let audioContext;
let mediaStream;
let recognition;
let isCapturing = false;
let overlayInitialized = false;
let activeCaptureMode = 'tab';
let overlayListening = false;
let overlayHidden = false;
let analyserNode = null;
let meterSource = null;
let meterRaf = null;

chrome.runtime.onMessage.addListener((request, sender, sendResponse) => {
  if (request.action === 'startCapture') {
    activeCaptureMode = 'tab';
    startCapture(request.streamId);
    sendResponse({ success: true });
    return false;
  }
  if (request.action === 'startMicCapture') {
    activeCaptureMode = 'mic';
    startMicCapture();
    sendResponse({ success: true });
    return false;
  }
  if (request.action === 'startMixedCapture') {
    activeCaptureMode = 'mixed';
    startMixedCapture(request.streamId);
    sendResponse({ success: true });
    return false;
  }
  if (request.action === 'stopCapture') {
    stopCapture();
    sendResponse({ success: true });
    return false;
  }
  if (request.action === 'requestMicPermission') {
    requestMicPermission().then(sendResponse);
    return true;
  }
  if (request.action === 'updateTranscript') {
    updateOverlay('transcript', request.transcript);
    return false;
  }
  if (request.action === 'updateAIResponse') {
    updateOverlay('response', request.response);
    return false;
  }
  if (request.action === 'showOverlay') {
    setOverlayHidden(false);
    return false;
  }
  if (request.action === 'hideOverlay') {
    setOverlayHidden(true);
    return false;
  }
  return false;
});

async function requestMicPermission() {
  try {
    const stream = await navigator.mediaDevices.getUserMedia({ audio: true });
    stream.getTracks().forEach(track => track.stop());
    return { success: true };
  } catch (error) {
    let errorMessage = 'Microphone permission denied.';
    if (error.name === 'NotAllowedError') {
      errorMessage = 'Microphone permission denied.';
    } else if (error.name === 'NotFoundError') {
      errorMessage = 'No microphone found.';
    } else {
      errorMessage = error.message || 'Unknown error occurred.';
    }
    return { success: false, error: errorMessage };
  }
}

function startCapture(streamId) {
  isCapturing = true;
  overlayListening = true;
  ensureOverlay();
  updateOverlayIndicator();
  updateOverlay(
    'response',
    'Tab audio is captured, but speech recognition uses the microphone. Use mic or mixed mode if you want transcription.'
  );
  navigator.mediaDevices.getUserMedia({
    audio: {
      chromeMediaSource: 'tab',
      chromeMediaSourceId: streamId
    }
  }).then((stream) => {
    mediaStream = stream;
    audioContext = new AudioContext();
    createAudioMeter(stream);
    if (ensureSpeechRecognitionAvailable()) {
      startRecognition();
    }
  }).catch((error) => {
    console.error('Error starting capture:', error);
    let errorMessage = 'Failed to start audio capture. ';
    if (error.name === 'NotAllowedError') {
      errorMessage += 'Please allow microphone access and try again.';
    } else if (error.name === 'NotFoundError') {
      errorMessage += 'No microphone found.';
    } else {
      errorMessage += error.message || 'Unknown error occurred.';
    }
    chrome.runtime.sendMessage({action: 'updateAIResponse', response: errorMessage});
    updateOverlay('response', errorMessage);
    overlayListening = false;
    updateOverlayIndicator();
  });
}

function startMicCapture() {
  isCapturing = true;
  overlayListening = true;
  ensureOverlay();
  updateOverlayIndicator();
  navigator.mediaDevices.getUserMedia({ audio: true }).then((stream) => {
    mediaStream = stream;
    audioContext = new AudioContext();
    createAudioMeter(stream);
    if (ensureSpeechRecognitionAvailable()) {
      startRecognition();
    }
  }).catch((error) => {
    console.error('Error starting mic capture:', error);
    let errorMessage = 'Failed to start microphone capture. ';
    if (error.name === 'NotAllowedError') {
      errorMessage += 'Please allow microphone access and try again.';
    } else if (error.name === 'NotFoundError') {
      errorMessage += 'No microphone found.';
    } else {
      errorMessage += error.message || 'Unknown error occurred.';
    }
    chrome.runtime.sendMessage({action: 'updateAIResponse', response: errorMessage});
    updateOverlay('response', errorMessage);
    overlayListening = false;
    updateOverlayIndicator();
  });
}

function startMixedCapture(streamId) {
  isCapturing = true;
  overlayListening = true;
  ensureOverlay();
  updateOverlayIndicator();
  navigator.mediaDevices.getUserMedia({
    audio: {
      chromeMediaSource: 'tab',
      chromeMediaSourceId: streamId
    }
  }).then((stream) => {
    mediaStream = stream;
    audioContext = new AudioContext();
    createAudioMeter(stream);
    if (ensureSpeechRecognitionAvailable()) {
      startRecognition();
    }
  }).catch((error) => {
    console.error('Error starting mixed capture:', error);
    chrome.runtime.sendMessage({action: 'updateAIResponse', response: 'Failed to start mixed capture.'});
    updateOverlay('response', 'Failed to start mixed capture.');
    overlayListening = false;
    updateOverlayIndicator();
  });
}

function startRecognition() {
  if (recognition) {
    try {
      recognition.stop();
    } catch (error) {
      console.warn('Failed to stop previous recognition:', error);
    }
  }

  recognition = new webkitSpeechRecognition();
  recognition.continuous = true;
  recognition.interimResults = true;

  recognition.onresult = function(event) {
    let finalTranscript = '';
    for (let i = event.resultIndex; i < event.results.length; ++i) {
      if (event.results[i].isFinal) {
        finalTranscript += event.results[i][0].transcript;
      }
    }

    if (finalTranscript.trim() !== '') {
      chrome.runtime.sendMessage({action: 'updateTranscript', transcript: finalTranscript});
      updateOverlay('transcript', finalTranscript);
      chrome.runtime.sendMessage({action: 'getAIResponse', question: finalTranscript});
    }
  };

  recognition.onerror = function(event) {
    console.error('Speech recognition error:', event.error);
    if (event.error === 'no-speech' && isCapturing) {
      try {
        recognition.start();
      } catch (error) {
        console.warn('Failed to restart recognition after no-speech:', error);
      }
      return;
    }
    chrome.runtime.sendMessage({action: 'updateAIResponse', response: `Speech recognition error: ${event.error}. Please try again.`});
    updateOverlay('response', `Speech recognition error: ${event.error}. Please try again.`);
  };

  recognition.onend = function() {
    if (!isCapturing) return;
    try {
      recognition.start();
    } catch (error) {
      console.warn('Failed to restart recognition:', error);
    }
  };

  recognition.start();
}

function ensureSpeechRecognitionAvailable() {
  const SpeechRecognition = window.SpeechRecognition || window.webkitSpeechRecognition;
  if (!SpeechRecognition) {
    const message = 'Speech recognition is not available in this browser context. Use mic mode in Chrome or enable speech recognition.';
    chrome.runtime.sendMessage({ action: 'updateAIResponse', response: message });
    updateOverlay('response', message);
    overlayListening = false;
    updateOverlayIndicator();
    return false;
  }
  return true;
}

function stopCapture() {
  isCapturing = false;
  overlayListening = false;
  updateOverlayIndicator();
  stopAudioMeter();
  if (mediaStream) {
    mediaStream.getTracks().forEach(track => track.stop());
  }
  if (audioContext) {
    audioContext.close();
    audioContext = null;
  }
  if (recognition) {
    recognition.stop();
  }
}

function ensureOverlay() {
  if (overlayInitialized) return;
  overlayInitialized = true;

  if (document.getElementById('ai-interview-overlay')) {
    return;
  }

  const style = document.createElement('style');
  style.textContent = `
    #ai-interview-overlay {
      position: fixed;
      top: 24px;
      right: 24px;
      width: 420px;
      min-width: 280px;
      min-height: 240px;
      background: rgba(20, 20, 20, 0.35);
      color: #f5f5f5;
      border: 1px solid rgba(255, 255, 255, 0.15);
      border-radius: 12px;
      backdrop-filter: blur(10px);
      z-index: 2147483647;
      font-family: "Helvetica Neue", Arial, sans-serif;
      box-shadow: 0 10px 30px rgba(0, 0, 0, 0.35);
      user-select: none;
      resize: both;
      overflow: auto;
    }
    #ai-interview-resize {
      position: absolute;
      right: 6px;
      bottom: 6px;
      width: 14px;
      height: 14px;
      cursor: se-resize;
      background: radial-gradient(circle at center, rgba(255, 255, 255, 0.8) 0 2px, transparent 2px);
      opacity: 0.6;
    }
    #ai-interview-overlay.minimized #ai-interview-body {
      display: none;
    }
    #ai-interview-header {
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding: 10px 12px;
      cursor: move;
      font-weight: 600;
      font-size: 13px;
      letter-spacing: 0.02em;
      border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    }
    #ai-interview-title {
      display: flex;
      align-items: center;
      gap: 8px;
    }
    #ai-interview-indicator {
      width: 10px;
      height: 10px;
      border-radius: 50%;
      background: rgba(255, 255, 255, 0.25);
      box-shadow: 0 0 0 rgba(255, 255, 255, 0.3);
    }
    #ai-interview-indicator.active {
      background: #41f59a;
      animation: aiPulse 1.2s ease-in-out infinite;
      box-shadow: 0 0 8px rgba(65, 245, 154, 0.7);
    }
    @keyframes aiPulse {
      0% { transform: scale(0.9); opacity: 0.6; }
      50% { transform: scale(1.3); opacity: 1; }
      100% { transform: scale(0.9); opacity: 0.6; }
    }
    #ai-interview-controls {
      display: flex;
      gap: 6px;
    }
    .ai-interview-btn {
      background: rgba(255, 255, 255, 0.12);
      border: none;
      color: #f5f5f5;
      font-size: 12px;
      padding: 4px 8px;
      border-radius: 6px;
      cursor: pointer;
    }
    .ai-interview-btn:hover {
      background: rgba(255, 255, 255, 0.22);
    }
    #ai-interview-body {
      padding: 12px;
      font-size: 12px;
      line-height: 1.4;
    }
    #ai-interview-mode {
      font-size: 11px;
      opacity: 0.8;
      margin-bottom: 6px;
    }
    #ai-interview-meter {
      height: 6px;
      background: rgba(255, 255, 255, 0.12);
      border-radius: 999px;
      overflow: hidden;
      margin-bottom: 10px;
    }
    #ai-interview-meter-bar {
      height: 100%;
      width: 0%;
      background: linear-gradient(90deg, #41f59a, #48c5ff);
      transition: width 80ms linear;
    }
    #ai-interview-transcript,
    #ai-interview-response {
      background: rgba(0, 0, 0, 0.35);
      border-radius: 8px;
      padding: 8px;
      margin-bottom: 8px;
      max-height: 200px;
      overflow: auto;
      user-select: text;
    }
  `;
  document.head.appendChild(style);

  const overlay = document.createElement('div');
  overlay.id = 'ai-interview-overlay';
  overlay.innerHTML = `
    <div id="ai-interview-header">
      <div id="ai-interview-title">
        <span id="ai-interview-indicator"></span>
        <span>AI Interview Assistant</span>
      </div>
      <div id="ai-interview-controls">
        <button class="ai-interview-btn" id="ai-interview-detach">Detach</button>
        <button class="ai-interview-btn" id="ai-interview-minimize">Minimize</button>
        <button class="ai-interview-btn" id="ai-interview-hide">Hide</button>
      </div>
    </div>
    <div id="ai-interview-body">
      <div id="ai-interview-mode">Mode: ${activeCaptureMode}</div>
      <div id="ai-interview-meter"><div id="ai-interview-meter-bar"></div></div>
      <div id="ai-interview-transcript">Transcript will appear here.</div>
      <div id="ai-interview-response">Answer will appear here.</div>
    </div>
    <div id="ai-interview-resize" title="Resize"></div>
  `;
  document.body.appendChild(overlay);

  const header = overlay.querySelector('#ai-interview-header');
  const minimizeBtn = overlay.querySelector('#ai-interview-minimize');
  const detachBtn = overlay.querySelector('#ai-interview-detach');
  const hideBtn = overlay.querySelector('#ai-interview-hide');
  const resizeHandle = overlay.querySelector('#ai-interview-resize');

  let isDragging = false;
  let startX = 0;
  let startY = 0;
  let startLeft = 0;
  let startTop = 0;

  header.addEventListener('mousedown', (event) => {
    isDragging = true;
    startX = event.clientX;
    startY = event.clientY;
    const rect = overlay.getBoundingClientRect();
    startLeft = rect.left;
    startTop = rect.top;
    overlay.style.right = 'auto';
  });

  document.addEventListener('mousemove', (event) => {
    if (!isDragging) return;
    const nextLeft = startLeft + (event.clientX - startX);
    const nextTop = startTop + (event.clientY - startY);
    overlay.style.left = `${Math.max(8, nextLeft)}px`;
    overlay.style.top = `${Math.max(8, nextTop)}px`;
  });

  document.addEventListener('mouseup', () => {
    isDragging = false;
  });

  resizeHandle.addEventListener('mousedown', (event) => {
    event.preventDefault();
    event.stopPropagation();
    const startWidth = overlay.offsetWidth;
    const startHeight = overlay.offsetHeight;
    const startMouseX = event.clientX;
    const startMouseY = event.clientY;

    const onMove = (moveEvent) => {
      const nextWidth = Math.max(280, startWidth + (moveEvent.clientX - startMouseX));
      const nextHeight = Math.max(240, startHeight + (moveEvent.clientY - startMouseY));
      overlay.style.width = `${nextWidth}px`;
      overlay.style.height = `${nextHeight}px`;
    };

    const onUp = () => {
      document.removeEventListener('mousemove', onMove);
      document.removeEventListener('mouseup', onUp);
    };

    document.addEventListener('mousemove', onMove);
    document.addEventListener('mouseup', onUp);
  });

  minimizeBtn.addEventListener('click', () => {
    overlay.classList.toggle('minimized');
    minimizeBtn.textContent = overlay.classList.contains('minimized') ? 'Expand' : 'Minimize';
  });

  detachBtn.addEventListener('click', () => {
    chrome.runtime.sendMessage({ action: 'openAssistantWindow' });
  });

  hideBtn.addEventListener('click', () => {
    setOverlayHidden(true);
  });

  updateOverlayIndicator();
}

function updateOverlay(type, text) {
  ensureOverlay();
  applyOverlayHiddenState();
  const modeEl = document.getElementById('ai-interview-mode');
  if (modeEl) {
    modeEl.textContent = `Mode: ${activeCaptureMode}`;
  }
  if (type === 'transcript') {
    const transcriptEl = document.getElementById('ai-interview-transcript');
    if (transcriptEl) transcriptEl.textContent = text;
  }
  if (type === 'response') {
    const responseEl = document.getElementById('ai-interview-response');
    if (responseEl) responseEl.textContent = text;
  }
}

function updateOverlayIndicator() {
  const indicator = document.getElementById('ai-interview-indicator');
  if (!indicator) return;
  if (overlayListening) {
    indicator.classList.add('active');
  } else {
    indicator.classList.remove('active');
  }

  if (!overlayListening) {
    const bar = document.getElementById('ai-interview-meter-bar');
    if (bar) bar.style.width = '0%';
  }
}

function setOverlayHidden(hidden) {
  overlayHidden = hidden;
  applyOverlayHiddenState();
}

function applyOverlayHiddenState() {
  const overlay = document.getElementById('ai-interview-overlay');
  if (!overlay) return;
  overlay.style.display = overlayHidden ? 'none' : '';
}

function createAudioMeter(stream) {
  if (!audioContext) {
    audioContext = new AudioContext();
  }
  stopAudioMeter();

  analyserNode = audioContext.createAnalyser();
  analyserNode.fftSize = 512;
  analyserNode.smoothingTimeConstant = 0.8;

  meterSource = audioContext.createMediaStreamSource(stream);
  meterSource.connect(analyserNode);

  const data = new Uint8Array(analyserNode.fftSize);

  const tick = () => {
    if (!analyserNode) return;
    analyserNode.getByteTimeDomainData(data);
    let sum = 0;
    for (let i = 0; i < data.length; i++) {
      const v = (data[i] - 128) / 128;
      sum += v * v;
    }
    const rms = Math.sqrt(sum / data.length);
    const normalized = Math.min(1, rms * 2.5);
    const bar = document.getElementById('ai-interview-meter-bar');
    if (bar) {
      bar.style.width = `${Math.round(normalized * 100)}%`;
    }
    meterRaf = requestAnimationFrame(tick);
  };

  meterRaf = requestAnimationFrame(tick);
}

function stopAudioMeter() {
  if (meterRaf) {
    cancelAnimationFrame(meterRaf);
    meterRaf = null;
  }
  if (meterSource) {
    try {
      meterSource.disconnect();
    } catch (error) {
      console.warn('Failed to disconnect meter source:', error);
    }
    meterSource = null;
  }
  if (analyserNode) {
    try {
      analyserNode.disconnect();
    } catch (error) {
      console.warn('Failed to disconnect analyser:', error);
    }
    analyserNode = null;
  }
}