import React, { useState, useEffect, useRef } from 'react';
import CalibrationOverlay from './CalibrationOverlay';

const FLOW_STEPS = {
  intro: 'intro',
  permission: 'permission',
  ready: 'ready'
};

const FOCUS_STATES = {
  pending: 'pending',
  focused: 'focused',
  notFocused: 'not-focused'
};

function HelloIcon() {
  return (
    <svg width="96" height="96" viewBox="0 0 96 96" aria-hidden="true">
      <circle cx="48" cy="48" r="40" fill="#007BFF" />
      <path d="M30 38c0-4 2.7-7 6-7s6 3 6 7" fill="none" stroke="#fff" strokeWidth="6" strokeLinecap="round" />
      <path d="M54 38c0-4 2.7-7 6-7s6 3 6 7" fill="none" stroke="#fff" strokeWidth="6" strokeLinecap="round" />
      <path d="M30 52c3 11 10 17 18 17s15-6 18-17" fill="none" stroke="#fff" strokeWidth="6" strokeLinecap="round" />
    </svg>
  );
}

function CameraIcon() {
  return (
    <svg width="110" height="110" viewBox="0 0 110 110" aria-hidden="true">
      <rect x="30" y="36" width="50" height="34" rx="5" fill="none" stroke="#007BFF" strokeWidth="6" />
      <path d="M24 72h62c0 9-7 16-16 16H40c-9 0-16-7-16-16Z" fill="none" stroke="#007BFF" strokeWidth="6" />
      <path d="M55 28v8" stroke="#007BFF" strokeWidth="6" strokeLinecap="round" />
      <circle cx="55" cy="36" r="14" fill="none" stroke="#007BFF" strokeWidth="6" />
      <circle cx="55" cy="36" r="4" fill="#007BFF" />
      <path d="M46 83h18" stroke="#007BFF" strokeWidth="6" strokeLinecap="round" />
    </svg>
  );
}

const MODEL_ORDER = ['hybrid', 'xgboost', 'mlp', 'geometric'];

const MODEL_INFO = {
  hybrid: {
    label: 'Hybrid',
    tagline: 'Best overall — combines ML with geometric scoring',
    how: 'Fuses XGBoost predictions (30%) with geometric face/eye scores (70%). A logistic regression meta-classifier combines both signals for the final decision.',
    accuracy: '84.3%',
    f1: '0.864',
    auc: '0.880',
    threshold: '0.46',
    evaluation: 'Leave-One-Person-Out (9 participants, 144K frames)',
    features: '10 features: head deviation, face score, eye scores (EAR), gaze offset, pitch, horizontal gaze, PERCLOS',
    strengths: 'Most robust across different people. Geometric scoring generalises well; ML catches subtle patterns.',
    badge: 'Recommended',
  },
  xgboost: {
    label: 'XGBoost',
    tagline: 'Highest raw accuracy — gradient-boosted decision trees',
    how: 'Ensemble of 600 decision trees (max depth 8). Each tree learns to correct errors from previous trees. Outputs probability of focused state.',
    accuracy: '84.3%',
    f1: '0.859',
    auc: '0.880',
    threshold: '0.38',
    evaluation: 'Leave-One-Person-Out (9 participants, 144K frames)',
    features: '10 features: head deviation, face score, eye scores (EAR), gaze offset, pitch, horizontal gaze, PERCLOS',
    strengths: 'Strong pattern recognition. Handles non-linear feature interactions. 95.9% accuracy on random split (but LOPO is the fairer test).',
    badge: null,
  },
  mlp: {
    label: 'MLP',
    tagline: 'Lightweight neural network — fast and efficient',
    how: 'Two-layer neural network (64→32 neurons). Takes 10 face features, applies learned weights, outputs focused/unfocused probability via softmax.',
    accuracy: '82.7%',
    f1: '0.858',
    auc: '0.862',
    threshold: '0.23',
    evaluation: 'Leave-One-Person-Out (9 participants, 144K frames)',
    features: '10 features: head deviation, face score, eye scores (EAR), gaze offset, pitch, horizontal gaze, PERCLOS',
    strengths: 'Fastest inference. Smallest model size. Good baseline. 92.9% accuracy on random split.',
    badge: null,
  },
  geometric: {
    label: 'Geometric',
    tagline: 'Baseline only — hardcoded thresholds, no learning',
    how: 'Uses fixed thresholds on head orientation (70%) and eye openness (30%). No training — just hand-tuned rules on 478 face landmarks. Cannot adapt to new faces or environments.',
    accuracy: '~77%',
    f1: '0.772',
    auc: 'N/A',
    threshold: '0.55',
    evaluation: 'Leave-One-Person-Out geometric sweep',
    features: 'Head yaw/pitch/roll angles, eye aspect ratio (EAR), iris gaze offset, mouth aspect ratio (MAR)',
    strengths: 'No model files needed. Useful as a fallback. This is the baseline that motivated building the ML models — its fixed thresholds struggle with different face shapes, lighting, and camera angles.',
    badge: 'Baseline',
  },
};

function FocusPageLocal({ videoManager, sessionResult, setSessionResult, isActive }) {
  const [currentFrame, setCurrentFrame] = useState(15);
  const [timelineEvents, setTimelineEvents] = useState([]);
  const [stats, setStats] = useState(null);
  const [systemStats, setSystemStats] = useState(null);
  const [availableModels, setAvailableModels] = useState([]);
  const [currentModel, setCurrentModel] = useState('mlp');
  const [flowStep, setFlowStep] = useState(FLOW_STEPS.intro);
  const [cameraReady, setCameraReady] = useState(false);
  const [isStarting, setIsStarting] = useState(false);
  const [focusState, setFocusState] = useState(FOCUS_STATES.pending);
  const [cameraError, setCameraError] = useState('');
  const [calibration, setCalibration] = useState(null);
  const [l2csBoost, setL2csBoost] = useState(false);
  const [l2csBoostAvailable, setL2csBoostAvailable] = useState(false);

  const localVideoRef = useRef(null);
  const displayCanvasRef = useRef(null);
  const pipVideoRef = useRef(null);
  const pipStreamRef = useRef(null);
  const previewFrameRef = useRef(null);

  const formatDuration = (seconds) => {
    if (seconds === 0) return '0s';
    const mins = Math.floor(seconds / 60);
    const secs = Math.floor(seconds % 60);
    return `${mins}m ${secs}s`;
  };
  
  const stopPreviewLoop = () => {
    if (previewFrameRef.current) {
      cancelAnimationFrame(previewFrameRef.current);
      previewFrameRef.current = null;
    }
  };

  const startPreviewLoop = () => {
    stopPreviewLoop();
    const renderPreview = () => {
      const canvas = displayCanvasRef.current;
      const video = localVideoRef.current;

      if (!canvas || !video || !cameraReady || videoManager?.isStreaming) {
        previewFrameRef.current = null;
        return;
      }

      if (video.readyState >= 2) {
        const ctx = canvas.getContext('2d');
        ctx.drawImage(video, 0, 0, canvas.width, canvas.height);
      }

      previewFrameRef.current = requestAnimationFrame(renderPreview);
    };

    previewFrameRef.current = requestAnimationFrame(renderPreview);
  };

  const getErrorMessage = (err) => {
    if (err?.name === 'NotAllowedError') {
      return 'Camera permission denied. Please allow camera access.';
    }
    if (err?.name === 'NotFoundError') {
      return 'No camera found. Please connect a camera.';
    }
    if (err?.name === 'NotReadableError') {
      return 'Camera is already in use by another application.';
    }
    if (err?.target?.url) {
      return `WebSocket connection failed: ${err.target.url}. Check that the backend server is running.`;
    }
    return err?.message || 'Failed to start focus session.';
  };

  useEffect(() => {
    if (!videoManager) return;

    const originalOnStatusUpdate = videoManager.callbacks.onStatusUpdate;
    const originalOnSessionEnd = videoManager.callbacks.onSessionEnd;

    videoManager.callbacks.onStatusUpdate = (isFocused) => {
      setTimelineEvents((prev) => {
        const newEvents = [...prev, { isFocused, timestamp: Date.now() }];
        if (newEvents.length > 60) newEvents.shift();
        return newEvents;
      });
      setFocusState(isFocused ? FOCUS_STATES.focused : FOCUS_STATES.notFocused);
      if (originalOnStatusUpdate) originalOnStatusUpdate(isFocused);
    };

    videoManager.callbacks.onSessionEnd = (summary) => {
      setFocusState(FOCUS_STATES.pending);
      setCameraReady(false);
      if (originalOnSessionEnd) originalOnSessionEnd(summary);
    };

    videoManager.callbacks.onCalibrationUpdate = (cal) => {
      setCalibration(cal && cal.active ? { ...cal } : null);
    };

    const statsInterval = setInterval(() => {
      if (videoManager && videoManager.getStats) {
        setStats(videoManager.getStats());
      }
    }, 1000);

    return () => {
      if (videoManager) {
        videoManager.callbacks.onStatusUpdate = originalOnStatusUpdate;
        videoManager.callbacks.onSessionEnd = originalOnSessionEnd;
        videoManager.callbacks.onCalibrationUpdate = null;
      }
      clearInterval(statsInterval);
    };
  }, [videoManager]);

  // Fetch available models on mount
  useEffect(() => {
    fetch('/api/models')
      .then((res) => res.json())
      .then((data) => {
        if (data.available) setAvailableModels(data.available);
        if (data.current) {
          // If L2CS was the active model, switch to a base model + enable boost
          if (data.current === 'l2cs') {
            const fallback = data.available.find((m) => m !== 'l2cs') || 'mlp';
            setCurrentModel(fallback);
            handleModelChange(fallback);
          } else {
            setCurrentModel(data.current);
          }
        }
        if (data.l2cs_boost !== undefined) setL2csBoost(data.l2cs_boost);
        if (data.l2cs_boost_available !== undefined) setL2csBoostAvailable(data.l2cs_boost_available);
      })
      .catch((err) => console.error('Failed to fetch models:', err));
  }, []);

  useEffect(() => {
    if (flowStep === FLOW_STEPS.ready && cameraReady && !videoManager?.isStreaming) {
      startPreviewLoop();
      return;
    }
    stopPreviewLoop();
  }, [cameraReady, flowStep, videoManager?.isStreaming]);

  useEffect(() => {
    if (!isActive) {
      stopPreviewLoop();
    }
  }, [isActive]);

  useEffect(() => {
    return () => {
      stopPreviewLoop();
      if (pipVideoRef.current) {
        pipVideoRef.current.pause();
        pipVideoRef.current.srcObject = null;
      }
      if (pipStreamRef.current) {
        pipStreamRef.current.getTracks().forEach((t) => t.stop());
        pipStreamRef.current = null;
      }
    };
  }, []);

  // Poll server CPU/memory for UI
  useEffect(() => {
    const fetchSystem = () => {
      fetch('/api/stats/system')
        .then(res => res.json())
        .then(data => setSystemStats(data))
        .catch(() => setSystemStats(null));
    };
    fetchSystem();
    const interval = setInterval(fetchSystem, 3000);
    return () => clearInterval(interval);
  }, []);

  const handleModelChange = async (modelName) => {
    try {
      const res = await fetch('/api/settings', {
        method: 'PUT',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ model_name: modelName })
      });
      const result = await res.json();
      if (result.updated) {
        setCurrentModel(modelName);
      }
    } catch (err) {
      console.error('Failed to switch model:', err);
    }
  };

  const handleEnableCamera = async () => {
    if (!videoManager) return;

    try {
      setCameraError('');
      await videoManager.initCamera(localVideoRef.current, displayCanvasRef.current);
      setCameraReady(true);
      setFlowStep(FLOW_STEPS.ready);
      setFocusState(FOCUS_STATES.pending);
    } catch (err) {
      const errorMessage = getErrorMessage(err);
      setCameraError(errorMessage);
      console.error('Camera init error:', err);
    }
  };

  const handleEyeGazeToggle = async () => {
    const next = !l2csBoost;
    try {
      const res = await fetch('/api/settings', {
        method: 'PUT',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ l2cs_boost: next })
      });
      if (!res.ok) return;
      setL2csBoost(next);

      if (next && videoManager && videoManager.isStreaming) {
        // Turning ON → auto-start calibration
        videoManager.startCalibration();
      } else if (!next && videoManager) {
        // Turning OFF → cancel any active calibration
        videoManager.cancelCalibration();
      }
    } catch (err) {
      console.error('Failed to toggle eye gaze:', err);
    }
  };

  const handleStart = async () => {
    try {
      setIsStarting(true);
      setSessionResult(null);
      setTimelineEvents([]);
      setFocusState(FOCUS_STATES.pending);
      setCameraError('');

      if (!cameraReady) {
        await videoManager.initCamera(localVideoRef.current, displayCanvasRef.current);
        setCameraReady(true);
        setFlowStep(FLOW_STEPS.ready);
      }

      await videoManager.startStreaming();
    } catch (err) {
      const errorMessage = getErrorMessage(err);
      setCameraError(errorMessage);
      setFocusState(FOCUS_STATES.pending);
      console.error('Start error:', err);
      alert(`Failed to start: ${errorMessage}\n\nCheck browser console for details.`);
    } finally {
      setIsStarting(false);
    }
  };

  const handleStop = async () => {
    if (videoManager) {
      await videoManager.stopStreaming();
    }
    try {
      if (document.pictureInPictureElement === pipVideoRef.current) {
        await document.exitPictureInPicture();
      }
    } catch (_) {}
    if (pipVideoRef.current) {
      pipVideoRef.current.pause();
      pipVideoRef.current.srcObject = null;
    }
    if (pipStreamRef.current) {
      pipStreamRef.current.getTracks().forEach((t) => t.stop());
      pipStreamRef.current = null;
    }
    stopPreviewLoop();
    setFocusState(FOCUS_STATES.pending);
    setCameraReady(false);
  };

  const handlePiP = async () => {
    try {
      //
      if (!videoManager || !videoManager.isStreaming) {
        alert('Please start the video first.');
        return;
      }

      if (!displayCanvasRef.current) {
        alert('Video not ready.');
        return;
      }

      //
      if (document.pictureInPictureElement === pipVideoRef.current) {
        await document.exitPictureInPicture();
        console.log('PiP exited');
        return;
      }

      //
      if (!document.pictureInPictureEnabled) {
        alert('Picture-in-Picture is not supported in this browser.');
        return;
      }

      //
      const pipVideo = pipVideoRef.current;
      if (!pipVideo) {
        alert('PiP video element not ready.');
        return;
      }

      const isSafariPiP = typeof pipVideo.webkitSetPresentationMode === 'function';

      //
      let stream = pipStreamRef.current;
      if (!stream) {
        const capture = displayCanvasRef.current.captureStream;
        if (typeof capture === 'function') {
          stream = capture.call(displayCanvasRef.current, 30);
        }
        if (!stream || stream.getTracks().length === 0) {
          const cameraStream = localVideoRef.current?.srcObject;
          if (!cameraStream) {
            alert('Camera stream not ready.');
            return;
          }
          stream = cameraStream;
        }
        pipStreamRef.current = stream;
      }

      //
      if (!stream || stream.getTracks().length === 0) {
        alert('Failed to capture video stream from canvas.');
        return;
      }

      pipVideo.srcObject = stream;

      //
      if (pipVideo.readyState < 2) {
        await new Promise((resolve) => {
          const onReady = () => {
            pipVideo.removeEventListener('loadeddata', onReady);
            pipVideo.removeEventListener('canplay', onReady);
            resolve();
          };
          pipVideo.addEventListener('loadeddata', onReady);
          pipVideo.addEventListener('canplay', onReady);
          //
          setTimeout(resolve, 600);
        });
      }

      try {
        await pipVideo.play();
      } catch (_) {}

      //
      if (isSafariPiP) {
        try {
          pipVideo.webkitSetPresentationMode('picture-in-picture');
          console.log('PiP activated (Safari)');
          return;
        } catch (e) {
          //
          const cameraStream = localVideoRef.current?.srcObject;
          if (cameraStream && cameraStream !== pipVideo.srcObject) {
            pipVideo.srcObject = cameraStream;
            try {
              await pipVideo.play();
            } catch (_) {}
            pipVideo.webkitSetPresentationMode('picture-in-picture');
            console.log('PiP activated (Safari fallback)');
            return;
          }
          throw e;
        }
      }

      //
      if (typeof pipVideo.requestPictureInPicture === 'function') {
        await pipVideo.requestPictureInPicture();
        console.log('PiP activated');
      } else {
        alert('Picture-in-Picture is not supported in this browser.');
      }

    } catch (err) {
      console.error('PiP error:', err);
      alert(`Failed to enter Picture-in-Picture: ${err.message}`);
    }
  };

  const handleFloatingWindow = () => {
    handlePiP();
  };

  const handleFrameChange = (val) => {
    const rate = parseInt(val, 10);
    setCurrentFrame(rate);
    if (videoManager) {
      videoManager.setFrameRate(rate);
    }
  };

  const handlePreview = () => {
    if (!videoManager || !videoManager.isStreaming) {
      alert('Please start a session first.');
      return;
    }

    //
    const currentStats = videoManager.getStats();

    if (!currentStats.sessionId) {
      alert('No active session.');
      return;
    }

    //
    const sessionDuration = Math.floor((Date.now() - (videoManager.sessionStartTime || Date.now())) / 1000);

    //
    const focusScore = currentStats.framesProcessed > 0
      ? (currentStats.framesProcessed * (currentStats.currentStatus ? 1 : 0)) / currentStats.framesProcessed
      : 0;

    //
    setSessionResult({
      duration_seconds: sessionDuration,
      focus_score: focusScore,
      total_frames: currentStats.framesProcessed,
      focused_frames: Math.floor(currentStats.framesProcessed * focusScore)
    });
  };

  const handleCloseOverlay = () => {
    setSessionResult(null);
  };

  const pageStyle = isActive
    ? undefined
    : {
        position: 'absolute',
        width: '1px',
        height: '1px',
        overflow: 'hidden',
        opacity: 0,
        pointerEvents: 'none'
      };

  const focusStateLabel = {
    [FOCUS_STATES.pending]: 'Pending',
    [FOCUS_STATES.focused]: 'Focused',
    [FOCUS_STATES.notFocused]: 'Not Focused'
  }[focusState];

  const introHighlights = [
    {
      title: 'Live focus tracking',
      text: 'Head pose, gaze, and eye openness are read continuously during the session.'
    },
    {
      title: 'Quick setup',
      text: 'Front-facing light and a stable camera angle give the cleanest preview.'
    },
    {
      title: 'Private by default',
      text: 'Only session metadata is stored, not the raw camera footage.'
    }
  ];

  const permissionSteps = [
    {
      title: 'Allow browser access',
      text: 'Approve the camera prompt so the preview can appear immediately.'
    },
    {
      title: 'Check your framing',
      text: 'Keep your face visible and centered for more stable landmark detection.'
    },
    {
      title: 'Start when ready',
      text: 'After the preview appears, use the page controls to begin or stop.'
    }
  ];

  const renderIntroCard = () => {
    if (flowStep === FLOW_STEPS.intro) {
      return (
        <div className="focus-flow-overlay">
          <div className="focus-flow-card">
            <div className="focus-flow-header">
              <div>
                <div className="focus-flow-eyebrow">Focus Session</div>
                <h2>Before you begin</h2>
              </div>
              <div className="focus-flow-icon">
                <HelloIcon />
              </div>
            </div>

            <p className="focus-flow-lead">
              The focus page uses your live camera preview to estimate attention in real time.
              Review the setup notes below, then continue to camera access.
            </p>

            <div className="focus-flow-grid">
              {introHighlights.map((item) => (
                <article key={item.title} className="focus-flow-panel">
                  <h3>{item.title}</h3>
                  <p>{item.text}</p>
                </article>
              ))}
            </div>

            <div className="focus-flow-footer">
              <div className="focus-flow-note">
                You can still change frame rate and available model options after the preview loads.
              </div>
              <button className="focus-flow-button" onClick={() => setFlowStep(FLOW_STEPS.permission)}>
                Continue
              </button>
            </div>
          </div>
        </div>
      );
    }

    if (flowStep === FLOW_STEPS.permission && !cameraReady) {
      return (
        <div className="focus-flow-overlay">
          <div className="focus-flow-card">
            <div className="focus-flow-header">
              <div>
                <div className="focus-flow-eyebrow">Camera Setup</div>
                <h2>Enable camera access</h2>
              </div>
              <div className="focus-flow-icon">
                <CameraIcon />
              </div>
            </div>

            <p className="focus-flow-lead">
              Once access is granted, your preview appears here and the rest of the Focus page
              behaves like the other dashboard screens.
            </p>

            <div className="focus-flow-steps">
              {permissionSteps.map((item, index) => (
                <div key={item.title} className="focus-flow-step">
                  <div className="focus-flow-step-number">{index + 1}</div>
                  <div className="focus-flow-step-copy">
                    <h3>{item.title}</h3>
                    <p>{item.text}</p>
                  </div>
                </div>
              ))}
            </div>

            {cameraError ? <div className="focus-inline-error">{cameraError}</div> : null}

            <div className="focus-flow-footer">
              <button
                type="button"
                className="focus-flow-secondary"
                onClick={() => setFlowStep(FLOW_STEPS.intro)}
              >
                Back
              </button>
              <button className="focus-flow-button" onClick={handleEnableCamera}>
                Enable Camera
              </button>
            </div>
          </div>
        </div>
      );
    }

    return null;
  };

  return (
    <main id="page-b" className="page" style={pageStyle}>
      {renderIntroCard()}

      <section id="display-area" className="focus-display-shell">
        <video
          ref={pipVideoRef}
          muted
          playsInline
          autoPlay
          style={{
            position: 'absolute',
            width: '1px',
            height: '1px',
            opacity: 0,
            pointerEvents: 'none'
          }}
        />
        {/* local video (hidden, for capture) */}
        <video
          ref={localVideoRef}
          muted
          playsInline
          autoPlay
          style={{ display: 'none' }}
        />

        {/* processed video (canvas) */}
        <canvas
          ref={displayCanvasRef}
          width={640}
          height={480}
          style={{
            width: '100%',
            height: '100%',
            objectFit: 'contain',
            backgroundColor: '#101010'
          }}
        />

        {flowStep === FLOW_STEPS.ready ? (
          <>
            <div className={`focus-state-pill ${focusState}`}>
              <span className="focus-state-dot" />
              {focusStateLabel}
            </div>
            {!cameraReady && !videoManager?.isStreaming ? (
              <div className="focus-idle-overlay">
                <p>Camera is paused.</p>
                <span>Use Start to enable the camera and begin detection.</span>
              </div>
            ) : null}
          </>
        ) : null}

        {sessionResult && (
          <div className="session-result-overlay">
            <h3>Session Complete!</h3>
            <div className="result-item">
              <span className="label">Duration:</span>
              <span className="value">{formatDuration(sessionResult.duration_seconds)}</span>
            </div>
            <div className="result-item">
              <span className="label">Focus Score:</span>
              <span className="value">{(sessionResult.focus_score * 100).toFixed(1)}%</span>
            </div>

            <button
              onClick={handleCloseOverlay}
              style={{
                marginTop: '20px',
                padding: '8px 20px',
                background: 'transparent',
                border: '1px solid white',
                color: 'white',
                borderRadius: '20px',
                cursor: 'pointer'
              }}
            >
              Close
            </button>
          </div>
        )}

      </section>

      {flowStep === FLOW_STEPS.ready ? (
        <>
          {/* Model selector */}
          {availableModels.length > 0 ? (
            <section className="focus-model-strip">
              <span className="focus-model-label">Model:</span>
              {MODEL_ORDER.filter((n) => availableModels.includes(n)).map((name) => (
                <button
                  key={name}
                  onClick={() => handleModelChange(name)}
                  className={`focus-model-button ${currentModel === name ? 'active' : ''}`}
                >
                  {MODEL_INFO[name]?.label || name}
                </button>
              ))}

              {l2csBoostAvailable && (
                <>
                  <span className="focus-model-sep" />
                  <button
                    onClick={handleEyeGazeToggle}
                    className={`eye-gaze-toggle ${l2csBoost ? 'on' : 'off'}`}
                    title={l2csBoost ? 'Eye gaze tracking active — click to disable' : 'Enable eye gaze tracking (requires calibration)'}
                  >
                    <svg width="16" height="16" viewBox="0 0 16 16" className="eye-gaze-icon" aria-hidden="true">
                      <ellipse cx="8" cy="8" rx="7" ry="4.5" fill="none" stroke="currentColor" strokeWidth="1.4" />
                      <circle cx="8" cy="8" r="2.2" fill="currentColor" />
                    </svg>
                    {l2csBoost ? 'Eye Gaze On' : 'Eye Gaze'}
                  </button>
                  {l2csBoost && stats && stats.isStreaming && (
                    <button
                      onClick={() => videoManager && videoManager.startCalibration()}
                      className="focus-model-button recalibrate"
                      title="Re-run gaze calibration"
                    >
                      Recalibrate
                    </button>
                  )}
                </>
              )}
            </section>
          ) : null}

          {/* Server stats */}
          {systemStats && systemStats.cpu_percent != null && (
            <section className="focus-system-stats">
              <span>CPU: <strong>{systemStats.cpu_percent}%</strong></span>
              <span className="focus-system-stats-sep" />
              <span>RAM: <strong>{systemStats.memory_percent}%</strong> ({systemStats.memory_used_mb}/{systemStats.memory_total_mb} MB)</span>
            </section>
          )}

          <section id="timeline-area">
            <div className="timeline-label">Timeline</div>
            <div id="timeline-visuals">
              {timelineEvents.map((event, index) => (
                <div
                  key={index}
                  className="timeline-block"
                  style={{
                    backgroundColor: event.isFocused ? '#28a745' : '#dc3545',
                    width: '10px',
                    height: '20px',
                    display: 'inline-block',
                    marginRight: '2px',
                    borderRadius: '2px'
                  }}
                  title={event.isFocused ? 'Focused' : 'Distracted'}
                />
              ))}
            </div>
            <div id="timeline-line" />
          </section>

          <section id="control-panel">
            <button id="btn-cam-start" className="action-btn green" onClick={handleStart} disabled={isStarting}>
              {isStarting ? 'Starting...' : 'Start'}
            </button>

            <button id="btn-floating" className="action-btn blue" onClick={handlePiP}>
              Floating Window
            </button>

            <button id="btn-preview" className="action-btn orange" onClick={handlePreview}>
              Preview Result
            </button>

            <button id="btn-cam-stop" className="action-btn red" onClick={handleStop}>
              Stop
            </button>
          </section>

          {cameraError ? (
            <div className="focus-inline-error focus-inline-error-standalone">{cameraError}</div>
          ) : null}

          {/* Model info card — below action buttons */}
          {MODEL_INFO[currentModel] && (
            <section className="model-card">
              <div className="model-card-header">
                <h3 className="model-card-title">{MODEL_INFO[currentModel].label}</h3>
                {MODEL_INFO[currentModel].badge && (
                  <span className={MODEL_INFO[currentModel].badge === 'Baseline' ? 'model-card-badge-baseline' : 'model-card-badge'}>
                    {MODEL_INFO[currentModel].badge}
                  </span>
                )}
              </div>
              <p className="model-card-tagline">{MODEL_INFO[currentModel].tagline}</p>

              <div className="model-card-metrics">
                <div className="model-card-metric">
                  <span className="model-card-metric-value">{MODEL_INFO[currentModel].accuracy}</span>
                  <span className="model-card-metric-label">Accuracy</span>
                </div>
                <div className="model-card-metric">
                  <span className="model-card-metric-value">{MODEL_INFO[currentModel].f1}</span>
                  <span className="model-card-metric-label">F1 Score</span>
                </div>
                <div className="model-card-metric">
                  <span className="model-card-metric-value">{MODEL_INFO[currentModel].auc}</span>
                  <span className="model-card-metric-label">ROC-AUC</span>
                </div>
                <div className="model-card-metric">
                  <span className="model-card-metric-value">{MODEL_INFO[currentModel].threshold}</span>
                  <span className="model-card-metric-label">Threshold</span>
                </div>
              </div>

              <div className="model-card-details">
                <div className="model-card-section">
                  <h4>How it works</h4>
                  <p>{MODEL_INFO[currentModel].how}</p>
                </div>
                <div className="model-card-section">
                  <h4>Features used</h4>
                  <p>{MODEL_INFO[currentModel].features}</p>
                </div>
                <div className="model-card-section">
                  <h4>Strengths</h4>
                  <p>{MODEL_INFO[currentModel].strengths}</p>
                </div>
              </div>

              <div className="model-card-eval">
                Evaluated with {MODEL_INFO[currentModel].evaluation}
              </div>
            </section>
          )}

          <section id="frame-control">
            <label htmlFor="frame-slider">Frame Rate (FPS)</label>
            <input
              type="range"
              id="frame-slider"
              min="10"
              max="30"
              value={currentFrame}
              onChange={(e) => handleFrameChange(e.target.value)}
            />
            <input
              type="number"
              id="frame-input"
              min="10"
              max="30"
              value={currentFrame}
              onChange={(e) => handleFrameChange(e.target.value)}
            />
          </section>
        </>
      ) : null}

      {/* Calibration overlay (fixed fullscreen, must be outside overflow:hidden containers) */}
      <CalibrationOverlay calibration={calibration} videoManager={videoManager} />
    </main>
  );
}

export default FocusPageLocal;