/**
 * AI SquadX VIP – Viral Shorts Generator
 * State Machine: idle → loading → results | error
 */

'use strict';

// ─── Constants ──────────────────────────────────────────────────────────────
// Local AI Clipper backend (start with start_backend.bat)
// Relative path so it follows <base href> on Hugging Face Spaces (path prefix)
const BACKEND_URL = 'api/process';

const LOADING_MESSAGES = [
  'Connecting to AI engine...',
  'Fetching video metadata...',
  'Transcribing audio...',
  'Analyzing viral hooks...',
  'Scoring engagement moments...',
  'Identifying key highlights...',
  'Clipping best segments...',
  'Formatting to 9:16 vertical...',
  'Rendering your shorts...',
  'Almost there...',
];

const STEPS = [
  { id: 'step-1', label: 'Fetching video metadata', progress: 25 },
  { id: 'step-2', label: 'Analyzing viral hooks', progress: 50 },
  { id: 'step-3', label: 'Clipping & formatting', progress: 75 },
  { id: 'step-4', label: 'Rendering shorts', progress: 95 },
];

// ─── DOM Refs ────────────────────────────────────────────────────────────────
const screens = {
  input: document.getElementById('screen-input'),
  loading: document.getElementById('screen-loading'),
  results: document.getElementById('screen-results'),
  error: document.getElementById('screen-error'),
};

const urlInput = document.getElementById('youtube-url-input');
const generateBtn = document.getElementById('generate-btn');
const loadingMsg = document.getElementById('loading-message');
const progressBar = document.getElementById('progress-bar');
const resultsGallery = document.getElementById('results-gallery');
const resultsCount = document.getElementById('results-count');
const newVideoBtn = document.getElementById('new-video-btn');
const retryBtn = document.getElementById('retry-btn');
const errorMessage = document.getElementById('error-message');

// Advanced refs
const captionsToggle = document.getElementById('captions-toggle');
const captionStyleSelect = document.getElementById('caption-style-select');
const captionStyleWrapper = document.getElementById('caption-style-wrapper');
const headlineInput = document.getElementById('headline-input');
const ctaInput = document.getElementById('cta-input');

// Phase 2 refs
const reframeToggle = document.getElementById('reframe-toggle');
const progressBarToggle = document.getElementById('progress-bar-toggle');
const vibeSelect = document.getElementById('vibe-select');

// Retention Psychology refs
const retentionModeToggle = document.getElementById('retention-mode-toggle');
const colorModeSelect = document.getElementById('color-mode-select');
const watermarkInput = document.getElementById('watermark-input');
const safeZoneToggle = document.getElementById('safe-zone-toggle');
const durationRangeSelect = document.getElementById('duration-range-select');
const retentionToggleBtn = document.getElementById('retention-toggle-btn');
const retentionBody = document.getElementById('retention-body');

// ─── App State ───────────────────────────────────────────────────────────────
let loadingTimer = null;
let messageInterval = null;
let stepIndex = 0;
let msgIndex = 0;
let savedUrl = '';
let clipsCount = null;  // null = Default (backend decides)

// ─── Screen Manager ──────────────────────────────────────────────────────────
function showScreen(name) {
  Object.values(screens).forEach(s => s.classList.remove('active'));
  const target = screens[name];
  if (target) {
    target.classList.add('active');
  }
}

// ─── Loading Animations ───────────────────────────────────────────────────────
function startLoadingAnimation() {
  // Reset
  progressBar.style.width = '0%';
  stepIndex = 0;
  msgIndex = 0;
  STEPS.forEach(s => {
    const el = document.getElementById(s.id);
    el.classList.remove('active', 'done');
  });

  // Rotate messages
  loadingMsg.textContent = LOADING_MESSAGES[0];
  messageInterval = setInterval(() => {
    msgIndex = (msgIndex + 1) % LOADING_MESSAGES.length;
    loadingMsg.style.opacity = '0';
    setTimeout(() => {
      loadingMsg.textContent = LOADING_MESSAGES[msgIndex];
      loadingMsg.style.opacity = '1';
    }, 250);
  }, 2200);

  // Advance steps
  advanceStep();
}

function advanceStep() {
  if (stepIndex >= STEPS.length) return;
  const step = STEPS[stepIndex];
  const stepEl = document.getElementById(step.id);

  // Mark previous as done
  if (stepIndex > 0) {
    const prevEl = document.getElementById(STEPS[stepIndex - 1].id);
    prevEl.classList.remove('active');
    prevEl.classList.add('done');
  }

  stepEl.classList.add('active');
  progressBar.style.width = step.progress + '%';

  stepIndex++;
  if (stepIndex < STEPS.length) {
    loadingTimer = setTimeout(advanceStep, 3500);
  }
}

function stopLoadingAnimation() {
  clearInterval(messageInterval);
  clearTimeout(loadingTimer);
  messageInterval = null;
  loadingTimer = null;
}

function completeAllSteps() {
  STEPS.forEach(s => {
    const el = document.getElementById(s.id);
    el.classList.remove('active');
    el.classList.add('done');
  });
  progressBar.style.width = '100%';
}

// ─── Backend Call (streaming NDJSON) ───────────────────────────────────────────
async function callBackend(youtubeUrl, { onTotal, onClip }) {
  const modeEl = document.querySelector('input[name="crop-mode"]:checked');
  const mode = modeEl ? modeEl.value : 'fill';

  const payload = {
    youtubeUrl,
    mode,
    captions: captionsToggle.checked,
    captionStyle: captionStyleSelect ? captionStyleSelect.value : 'mrbeast',
    headline: headlineInput.value.trim(),
    cta: ctaInput.value.trim(),
    reframe: reframeToggle.checked,
    progressBar: progressBarToggle.checked,
    vibe: vibeSelect.value,
    // Retention Psychology
    retentionMode: retentionModeToggle ? retentionModeToggle.checked : false,
    colorMode: colorModeSelect ? colorModeSelect.value : 'off',
    watermarkText: watermarkInput ? watermarkInput.value.trim() : '',
    safeZone: safeZoneToggle ? safeZoneToggle.checked : false,
    durationRange: durationRangeSelect ? durationRangeSelect.value : 'auto',
  };

  if (clipsCount !== null) payload.clips = clipsCount;  // omit = backend default

  let response;
  try {
    response = await fetch(BACKEND_URL, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify(payload),
    });
  } catch (e) {
    console.error('[ClipperApp] Network error:', e);
    throw new Error(
      'Cannot reach the local backend. Make sure start_backend.bat is running on port 5000.'
    );
  }

  const reader = response.body.getReader();
  const decoder = new TextDecoder();
  let buffer = '';

  while (true) {
    const { done, value } = await reader.read();
    if (done) break;

    buffer += decoder.decode(value, { stream: true });
    const lines = buffer.split('\n');
    buffer = lines.pop(); // keep any incomplete trailing chunk

    for (const line of lines) {
      if (!line.trim()) continue;
      let msg;
      try { msg = JSON.parse(line); } catch { continue; }

      if (msg.error) throw new Error(msg.error);
      if (msg.total !== undefined) await onTotal(msg.total);
      if (msg.clip !== undefined) await onClip(msg.clip, msg.index, msg);
      // msg.warning is silently ignored (non-fatal)
    }
  }
}

// ─── Gallery Rendering ────────────────────────────────────────────────────────
function renderGallery(videoUrls) {
  resultsGallery.innerHTML = '';
  resultsCount.textContent = videoUrls.length;

  videoUrls.forEach((url, i) => {
    const card = createVideoCard(url, i + 1);
    resultsGallery.appendChild(card);
  });
}

function createVideoCard(url, index, retentionData = {}) {
  const { viral_analysis = null, pacing = null, structure = null, triggers = null } = retentionData;
  const card = document.createElement('article');
  card.className = 'video-card';
  card.style.animationDelay = `${(index - 1) * 0.08}s`;
  card.setAttribute('role', 'listitem');

  // ─── Viral Score Bar ──────────────────────────────────────────────────────
  if (viral_analysis) {
    const score = viral_analysis.final_score || 0;
    const scorePct = Math.min(100, Math.max(0, score * 100));
    const scoreColorClass = score > 0.75 ? 'score-green' : score >= 0.5 ? 'score-amber' : 'score-red';
    
    const scoreBar = document.createElement('div');
    scoreBar.className = 'viral-score-container';
    scoreBar.innerHTML = `<div class="viral-score-fill ${scoreColorClass}" style="width: ${scorePct}%"></div>`;
    card.appendChild(scoreBar);

    // ─── Viral Signal Badges ────────────────────────────────────────────────
    const signalsRow = document.createElement('div');
    signalsRow.className = 'viral-signals-row';

    const sigs = [
        { label: 'YT Heat', val: viral_analysis.heatmap_score, cls: 'badge-heat', id: 'heatmap' },
        { label: 'Energy',  val: viral_analysis.energy_score,  cls: 'badge-energy', id: 'energy' },
        { label: 'Text',    val: viral_analysis.transcript_score, cls: 'badge-text', id: 'transcript' }
    ];

    sigs.forEach(s => {
        const badge = document.createElement('span');
        badge.className = `viral-badge ${s.cls}`;
        badge.textContent = `${s.label}: ${s.val.toFixed(2)}`;
        
        // Highlight if it's the top signal
        if (viral_analysis.top_signal === s.id) {
            const topTag = document.createElement('span');
            topTag.className = 'top-signal-tag';
            topTag.textContent = 'TOP';
            badge.appendChild(topTag);
        }
        signalsRow.appendChild(badge);
    });
    card.appendChild(signalsRow);
  }

  const videoWrapper = document.createElement('div');
  videoWrapper.className = 'video-wrapper';

  const video = document.createElement('video');
  video.src = url;
  video.controls = true;
  video.setAttribute('preload', 'metadata');
  video.setAttribute('playsinline', '');
  video.setAttribute('aria-label', `Generated Short #${index}`);

  videoWrapper.appendChild(video);

  const footer = document.createElement('div');
  footer.className = 'video-card-footer';

  const label = document.createElement('p');
  label.className = 'video-card-label';
  label.textContent = `Short #${index}`;

  const downloadBtn = document.createElement('button');
  downloadBtn.className = 'btn-download';
  downloadBtn.setAttribute('aria-label', `Download Short #${index}`);
  downloadBtn.innerHTML = `
    <svg class="dl-icon" width="13" height="13" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round">
      <path d="M21 15v4a2 2 0 01-2 2H5a2 2 0 01-2-2v-4"/>
      <polyline points="7 10 12 15 17 10"/>
      <line x1="12" y1="15" x2="12" y2="3"/>
    </svg>
    <span class="dl-label">Download</span>`;

  downloadBtn.addEventListener('click', async () => {
    if (downloadBtn.disabled) return;
    downloadBtn.disabled = true;
    downloadBtn.querySelector('.dl-label').textContent = 'Downloading…';
    try {
      const res = await fetch(url);
      const blob = await res.blob();
      const blobUrl = URL.createObjectURL(blob);
      const a = document.createElement('a');
      a.href = blobUrl;
      a.download = `viral-short-${index}.mp4`;
      document.body.appendChild(a);
      a.click();
      document.body.removeChild(a);
      setTimeout(() => URL.revokeObjectURL(blobUrl), 10000);
    } catch (err) {
      console.error('Download failed:', err);
      alert('Download failed. Please try right-clicking the video and saving it.');
    }
    downloadBtn.disabled = false;
    downloadBtn.querySelector('.dl-label').textContent = 'Download';
  });

  footer.appendChild(label);
  footer.appendChild(downloadBtn);

  // ─── Retention Psychology Badges ─────────────────────────────────────────
  if (pacing !== null || structure !== null || triggers !== null) {
    const rp = document.createElement('div');
    rp.className = 'rp-badges';

    // Pacing score badge
    if (pacing !== null) {
      const pacingColor = pacing >= 70 ? '#22c55e' : pacing >= 40 ? '#fbbf24' : '#f87171';
      const pacingBadge = document.createElement('div');
      pacingBadge.className = 'rp-badge rp-pacing';
      pacingBadge.innerHTML = `
        <svg width="28" height="28" viewBox="0 0 36 36" aria-hidden="true">
          <circle cx="18" cy="18" r="14" fill="none" stroke="rgba(255,255,255,0.08)" stroke-width="3"/>
          <circle cx="18" cy="18" r="14" fill="none" stroke="${pacingColor}" stroke-width="3"
            stroke-dasharray="${Math.round(pacing * 0.88)} 88"
            stroke-dashoffset="22" stroke-linecap="round" transform="rotate(-90 18 18)"/>
          <text x="18" y="22" text-anchor="middle" fill="${pacingColor}" font-size="9" font-weight="700"
            font-family="Inter,sans-serif">${pacing}</text>
        </svg>
        <span class="rp-badge-label">Pacing</span>
      `;
      rp.appendChild(pacingBadge);
    }

    // Hook / Body / Reward structure labels
    if (structure) {
      const segBadge = document.createElement('div');
      segBadge.className = 'rp-badge rp-structure';
      const hookDur = Math.round((structure.hook.end - structure.hook.start) * 10) / 10;
      const rewardDur = Math.round((structure.reward.end - structure.reward.start) * 10) / 10;
      segBadge.innerHTML = `
        <span class="seg-pill seg-hook">🎣 Hook ${hookDur}s</span>
        <span class="seg-pill seg-body">📹 Body</span>
        <span class="seg-pill seg-reward">🏆 Reward ${rewardDur}s</span>
      `;
      rp.appendChild(segBadge);
    }

    // Trigger tag pills
    if (triggers && triggers.tags && triggers.tags.length > 0) {
      const tagRow = document.createElement('div');
      tagRow.className = 'rp-badge rp-triggers';
      tagRow.innerHTML = triggers.tags
        .map(tag => `<span class="trigger-tag">${tag}</span>`)
        .join('');
      rp.appendChild(tagRow);
    }

    card.appendChild(rp);
  }

  card.appendChild(videoWrapper);
  card.appendChild(footer);

  return card;
}

// ─── Placeholder card (shown while clip is encoding) ──────────────────────────
function createPlaceholderCard(index) {
  const card = document.createElement('article');
  card.className = 'video-card video-card-placeholder';
  card.dataset.cardIndex = index;
  card.setAttribute('role', 'listitem');
  card.style.animationDelay = `${index * 0.07}s`;

  const wrapper = document.createElement('div');
  wrapper.className = 'video-wrapper';
  wrapper.innerHTML = `
    <div class="placeholder-inner">
      <div class="placeholder-spinner"></div>
      <span class="placeholder-label">PROCESSING...</span>
    </div>`;

  const footer = document.createElement('div');
  footer.className = 'video-card-footer';
  footer.innerHTML = `
    <p class="video-card-label" style="opacity:0.35">Short #${index + 1}</p>
    <div class="btn-download-ghost"></div>`;

  card.appendChild(wrapper);
  card.appendChild(footer);
  return card;
}

// ─── Validation ───────────────────────────────────────────────────────────────
function isValidYouTubeUrl(url) {
  try {
    const u = new URL(url.trim());
    return (
      (u.hostname === 'www.youtube.com' || u.hostname === 'youtube.com') && u.searchParams.has('v') ||
      u.hostname === 'youtu.be' && u.pathname.length > 1 ||
      u.hostname === 'www.youtube.com' && u.pathname.startsWith('/shorts/')
    );
  } catch {
    return false;
  }
}

// ─── Results badge ─────────────────────────────────────────────────────────────
function showResultsBadge(visible) {
  const badge = document.getElementById('results-loading-badge');
  if (badge) badge.style.display = visible ? 'flex' : 'none';
}

// ─── Main Generate Flow ───────────────────────────────────────────────────────────
async function handleGenerate() {
  const rawUrl = urlInput.value.trim();

  if (!rawUrl) { shakeInput(); return; }

  if (!isValidYouTubeUrl(rawUrl)) {
    shakeInput();
    showInputError('Please enter a valid YouTube URL.');
    return;
  }

  clearInputError();
  savedUrl = rawUrl;
  urlInput.disabled = true;
  generateBtn.disabled = true;

  showScreen('loading');
  startLoadingAnimation();

  let firstClip = true;
  let totalClips = 0;
  let receivedClips = 0;
  let receivedClipsData = [];

  try {
    await callBackend(rawUrl, {
      async onTotal(n) {
        totalClips = n;
        stopLoadingAnimation();
        completeAllSteps();
        await delay(300);
        resultsGallery.innerHTML = '';
        resultsCount.textContent = '0';
        showScreen('results');
        showResultsBadge(true);
        for (let i = 0; i < n; i++) {
          resultsGallery.appendChild(createPlaceholderCard(i));
        }
      },
      async onClip(url, index, data) {
        receivedClips++;
        // Collect data for sorting
        receivedClipsData.push({ url, index, data });
        
        // Sort by final_score descending
        receivedClipsData.sort((a, b) => {
          const sA = (a.data.viral_analysis || {}).final_score || 0;
          const sB = (b.data.viral_analysis || {}).final_score || 0;
          return sB - sA;
        });

        // Re-render gallery (to maintain sort order)
        // We find the current cards/placeholders and update them or just refresh the whole gallery
        // To keep it simple and correct, we re-render the gallery each time
        resultsGallery.innerHTML = '';
        
        // 1. First add the real cards (sorted)
        receivedClipsData.forEach((clip, i) => {
           const realCard = createVideoCard(clip.url, i + 1, clip.data);
           resultsGallery.appendChild(realCard);
        });

        // 2. Then add the placeholders for the remaining slots
        for (let i = receivedClips; i < totalClips; i++) {
           resultsGallery.appendChild(createPlaceholderCard(i));
        }

        resultsCount.textContent = receivedClips;
        if (receivedClips >= totalClips) showResultsBadge(false);
      },
    });

    if (totalClips === 0) {
      throw new Error('No shorts were generated. Please try a different video.');
    }
    showResultsBadge(false);

  } catch (err) {
    stopLoadingAnimation();
    console.error('[ClipperApp] Error:', err);

    // Detect common failure patterns and show user-friendly messages
    const raw = (err.message || '').toLowerCase();
    let friendlyMsg = '';

    if (raw.includes('failed to resolve') || raw.includes('dns resolution failed') || raw.includes('no address associated')) {
      friendlyMsg = '🌐 YouTube is unreachable from this server.\n\n'
        + 'This hosting platform appears to block outbound connections to YouTube.\n\n'
        + 'Try these fixes:\n'
        + '1. Upload a cookies.txt file to the Space\n'
        + '2. Switch to a GPU-enabled Space (better network access)\n'
        + '3. Try again in a few minutes (may be a temporary DNS issue)';
    } else if (raw.includes('failed to extract') || raw.includes('player response')) {
      friendlyMsg = '⚠️ YouTube blocked this request.\n\n'
        + 'YouTube detected automated access and refused the download.\n\n'
        + 'Fix: Upload a cookies.txt file exported from your browser to bypass this restriction.';
    } else if (raw.includes('cannot reach') || raw.includes('network error') || raw.includes('failed to fetch')) {
      friendlyMsg = '🔌 Cannot connect to the backend server.\n\n'
        + 'Make sure your backend is running (start_backend.bat or check HF Space logs).';
    }

    errorMessage.textContent = friendlyMsg || err.message || 'An unexpected error occurred.';
    errorMessage.style.whiteSpace = 'pre-line';
    showScreen('error');
  }
}

// ─── Input helpers ────────────────────────────────────────────────────────────
function shakeInput() {
  const wrapper = urlInput.closest('.input-wrapper');
  wrapper.style.animation = 'none';
  wrapper.offsetHeight; // force reflow
  wrapper.style.animation = 'shake 0.4s ease';
  wrapper.addEventListener('animationend', () => {
    wrapper.style.animation = '';
  }, { once: true });
}

function showInputError(msg) {
  let errEl = document.getElementById('input-error');
  if (!errEl) {
    errEl = document.createElement('p');
    errEl.id = 'input-error';
    errEl.style.cssText = 'font-size:0.8rem;color:#F87171;margin-top:-0.25rem;padding-left:0.25rem;';
    urlInput.closest('.input-card').insertBefore(errEl, document.querySelector('.btn-generate'));
  }
  errEl.textContent = msg;
}

function clearInputError() {
  const errEl = document.getElementById('input-error');
  if (errEl) errEl.remove();
}

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

// ─── Reset to Input Screen ────────────────────────────────────────────────────
function resetToInput() {
  urlInput.disabled = false;
  generateBtn.disabled = false;
  urlInput.value = '';
  clearInputError();
  showScreen('input');
  urlInput.focus();
}

// ─── Shake Keyframe (injected via JS for portability) ────────────────────────
(function injectShakeKeyframe() {
  const style = document.createElement('style');
  style.textContent = `
    @keyframes shake {
      0%,100% { transform: translateX(0); }
      20%      { transform: translateX(-6px); }
      40%      { transform: translateX(6px); }
      60%      { transform: translateX(-4px); }
      80%      { transform: translateX(4px); }
    }
  `;
  document.head.appendChild(style);
})();

// ─── Event Listeners ──────────────────────────────────────────────────────────
generateBtn.addEventListener('click', handleGenerate);

urlInput.addEventListener('keydown', e => {
  if (e.key === 'Enter') handleGenerate();
});

newVideoBtn.addEventListener('click', resetToInput);
retryBtn.addEventListener('click', resetToInput);

// Auto-focus input on load
window.addEventListener('DOMContentLoaded', () => {
  urlInput.focus();

  // Character counter for inputs with maxlength attribute
  document.querySelectorAll('input[maxlength]').forEach(input => {
    const counter = input.parentElement.querySelector('.char-count');
    if (counter) {
      const update = () => { counter.textContent = input.value.length; };
      input.addEventListener('input', update);
      update();
    }
  });
});

// Show/hide caption style selector based on captions toggle
if (captionsToggle && captionStyleWrapper) {
  captionsToggle.addEventListener('change', () => {
    captionStyleWrapper.style.display = captionsToggle.checked ? 'block' : 'none';
  });
}

// ─── Clip Count Stepper ───────────────────────────────────────────────────────
const clipsDisplay = document.getElementById('clips-display');
const clipsDecBtn = document.getElementById('clips-dec');
const clipsIncBtn = document.getElementById('clips-inc');

function updateClipsDisplay() {
  clipsDisplay.classList.remove('count-pop');
  void clipsDisplay.offsetWidth; // force reflow for re-trigger
  clipsDisplay.classList.add('count-pop');

  if (clipsCount === null) {
    clipsDisplay.textContent = 'Default';
    clipsDisplay.classList.add('clips-default');
  } else {
    clipsDisplay.textContent = clipsCount;
    clipsDisplay.classList.remove('clips-default');
  }
}

// Clips count stepper logic:
// Default (null) implies 5 clips (center value on 1-10 scale).
// Decrementing from Default → 4, Incrementing from Default → 6.
clipsDecBtn.addEventListener('click', () => {
  if (clipsCount === null) {
    clipsCount = 4;          // Default (5) → 4 (one step below)
  } else if (clipsCount <= 1) {
    clipsCount = null;       // back to Default
  } else {
    clipsCount--;
  }
  updateClipsDisplay();
});

clipsIncBtn.addEventListener('click', () => {
  if (clipsCount === null) {
    clipsCount = 6;          // Default (5) → 6 (one step above)
  } else {
    clipsCount = Math.min(10, clipsCount + 1);
  }
  updateClipsDisplay();
});

// ─── Retention Psychology: collapsible toggle ─────────────────────────────────
if (retentionToggleBtn && retentionBody) {
  // Start collapsed
  retentionBody.style.maxHeight = '0';
  retentionBody.style.opacity = '0';
  retentionBody.style.overflow = 'hidden';

  retentionToggleBtn.addEventListener('click', () => {
    const isOpen = retentionToggleBtn.getAttribute('aria-expanded') === 'true';
    retentionToggleBtn.setAttribute('aria-expanded', String(!isOpen));

    if (isOpen) {
      retentionBody.style.maxHeight = '0';
      retentionBody.style.opacity = '0';
    } else {
      retentionBody.style.maxHeight = retentionBody.scrollHeight + 'px';
      retentionBody.style.opacity = '1';
    }
    retentionToggleBtn.querySelector('.retention-chevron')
      .style.transform = isOpen ? 'rotate(0deg)' : 'rotate(180deg)';
  });
}