

    /**
     * Sends a `message` event.
     *
     * @return self
     * @public
     */
    public send(...args: any[]): this {
        args.unshift("message")
        // @ts-ignore
        this.emit.apply(this, args)
        return this
    }

    /**
     * Override `emit`.
     * If the event is in `events`, it's emitted normally.
     *
     * @return self
     * @public
     */
    public emit<Ev extends EventNames<EmitEvents>>(
        ev: Ev,
        ...args: EventParams<EmitEvents, Ev>
    ): this {
        if (RESERVED_EVENTS.hasOwnProperty(ev)) {
            throw new Error('"' + ev + '" is a reserved event name')
        }

        args.unshift(ev)
        const packet: any = {
            type: PacketType.EVENT,
            data: args,
        }

        packet.options = {}
        packet.options.compress = this.flags.compress !== false

        // event ack callback
        if ("function" === typeof args[args.length - 1]) {
            debug("emitting packet with ack id %d", this.ids)
            this.acks[this.ids] = args.pop()
            packet.id = this.ids++
        }

        const isTransportWritable =
            this.io.engine &&
            this.io.engine.transport &&
            this.io.engine.transport.writable

        const discardPacket =
            this.flags.volatile && (!isTransportWritable || !this.connected)
        if (discardPacket) {
            debug("discard packet as the transport is not currently writable")
        } else if (this.connected) {
            this.packet(packet)
        } else {
            this.sendBuffer.push(packet)
        }

        this.flags = {}

        return this
    }

    /**
     * Sends a packet.
     *
     * @param packet
     * @private
     */
    private packet(packet: Partial<Packet>): void {
        packet.nsp = this.nsp
        this.io._packet(packet)
    }

    /**
     * Called upon engine `open`.
     *
     * @private
     */
    private onopen(): void {
        debug("transport is open - connecting")
        if (typeof this.auth == "function") {
            this.auth((data) => {
                this.packet({ type: PacketType.CONNECT, data })
            })
        } else {
            this.packet({ type: PacketType.CONNECT, data: this.auth })
        }
    }

    /**
     * Called upon engine or manager `error`.
     *
     * @param err
     * @private
     */
    private onerror(err: Error): void {
        if (!this.connected) {
            this.emitReserved("connect_error", err)
        }
    }

    /**
     * Called upon engine `close`.
     *
     * @param reason
     * @private
     */
    private onclose(reason: Socket.DisconnectReason): void {
        debug("close (%s)", reason)
        this.connected = false
        this.disconnected = true
        delete this.id
        this.emitReserved("disconnect", reason)
    }

    /**
     * Called with socket packet.
     *
     * @param packet
     * @private
     */
    private onpacket(packet: Packet): void {
        const sameNamespace = packet.nsp === this.nsp

        if (!sameNamespace) return

        switch (packet.type) {
            case PacketType.CONNECT:
                if (packet.data && packet.data.sid) {
                    const id = packet.data.sid
                    this.onconnect(id)
                } else {
                    this.emitReserved(
                        "connect_error",
                        new Error(
                            "It seems you are trying to reach a Socket.IO server in v2.x with a v3.x client, but they are not compatible (more information here: https://socket.io/docs/v3/migrating-from-2-x-to-3-0/)"
                        )
                    )
                }
                break

            case PacketType.EVENT:
                this.onevent(packet)
                break

            case PacketType.BINARY_EVENT:
                this.onevent(packet)
                break

            case PacketType.ACK:
                this.onack(packet)
                break

            case PacketType.BINARY_ACK:
                this.onack(packet)
                break

            case PacketType.DISCONNECT:
                this.ondisconnect()
                break

            case PacketType.CONNECT_ERROR:
                const err = new Error(packet.data.message)
                // @ts-ignore
                err.data = packet.data.data
                this.emitReserved("connect_error", err)
                break
        }
    }

    /**
     * Called upon a server event.
     *
     * @param packet
     * @private
     */
    private onevent(packet: Packet): void {
        const args: Array<any> = packet.data || []
        debug("emitting event %j", args)

        if (null != packet.id) {
            debug("attaching ack callback to event")
            args.push(this.ack(packet.id))
        }

        if (this.connected) {
            this.emitEvent(args)
        } else {
            this.receiveBuffer.push(Object.freeze(args))
        }
    }

    private emitEvent(args: ReadonlyArray<any>): void {
        if (this._anyListeners && this._anyListeners.length) {
            const listeners = this._anyListeners.slice()
            for (const listener of listeners) {
                // @ts-ignore
                listener.apply(this, args)
            }
        }
        // @ts-ignore
        super.emit.apply(this, args)
    }

    /**
     * Produces an ack callback to emit with an event.
     *
     * @private
     */
    private ack(id: number): (...args: any[]) => void {
        const self = this
        let sent = false
        return function (...args: any[]) {
            // prevent double callbacks
            if (sent) return
            sent = true
            debug("sending ack %j", args)

            self.packet({
                type: PacketType.ACK,
                id: id,
                data: args,
            })
        }
    }

    /**
     * Called upon a server acknowlegement.
     *
     * @param packet
     * @private
     */
    private onack(packet: Packet): void {
        const ack = this.acks[packet.id]
        if ("function" === typeof ack) {
            debug("calling ack %s with %j", packet.id, packet.data)
            ack.apply(this, packet.data)
            delete this.acks[packet.id]
        } else {
            debug("bad ack %s", packet.id)
        }
    }

    /**
     * Called upon server connect.
     *
     * @private
     */
    private onconnect(id: string): void {
        debug("socket connected with id %s", id)
        this.id = id
        this.connected = true
        this.disconnected = false
        this.emitBuffered()
        this.emitReserved("connect")
    }

    /**
     * Emit buffered events (received and emitted).
     *
     * @private
     */
    private emitBuffered(): void {
        this.receiveBuffer.forEach((args) => this.emitEvent(args))
        this.receiveBuffer = []

        this.sendBuffer.forEach((packet) => this.packet(packet))
        this.sendBuffer = []
    }

    /**
     * Called upon server disconnect.
     *
     * @private
     */
    private ondisconnect(): void {
        debug("server disconnect (%s)", this.nsp)
        this.destroy()
        this.onclose("io server disconnect")
    }

    /**
     * Called upon forced client/server side disconnections,
     * this method ensures the manager stops tracking us and
     * that reconnections don't get triggered for this.
     *
     * @private
     */
    private destroy(): void {
        if (this.subs) {
            // clean subscriptions to avoid reconnections
            this.subs.forEach((subDestroy) => subDestroy())
            this.subs = undefined
        }
        this.io["_destroy"](this)
    }

    /**
     * Disconnects the socket manually.
     *
     * @return self
     * @public
     */
    public disconnect(): this {
        if (this.connected) {
            debug("performing disconnect (%s)", this.nsp)
            this.packet({ type: PacketType.DISCONNECT })
        }

        // remove socket from pool
        this.destroy()

        if (this.connected) {
            // fire events
            this.onclose("io client disconnect")
        }
        return this
    }

    /**
     * Alias for disconnect()
     *
     * @return self
     * @public
     */
    public close(): this {
        return this.disconnect()
    }

    /**
     * Sets the compress flag.
     *
     * @param compress - if `true`, compresses the sending data
     * @return self
     * @public
     */
    public compress(compress: boolean): this {
        this.flags.compress = compress
        return this
    }

    /**
     * Sets a modifier for a subsequent event emission that the event message will be dropped when this socket is not
     * ready to send messages.
     *
     * @returns self
     * @public
     */
    public get volatile(): this {
        this.flags.volatile = true
        return this
    }

    /**
     * Adds a listener that will be fired when any event is emitted. The event name is passed as the first argument to the
     * callback.
     *
     * @param listener
     * @public
     */
    public onAny(listener: (...args: any[]) => void): this {
        this._anyListeners = this._anyListeners || []
        this._anyListeners.push(listener)
        return this
    }

    /**
     * Adds a listener that will be fired when any event is emitted. The event name is passed as the first argument to the
     * callback. The listener is added to the beginning of the listeners array.
     *
     * @param listener
     * @public
     */
    public prependAny(listener: (...args: any[]) => void): this {
        this._anyListeners = this._anyListeners || []
        this._anyListeners.unshift(listener)
        return this
    }

    /**
     * Removes the listener that will be fired when any event is emitted.
     *
     * @param listener
     * @public
     */
    public offAny(listener?: (...args: any[]) => void): this {
        if (!this._anyListeners) {
            return this
        }
        if (listener) {
            const listeners = this._anyListeners
            for (let i = 0; i < listeners.length; i++) {
                if (listener === listeners[i]) {
                    listeners.splice(i, 1)
                    return this
                }
            }
        } else {
            this._anyListeners = []
        }
        return this
    }

    /**
     * Returns an array of listeners that are listening for any event that is specified. This array can be manipulated,
     * e.g. to remove listeners.
     *
     * @public
     */
    public listenersAny() {
        return this._anyListeners || []
    }
}

export namespace Socket {
    export type DisconnectReason =
        | "io server disconnect"
        | "io client disconnect"
        | "ping timeout"
        | "transport close"
        | "transport error"
}