/**
 * MicroPython raw REPL over Web Serial (mpremote-compatible).
 */
(function (global) {
  const RAW_REPL_BANNER = 'raw REPL; CTRL-B to exit\r\n';
  const SOFT_REBOOT_MARKERS = ['soft reboot\r\n', 'MPY: soft reboot\r\n'];
  const LOG = '[led-tool/serial]';

  function log(...args) {
    console.log(LOG, ...args);
  }

  function logDebug(...args) {
    console.debug(LOG, ...args);
  }

  function describeBytes(data) {
    if (!data || !data.length) return '(empty)';
    const u8 = data instanceof Uint8Array ? data : new Uint8Array(data);
    if (u8.length <= 64) {
      return Array.from(u8)
        .map((b) => (b >= 0x20 && b < 0x7f ? String.fromCharCode(b) : `\\x${b.toString(16).padStart(2, '0')}`))
        .join('');
    }
    return `${u8.length} bytes: ${decodeText(u8.slice(0, 80))}…`;
  }

  function sleep(ms) {
    return new Promise((resolve) => setTimeout(resolve, ms));
  }

  /** Common ESP32 USB-UART bridges (usbVendorId only per Web Serial API). */
  const ESP32_USB_FILTERS = [
    { usbVendorId: 0x303a }, /* Espressif */
    { usbVendorId: 0x10c4 }, /* Silicon Labs CP210x */
    { usbVendorId: 0x1a86 }, /* WCH CH340 */
    { usbVendorId: 0x0403 }, /* FTDI */
  ];

  async function deassertDtrRts(port) {
    if (!port || !port.setSignals) return;
    try {
      await port.setSignals({ dataTerminalReady: false, requestToSend: false });
    } catch (_) {
      /* ignore — some adapters/browsers reject setSignals */
    }
  }

  function bytesIndexOf(buf, suffix) {
    if (!suffix.length) return 0;
    if (buf.length < suffix.length) return -1;
    for (let i = 0; i <= buf.length - suffix.length; i += 1) {
      let ok = true;
      for (let j = 0; j < suffix.length; j += 1) {
        if (buf[i + j] !== suffix[j]) {
          ok = false;
          break;
        }
      }
      if (ok) return i;
    }
    return -1;
  }

  function bufferEndsWithFriendlyRepl(buf) {
    if (bufferLooksLikeEspRomBoot(buf) && !bufferHasMicroPython(buf)) return false;
    const tail = decodeText(Uint8Array.from(buf.slice(-80)));
    return /(?:\r\n|\n)>>> ?$/.test(tail);
  }

  function bufferLooksLikeEspRomBoot(buf) {
    if (bufferIndicatesRuntime(buf)) return false;
    const text = decodeText(Uint8Array.from(buf.slice(-512)));
    return /SPI_FAST_FLASH_BOOT|rst:0x/.test(text) && !/entry 0x403/.test(text);
  }

  /** MicroPython is up (banner, REPL, raw REPL, or post-ROM heap lines from boot). */
  function bufferIndicatesRuntime(buf) {
    const text = decodeText(Uint8Array.from(buf));
    if (text.includes('MicroPython')) return true;
    if (text.includes('raw REPL; CTRL-B to exit')) return true;
    if (/(?:\r\n|\n)>>> ?/.test(text)) return true;
    if (text.includes('entry 0x') && (/['"]?free['"]?\s*:/.test(text) || /,\s*'free'/.test(text))) {
      return true;
    }
    return false;
  }

  function bufferHasMicroPython(buf) {
    return bufferIndicatesRuntime(buf);
  }

  function decodeText(u8) {
    return new TextDecoder('utf-8', { fatal: false }).decode(u8);
  }

  function extractJsonObject(text) {
    const t = (text || '').trim();
    const start = t.indexOf('{');
    const end = t.lastIndexOf('}');
    if (start === -1 || end === -1 || end < start) {
      throw new Error(`No JSON object in device output: ${t.slice(0, 400)}`);
    }
    return JSON.parse(t.slice(start, end + 1));
  }

  class MicroPythonRawRepl {
    constructor() {
      this.port = null;
      this.reader = null;
      this.writer = null;
      this.portOpen = false;
      this.inRawRepl = false;
      this._rxBuf = [];
      this.useRawPaste = true;
      this._replLock = null;
    }

    get connected() {
      return Boolean(this.portOpen && this.writer);
    }

    _appendRx(chunk) {
      if (!chunk || !chunk.length) return;
      logDebug('rx chunk', chunk.length, describeBytes(chunk));
      for (let i = 0; i < chunk.length; i += 1) this._rxBuf.push(chunk[i]);
    }

    async _readStreamChunk(timeoutMs) {
      if (!this.reader) return null;
      const result = await Promise.race([
        this.reader.read(),
        sleep(timeoutMs).then(() => ({ timedOut: true })),
      ]);
      if (result.timedOut) return null;
      if (result.done) return null;
      return result.value || null;
    }

    /** Match suffix anywhere in the buffer; keep bytes after the match for the next read. */
    async readUntil(suffixBytes, timeoutMs = 15000) {
      const deadline = Date.now() + timeoutMs;
      while (Date.now() < deadline) {
        const idx = bytesIndexOf(this._rxBuf, suffixBytes);
        if (idx >= 0) {
          const end = idx + suffixBytes.length;
          const matched = Uint8Array.from(this._rxBuf.slice(0, end));
          this._rxBuf.splice(0, end);
          logDebug('readUntil matched', JSON.stringify(decodeText(suffixBytes)), 'len', matched.length);
          return matched;
        }
        const chunk = await this._readStreamChunk(Math.min(300, Math.max(1, deadline - Date.now())));
        if (chunk && chunk.length) {
          this._appendRx(chunk);
        } else {
          await sleep(5);
        }
      }
      const tail = decodeText(Uint8Array.from(this._rxBuf.slice(-240)));
      const err = `Timed out waiting for ${JSON.stringify(decodeText(suffixBytes))} (tail: ${JSON.stringify(tail)})`;
      log('readUntil timeout', err);
      throw new Error(err);
    }

    async readUntilAny(suffixList, timeoutMs = 15000) {
      const deadline = Date.now() + timeoutMs;
      while (Date.now() < deadline) {
        for (const suffixBytes of suffixList) {
          const idx = bytesIndexOf(this._rxBuf, suffixBytes);
          if (idx >= 0) {
            const end = idx + suffixBytes.length;
            const matched = Uint8Array.from(this._rxBuf.slice(0, end));
            this._rxBuf.splice(0, end);
            logDebug('readUntilAny matched', JSON.stringify(decodeText(suffixBytes)));
            return matched;
          }
        }
        const chunk = await this._readStreamChunk(Math.min(300, Math.max(1, deadline - Date.now())));
        if (chunk && chunk.length) this._appendRx(chunk);
        else await sleep(5);
      }
      const tail = decodeText(Uint8Array.from(this._rxBuf.slice(-240)));
      throw new Error(
        `Timed out waiting for one of ${suffixList.map((s) => JSON.stringify(decodeText(s))).join(', ')} (tail: ${JSON.stringify(tail)})`,
      );
    }

    async readExact(n, timeoutMs = 10000) {
      const deadline = Date.now() + timeoutMs;
      while (this._rxBuf.length < n && Date.now() < deadline) {
        const chunk = await this._readStreamChunk(Math.min(300, Math.max(1, deadline - Date.now())));
        if (chunk && chunk.length) this._appendRx(chunk);
        else await sleep(5);
      }
      if (this._rxBuf.length < n) {
        throw new Error(`Expected ${n} bytes, got ${this._rxBuf.length}`);
      }
      return Uint8Array.from(this._rxBuf.splice(0, n));
    }

    async connect(serialPort) {
      log('connect: opening port');
      await this.disconnect();
      this.port = serialPort;
      this._rxBuf = [];
      await this.port.open({
        baudRate: 115200,
        dataBits: 8,
        stopBits: 1,
        parity: 'none',
        flowControl: 'none',
        bufferSize: 65536,
      });
      await deassertDtrRts(this.port);
      await sleep(50);
      await deassertDtrRts(this.port);
      this.reader = this.port.readable.getReader();
      this.writer = this.port.writable.getWriter();
      this.portOpen = true;
      await sleep(100);
      await this.collectIncoming(8000);
      if (bufferIndicatesRuntime(this._rxBuf)) {
        log('connect: MicroPython output seen during open');
      }
      log('connect: port open (raw REPL not entered yet)');
    }

    /** Read serial into _rxBuf without discarding (for post-open boot). */
    async collectIncoming(maxMs) {
      const deadline = Date.now() + maxMs;
      while (Date.now() < deadline) {
        const chunk = await this._readStreamChunk(Math.min(80, Math.max(1, deadline - Date.now())));
        if (chunk && chunk.length) this._appendRx(chunk);
        else if (
          bufferHasMicroPython(this._rxBuf) ||
          bufferEndsWithFriendlyRepl(this._rxBuf) ||
          bytesIndexOf(this._rxBuf, new TextEncoder().encode(RAW_REPL_BANNER)) >= 0
        ) {
          break;
        } else {
          await sleep(15);
        }
      }
    }

    async ensureRawRepl() {
      if (this.inRawRepl) return;
      if (this._replLock) {
        await this._replLock;
        return;
      }
      log('ensureRawRepl: entering raw REPL');
      // USB open already resets the ESP32; skip soft-reset (unlike host led-cli/mpremote).
      this._replLock = this.enterRawRepl(false).finally(() => {
        this._replLock = null;
      });
      await this._replLock;
    }

    async disconnect() {
      log('disconnect');
      this._replLock = null;
      const wasRaw = this.inRawRepl;
      this.inRawRepl = false;
      this.portOpen = false;
      this.useRawPaste = true;
      if (this.writer && wasRaw) {
        try {
          await this.writer.write(new Uint8Array([0x0d, 0x02]));
        } catch (_) {
          /* ignore */
        }
      }
      if (this.reader) {
        try {
          await this.reader.cancel();
          this.reader.releaseLock();
        } catch (_) {
          /* ignore */
        }
        this.reader = null;
      }
      if (this.writer) {
        try {
          await this.writer.close();
          this.writer.releaseLock();
        } catch (_) {
          /* ignore */
        }
        this.writer = null;
      }
      if (this.port) {
        try {
          await deassertDtrRts(this.port);
        } catch (_) {
          /* ignore */
        }
        try {
          await this.port.close();
        } catch (_) {
          /* ignore */
        }
        this.port = null;
      }
      this._rxBuf = [];
    }

    async writeBytes(data) {
      if (!this.writer) throw new Error('Serial not connected');
      logDebug('tx', describeBytes(data));
      await this.writer.write(data);
    }

    async drainInput(maxMs = 400, clearBuffer = true) {
      const deadline = Date.now() + maxMs;
      while (Date.now() < deadline) {
        const chunk = await this._readStreamChunk(40);
        if (!chunk || !chunk.length) break;
        if (!clearBuffer && chunk.length) this._appendRx(chunk);
      }
      if (clearBuffer) this._rxBuf.length = 0;
    }

    async sendCtrlA() {
      await this.writeBytes(new Uint8Array([0x0d, 0x01]));
    }

    /** USB open often resets the ESP32; wait through ROM boot until MicroPython is up. */
    async waitForMicroPythonBoot(timeoutMs = 60000) {
      log('enterRawRepl: wait for MicroPython after boot', 'buf', this._rxBuf.length);
      if (bufferHasMicroPython(this._rxBuf) || bufferEndsWithFriendlyRepl(this._rxBuf)) {
        log('enterRawRepl: MicroPython already in buffer');
        return;
      }
      const deadline = Date.now() + timeoutMs;
      let nudgeSent = false;
      let lastLog = Date.now();
      while (Date.now() < deadline) {
        if (bufferHasMicroPython(this._rxBuf) || bufferEndsWithFriendlyRepl(this._rxBuf)) {
          log('enterRawRepl: MicroPython running');
          return;
        }
        const text = decodeText(Uint8Array.from(this._rxBuf));
        if (!nudgeSent && text.includes('entry 0x')) {
          nudgeSent = true;
          log('enterRawRepl: past ROM loader, nudge REPL');
          await this.writeBytes(new Uint8Array([0x0d]));
          await sleep(200);
        }
        if (Date.now() - lastLog > 5000) {
          lastLog = Date.now();
          log('enterRawRepl: still waiting…', 'buf', this._rxBuf.length);
        }
        const rem = Math.max(1, deadline - Date.now());
        const chunk = await this._readStreamChunk(Math.min(300, rem));
        if (chunk && chunk.length) this._appendRx(chunk);
        else await sleep(bufferLooksLikeEspRomBoot(this._rxBuf) ? 20 : 10);
      }
      const tail = decodeText(Uint8Array.from(this._rxBuf.slice(-240)));
      throw new Error(`Timed out waiting for MicroPython boot (tail: ${JSON.stringify(tail)})`);
    }

    /** Wait until raw REPL banner and `>` prompt (not banner alone — device may still be booting). */
    async waitRawReplAfterSoftReboot(bannerBytes, bannerPromptBytes, timeoutMs = 15000) {
      const deadline = Date.now() + timeoutMs;
      while (Date.now() < deadline) {
        const rem = Math.max(1, deadline - Date.now());
        const promptAt = bytesIndexOf(this._rxBuf, bannerPromptBytes);
        if (promptAt >= 0) {
          this._rxBuf.splice(0, promptAt + bannerPromptBytes.length);
          log('enterRawRepl: raw REPL prompt ready');
          return;
        }
        if (bufferEndsWithFriendlyRepl(this._rxBuf)) {
          log('enterRawRepl: friendly REPL, ctrl-A');
          await this.sendCtrlA();
          await sleep(30);
          continue;
        }
        if (bufferLooksLikeEspRomBoot(this._rxBuf) && !bufferHasMicroPython(this._rxBuf)) {
          logDebug('enterRawRepl: ROM boot in progress…');
        }
        const chunk = await this._readStreamChunk(Math.min(300, rem));
        if (chunk && chunk.length) this._appendRx(chunk);
        else await sleep(10);
      }
      const tail = decodeText(Uint8Array.from(this._rxBuf.slice(-240)));
      throw new Error(
        `Timed out waiting for raw REPL after soft reboot (tail: ${JSON.stringify(tail)})`,
      );
    }

    /** Match mpremote SerialTransport.enter_raw_repl(soft_reset). */
    async enterRawRepl(softReset = true) {
      log('enterRawRepl', { softReset });
      const bannerBytes = new TextEncoder().encode(RAW_REPL_BANNER);
      const bannerPromptBytes = new TextEncoder().encode(RAW_REPL_BANNER + '>');
      const softRebootBytes = SOFT_REBOOT_MARKERS.map((m) => new TextEncoder().encode(m));

      if (
        !bufferHasMicroPython(this._rxBuf) &&
        !bufferEndsWithFriendlyRepl(this._rxBuf) &&
        bytesIndexOf(this._rxBuf, bannerBytes) < 0
      ) {
        await this.waitForMicroPythonBoot(60000);
      } else {
        log('enterRawRepl: already have REPL output in buffer');
      }

      if (bufferEndsWithFriendlyRepl(this._rxBuf)) {
        await this.writeBytes(new Uint8Array([0x0d, 0x03]));
        await sleep(50);
      }

      let ctrlARetries = 0;
      const maxCtrlARetries = 3;
      while (ctrlARetries <= maxCtrlARetries) {
        try {
          await this.sendCtrlA();
          await this.waitRawReplAfterSoftReboot(bannerBytes, bannerPromptBytes, 20000);
          break;
        } catch (e) {
          if (ctrlARetries >= maxCtrlARetries) throw e;
          ctrlARetries += 1;
          log('enterRawRepl: retry ctrl-A', ctrlARetries, e.message);
          this._rxBuf.length = 0;
        }
      }

      if (softReset) {
        log('enterRawRepl: soft reset');
        await this.writeBytes(new Uint8Array([0x04]));
        try {
          await this.readUntilAny(softRebootBytes, 20000);
          log('enterRawRepl: saw soft reboot');
          this._rxBuf.length = 0;
        } catch (e) {
          log('enterRawRepl: no soft reboot banner', e.message);
        }
        ctrlARetries = 0;
        while (ctrlARetries <= maxCtrlARetries) {
          try {
            await this.waitRawReplAfterSoftReboot(bannerBytes, bannerPromptBytes, 60000);
            break;
          } catch (e) {
            if (ctrlARetries >= maxCtrlARetries) throw e;
            ctrlARetries += 1;
            log('enterRawRepl: post-reboot retry ctrl-A', ctrlARetries, e.message);
            this._rxBuf.length = 0;
            await this.sendCtrlA();
          }
        }
      }

      this.inRawRepl = true;
      log('enterRawRepl: ready');
    }

    async rawPasteWrite(commandBytes) {
      await this.writeBytes(new Uint8Array([0x05, 0x41, 0x01]));
      const hdr = await this.readExact(2, 8000);
      const windowSize = hdr[0] | (hdr[1] << 8);
      let windowRemain = windowSize;
      let i = 0;
      while (i < commandBytes.length) {
        while (windowRemain === 0) {
          const b = await this.readExact(1, 15000);
          if (b[0] === 0x01) {
            windowRemain += windowSize;
          } else if (b[0] === 0x04) {
            await this.writeBytes(new Uint8Array([0x04]));
            return;
          } else {
            throw new Error(`Unexpected byte during raw paste: 0x${b[0].toString(16)}`);
          }
        }
        const n = Math.min(windowRemain, commandBytes.length - i);
        await this.writeBytes(commandBytes.subarray(i, i + n));
        windowRemain -= n;
        i += n;
      }
      await this.writeBytes(new Uint8Array([0x04]));
      await this.readUntil(new Uint8Array([0x04]), 30000);
    }

    async awaitRawReplExecPrompt(timeoutMs = 60000) {
      const bannerPromptBytes = new TextEncoder().encode(RAW_REPL_BANNER + '>');
      const deadline = Date.now() + timeoutMs;
      while (Date.now() < deadline) {
        const promptAt = bytesIndexOf(this._rxBuf, bannerPromptBytes);
        if (promptAt >= 0) {
          this._rxBuf.splice(0, promptAt + bannerPromptBytes.length);
          return;
        }
        if (bufferEndsWithFriendlyRepl(this._rxBuf)) {
          log('exec: friendly REPL before prompt, ctrl-A');
          this._rxBuf.length = 0;
          await this.sendCtrlA();
        } else if (bufferLooksLikeEspRomBoot(this._rxBuf)) {
          logDebug('exec: still in ROM boot, waiting…');
        }
        const rem = Math.max(1, deadline - Date.now());
        const chunk = await this._readStreamChunk(Math.min(300, rem));
        if (chunk && chunk.length) this._appendRx(chunk);
        else await sleep(10);
      }
      const tail = decodeText(Uint8Array.from(this._rxBuf.slice(-240)));
      throw new Error(`Timed out waiting for raw REPL prompt (tail: ${JSON.stringify(tail)})`);
    }

    async execRawNoFollow(commandBytes) {
      log('execRawNoFollow', commandBytes.length, 'bytes');
      await this.awaitRawReplExecPrompt(60000);

      if (this.useRawPaste) {
        await this.writeBytes(new Uint8Array([0x05, 0x41, 0x01]));
        let data;
        try {
          data = await this.readExact(2, 3000);
        } catch (_) {
          this.useRawPaste = false;
          data = null;
        }
        if (data) {
          if (data[0] === 0x52 && data[1] === 0x01) {
            log('exec: using raw paste mode');
            await this.rawPasteWrite(commandBytes);
            const ok = await this.readExact(2, 15000);
            if (ok[0] !== 0x4f || ok[1] !== 0x4b) {
              throw new Error(`Device did not return OK after paste (got ${decodeText(ok)})`);
            }
            log('exec: paste OK');
            return;
          }
          if (data[0] === 0x52 && data[1] === 0x00) {
            log('exec: raw paste not supported (R\\x00)');
            this.useRawPaste = false;
          } else {
            log('exec: raw paste probe unexpected', describeBytes(data));
            this.useRawPaste = false;
            try {
              await this.readUntil(new TextEncoder().encode(RAW_REPL_BANNER + '>'), 5000);
            } catch (_) {
              /* ignore */
            }
          }
        }
      }

      for (let i = 0; i < commandBytes.length; i += 256) {
        await this.writeBytes(commandBytes.subarray(i, Math.min(i + 256, commandBytes.length)));
        await sleep(10);
      }
      log('exec: standard raw REPL write');
      await this.writeBytes(new Uint8Array([0x04]));
      const ok = await this.readExact(2, 15000);
      if (ok[0] !== 0x4f || ok[1] !== 0x4b) {
        throw new Error(`Device did not return OK (got ${decodeText(ok)})`);
      }
      log('exec: got OK');
    }

    async follow(timeoutMs = 30000) {
      const out1 = await this.readUntil(new Uint8Array([0x04]), timeoutMs);
      const stdout = decodeText(out1.slice(0, -1));
      const out2 = await this.readUntil(new Uint8Array([0x04]), timeoutMs);
      const stderr = decodeText(out2.slice(0, -1));
      log('follow stdout', stdout.slice(0, 500));
      if (stderr) log('follow stderr', stderr.slice(0, 500));
      return { stdout, stderr };
    }

    async exec(command, timeoutMs = 30000) {
      const preview =
        typeof command === 'string' ? command.split('\n').slice(0, 3).join('\n') : '<bytes>';
      log('exec', preview);
      await this.ensureRawRepl();
      const commandBytes =
        typeof command === 'string' ? new TextEncoder().encode(command) : command;
      await this.execRawNoFollow(commandBytes);
      return this.follow(timeoutMs);
    }

    async readSettingsJson() {
      log('readSettingsJson');
      const code = [
        'import json',
        'try:',
        "    f=open('settings.json','r')",
        '    d=json.load(f)',
        '    f.close()',
        'except Exception:',
        '    d={}',
        'print(json.dumps(d))',
      ].join('\n');
      const { stdout, stderr } = await this.exec(code);
      const text = (stdout || '').trim() || (stderr || '').trim();
      if (!text) {
        log('readSettingsJson: empty response');
        return {};
      }
      const parsed = extractJsonObject(text);
      log('readSettingsJson: ok', Object.keys(parsed));
      return parsed;
    }

    async writeSettingsJson(settings) {
      log('writeSettingsJson', settings);
      const jsonText = JSON.stringify(settings);
      const escaped = JSON.stringify(jsonText);
      const code = [
        'import json',
        `s=json.loads(${escaped})`,
        "f=open('settings.json','w')",
        'f.write(s)',
        'f.close()',
        'import machine',
        'machine.reset()',
      ].join('\n');
      await this.exec(code, 60000);
    }
  }

  function serialSupported() {
    return typeof navigator !== 'undefined' && 'serial' in navigator;
  }

  async function getGrantedPorts() {
    if (!serialSupported()) return [];
    return navigator.serial.getPorts();
  }

  async function requestPort() {
    if (!serialSupported()) {
      throw new Error('Web Serial not supported');
    }
    const granted = await navigator.serial.getPorts();
    if (granted.length === 1) {
      log('requestPort: reusing single granted port');
      return granted[0];
    }
    log('requestPort: showing picker', { grantedCount: granted.length });
    return navigator.serial.requestPort({ filters: ESP32_USB_FILTERS });
  }

  global.LedToolWebSerial = {
    supported: serialSupported,
    getGrantedPorts,
    requestPort,
    MicroPythonRawRepl,
    _test: { bytesIndexOf, decodeText },
  };
})(typeof window !== 'undefined' ? window : globalThis);