const Bzip2 = require('seek-bzip');
const Core = require('./core');
const Results = require('../lib/Results');
const Reader = require('../lib/reader');

const AppId = {
    Squad: 393380,
    Bat1944: 489940,
    Ship: 2400,
    DayZ: 221100,
    Rust: 252490,
    CSGO: 730,
    CS_Source: 240,
    EternalSilence: 17550,
    Insurgency_MIC: 17700,
    Source_SDK_Base_2006: 215
};

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(/** Results */ state) {
        this.debugLog("Requesting info ...");
        const b = await this.sendPacket(
            this.goldsrcInfo ? undefined : 0x54,
            this.goldsrcInfo ? 'details' : '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();
        if(!this.goldsrcInfo) state.raw.appId = 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 = String.fromCharCode(reader.uint(1));
        state.raw.environment = String.fromCharCode(reader.uint(1));

        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);
            }
        } else {
            state.raw.secure = reader.uint(1);
            if(state.raw.appId === AppId.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).toString();
            if(extraFlag & 0x40) {
                state.raw.sourcetvport = reader.uint(2);
                state.raw.sourcetvname = reader.string();
            }
            if(extraFlag & 0x20) state.raw.tags = reader.string().split(',');
            if(extraFlag & 0x01) {
                const gameId = reader.uint(8);
                const betterAppId = gameId.getLowBitsUnsigned() & 0xffffff;
                if (betterAppId) {
                    state.raw.appId = betterAppId;
                }
            }
        }

        const appId = state.raw.appId;

        // from https://developer.valvesoftware.com/wiki/Server_queries
        if(
            state.raw.protocol === 7 && (
                state.raw.appId === AppId.Source_SDK_Base_2006
                || state.raw.appId === AppId.EternalSilence
                || state.raw.appId === AppId.Insurgency_MIC
                || state.raw.appId === AppId.CS_Source
            )
        ) {
            this._skipSizeInSplitHeader = true;
        }
        this.logger.debug("INFO: ", state.raw);
        if(state.raw.protocol === 48) {
            this.logger.debug("GOLDSRC DETECTED - USING MODIFIED SPLIT FORMAT");
            this.goldsrcSplits = true;
        }

        // DayZ embeds some of the server information inside the tags attribute
        if (appId === AppId.DayZ) {
            if (state.raw.tags) {
                state.raw.dlcEnabled = false
                state.raw.firstPerson = false
                for (const tag of state.raw.tags) {
                    if (tag.startsWith('lqs')) {
                        const value = parseInt(tag.replace('lqs', ''));
                        if (!isNaN(value)) {
                            state.raw.queue = value;
                        }
                    }
                    if (tag.includes('no3rd')) {
                        state.raw.firstPerson = true;
                    }
                    if (tag.includes('isDLC')) {
                        state.raw.dlcEnabled = true;
                    }
                    if (tag.includes(':')) {
                        state.raw.time = tag;
                    }
                    if (tag.startsWith('etm')) {
                        const value = parseInt(tag.replace('etm', ''));
                        if (!isNaN(value)) {
                            state.raw.dayAcceleration = value;
                        }
                    }
                    if (tag.startsWith('entm')) {
                        const value = parseInt(tag.replace('entm', ''));
                        if (!isNaN(value)) {
                            state.raw.nightAcceleration = value;
                        }
                    }
                }
            }
        }

        if (appId === AppId.Rust) {
            if (state.raw.tags) {
                for (const tag of state.raw.tags) {
                    if (tag.startsWith('mp')) {
                        const value = parseInt(tag.replace('mp', ''));
                        if (!isNaN(value)) {
                            state.maxplayers = value;
                        }
                    }
                }
            }
        }
    }

    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,
                null,
                0x41,
                false
            );
        }
    }

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

        this.debugLog("Requesting player list ...");
        const b = await this.sendPacket(
            this.goldsrcInfo ? undefined : 0x55,
            this.goldsrcInfo ? 'players' : null,
            0x44,
            true
        );

        if (b === null) {
            // Player query timed out
            // CSGO doesn't respond to player query if host_players_show is not 2
            // Conan Exiles never responds to player query
            // Just skip it, and we'll fill with dummy objects in cleanup()
            return;
        }

        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.appId === AppId.CSGO && name === 'Max Players') continue;

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

    async queryRules(/** Results */ state) {
        const appId = state.raw.appId;
        if (appId === AppId.Squad
            || appId === AppId.Bat1944
            || this.options.requestRules) {
            // let's get 'em
        } else {
            return;
        }

        const rules = {};
        state.raw.rules = rules;
        const dayZPayload = [];

        this.debugLog("Requesting rules ...");

        if (this.goldsrcInfo) {
            const b = await this.udpSend('\xff\xff\xff\xffrules', b=>b, ()=>null);
            if (b === null) return; // timed out - the server probably has rules disabled
            const reader = this.reader(b);
            while (!reader.done()) {
                const key = reader.string();
                const value = reader.string();
                rules[key] = value;
            }
        } else {
            const b = await this.sendPacket(0x56,null,0x45,true);
            if (b === null) return; // timed out - the server probably has rules disabled

            let dayZPayloadEnded = false;

            const reader = this.reader(b);
            const num = reader.uint(2);
            for (let i = 0; i < num; i++) {
                if (appId === AppId.DayZ && !dayZPayloadEnded) {
                    const one = reader.uint(1);
                    const two = reader.uint(1);
                    const three = reader.uint(1);
                    if (one !== 0 && two !== 0 && three === 0) {
                        while (true) {
                            const byte = reader.uint(1);
                            if (byte === 0) break;
                            dayZPayload.push(byte);
                        }
                        continue;
                    } else {
                        reader.skip(-3);
                        dayZPayloadEnded = true;
                    }
                }

                const key = reader.string();
                const value = reader.string();
                rules[key] = value;
            }
        }

        // Battalion 1944 puts its info into rules fields for some reason
        if (appId === AppId.Bat1944) {
            if ('bat_name_s' in rules) {
                state.name = rules.bat_name_s;
                delete rules.bat_name_s;
                if ('bat_player_count_s' in rules) {
                    state.raw.numplayers = parseInt(rules.bat_player_count_s);
                    delete rules.bat_player_count_s;
                }
                if ('bat_max_players_i' in rules) {
                    state.maxplayers = parseInt(rules.bat_max_players_i);
                    delete rules.bat_max_players_i;
                }
                if ('bat_has_password_s' in rules) {
                    state.password = rules.bat_has_password_s === 'Y';
                    delete rules.bat_has_password_s;
                }
                // apparently map is already right, and this var is often wrong
                delete rules.bat_map_s;
            }
        }

        // Squad keeps its password in a separate field
        if (appId === AppId.Squad) {
            if (rules.Password_b === "true") {
                state.password = true;
            }
        }

        if (appId === AppId.DayZ) {
            state.raw.dayzMods = this.readDayzMods(Buffer.from(dayZPayload));
        }
    }

    readDayzMods(/** Buffer */ buffer) {
        if (!buffer.length) {
            return {};
        }

        this.logger.debug("DAYZ BUFFER");
        this.logger.debug(buffer);

        const reader = this.reader(buffer);
        const version = this.readDayzByte(reader);
        const overflow = this.readDayzByte(reader);
        const dlc1 = this.readDayzByte(reader);
        const dlc2 = this.readDayzByte(reader);
        this.logger.debug("version " + version);
        this.logger.debug("overflow " + overflow);
        this.logger.debug("dlc1 " + dlc1);
        this.logger.debug("dlc2 " + dlc2);
        if (dlc1) {
            const unknown = this.readDayzUint(reader, 4); // ?
            this.logger.debug("unknown " + unknown);
        }
        if (dlc2) {
            const unknown = this.readDayzUint(reader, 4); // ?
            this.logger.debug("unknown " + unknown);
        }
        const mods = [];
        mods.push(...this.readDayzModsSection(reader, true));
        mods.push(...this.readDayzModsSection(reader, false));
        this.logger.debug("dayz buffer rest:", reader.rest());
        return mods;
    }
    readDayzModsSection(/** Reader */ reader, withHeader) {
        const out = [];
        const count = this.readDayzByte(reader);
        this.logger.debug("dayz mod section withHeader:" + withHeader + " count:" + count);
        for(let i = 0; i < count; i++) {
            if (reader.done()) break;
            const mod = {};
            if (withHeader) {
                mod.unknown = this.readDayzUint(reader, 4); // ?

                // For some reason this is 4 on all of them, but doesn't exist on the last one? but only sometimes?
                const offset = reader.offset();
                const flag = this.readDayzByte(reader);
                if (flag !== 4) reader.setOffset(offset);

                mod.workshopId = this.readDayzUint(reader, 4);
            }
            mod.title = this.readDayzString(reader);
            this.logger.debug(mod);
            out.push(mod);
        }
        return out;
    }
    readDayzUint(reader, bytes) {
        const out = [];
        for (let i = 0; i < bytes; i++) {
            out.push(this.readDayzByte(reader));
        }
        const buf = Buffer.from(out);
        const r2 = this.reader(buf);
        return r2.uint(bytes);
    }
    readDayzByte(reader) {
        const byte = reader.uint(1);
        if (byte === 1) {
            const byte2 = reader.uint(1);
            if (byte2 === 1) return 1;
            if (byte2 === 2) return 0;
            if (byte2 === 3) return 0xff;
            return 0; // ?
        }
        return byte;
    }
    readDayzString(reader) {
        const length = this.readDayzByte(reader);
        const out = [];
        for (let i = 0; i < length; i++) {
            out.push(this.readDayzByte(reader));
        }
        return Buffer.from(out).toString('utf8');
    }

    async cleanup(/** Results */ state) {
        // 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 || 0;
        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,
        payload,
        expect,
        allowTimeout
    ) {
        for (let keyRetry = 0; keyRetry < 3; keyRetry++) {
            let receivedNewChallengeKey = false;
            const response = await this.sendPacketRaw(
                type, payload,
                (payload) => {
                    const reader = this.reader(payload);
                    const type = reader.uint(1);
                    this.debugLog(() => "Received 0x" + type.toString(16) + " expected 0x" + expect.toString(16));
                    if (type === 0x41) {
                        const key = reader.uint(4);
                        if (this._challenge !== key) {
                            this.debugLog('Received new challenge key: 0x' + key.toString(16));
                            this._challenge = key;
                            receivedNewChallengeKey = true;
                        }
                    }
                    if (type === expect) {
                        return reader.rest();
                    } else if (receivedNewChallengeKey) {
                        return null;
                    }
                },
                () => {
                    if (allowTimeout) return null;
                }
            );
            if (!receivedNewChallengeKey) {
                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,
        payload,
        onResponse,
        onTimeout
    ) {
        const challengeAtBeginning = type === 0x55 || type === 0x56;
        const challengeAtEnd = type === 0x54 && !!this._challenge;

        if (typeof payload === 'string') payload = Buffer.from(payload, 'binary');

        const b = Buffer.alloc(4
            + (type !== undefined ? 1 : 0)
            + (challengeAtBeginning ? 4 : 0)
            + (challengeAtEnd ? 4 : 0)
            + (payload ? payload.length : 0)
        );
        let offset = 0;

        let challenge = this._challenge;
        if (!challenge) challenge = 0xffffffff;

        b.writeInt32LE(-1, offset);
        offset += 4;

        if (type !== undefined) {
            b.writeUInt8(type, offset);
            offset += 1;
        }

        if (challengeAtBeginning) {
            if (this.byteorder === 'le') b.writeUInt32LE(challenge, offset);
            else b.writeUInt32BE(challenge, offset);
            offset += 4;
        }

        if (payload) {
            payload.copy(b, offset);
            offset += payload.length;
        }

        if (challengeAtEnd) {
            if (this.byteorder === 'le') b.writeUInt32LE(challenge, offset);
            else b.writeUInt32BE(challenge, offset);
            offset += 4;
        }

        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: 0x"+uid.toString(16)+" 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 = Bzip2.decode(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;