// App State Management
const state = {
  videoFile: null,
  videoUrl: null,
  audioBuffer: null,
  wavBlob: null,
  transcriptData: null,
  isProcessing: false,
  isDemoMode: false,
  currentActiveIndex: -1,
  apiKey: localStorage.getItem('typhoon_api_key') || 'sk-9gvN1OPfmjUnnBxWTrcLSe5viRBPyzOSdTuR6zaL5HuxRSS6',
  model: localStorage.getItem('typhoon_model') || 'typhoon-asr-realtime',
  language: localStorage.getItem('typhoon_language') || ''
};

// UI Elements
const els = {
  uploadZone: document.getElementById('uploadZone'),
  fileInput: document.getElementById('fileInput'),
  videoContainer: document.getElementById('videoContainer'),
  videoPlayer: document.getElementById('videoPlayer'),
  settingsBtn: document.getElementById('settingsBtn'),
  settingsPanel: document.getElementById('settingsPanel'),
  closeSettings: document.getElementById('closeSettings'),
  apiKeyInput: document.getElementById('apiKey'),
  modelSelect: document.getElementById('modelSelect'),
  languageSelect: document.getElementById('languageSelect'),
  saveSettings: document.getElementById('saveSettings'),
  
  transcribeBtn: document.getElementById('transcribeBtn'),
  demoBtn: document.getElementById('demoBtn'),
  loadingOverlay: document.getElementById('loadingOverlay'),
  loadingStatus: document.getElementById('loadingStatus'),
  loadingProgress: document.getElementById('loadingProgress'),
  progressBarFill: document.getElementById('progressBarFill'),
  
  mainDashboard: document.getElementById('mainDashboard'),
  transcriptPanel: document.getElementById('transcriptPanel'),
  fullTextContent: document.getElementById('fullTextContent'),
  segmentsList: document.getElementById('segmentsList'),
  searchTranscript: document.getElementById('searchTranscript'),
  
  tabText: document.getElementById('tabText'),
  tabSegments: document.getElementById('tabSegments'),
  panelText: document.getElementById('panelText'),
  panelSegments: document.getElementById('panelSegments'),
  
  exportBtn: document.getElementById('exportBtn'),
  exportMenu: document.getElementById('exportMenu'),
  exportTxt: document.getElementById('exportTxt'),
  exportSrt: document.getElementById('exportSrt'),
  exportVtt: document.getElementById('exportVtt'),
  exportJson: document.getElementById('exportJson'),
  
  fileInfo: document.getElementById('fileInfo'),
  fileName: document.getElementById('fileName'),
  fileSize: document.getElementById('fileSize')
};

// Initialize Application
function init() {
  setupEventListeners();
  loadSettings();
  
  // Set default api key if present
  if (state.apiKey) {
    els.apiKeyInput.value = state.apiKey;
  }
}

// Load configurations from state
function loadSettings() {
  els.apiKeyInput.value = state.apiKey;
  els.modelSelect.value = state.model;
  els.languageSelect.value = state.language;
}

// Setup Event Listeners
function setupEventListeners() {
  // Drag and Drop
  els.uploadZone.addEventListener('dragover', (e) => {
    e.preventDefault();
    els.uploadZone.classList.add('dragover');
  });

  els.uploadZone.addEventListener('dragleave', () => {
    els.uploadZone.classList.remove('dragover');
  });

  els.uploadZone.addEventListener('drop', (e) => {
    e.preventDefault();
    els.uploadZone.classList.remove('dragover');
    const file = e.dataTransfer.files[0];
    if (file && file.type.startsWith('video/')) {
      handleVideoSelect(file);
    } else {
      showNotification('กรุณาเลือกไฟล์วิดีโอเท่านั้น', 'error');
    }
  });

  els.uploadZone.addEventListener('click', () => {
    els.fileInput.click();
  });

  els.fileInput.addEventListener('change', (e) => {
    const file = e.target.files[0];
    if (file) {
      handleVideoSelect(file);
    }
  });

  // Settings Panel
  els.settingsBtn.addEventListener('click', () => {
    els.settingsPanel.classList.toggle('open');
  });

  els.closeSettings.addEventListener('click', () => {
    els.settingsPanel.classList.remove('open');
  });

  els.saveSettings.addEventListener('click', () => {
    state.apiKey = els.apiKeyInput.value.trim();
    state.model = els.modelSelect.value;
    state.language = els.languageSelect.value;
    
    localStorage.setItem('typhoon_api_key', state.apiKey);
    localStorage.setItem('typhoon_model', state.model);
    localStorage.setItem('typhoon_language', state.language);
    
    els.settingsPanel.classList.remove('open');
    showNotification('บันทึกการตั้งค่าแล้ว', 'success');
  });

  // Transcription Controls
  els.transcribeBtn.addEventListener('click', () => startTranscriptionFlow(false));
  els.demoBtn.addEventListener('click', () => startTranscriptionFlow(true));

  // Tab Navigation
  els.tabText.addEventListener('click', () => switchTab('text'));
  els.tabSegments.addEventListener('click', () => switchTab('segments'));

  // Video Timeupdate for Interactive Transcript Sync
  els.videoPlayer.addEventListener('timeupdate', syncTranscriptHighlight);

  // Search Transcript
  els.searchTranscript.addEventListener('input', handleSearch);

  // Export Dropdown
  els.exportBtn.addEventListener('click', (e) => {
    e.stopPropagation();
    els.exportMenu.classList.toggle('show');
  });

  document.addEventListener('click', () => {
    els.exportMenu.classList.remove('show');
  });

  els.exportTxt.addEventListener('click', () => exportTranscript('txt'));
  els.exportSrt.addEventListener('click', () => exportTranscript('srt'));
  els.exportVtt.addEventListener('click', () => exportTranscript('vtt'));
  els.exportJson.addEventListener('click', () => exportTranscript('json'));
}

// Handle File Selection
function handleVideoSelect(file) {
  state.videoFile = file;
  
  // Format file size
  const sizeMB = (file.size / (1024 * 1024)).toFixed(1);
  els.fileName.textContent = file.name;
  els.fileSize.textContent = `${sizeMB} MB`;
  
  if (file.size > 200 * 1024 * 1024) {
    showNotification('ไฟล์มีขนาดใหญ่กว่า 200MB การประมวลผลเสียงในเบราว์เซอร์อาจใช้เวลานานขึ้น', 'warning');
  }

  // Create Video URL and load it
  if (state.videoUrl) {
    URL.revokeObjectURL(state.videoUrl);
  }
  state.videoUrl = URL.createObjectURL(file);
  els.videoPlayer.src = state.videoUrl;
  
  // Reset previous data
  state.transcriptData = null;
  state.audioBuffer = null;
  state.wavBlob = null;
  els.mainDashboard.classList.add('hidden');
  els.fileInfo.classList.remove('hidden');
  els.videoContainer.classList.remove('hidden');
  
  showNotification('โหลดไฟล์วิดีโอสำเร็จ', 'success');
}

// Switch between full text and interactive segments tabs
function switchTab(tabType) {
  if (tabType === 'text') {
    els.tabText.classList.add('active');
    els.tabSegments.classList.remove('active');
    els.panelText.classList.remove('hidden');
    els.panelSegments.classList.add('hidden');
  } else {
    els.tabText.classList.remove('active');
    els.tabSegments.classList.add('active');
    els.panelText.classList.add('hidden');
    els.panelSegments.classList.remove('hidden');
  }
}

// Flow Manager: Audio Extraction -> Worker Encoding -> ASR API Call
async function startTranscriptionFlow(isDemo = false) {
  if (!state.videoFile) {
    showNotification('กรุณาอัปโหลดไฟล์วิดีโอก่อน', 'error');
    return;
  }

  if (!isDemo && !state.apiKey) {
    els.settingsPanel.classList.add('open');
    showNotification('กรุณากรอก Typhoon API Key ในหน้าการตั้งค่าก่อนเริ่มถอดความ', 'warning');
    return;
  }

  state.isDemoMode = isDemo;
  state.isProcessing = true;
  updateLoadingUI('เริ่มกระบวนการ...', 0);
  els.loadingOverlay.classList.remove('hidden');

  try {
    // 1. Extract audio
    updateLoadingUI('กำลังสกัดสัญญาณเสียงจากไฟล์วิดีโอ...', 15);
    const audioBuffer = await extractAudioFromVideo(state.videoFile);
    state.audioBuffer = audioBuffer;

    // 2. Encode to WAV
    updateLoadingUI('กำลังแปลงสัญญาณเสียงเป็น 16kHz WAV...', 40);
    const wavBlob = await encodeAudioToWav(audioBuffer);
    state.wavBlob = wavBlob;

    // 3. Call Typhoon API
    if (isDemo) {
      updateLoadingUI('จำลองการเรียกใช้งาน Typhoon AI (Demo Mode)...', 80);
      await delay(1500); // Simulate API latency
      state.transcriptData = generateDemoTranscript(els.videoPlayer.duration || 20);
    } else {
      updateLoadingUI('กำลังส่งไฟล์เสียงไปประมวลผลที่ Typhoon AI ASR...', 70);
      const transcript = await callTyphoonASR(wavBlob);
      state.transcriptData = transcript;
    }

    // 4. Render results
    renderTranscript(state.transcriptData);
    els.mainDashboard.classList.remove('hidden');
    showNotification('ถอดความวิดีโอสำเร็จ!', 'success');
  } catch (error) {
    console.error(error);
    showNotification(`เกิดข้อผิดพลาด: ${error.message}`, 'error');
  } finally {
    state.isProcessing = false;
    els.loadingOverlay.classList.add('hidden');
  }
}

// Update loader screen text and bar width
function updateLoadingUI(statusText, progressPercent) {
  els.loadingStatus.textContent = statusText;
  els.progressBarFill.style.width = `${progressPercent}%`;
  els.loadingProgress.textContent = `${progressPercent}%`;
}

// Web Audio API: Extract audio from video blob
async function extractAudioFromVideo(file) {
  const fileReader = new FileReader();
  
  const arrayBufferPromise = new Promise((resolve, reject) => {
    fileReader.onload = () => resolve(fileReader.result);
    fileReader.onerror = () => reject(new Error('ไม่สามารถอ่านไฟล์วิดีโอได้'));
  });
  
  fileReader.readAsArrayBuffer(file);
  const arrayBuffer = await arrayBufferPromise;

  // Use AudioContext to decode
  const AudioContextClass = window.AudioContext || window.webkitAudioContext;
  const audioCtx = new AudioContextClass();
  
  try {
    return await audioCtx.decodeAudioData(arrayBuffer);
  } catch (e) {
    throw new Error('ไม่สามารถถอดรหัสเสียงจากวิดีโอนี้ได้ (บราวเซอร์ไม่รองรับ Codec นี้)');
  } finally {
    audioCtx.close();
  }
}

// Web Worker Helper: Encode AudioBuffer to WAV
function encodeAudioToWav(audioBuffer) {
  return new Promise((resolve, reject) => {
    const channelData = audioBuffer.getChannelData(0); // Mono channel
    const sampleRate = audioBuffer.sampleRate;

    // Load web worker
    const worker = new Worker('wav-worker.js');
    
    worker.postMessage({
      channelData: channelData,
      sampleRate: sampleRate
    });

    worker.onmessage = function(e) {
      const data = e.data;
      if (data.type === 'progress') {
        // Map progress from worker into loader progress (40% to 70% range)
        const mappedProgress = Math.round(40 + (data.progress * 0.3));
        updateLoadingUI(`แปลงสัญญาณเสียงเป็น 16kHz WAV (${data.status === 'downsampling' ? 'Downsampling' : 'Encoding'})...`, mappedProgress);
      } else if (data.type === 'done') {
        const blob = new Blob([data.buffer], { type: 'audio/wav' });
        worker.terminate();
        resolve(blob);
      } else if (data.type === 'error') {
        worker.terminate();
        reject(new Error(data.message));
      }
    };

    worker.onerror = function(err) {
      worker.terminate();
      reject(new Error('เกิดความล้มเหลวในการทำงานของ Web Worker'));
    };
  });
}

// Call OpenTyphoon Speech-To-Text API
async function callTyphoonASR(wavBlob) {
  const formData = new FormData();
  formData.append('file', wavBlob, 'audio.wav');
  formData.append('model', state.model);
  formData.append('response_format', 'verbose_json');
  
  if (state.language) {
    formData.append('language', state.language);
  }

  const url = 'https://api.opentyphoon.ai/v1/audio/transcriptions';
  const headers = {
    'Authorization': `Bearer ${state.apiKey}`
  };

  const response = await fetch(url, {
    method: 'POST',
    headers: headers,
    body: formData
  });

  if (!response.ok) {
    const errorText = await response.text();
    let errorJson;
    try {
      errorJson = JSON.parse(errorText);
    } catch(e) {}
    const msg = errorJson?.error?.message || errorText || `HTTP ${response.status}`;
    throw new Error(`การสื่อสารกับ API ล้มเหลว: ${msg}`);
  }

  return await response.json();
}

// Generate high-quality mock data for demo mode
function generateDemoTranscript(duration) {
  const baseSegments = [
    { text: "สวัสดีครับ ยินดีต้อนรับสู่แอปพลิเคชันถอดสคริปต์วิดีโอด้วยเทคโนโลยี AI จาก Typhoon" },
    { text: "โดยแอปพลิเคชันนี้ทำงานบนเว็บบราวเซอร์ของคุณโดยตรง มีความปลอดภัยสูง และทำงานได้รวดเร็ว" },
    { text: "คุณสามารถสกัดเสียงจากวิดีโอ แปลงฟอร์แมต และส่งให้โมเดล Typhoon ASR ถอดความออกมา" },
    { text: "ระบบอินเตอร์แอคทีฟของเราจะไฮไลต์ข้อความประโยคต่างๆ ตามที่กำลังเล่นอยู่ในวิดีโอแบบสดๆ" },
    { text: "หากคุณต้องการย้อนกลับไปฟังเฉพาะบางคำหรือบางประโยค ก็เพียงแค่คลิกเลือกประโยคนั้นเพื่อรับชมได้ทันที" },
    { text: "และสุดท้าย คุณยังสามารถดาวน์โหลดเอกสารเก็บไว้ใช้งานต่อได้ ไม่ว่าจะเป็นรูปแบบไฟล์ Text ธรรมดา หรือ ซับไตเติล SRT และ VTT" }
  ];

  const count = baseSegments.length;
  const segmentDuration = duration / count;
  
  const segments = baseSegments.map((seg, index) => {
    return {
      id: index,
      start: index * segmentDuration,
      end: (index + 1) * segmentDuration,
      text: seg.text
    };
  });

  const fullText = segments.map(s => s.text).join(' ');

  return {
    text: fullText,
    segments: segments
  };
}

// Render Transcript results into UI
function renderTranscript(data) {
  // Render Full Text
  els.fullTextContent.innerHTML = `<p>${data.text}</p>`;

  // Render Interactive Segments
  els.segmentsList.innerHTML = '';
  
  if (data.segments && data.segments.length > 0) {
    data.segments.forEach((seg, index) => {
      const segmentEl = document.createElement('div');
      segmentEl.className = 'segment-item';
      segmentEl.dataset.index = index;
      segmentEl.dataset.start = seg.start;
      segmentEl.dataset.end = seg.end;
      
      const timeStr = formatTimeShort(seg.start);
      
      segmentEl.innerHTML = `
        <span class="segment-time" title="คลิกเพื่อข้ามวิดีโอไปช่วงเวลานี้">${timeStr}</span>
        <span class="segment-text" contenteditable="true" spellcheck="false" title="คลิกเพื่อแก้ไขข้อความ">${seg.text}</span>
      `;
      
      // Jump video when clicking on a segment (but not if editing text)
      segmentEl.addEventListener('click', (e) => {
        if (e.target.classList.contains('segment-text')) {
          return; // Avoid jumping video when trying to edit text
        }
        els.videoPlayer.currentTime = seg.start;
        els.videoPlayer.play();
      });

      const textEl = segmentEl.querySelector('.segment-text');

      // Save changes on blur
      textEl.addEventListener('blur', () => {
        const newText = textEl.textContent.trim();
        if (newText !== seg.text) {
          seg.text = newText;
          // Sync with state.transcriptData
          state.transcriptData.text = state.transcriptData.segments.map(s => s.text).join(' ');
          els.fullTextContent.innerHTML = `<p>${state.transcriptData.text}</p>`;
          showNotification('บันทึกการแก้ไขคำถอดความแล้ว', 'success');
        }
      });

      // Pressing enter blurs input (saves changes)
      textEl.addEventListener('keydown', (e) => {
        if (e.key === 'Enter') {
          e.preventDefault();
          textEl.blur();
        }
      });
      
      els.segmentsList.appendChild(segmentEl);
    });
  } else {
    // If API response doesn't contain segments array, construct single segment
    els.segmentsList.innerHTML = `
      <div class="segment-item" data-index="0" data-start="0" data-end="${els.videoPlayer.duration || 10}">
        <span class="segment-time">00:00</span>
        <span class="segment-text" contenteditable="true" spellcheck="false" title="คลิกเพื่อแก้ไขข้อความ">${data.text}</span>
      </div>
    `;

    const segmentEl = els.segmentsList.querySelector('.segment-item');
    const textEl = segmentEl.querySelector('.segment-text');

    segmentEl.addEventListener('click', (e) => {
      if (e.target.classList.contains('segment-text')) return;
      els.videoPlayer.currentTime = 0;
      els.videoPlayer.play();
    });

    textEl.addEventListener('blur', () => {
      const newText = textEl.textContent.trim();
      if (newText !== data.text) {
        data.text = newText;
        els.fullTextContent.innerHTML = `<p>${newText}</p>`;
        showNotification('บันทึกการแก้ไขคำถอดความแล้ว', 'success');
      }
    });

    textEl.addEventListener('keydown', (e) => {
      if (e.key === 'Enter') {
        e.preventDefault();
        textEl.blur();
      }
    });
  }
}

// Sync video timeline with highlighted transcript segment
function syncTranscriptHighlight() {
  if (!state.transcriptData || !state.transcriptData.segments) return;
  
  const currentTime = els.videoPlayer.currentTime;
  const segments = state.transcriptData.segments;
  
  // Find current segment index
  let activeIndex = -1;
  for (let i = 0; i < segments.length; i++) {
    if (currentTime >= segments[i].start && currentTime <= segments[i].end) {
      activeIndex = i;
      break;
    }
  }
  
  // If active segment changed, update classes and scroll
  if (activeIndex !== state.currentActiveIndex) {
    state.currentActiveIndex = activeIndex;
    
    // Remove active state from all
    const items = els.segmentsList.querySelectorAll('.segment-item');
    items.forEach(item => item.classList.remove('active'));
    
    if (activeIndex !== -1) {
      const activeItem = els.segmentsList.querySelector(`.segment-item[data-index="${activeIndex}"]`);
      if (activeItem) {
        activeItem.classList.add('active');
        
        // Auto scroll segment list to center the active item
        const containerHeight = els.segmentsList.clientHeight;
        const itemTop = activeItem.offsetTop;
        const itemHeight = activeItem.clientHeight;
        
        els.segmentsList.scrollTo({
          top: itemTop - (containerHeight / 2) + (itemHeight / 2),
          behavior: 'smooth'
        });
      }
    }
  }
}

// Handle search functionality inside segments
function handleSearch(e) {
  const query = e.target.value.toLowerCase().trim();
  const items = els.segmentsList.querySelectorAll('.segment-item');
  
  items.forEach(item => {
    const text = item.querySelector('.segment-text').textContent.toLowerCase();
    if (text.includes(query)) {
      item.classList.remove('hidden-search');
      // Highlight matching search term in text
      if (query !== '') {
        const originalText = state.transcriptData.segments[item.dataset.index].text;
        const regex = new RegExp(`(${escapeRegExp(query)})`, 'gi');
        item.querySelector('.segment-text').innerHTML = originalText.replace(regex, '<mark class="highlight-mark">$1</mark>');
      } else {
        item.querySelector('.segment-text').innerHTML = state.transcriptData.segments[item.dataset.index].text;
      }
    } else {
      item.classList.add('hidden-search');
    }
  });
}

function escapeRegExp(string) {
  return string.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
}

// Helpers: Time Formatting
function formatTimeShort(seconds) {
  const m = Math.floor(seconds / 60).toString().padStart(2, '0');
  const s = Math.floor(seconds % 60).toString().padStart(2, '0');
  return `${m}:${s}`;
}

function formatTimeSRT(seconds) {
  const h = Math.floor(seconds / 3600).toString().padStart(2, '0');
  const m = Math.floor((seconds % 3600) / 60).toString().padStart(2, '0');
  const s = Math.floor(seconds % 60).toString().padStart(2, '0');
  const ms = Math.floor((seconds % 1) * 1000).toString().padStart(3, '0');
  return `${h}:${m}:${s},${ms}`;
}

function formatTimeVTT(seconds) {
  const h = Math.floor(seconds / 3600).toString().padStart(2, '0');
  const m = Math.floor((seconds % 3600) / 60).toString().padStart(2, '0');
  const s = Math.floor(seconds % 60).toString().padStart(2, '0');
  const ms = Math.floor((seconds % 1) * 1000).toString().padStart(3, '0');
  return `${h}:${m}:${s}.${ms}`;
}

// Export Transcript in diverse formats
function exportTranscript(format) {
  if (!state.transcriptData) {
    showNotification('ไม่มีข้อมูลทรานสคริปต์ให้ดาวน์โหลด', 'error');
    return;
  }

  let content = '';
  let filename = `${state.videoFile ? state.videoFile.name.replace(/\.[^/.]+$/, "") : "transcript"}`;
  let mimeType = 'text/plain';

  const segments = state.transcriptData.segments || [];

  if (format === 'txt') {
    content = state.transcriptData.text;
    filename += '.txt';
  } else if (format === 'srt') {
    filename += '.srt';
    content = segments.map((seg, index) => {
      return `${index + 1}\n${formatTimeSRT(seg.start)} --> ${formatTimeSRT(seg.end)}\n${seg.text}\n`;
    }).join('\n');
  } else if (format === 'vtt') {
    filename += '.vtt';
    content = 'WEBVTT\n\n' + segments.map((seg, index) => {
      return `${index + 1}\n${formatTimeVTT(seg.start)} --> ${formatTimeVTT(seg.end)}\n${seg.text}\n`;
    }).join('\n');
  } else if (format === 'json') {
    filename += '.json';
    content = JSON.stringify(state.transcriptData, null, 2);
    mimeType = 'application/json';
  }

  // Trigger browser download
  const blob = new Blob([content], { type: `${mimeType};charset=utf-8` });
  const url = URL.createObjectURL(blob);
  const a = document.createElement('a');
  a.href = url;
  a.download = filename;
  document.body.appendChild(a);
  a.click();
  document.body.removeChild(a);
  URL.revokeObjectURL(url);
  
  showNotification(`ดาวน์โหลดไฟล์ ${format.toUpperCase()} สำเร็จ`, 'success');
}

// Utility: Show Toast Notifications
function showNotification(message, type = 'info') {
  // Check if notification container exists, if not create it
  let container = document.getElementById('notificationContainer');
  if (!container) {
    container = document.createElement('div');
    container.id = 'notificationContainer';
    document.body.appendChild(container);
  }

  const toast = document.createElement('div');
  toast.className = `toast toast-${type}`;
  
  let icon = '🔔';
  if (type === 'success') icon = '✅';
  if (type === 'error') icon = '❌';
  if (type === 'warning') icon = '⚠️';

  toast.innerHTML = `
    <span class="toast-icon">${icon}</span>
    <span class="toast-message">${message}</span>
  `;

  container.appendChild(toast);
  
  // Triggers smooth slide in
  setTimeout(() => toast.classList.add('show'), 10);

  // Remove toast after 4s
  setTimeout(() => {
    toast.classList.remove('show');
    setTimeout(() => {
      toast.remove();
    }, 300);
  }, 4000);
}

// Delay helper
function delay(ms) {
  return new Promise(resolve => setTimeout(resolve, ms));
}

// Start the app when content is loaded
document.addEventListener('DOMContentLoaded', init);