import { Boom } from '@hapi/boom'
import EventEmitter from "events"
import { STATUS_CODES } from "http"
import { promisify } from "util"
import WebSocket from "ws"
import BinaryNode from "../BinaryNode"
import { DisconnectReason, SocketConfig, SocketQueryOptions, SocketSendMessageOptions } from "../Types"
import { aesEncrypt, hmacSign, promiseTimeout, unixTimestampSeconds, decodeWAMessage } from "../Utils"
import { WAFlag, WAMetric, WATag } from "../Types"
import { DEFAULT_ORIGIN, DEF_CALLBACK_PREFIX, DEF_TAG_PREFIX, PHONE_CONNECTION_CB } from "../Defaults"

/**
 * Connects to WA servers and performs:
 * - simple queries (no retry mechanism, wait for connection establishment)
 * - listen to messages and emit events
 * - query phone connection
 */
export const makeSocket = ({
    waWebSocketUrl, 
    connectTimeoutMs, 
    phoneResponseTimeMs, 
    logger, 
    agent, 
    keepAliveIntervalMs,
    expectResponseTimeout,
    phoneConnectionChanged 
}: SocketConfig) => {
	const socketEvents = new EventEmitter()
	// for generating tags
	const referenceDateSeconds = unixTimestampSeconds(new Date())
	const ws = new WebSocket(waWebSocketUrl, undefined, {
		origin: DEFAULT_ORIGIN,
		timeout: connectTimeoutMs,
		agent,
		headers: {
			'Accept-Encoding': 'gzip, deflate, br',
			'Accept-Language': 'en-US,en;q=0.9',
			'Cache-Control': 'no-cache',
			'Host': 'web.whatsapp.com',
			'Pragma': 'no-cache',
			'Sec-WebSocket-Extensions': 'permessage-deflate; client_max_window_bits',
		}
	})
	let lastDateRecv: Date
	let epoch = 0
	let authInfo: { encKey: Buffer, macKey: Buffer }
	let keepAliveReq: NodeJS.Timeout

    let phoneCheckInterval: NodeJS.Timeout
    let phoneCheckListeners = 0

	const sendPromise = promisify(ws.send)
	/** generate message tag and increment epoch */
	const generateMessageTag = (longTag: boolean = false) => {
        const tag = `${longTag ? referenceDateSeconds : (referenceDateSeconds%1000)}.--${epoch}`
        epoch += 1 // increment message count, it makes the 'epoch' field when sending binary messages
        return tag
    }
	const sendRawMessage = (data: Buffer | string) => sendPromise.call(ws, data) as Promise<void>
	/** 
	 * Send a message to the WA servers
	 * @returns the tag attached in the message
	 * */
	const sendMessage = async(
		{ json, binaryTag, tag, longTag }: SocketSendMessageOptions
	) => {
		tag = tag || generateMessageTag(longTag)
		let data: Buffer | string
        if(logger.level === 'trace') {
            logger.trace({ tag, fromMe: true, json, binaryTag }, 'communication')
        }

		if(binaryTag) {
			if(!(json instanceof BinaryNode)) {
				throw new Boom(`Invalid binary message of type "${typeof json}". Must be BinaryNode`, { statusCode: 400 })
			}
			if(!authInfo) {
				throw new Boom('No encryption/mac keys to encrypt node with', { statusCode: 400 })
			}
			const binary = json.toBuffer() // encode the JSON to the WhatsApp binary format

			const buff = aesEncrypt(binary, authInfo.encKey) // encrypt it using AES and our encKey
			const sign = hmacSign(buff, authInfo.macKey) // sign the message using HMAC and our macKey

			data = Buffer.concat([
				Buffer.from(tag + ','), // generate & prefix the message tag
				Buffer.from(binaryTag), // prefix some bytes that tell whatsapp what the message is about
				sign, // the HMAC sign of the message
				buff, // the actual encrypted buffer
			])
		} else {
			data = `${tag},${JSON.stringify(json)}`
		}
		await sendRawMessage(data)
		return tag
	}
	const end = (error: Error | undefined) => {
		ws.removeAllListeners('close')
        ws.removeAllListeners('error')
        ws.removeAllListeners('open')
        ws.removeAllListeners('message')

        phoneCheckListeners = 0
        clearInterval(keepAliveReq)
        clearPhoneCheckInterval()

        if(ws.readyState !== ws.CLOSED && ws.readyState !== ws.CLOSING) {
            socketEvents.emit('ws-close', error)
            try { ws.close() } catch { }
        }
	}
	const onMessageRecieved = (message: string | Buffer) => {
        if(message[0] === '!') {
            // when the first character in the message is an '!', the server is sending a pong frame
            const timestamp = message.slice(1, message.length).toString ('utf-8')
            lastDateRecv = new Date(parseInt(timestamp))
            socketEvents.emit('received-pong')
        } else {
            let messageTag: string
            let json: any
            try {
                const dec = decodeWAMessage(message, authInfo)
                messageTag = dec[0]
                json = dec[1]
				if (!json) return
            } catch (error) {
                end(error)
				return
            }
            //if (this.shouldLogMessages) this.messageLog.push ({ tag: messageTag, json: JSON.stringify(json), fromMe: false })
            
            if (logger.level === 'trace') {
                logger.trace({ tag: messageTag, fromMe: false, json }, 'communication')
            }

            let anyTriggered = false
            /* Check if this is a response to a message we sent */
            anyTriggered = socketEvents.emit(`${DEF_TAG_PREFIX}${messageTag}`, json)
            /* Check if this is a response to a message we are expecting */
            const l0 = json.header || json[0] || ''
            const l1 = json?.attributes || json?.[1] || { }
            const l2 = json?.data?.[0]?.header || json[2]?.[0] || ''

            Object.keys(l1).forEach(key => {
                anyTriggered = socketEvents.emit(`${DEF_CALLBACK_PREFIX}${l0},${key}:${l1[key]},${l2}`, json) || anyTriggered
                anyTriggered = socketEvents.emit(`${DEF_CALLBACK_PREFIX}${l0},${key}:${l1[key]}`, json) || anyTriggered
                anyTriggered = socketEvents.emit(`${DEF_CALLBACK_PREFIX}${l0},${key}`, json) || anyTriggered
            })
            anyTriggered = socketEvents.emit(`${DEF_CALLBACK_PREFIX}${l0},,${l2}`, json) || anyTriggered
            anyTriggered = socketEvents.emit(`${DEF_CALLBACK_PREFIX}${l0}`, json) || anyTriggered

            if (!anyTriggered && logger.level === 'debug') {
                logger.debug({ unhandled: true, tag: messageTag, fromMe: false, json }, 'communication recv')
            }
        }
    }

	/** Exits a query if the phone connection is active and no response is still found */
    const exitQueryIfResponseNotExpected = (tag: string, cancel: (error: Boom) => void) => {
        let timeout: NodeJS.Timeout
        const listener = ([, connected]) => {
            if(connected) {
                timeout = setTimeout(() => {
                    logger.info({ tag }, `cancelling wait for message as a response is no longer expected from the phone`)
					cancel(new Boom('Not expecting a response', { statusCode: 422 }))
                }, expectResponseTimeout)
                socketEvents.off(PHONE_CONNECTION_CB, listener)
            }
        }
        socketEvents.on(PHONE_CONNECTION_CB, listener)
        return () => {
            socketEvents.off(PHONE_CONNECTION_CB, listener)
            timeout && clearTimeout(timeout)
        }
    }
    /** interval is started when a query takes too long to respond */
    const startPhoneCheckInterval = () => {
        phoneCheckListeners += 1
        if (!phoneCheckInterval) {
            // if its been a long time and we haven't heard back from WA, send a ping
            phoneCheckInterval = setInterval(() => {
                if(phoneCheckListeners <= 0) {
                    logger.warn('phone check called without listeners')
                    return
                }
                logger.info('checking phone connection...')
                sendAdminTest()

                phoneConnectionChanged(false)
            }, phoneResponseTimeMs)
        }   
    }
    const clearPhoneCheckInterval = () => {
        phoneCheckListeners -= 1
        if (phoneCheckListeners <= 0) {
            clearInterval(phoneCheckInterval)
            phoneCheckInterval = undefined
            phoneCheckListeners = 0
        }
    }
	/** checks for phone connection */
    const sendAdminTest = () => sendMessage({ json: ['admin', 'test'] })
    /**
     * Wait for a message with a certain tag to be received
     * @param tag the message tag to await
     * @param json query that was sent
     * @param timeoutMs timeout after which the promise will reject
     */
	 const waitForMessage = async(tag: string, requiresPhoneConnection: boolean, timeoutMs?: number) => {
        let onRecv: (json) => void
        let onErr: (err) => void
        let cancelPhoneChecker: () => void
        if (requiresPhoneConnection) {
            startPhoneCheckInterval()
            cancelPhoneChecker = exitQueryIfResponseNotExpected(tag, onErr)
        }
        try {
            const result = await promiseTimeout(timeoutMs,
                (resolve, reject) => {
                    onRecv = resolve
                    onErr = err => reject(err || new Boom('Connection Closed', { statusCode: 429 }))
                    
                    socketEvents.on(`TAG:${tag}`, onRecv)
                    socketEvents.on('ws-close', onErr) // if the socket closes, you'll never receive the message
                },
            )
            return result as any
        } finally {
            requiresPhoneConnection && clearPhoneCheckInterval()
			cancelPhoneChecker && cancelPhoneChecker()

            socketEvents.off(`TAG:${tag}`, onRecv)
            socketEvents.off(`ws-close`, onErr)
        }
    }
    /**
     * Query something from the WhatsApp servers
     * @param json the query itself
     * @param binaryTags the tags to attach if the query is supposed to be sent encoded in binary
     * @param timeoutMs timeout after which the query will be failed (set to null to disable a timeout)
     * @param tag the tag to attach to the message
     */
    const query = async(
        {json, timeoutMs, expect200, tag, longTag, binaryTag, requiresPhoneConnection}: SocketQueryOptions
    ) => {
		tag = tag || generateMessageTag(longTag)
        const promise = waitForMessage(tag, requiresPhoneConnection, timeoutMs)
       
        await sendMessage({ json, tag, binaryTag })
        const response = await promise
        const responseStatusCode = +(response.status ? response.status : 200) // default status
        // read here: http://getstatuscode.com/599
        if(responseStatusCode === 599) { // the connection has gone bad
            end(new Boom('WA server overloaded', { statusCode: 599 }))
        }
        if(expect200 && Math.floor(responseStatusCode/100) !== 2) {
            const message = STATUS_CODES[responseStatusCode] || 'unknown'
            throw new Boom(
                `Unexpected status in '${Object.values(json)[0] || 'query'}': ${message}(${responseStatusCode})`, 
                { data: { query: json, message }, statusCode: response.status }
            )
        }
        return response
    }
	const startKeepAliveRequest = () => (
        keepAliveReq = setInterval(() => {
            if (!lastDateRecv) lastDateRecv = new Date()
            const diff = Date.now() - lastDateRecv.getTime()
            /*
                check if it's been a suspicious amount of time since the server responded with our last seen
                it could be that the network is down
            */
            if (diff > keepAliveIntervalMs+5000) {
                end(new Boom('Connection was lost', { statusCode: DisconnectReason.connectionLost }))
            } else if(ws.readyState === ws.OPEN) {
                sendRawMessage('?,,') // if its all good, send a keep alive request
            } else {
                logger.warn('keep alive called when WS not open')
            }
        }, keepAliveIntervalMs)
    )

    const waitForSocketOpen = async() => {
        if(ws.readyState === ws.OPEN) return
        if(ws.readyState === ws.CLOSED || ws.readyState === ws.CLOSING) {
            throw new Boom('Connection Closed', { statusCode: DisconnectReason.connectionClosed })
        }
        let onOpen: () => void
        let onClose: (err: Error) => void
        await new Promise((resolve, reject) => {
            onOpen = () => resolve(undefined)
            onClose = reject
            socketEvents.on('ws-open', onOpen)
            socketEvents.on('ws-close', onClose)
        })
        .finally(() => {
            socketEvents.off('ws-open', onOpen)
            socketEvents.off('ws-close', onClose)
        })
    }

	ws.on('message', onMessageRecieved)
	ws.on('open', () => {
		startKeepAliveRequest()

		logger.info('Opened WS connection to WhatsApp Web')
		socketEvents.emit('ws-open')
	})
	ws.on('error', end)
	ws.on('close', () => end(new Boom('Connection Terminated', { statusCode: DisconnectReason.connectionLost })))

    socketEvents.on(PHONE_CONNECTION_CB, json => {
        if (!json[1]) {
            end(new Boom('Connection terminated by phone', { statusCode: DisconnectReason.connectionLost }))
            logger.info('Connection terminated by phone, closing...')
        } else {
            phoneConnectionChanged(true)
        }
    })
    socketEvents.on('CB:Cmd,type:disconnect', json => {
        const {kind} = json[1]
        let reason: DisconnectReason
        switch(kind) {
            case 'replaced':
                reason = DisconnectReason.connectionReplaced
                break
            default:
                reason = DisconnectReason.connectionLost
                break
        }
        end(new Boom(
            `Connection terminated by server: "${kind || 'unknown'}"`, 
            { statusCode: reason }
        ))
    })

	return {
		socketEvents,
        ws,
        updateKeys: (info: { encKey: Buffer, macKey: Buffer }) => authInfo = info,
        waitForSocketOpen,
		sendRawMessage,
		sendMessage,
		generateMessageTag,
        waitForMessage,
        query,
        /** Generic function for action, set queries */
        setQuery: async(nodes: BinaryNode[], binaryTag: WATag = [WAMetric.group, WAFlag.ignore], tag?: string) => (
            query({ 
                json: new BinaryNode(
                    'action', 
                    { epoch: epoch.toString(), type: 'set' },
                    nodes
                ), 
                binaryTag, 
                tag, 
                expect200: true, 
                requiresPhoneConnection: true 
            }) as Promise<{ status: number }>
        ),
		currentEpoch: () => epoch,
		end
	}
}
export type Socket = ReturnType<typeof makeSocket>