const { DTM } = require('./DTM.cjs');
const { DEFAULT_DEVICE, DEFAULT_SWD_SPEED } = require('./DTM_transport.cjs');
const {
    ChannelMode,
    DtmModulationMode,
    DtmPacketType,
    DtmPhysicalLayer,
} = require('./dtm-types.cjs');
const { listJLinkProbes, getJLinkSetupHint } = require('./jlink/jlinkProbe.cjs');
const { hasSeggerRttStack } = require('./jlink/jlinkPaths.cjs');
const { allocateSessionPorts, JLINK_PORTS_BY_SESSION } = require('./jlink/jlinkSessionPorts.cjs');

const BLE_CHANNELS = Array.from({ length: 40 }, (_, index) => index);
const SESSION_IDS = ['receiver', 'transmitter'];

const createInitialStatus = mode => ({
    running: false,
    mode,
    currentChannel: null,
    lastReceived: new Array(40).fill(0),
    txPower: 0,
    message: 'Idle',
    jlinkPorts: null,
});

const allocatedPortsBySession = {
    receiver: null,
    transmitter: null,
};

const getGloballyReservedPorts = () => {
    const reserved = new Set();
    for (const sessionId of SESSION_IDS) {
        const ports = allocatedPortsBySession[sessionId];
        if (!ports) continue;
        reserved.add(ports.gdb);
        reserved.add(ports.swo);
        reserved.add(ports.rtt);
    }
    return reserved;
};

const dtmBySession = {
    receiver: null,
    transmitter: null,
};

const configKeyBySession = {
    receiver: '',
    transmitter: '',
};

const lastConfigBySession = {
    receiver: null,
    transmitter: null,
};

const runningBySession = {
    receiver: false,
    transmitter: false,
};

const startingBySession = {
    receiver: false,
    transmitter: false,
};

const statusBySession = {
    receiver: createInitialStatus('receiver'),
    transmitter: createInitialStatus('transmitter'),
};

let dtmEventSink = () => undefined;

const configKey = config =>
    `${config.port}|${config.device || DEFAULT_DEVICE}|${Number(config.speed || DEFAULT_SWD_SPEED)}`;
const wait = ms => new Promise(resolve => setTimeout(resolve, ms));

const probeSerialForSession = sessionId => {
    const fromConfig = lastConfigBySession[sessionId]?.port;
    if (fromConfig) return String(fromConfig);
    const key = configKeyBySession[sessionId];
    return key ? key.split('|')[0] : '';
};

const emit = event => {
    dtmEventSink(event);
};

const emitForSession = (sessionId, event) => {
    emit({ sessionId, ...event });
};

const getSessionStatus = sessionId => statusBySession[sessionId];

const releaseDtm = async sessionId => {
    if (!dtmBySession[sessionId]) {
        allocatedPortsBySession[sessionId] = null;
        getSessionStatus(sessionId).jlinkPorts = null;
        return;
    }

    const instance = dtmBySession[sessionId];
    dtmBySession[sessionId] = null;
    configKeyBySession[sessionId] = '';
    allocatedPortsBySession[sessionId] = null;
    getSessionStatus(sessionId).jlinkPorts = null;
    await instance.dispose().catch(() => {});
    await wait(800);
};

const isSessionBusy = sessionId => {
    const status = getSessionStatus(sessionId);
    return runningBySession[sessionId] || startingBySession[sessionId] || status.running;
};

const sharesProbeSerial = (leftPort, rightPort) =>
    Boolean(leftPort) && Boolean(rightPort) && String(leftPort) === String(rightPort);

const findProbeConflict = (sessionId, config) => {
    if (!config.port) return null;

    for (const otherSessionId of SESSION_IDS) {
        if (otherSessionId === sessionId) continue;

        const sameProbe = sharesProbeSerial(probeSerialForSession(otherSessionId), config.port);

        if (!sameProbe) continue;

        if (startingBySession[otherSessionId] || runningBySession[otherSessionId] || dtmBySession[otherSessionId]) {
            return otherSessionId;
        }
    }

    return null;
};

const assertProbeAvailable = (sessionId, config) => {
    const conflict = findProbeConflict(sessionId, config);
    if (!conflict) return;

    throw new Error(
        `동일 J-Link(SN ${config.port})는 GDB Server를 하나만 쓸 수 있습니다. ${conflict} 세션을 Stop한 뒤 ${sessionId}를 시작하세요. 서로 다른 SN이면 동시 실행이 가능합니다.`
    );
};

const releaseInactiveSessionUsingProbe = async (sessionId, config) => {
    const nextKey = configKey(config);
    const otherSessionId = SESSION_IDS.find(id => id !== sessionId && configKeyBySession[id] === nextKey);

    if (!otherSessionId) return;

    if (isSessionBusy(otherSessionId) || dtmBySession[otherSessionId]) {
        throw new Error(
            `동일 J-Link(${config.port})는 RTT 세션을 하나만 열 수 있습니다. ${otherSessionId} 세션을 Stop한 뒤 다시 시도하세요.`
        );
    }

    await releaseDtm(otherSessionId);
};

const attachEvents = (sessionId, instance) => {
    instance.onReset(() => {
        const status = getSessionStatus(sessionId);
        status.currentChannel = null;
        status.lastReceived = new Array(40).fill(0);
        emitForSession(sessionId, { type: 'reset' });
    });

    instance.onStarted(event => {
        const status = getSessionStatus(sessionId);
        status.currentChannel = event.channel;
        emitForSession(sessionId, { type: 'started', channel: event.channel, mode: event.type });
    });

    instance.onEnded(event => {
        const status = getSessionStatus(sessionId);
        status.currentChannel = null;
        if (typeof event.packets === 'number') {
            if (event.accumulate) {
                status.lastReceived[event.channel] += event.packets;
            } else {
                status.lastReceived[event.channel] = Math.max(
                    status.lastReceived[event.channel] || 0,
                    event.packets
                );
            }
        }
        emitForSession(sessionId, {
            type: 'ended',
            channel: event.channel,
            mode: event.type,
            data: [...status.lastReceived],
            ...(typeof event.packets === 'number' ? { packets: event.packets } : {}),
        });
    });

    instance.onPackets(event => {
        const status = getSessionStatus(sessionId);
        if (typeof event.packets !== 'number' || typeof event.channel !== 'number') {
            return;
        }
        status.lastReceived[event.channel] = event.packets;
        emitForSession(sessionId, {
            type: 'packets',
            channel: event.channel,
            packets: event.packets,
            data: [...status.lastReceived],
        });
    });

    instance.onTraffic(event => {
        if (sessionId === 'transmitter' && event.kind === 'packetReport') {
            return;
        }
        emitForSession(sessionId, {
            type: 'traffic',
            direction: event.direction,
            data: event.data,
            note: event.note,
        });
    });
};

const ensureDtm = async (sessionId, config) => {
    const nextKey = configKey(config);
    await releaseInactiveSessionUsingProbe(sessionId, config);

    if (!dtmBySession[sessionId] || configKeyBySession[sessionId] !== nextKey) {
        await releaseDtm(sessionId);
        const ports = await allocateSessionPorts(sessionId, getGloballyReservedPorts());
        allocatedPortsBySession[sessionId] = ports;
        getSessionStatus(sessionId).jlinkPorts = ports;

        const instance = new DTM(config.port, {
            device: config.device || DEFAULT_DEVICE,
            speed: Number(config.speed || DEFAULT_SWD_SPEED),
            gdbPort: ports.gdb,
            swoPort: ports.swo,
            rttPort: ports.rtt,
        });
        attachEvents(sessionId, instance);
        await instance.connect();
        dtmBySession[sessionId] = instance;
        configKeyBySession[sessionId] = nextKey;

        emitForSession(sessionId, {
            type: 'status',
            message: `RTT ports GDB ${ports.gdb} / SWO ${ports.swo} / RTT ${ports.rtt}`,
            running: false,
            mode: getSessionStatus(sessionId).mode,
            jlinkPorts: ports,
        });
    }
    return dtmBySession[sessionId];
};

const runSetupStep = async (sessionId, label, action) => {
    const status = getSessionStatus(sessionId);
    status.message = label;
    emitForSession(sessionId, { type: 'status', message: label, running: true, mode: status.mode });

    try {
        return await action();
    } catch (error) {
        const message = error instanceof Error ? error.message : String(error);
        if (message === 'Timeout') {
            throw new Error(
                `${label} timed out. Check J-Link SN, SWD, target device (NRF52840_xxAA), DTM_TRANSPORT_RTT firmware flashed and running, and traffic log for TX without RX. Close Ozone or a second GDB Server on the same probe.`
            );
        }
        throw new Error(`${label} failed: ${message}`);
    }
};

const setupTest = async (sessionId, instance, config) => {
    const status = getSessionStatus(sessionId);

    await runSetupStep(sessionId, 'Resetting device', () => instance.setupReset());

    if (config.testMode === 'transmitter') {
        status.txPower = await runSetupStep(sessionId, 'Applying TX power', () =>
            instance.setTxPower(Number(config.txPower))
        );
        await runSetupStep(sessionId, 'Applying packet length', () =>
            instance.setupLength(Number(config.length))
        );
        await runSetupStep(sessionId, 'Applying modulation mode', () =>
            instance.setupModulation(Number(config.modulationMode))
        );
    } else {
        await runSetupStep(sessionId, 'Applying packet length', () =>
            instance.setupLength(Number(config.length))
        );
    }

    await runSetupStep(sessionId, 'Applying PHY mode', () => instance.setupPhy(Number(config.phy)));
};

const normalizeChannelIndexes = config => {
    const single = BLE_CHANNELS.indexOf(Number(config.singleChannel));
    const rangeValues = [Number(config.rangeStart), Number(config.rangeEnd)];
    const indexedRange = rangeValues.map(value => BLE_CHANNELS.indexOf(value)).sort((a, b) => a - b);
    return {
        singleChannelIndexed: single,
        rangeStart: indexedRange[0],
        rangeEnd: indexedRange[1],
    };
};

const startTest = async (sessionId, config, nextEmitter) => {
    if (typeof nextEmitter === 'function') {
        dtmEventSink = nextEmitter;
    }

    if (!SESSION_IDS.includes(sessionId)) {
        throw new Error(`Unknown session: ${sessionId}`);
    }

    if (!config.port) {
        throw new Error('J-Link serial number is required.');
    }

    if (!hasSeggerRttStack()) {
        throw new Error(getJLinkSetupHint() || 'SEGGER J-Link GDB Server is required for RTT.');
    }

    lastConfigBySession[sessionId] = config;
    startingBySession[sessionId] = true;

    const status = getSessionStatus(sessionId);
    status.mode = config.testMode;
    status.message = 'Connecting';
    status.lastReceived = new Array(40).fill(0);
    emitForSession(sessionId, { type: 'status', message: status.message, running: false, mode: status.mode });

    let instance;
    try {
        assertProbeAvailable(sessionId, config);
        instance = await ensureDtm(sessionId, config);
        runningBySession[sessionId] = true;
        status.running = true;
        emitForSession(sessionId, { type: 'status', message: status.message, running: true, mode: status.mode });

        status.message = 'Setting up device';
        emitForSession(sessionId, { type: 'status', message: status.message, running: true, mode: status.mode });
        await setupTest(sessionId, instance, config);
        startingBySession[sessionId] = false;
    } catch (error) {
        startingBySession[sessionId] = false;
        runningBySession[sessionId] = false;
        status.running = false;
        await releaseDtm(sessionId).catch(() => {});
        const message = error instanceof Error ? error.message : String(error);
        status.message = message;
        emitForSession(sessionId, { type: 'error', message });
        throw error;
    }

    const { singleChannelIndexed, rangeStart, rangeEnd } = normalizeChannelIndexes(config);

    status.message = 'Running test';
    emitForSession(sessionId, {
        type: 'status',
        message: status.message,
        running: true,
        mode: status.mode,
        txPower: status.txPower,
    });

    let testPromise;

    if (config.testMode === 'transmitter' && config.channelMode === ChannelMode.single) {
        testPromise = instance.singleChannelTransmitterTest(
            Number(config.bitpattern),
            Number(config.length),
            singleChannelIndexed,
            Number(config.timeoutMs)
        );
    } else if (config.testMode === 'transmitter') {
        testPromise = instance.sweepTransmitterTest(
            Number(config.bitpattern),
            Number(config.length),
            rangeStart,
            rangeEnd,
            Number(config.sweepTimeMs),
            Number(config.timeoutMs)
        );
    } else if (config.channelMode === ChannelMode.single) {
        testPromise = instance.singleChannelReceiverTest(
            Number(config.bitpattern),
            Number(config.length),
            singleChannelIndexed,
            Number(config.timeoutMs)
        );
    } else {
        testPromise = instance.sweepReceiverTest(
            Number(config.bitpattern),
            Number(config.length),
            rangeStart,
            rangeEnd,
            Number(config.sweepTimeMs),
            Number(config.timeoutMs)
        );
    }

    testPromise
        .then(result => {
            runningBySession[sessionId] = false;
            status.running = false;
            releaseDtm(sessionId).catch(() => {});
            if (result.type === 'error') {
                status.message = result.message;
                emitForSession(sessionId, { type: 'error', message: result.message });
                return;
            }

            if (result.type === 'receiver') {
                status.lastReceived = result.receivedPerChannel;
            } else {
                status.lastReceived = new Array(40).fill(0);
            }

            status.message = 'Test finished';
            emitForSession(sessionId, {
                type: 'complete',
                mode: result.type,
                data: [...status.lastReceived],
                txPower: status.txPower,
            });
        })
        .catch(error => {
            runningBySession[sessionId] = false;
            status.running = false;
            releaseDtm(sessionId).catch(() => {});
            status.message = error.message;
            emitForSession(sessionId, { type: 'error', message: error.message });
        });

    return { ok: true };
};

const stopTest = async sessionId => {
    if (!SESSION_IDS.includes(sessionId)) {
        throw new Error(`Unknown session: ${sessionId}`);
    }

    const instance = dtmBySession[sessionId];
    const status = getSessionStatus(sessionId);

    if (instance) {
        await instance.endTest().catch(() => {});
    }
    await releaseDtm(sessionId);

    startingBySession[sessionId] = false;
    runningBySession[sessionId] = false;
    status.running = false;
    status.message = 'Stopped';
    emitForSession(sessionId, { type: 'status', message: status.message, running: false, mode: status.mode });
    return { ok: true };
};

const listJLinks = async () => listJLinkProbes();

const syncSessionConfig = (sessionId, config) => {
    if (!SESSION_IDS.includes(sessionId)) {
        throw new Error(`Unknown session: ${sessionId}`);
    }
    lastConfigBySession[sessionId] = config;
    return { ok: true };
};

const canStartSession = async (sessionId, config) => {
    try {
        assertProbeAvailable(sessionId, config);

        if (!dtmBySession[sessionId]) {
            await allocateSessionPorts(sessionId, getGloballyReservedPorts());
        }

        return { ok: true };
    } catch (error) {
        return {
            ok: false,
            reason: error instanceof Error ? error.message : String(error),
        };
    }
};

const getStatus = async sessionId => {
    if (!SESSION_IDS.includes(sessionId)) {
        throw new Error(`Unknown session: ${sessionId}`);
    }
    return {
        ...getSessionStatus(sessionId),
        running: runningBySession[sessionId],
        starting: startingBySession[sessionId],
        jlinkPorts:
            allocatedPortsBySession[sessionId] ||
            getSessionStatus(sessionId).jlinkPorts ||
            JLINK_PORTS_BY_SESSION[sessionId],
    };
};

const stopAllSessions = async () => {
    await Promise.all(SESSION_IDS.map(sessionId => releaseDtm(sessionId)));
};

module.exports = {
    listJLinks,
    listSerialPorts: listJLinks,
    startTest,
    stopTest,
    getStatus,
    syncSessionConfig,
    canStartSession,
    stopAllSessions,
    constants: {
        ChannelMode,
        DtmPhysicalLayer,
        DtmModulationMode,
        DtmPacketType,
        DEFAULT_DEVICE,
        DEFAULT_SWD_SPEED,
    },
};