import { v3 } from "uuid"
import WebSocket from "ws"
import { ProxiedPlayer } from "./classes.js"
import {
    encodeULEB128 as encodeVarInt,
    decodeULEB128 as decodeVarInt,
    encodeSLEB128 as encodeSVarInt,
    decodeSLEB128 as decodeSVarInt
} from "@thi.ng/leb128"
import { DisconnectReason, EaglerPacketId, MAGIC_ENDING_IDENTIFYS_BYTES } from "./eaglerPacketDef.js"
import { Logger } from "./logger.js"
import { State } from "./types.js"
import { toBuffer } from "uuid-buffer"
import * as mc from "minecraft-protocol"
import { config } from "./config.js"

const MAGIC_UUID = "a7e774bc-7ea4-11ed-9a58-1f9e14304a59"
const logger = new Logger("LoginHandler")
const USERNAME_REGEX = /[^0-9^a-z^A-Z^_]/gi

export function genUUID(user: string): string {
    return v3(user, MAGIC_UUID)
}

export function bufferizeUUID(uuid: string): Buffer {
    return toBuffer(uuid)
}

export function validateUsername(user: string): void | never {
    if (user.length > 20)
        throw new Error("Username is too long!")
    if (!!user.match(USERNAME_REGEX))
        throw new Error("Invalid username. Username can only contain alphanumeric characters, and the underscore (_) character.")
}

export function disconnect(player: ProxiedPlayer, message: string, code?: DisconnectReason) {
    if (player.state == State.POST_HANDSHAKE) {
        const messageLen = encodeVarInt(message.length)
        const d = Buffer.alloc(1 + messageLen.length + message.length)
        d.set([0x40, ...messageLen, ...Buffer.from(message)])
        player.ws.send(d)
        player.ws.close()
    } else {
        const messageLen = encodeVarInt(message.length), codeEnc = encodeVarInt(code ?? DisconnectReason.CUSTOM)
        const d = Buffer.alloc(1 + codeEnc.length + messageLen.length + message.length)
        d.set([0xff,...codeEnc, ...messageLen, ...Buffer.from(message)])
        player.ws.send(d)
        player.ws.close()
    }
}

export function awaitPacket(ws: WebSocket, id?: EaglerPacketId): Promise<Buffer> {
    return new Promise<Buffer>((res, rej) => {
        let resolved = false
        const msgCb = (msg: any) => {
            if (id != null && msg[0] == id) {
                resolved = true
                ws.removeEventListener('message', msgCb)
                ws.removeEventListener('close', discon)
                ws.setMaxListeners(ws.getMaxListeners() - 2 < 0 ? 5 : ws.getMaxListeners() - 2)
                res(msg)
            } else if (id == null) {
                resolved = true
                ws.removeEventListener('message', msgCb)
                ws.removeEventListener('close', discon)
                ws.setMaxListeners(ws.getMaxListeners() - 2 < 0 ? 5 : ws.getMaxListeners() - 2)
                res(msg)
            }
        }
        const discon = () => {
            resolved = true
            ws.removeEventListener('message', msgCb)
            ws.removeEventListener('close', discon)
            ws.setMaxListeners(ws.getMaxListeners() - 2 < 0 ? 5 : ws.getMaxListeners() - 2)
            rej("Connection closed")
        }
        ws.setMaxListeners(ws.getMaxListeners() + 2)
        ws.on('message', msgCb)
        ws.on('close', discon)
        setTimeout(() => {
            ws.removeEventListener('message', msgCb)
            ws.removeEventListener('close', discon)
            ws.setMaxListeners(ws.getMaxListeners() - 2 < 0 ? 5 : ws.getMaxListeners() - 2)
            rej("Timed out")
        }, 10000)
    })
}

export function loginServer(ip: string, port: number, client: ProxiedPlayer) {
    return new Promise<void>((res, rej) => {
        let receivedCompression = false
        const mcClient = mc.createClient({
            host: ip,
            port: port,
            auth: 'offline',
            version: '1.8.8',
            username: client.username
        })
        mcClient.on('error', err => {
            mcClient.end()
            rej(err)
        })
        mcClient.on('end', () => {
            client.ws.close()
        })
        mcClient.on('connect', () => {
            client.remoteConnection = mcClient
            logger.info(`Player ${client.username} has been connected to the server.`)
            res()
        })
        mcClient.on('raw', p => {
            if (p[0] == 0x03 && !receivedCompression) {
                receivedCompression = true
                const compT = {
                    id: null,
                    thres: null
                }
                const id = decodeVarInt(p)
                compT.id = Number(id[0])
                const thres = decodeSVarInt(p.subarray(id[1]))
                compT.thres = thres[0]

                client.compressionThreshold = compT.thres
                client.ws.send(p)
            } else {
                client.ws.send(p)
            }
        })
    })
}

export async function doHandshake(client: ProxiedPlayer, initialPacket: Buffer) {
    client.ws.on('close', () => {
        client.state = State.DISCONNECTED
        if (client.remoteConnection) {
            client.remoteConnection.end()
        }
        PROXY.players.delete(client.username)
        PROXY.playerStats.onlineCount -= 1
        logger.info(`Client [/${client.ip}:${client.remotePort}]${client.username ? ` (${client.username})` : ""} disconnected from the server.`)
    })
    if (PROXY.players.size + 1 > PROXY.playerStats.max) {
        disconnect(client, "The proxy is full!", DisconnectReason.CUSTOM)
        return
    }
    const identifyC = {
        id: null,
        brandingLen: null,
        branding: null,
        verLen: null,
        ver: null
    }
    if (true) {
        // save namespace by nesting func declarations in a if true statement
        const Iid = decodeVarInt(initialPacket)
        identifyC.id = Number(Iid[0])
        const brandingLen = decodeVarInt(initialPacket.subarray(Iid[1] + 2))
        identifyC.brandingLen = Number(brandingLen[0])
        identifyC.branding = initialPacket.subarray(brandingLen[1] + Iid[1] + 2, brandingLen[1] + Iid[1] + Number(brandingLen[0]) + 2).toString()
        const verLen = decodeVarInt(initialPacket.subarray(brandingLen[1] + Iid[1] + Number(brandingLen[0]) + 2))
        identifyC.verLen = Number(verLen[0])
        identifyC.ver = initialPacket.subarray(brandingLen[1] + Number(brandingLen[0]) + Iid[1] + verLen[1] + 2).toString()
    }
    if (true) {
        const brandingLen = encodeVarInt(PROXY.brand.length), brand = PROXY.brand
        const verLen = encodeVarInt(PROXY.version.length), version = PROXY.version
        const buff = Buffer.alloc(2 + MAGIC_ENDING_IDENTIFYS_BYTES.length + brandingLen.length + brand.length + verLen.length + version.length)
        buff.set([EaglerPacketId.IDENTIFY_SERVER, 0x01, ...brandingLen, ...Buffer.from(brand), ...verLen, ...Buffer.from(version), ...Buffer.from(MAGIC_ENDING_IDENTIFYS_BYTES)])
        client.ws.send(buff)
    }
    client.clientBrand = identifyC.branding
    const login = await awaitPacket(client.ws)
    const loginP = {
        id: null,
        usernameLen: null,
        username: null,
        randomStrLen: null,
        randomStr: null,
        nullByte: null
    }
    if (login[0] === EaglerPacketId.LOGIN) {
        const Iid = decodeVarInt(login)
        loginP.id = Number(Iid[0])
        const usernameLen = decodeVarInt(login.subarray(loginP[1]))
        loginP.usernameLen = Number(usernameLen[0])
        loginP.username = login.subarray(Iid[1] + usernameLen[1], Iid[1] + usernameLen[1] + loginP.usernameLen).toString()
        const randomStrLen = decodeVarInt(login.subarray(Iid[1] + usernameLen[1] + loginP.usernameLen))
        loginP.randomStrLen = Number(randomStrLen[0])
        loginP.randomStr = login.subarray(Iid[1] + usernameLen[1] + loginP.usernameLen + randomStrLen[1], Iid[1] + usernameLen[1] + loginP.usernameLen + randomStrLen[1] + loginP.randomStrLen).toString()
        client.username = loginP.username
        client.uuid = genUUID(client.username)
        try { validateUsername(client.username) }
        catch (err) {
            disconnect(client, err.message, DisconnectReason.BAD_USERNAME)
            return
        }
        if (PROXY.players.has(client.username)) {
            disconnect(client, `Duplicate username: ${client.username}. Please connect under a different username.`, DisconnectReason.DUPLICATE_USERNAME)
            return
        }
        PROXY.players.set(client.username, client)
        if (true) {
            const usernameLen = encodeVarInt(client.username.length), username = client.username
            const uuidLen = encodeVarInt(client.uuid.length), uuid = client.uuid
            const buff = Buffer.alloc(1 + usernameLen.length + username.length + uuidLen.length + uuid.length)
            buff.set([EaglerPacketId.LOGIN_ACK, ...usernameLen, ...Buffer.from(username), ...uuidLen, ...Buffer.from(uuid)])
            client.ws.send(buff)
            
            if (true) {
                const [skin, ready] = await Promise.all([awaitPacket(client.ws, EaglerPacketId.SKIN), awaitPacket(client.ws, EaglerPacketId.C_READY)])
                if (ready[0] != 0x08) {
                    logger.error(`Client [/${client.ip}:${client.remotePort}] sent an unexpected packet! Disconnecting.`)
                    disconnect(client, "Received bad packet", DisconnectReason.UNEXPECTED_PACKET)
                    client.ws.close()
                    return
                }

                const buff = Buffer.alloc(1)
                buff.set([EaglerPacketId.COMPLETE_HANDSHAKE])
                client.ws.send(buff)

                client.state = State.POST_HANDSHAKE
                PROXY.playerStats.onlineCount += 1

                logger.info(`Client [/${client.ip}:${client.remotePort}] authenticated as player "${client.username}" and passed handshake. Connecting!`)
                try { await loginServer(config.server.host, config.server.port, client) }
                catch (err) {
                    logger.error(`Could not connect to remote server at [/${config.server.host}:${config.server.port}]: ${err}`)
                    disconnect(client, "Failed to connect to server. Please try again later.", DisconnectReason.CUSTOM)
                    client.state = State.DISCONNECTED
                    client.ws.close()
                    return
                }
            }
        }
    } else {
        logger.error(`Client [/${client.ip}:${client.remotePort}] sent an unexpected packet! Disconnecting.`)
        disconnect(client, "Received bad packet", DisconnectReason.UNEXPECTED_PACKET)
        client.ws.close()
    }
}