const Bzip2 = require('compressjs').Bzip2,
    Core = require('./core');

class Valve extends Core {
    constructor() {
        super();

        // legacy goldsrc info response -- basically not used by ANYTHING now,
        // as most (all?) goldsrc servers respond with the source info reponse
        // delete in a few years if nothing ends up using it anymore
        this.goldsrcInfo = false;

        // unfortunately, the split format from goldsrc is still around, but we
        // can detect that during the query
        this.goldsrcSplits = false;

        // some mods require a challenge, but don't provide them in the new format
        // at all, use the old dedicated challenge query if needed
        this.legacyChallenge = false;

        // 2006 engines don't pass packet switching size in split packet header
        // while all others do, this need is detected automatically
        this._skipSizeInSplitHeader = false;

        this._challenge = '';
    }

    async run(state) {
        if (!this.options.port) this.options.port = 27015;
        await this.queryInfo(state);
        await this.queryChallenge();
        await this.queryPlayers(state);
        await this.queryRules(state);
        await this.cleanup(state);
    }

    async queryInfo(state) {
        this.debugLog("Requesting info ...");
        const b = await this.sendPacket(
            0x54,
            false,
            'Source Engine Query\0',
            this.goldsrcInfo ? 0x6D : 0x49,
            false
        );

        const reader = this.reader(b);

        if(this.goldsrcInfo) state.raw.address = reader.string();
        else state.raw.protocol = reader.uint(1);

        state.name = reader.string();
        state.map = reader.string();
        state.raw.folder = reader.string();
        state.raw.game = reader.string();
        state.raw.steamappid = reader.uint(2);
        state.raw.numplayers = reader.uint(1);
        state.maxplayers = reader.uint(1);

        if(this.goldsrcInfo) state.raw.protocol = reader.uint(1);
        else state.raw.numbots = reader.uint(1);

        state.raw.listentype = reader.uint(1);
        state.raw.environment = reader.uint(1);
        if(!this.goldsrcInfo) {
            state.raw.listentype = String.fromCharCode(state.raw.listentype);
            state.raw.environment = String.fromCharCode(state.raw.environment);
        }

        state.password = !!reader.uint(1);
        if(this.goldsrcInfo) {
            state.raw.ismod = reader.uint(1);
            if(state.raw.ismod) {
                state.raw.modlink = reader.string();
                state.raw.moddownload = reader.string();
                reader.skip(1);
                state.raw.modversion = reader.uint(4);
                state.raw.modsize = reader.uint(4);
                state.raw.modtype = reader.uint(1);
                state.raw.moddll = reader.uint(1);
            }
        }
        state.raw.secure = reader.uint(1);

        if(this.goldsrcInfo) {
            state.raw.numbots = reader.uint(1);
        } else {
            if(state.raw.folder === 'ship') {
                state.raw.shipmode = reader.uint(1);
                state.raw.shipwitnesses = reader.uint(1);
                state.raw.shipduration = reader.uint(1);
            }
            state.raw.version = reader.string();
            const extraFlag = reader.uint(1);
            if(extraFlag & 0x80) state.gamePort = reader.uint(2);
            if(extraFlag & 0x10) state.raw.steamid = reader.uint(8);
            if(extraFlag & 0x40) {
                state.raw.sourcetvport = reader.uint(2);
                state.raw.sourcetvname = reader.string();
            }
            if(extraFlag & 0x20) state.raw.tags = reader.string();
            if(extraFlag & 0x01) state.raw.gameid = reader.uint(8);
        }

        // from https://developer.valvesoftware.com/wiki/Server_queries
        if(
            state.raw.protocol === 7 && (
                state.raw.steamappid === 215
                || state.raw.steamappid === 17550
                || state.raw.steamappid === 17700
                || state.raw.steamappid === 240
            )
        ) {
            this._skipSizeInSplitHeader = true;
        }
        this.debugLog("STEAM APPID: "+state.raw.steamappid);
        this.debugLog("PROTOCOL: "+state.raw.protocol);
        if(state.raw.protocol === 48) {
            this.debugLog("GOLDSRC DETECTED - USING MODIFIED SPLIT FORMAT");
            this.goldsrcSplits = true;
        }
    }

    async queryChallenge() {
        if(this.legacyChallenge) {
            // sendPacket will catch the response packet and
            // save the challenge for us
            this.debugLog("Requesting legacy challenge key ...");
            await this.sendPacket(
                0x57,
                false,
                null,
                0x41,
                false
            );
        }
    }

    async queryPlayers(state) {
        state.raw.players = [];

        // CSGO doesn't even respond sometimes if host_players_show is not 2
        // Ignore timeouts in only this case
        const allowTimeout = state.raw.steamappid === 730;

        this.debugLog("Requesting player list ...");
        const b = await this.sendPacket(
            0x55,
            true,
            null,
            0x44,
            allowTimeout
        );
        if (b === null) return; // timed out

        const reader = this.reader(b);
        const num = reader.uint(1);
        for(let i = 0; i < num; i++) {
            reader.skip(1);
            const name = reader.string();
            const score = reader.int(4);
            const time = reader.float();

            this.debugLog("Found player: "+name+" "+score+" "+time);

            // connecting players don't count as players.
            if(!name) continue;

            // CSGO sometimes adds a bot named 'Max Players' if host_players_show is not 2
            if (state.raw.steamappid === 730 && name === 'Max Players') continue;

            state.raw.players.push({
                name:name, score:score, time:time
            });
        }
    }

    async queryRules(state) {
        state.raw.rules = {};
        this.debugLog("Requesting rules ...");
        const b = await this.sendPacket(0x56,true,null,0x45,true);
        if (b === null) return; // timed out - the server probably just has rules disabled

        const reader = this.reader(b);
        const num = reader.uint(2);
        for(let i = 0; i < num; i++) {
            const key = reader.string();
            const value = reader.string();
            state.raw.rules[key] = value;
        }
    }

    async cleanup(state) {
        // Battalion 1944 puts its info into rules fields for some reason
        if ('bat_name_s' in state.raw.rules) {
            state.name = state.raw.rules.bat_name_s;
            delete state.raw.rules.bat_name_s;
            if ('bat_player_count_s' in state.raw.rules) {
                state.raw.numplayers = parseInt(state.raw.rules.bat_player_count_s);
                delete state.raw.rules.bat_player_count_s;
            }
            if ('bat_max_players_i' in state.raw.rules) {
                state.maxplayers = parseInt(state.raw.rules.bat_max_players_i);
                delete state.raw.rules.bat_max_players_i;
            }
            if ('bat_has_password_s' in state.raw.rules) {
                state.password = state.raw.rules.bat_has_password_s === 'Y';
                delete state.raw.rules.bat_has_password_s;
            }
            // apparently map is already right, and this var is often wrong
            delete state.raw.rules.bat_map_s;
        }

        // Organize players / hidden players into player / bot arrays
        const botProbability = (p) => {
            if (p.time === -1) return Number.MAX_VALUE;
            return p.time;
        };
        const sortedPlayers = state.raw.players.sort((a,b) => {
            return botProbability(a) - botProbability(b);
        });
        delete state.raw.players;
        const numBots = state.raw.numbots;
        const numPlayers = state.raw.numplayers - numBots;
        while(state.bots.length < numBots) {
            if (sortedPlayers.length) state.bots.push(sortedPlayers.pop());
            else state.bots.push({});
        }
        while(state.players.length < numPlayers || sortedPlayers.length) {
            if (sortedPlayers.length) state.players.push(sortedPlayers.pop());
            else state.players.push({});
        }
    }

    /**
     * Sends a request packet and returns only the response type expected
     * @param {number} type
     * @param {boolean} sendChallenge
     * @param {?string|Buffer} payload
     * @param {number} expect
     * @param {boolean=} allowTimeout
     * @returns Buffer|null
     **/
    async sendPacket(
        type,
        sendChallenge,
        payload,
        expect,
        allowTimeout
    ) {
        for (let keyRetry = 0; keyRetry < 3; keyRetry++) {
            let requestKeyChanged = false;
            const response = await this.sendPacketRaw(
                type, sendChallenge, payload,
                (payload) => {
                    const reader = this.reader(payload);
                    const type = reader.uint(1);
                    this.debugLog(() => "Received " + type.toString(16) + " expected " + expect.toString(16));
                    if (type === 0x41) {
                        const key = reader.uint(4);
                        if (this._challenge !== key) {
                            this.debugLog('Received new challenge key: ' + key);
                            this._challenge = key;
                            if (sendChallenge) {
                                this.debugLog('Challenge key changed -- allowing query retry if needed');
                                requestKeyChanged = true;
                            }
                        }
                    }
                    if (type === expect) {
                        return reader.rest();
                    } else if (requestKeyChanged) {
                        return null;
                    }
                },
                () => {
                    if (allowTimeout) return null;
                }
            );
            if (!requestKeyChanged) {
                return response;
            }
        }
        throw new Error('Received too many challenge key responses');
    }

    /**
     * Sends a request packet and assembles partial responses
     * @param {number} type
     * @param {boolean} sendChallenge
     * @param {?string|Buffer} payload
     * @param {function(Buffer)} onResponse
     * @param {function()} onTimeout
     **/
    async sendPacketRaw(
        type,
        sendChallenge,
        payload,
        onResponse,
        onTimeout
    ) {
        if (typeof payload === 'string') payload = Buffer.from(payload, 'binary');
        const challengeLength = sendChallenge ? 4 : 0;
        const payloadLength = payload ? payload.length : 0;

        const b = Buffer.alloc(5 + challengeLength + payloadLength);
        b.writeInt32LE(-1, 0);
        b.writeUInt8(type, 4);

        if (sendChallenge) {
            let challenge = this._challenge;
            if (!challenge) challenge = 0xffffffff;
            if (this.byteorder === 'le') b.writeUInt32LE(challenge, 5);
            else b.writeUInt32BE(challenge, 5);
        }
        if (payloadLength) payload.copy(b, 5 + challengeLength);

        const packetStorage = {};
        return await this.udpSend(
            b,
            (buffer) => {
                const reader = this.reader(buffer);
                const header = reader.int(4);
                if(header === -1) {
                    // full package
                    this.debugLog("Received full packet");
                    return onResponse(reader.rest());
                }
                if(header === -2) {
                    // partial package
                    const uid = reader.uint(4);
                    if(!(uid in packetStorage)) packetStorage[uid] = {};
                    const packets = packetStorage[uid];

                    let bzip = false;
                    if(!this.goldsrcSplits && uid & 0x80000000) bzip = true;

                    let packetNum,payload,numPackets;
                    if(this.goldsrcSplits) {
                        packetNum = reader.uint(1);
                        numPackets = packetNum & 0x0f;
                        packetNum = (packetNum & 0xf0) >> 4;
                        payload = reader.rest();
                    } else {
                        numPackets = reader.uint(1);
                        packetNum = reader.uint(1);
                        if(!this._skipSizeInSplitHeader) reader.skip(2);
                        if(packetNum === 0 && bzip) reader.skip(8);
                        payload = reader.rest();
                    }

                    packets[packetNum] = payload;

                    this.debugLog(() => "Received partial packet uid:"+uid+" num:"+packetNum);
                    this.debugLog(() => "Received "+Object.keys(packets).length+'/'+numPackets+" packets for this UID");

                    if(Object.keys(packets).length !== numPackets) return;

                    // assemble the parts
                    const list = [];
                    for(let i = 0; i < numPackets; i++) {
                        if(!(i in packets)) {
                            throw new Error('Missing packet #'+i);
                        }
                        list.push(packets[i]);
                    }

                    let assembled = Buffer.concat(list);
                    if(bzip) {
                        this.debugLog("BZIP DETECTED - Extracing packet...");
                        try {
                            assembled = Buffer.from(Bzip2.decompressFile(assembled));
                        } catch(e) {
                            throw new Error('Invalid bzip packet');
                        }
                    }
                    const assembledReader = this.reader(assembled);
                    assembledReader.skip(4); // header
                    return onResponse(assembledReader.rest());
                }
            },
            onTimeout
        );
    }
}

module.exports = Valve;