import { useEffect, useRef, useState } from "react";

export default function VideoEditor() {
  // --- State ---
  const [videoPath, setVideoPath] = useState<string | null>(null);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState<string | null>(null);
  const [isPlaying, setIsPlaying] = useState(false);
  const [currentTime, setCurrentTime] = useState(0);
  const [duration, setDuration] = useState(0);

  // --- Refs ---
  const videoRef = useRef<HTMLVideoElement | null>(null);
  const canvasRef = useRef<HTMLCanvasElement | null>(null);

  // --- Load video path on mount ---
  useEffect(() => {
    async function loadVideo() {
      try {
        const result = await window.electronAPI.getRecordedVideoPath();
        if (result.success && result.path) {
          setVideoPath(`file://${result.path}`);
        } else {
          setError(result.message || 'Failed to load video');
        }
      } catch (err) {
        setError('Error loading video: ' + String(err));
      } finally {
        setLoading(false);
      }
    }
    loadVideo();
  }, []);

  // --- Canvas drawing and video event listeners ---
  useEffect(() => {
    const video = videoRef.current;
    const canvas = canvasRef.current;
    if (!video || !canvas) return;
    let animationId: number;

    function drawFrame() {
      if (!video || !canvas) return;
      if (video.paused || video.ended) return;
      // Keep canvas size in sync with video
      if (canvas.width !== video.videoWidth || canvas.height !== video.videoHeight) {
        canvas.width = video.videoWidth;
        canvas.height = video.videoHeight;
      }
      const ctx = canvas.getContext('2d');
      if (ctx) {
        ctx.clearRect(0, 0, canvas.width, canvas.height);
        ctx.drawImage(video, 0, 0, canvas.width, canvas.height);
      }
      animationId = requestAnimationFrame(drawFrame);
    }

    function handlePlay() {
      drawFrame();
    }
    function handlePause() {
      cancelAnimationFrame(animationId);
    }

    video.addEventListener('play', handlePlay);
    video.addEventListener('pause', handlePause);
    video.addEventListener('ended', handlePause);

    return () => {
      video.removeEventListener('play', handlePlay);
      video.removeEventListener('pause', handlePause);
      video.removeEventListener('ended', handlePause);
      cancelAnimationFrame(animationId);
    };
  }, [videoPath]);

  // --- Handlers ---
  function togglePlayPause() {
    if (!videoRef.current) return;
    if (isPlaying) {
      videoRef.current.pause();
    } else {
      videoRef.current.play();
    }
  }

  function handleSeek(e: React.ChangeEvent<HTMLInputElement>) {
    if (!videoRef.current) return;
    const newTime = parseFloat(e.target.value);
    videoRef.current.currentTime = newTime;
  }

  function formatTime(seconds: number) {
    if (!isFinite(seconds) || isNaN(seconds) || seconds < 0) {
      return '0:00';
    }
    const mins = Math.floor(seconds / 60);
    const secs = Math.floor(seconds % 60);
    return `${mins}:${secs.toString().padStart(2, '0')}`;
  }

  // --- Early returns for loading/error ---
  if (loading) {
    return (
      <div className="flex items-center justify-center h-screen bg-background">
        <div className="text-foreground">Loading video...</div>
      </div>
    );
  }
  if (error) {
    return (
      <div className="flex items-center justify-center h-screen bg-background">
        <div className="text-destructive">{error}</div>
      </div>
    );
  }

  // --- Main render ---
  return (
    <div className="flex flex-col h-screen bg-background p-6">
      <div className="flex-1 flex items-center justify-center overflow-hidden relative">
        {videoPath && (
          <>
            <canvas
              ref={canvasRef}
              className="max-w-full max-h-full"
              style={{ 
                borderRadius: 8,
                objectFit: 'contain',
                width: 'auto',
                height: 'auto'
              }}
            />
            <video
              ref={videoRef}
              src={videoPath}
              style={{ display: 'none' }}
              preload="metadata"
              onLoadedMetadata={e => {
                const video = e.currentTarget;
                if (isFinite(video.duration) && !isNaN(video.duration) && video.duration > 0) {
                  setDuration(video.duration);
                }
              }}
              onCanPlay={() => {
                const video = videoRef.current;
                if (video && isFinite(video.duration) && video.duration > 0) {
                  setDuration(video.duration);
                }
              }}
              onTimeUpdate={e => {
                const time = e.currentTarget.currentTime;
                if (isFinite(time) && !isNaN(time)) {
                  setCurrentTime(time);
                }
              }}
              onError={() => setError('Failed to play video')}
              onPlay={() => setIsPlaying(true)}
              onPause={() => setIsPlaying(false)}
              onEnded={() => setIsPlaying(false)}
            />
          </>
        )}
      </div>

      <div className="mt-6 bg-card border border-border rounded-lg p-4">
        <div className="flex items-center gap-4">
          <button
            onClick={togglePlayPause}
            className="flex items-center justify-center w-10 h-10 rounded-full bg-primary text-primary-foreground hover:bg-primary/90 transition-colors"
            aria-label={isPlaying ? 'Pause' : 'Play'}
          >
            {isPlaying ? (
              <svg width="16" height="16" viewBox="0 0 16 16" fill="currentColor">
                <rect x="4" y="3" width="3" height="10" rx="0.5" />
                <rect x="9" y="3" width="3" height="10" rx="0.5" />
              </svg>
            ) : (
              <svg width="16" height="16" viewBox="0 0 16 16" fill="currentColor">
                <path d="M5 3.5v9l7-4.5z" />
              </svg>
            )}
          </button>
          <span className="text-sm text-muted-foreground font-mono min-w-[80px]">
            {formatTime(currentTime)}
          </span>
          <input
            type="range"
            min="0"
            max={duration || 100}
            value={currentTime}
            onChange={handleSeek}
            step="0.01"
            className="flex-1 h-2 bg-muted rounded-lg appearance-none cursor-pointer [&::-webkit-slider-thumb]:appearance-none [&::-webkit-slider-thumb]:w-4 [&::-webkit-slider-thumb]:h-4 [&::-webkit-slider-thumb]:rounded-full [&::-webkit-slider-thumb]:bg-primary [&::-webkit-slider-thumb]:cursor-pointer hover:[&::-webkit-slider-thumb]:bg-primary/80"
          />
          <span className="text-sm text-muted-foreground font-mono min-w-[80px] text-right">
            {formatTime(duration)}
          </span>
        </div>
      </div>
    </div>
  );
}