'use client';

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

interface WaveformEditorProps {
    audioUrl: string;
    startTime: number;
    duration: number; // Total puzzle duration (e.g., 60s)
    unlockSteps: number[]; // e.g., [2, 4, 7, 11, 16, 30, 60]
    onStartTimeChange: (newStartTime: number) => void;
}

export default function WaveformEditor({ audioUrl, startTime, duration, unlockSteps, onStartTimeChange }: WaveformEditorProps) {
    const canvasRef = useRef<HTMLCanvasElement>(null);
    const [audioBuffer, setAudioBuffer] = useState<AudioBuffer | null>(null);
    const [audioDuration, setAudioDuration] = useState(0);
    const [isPlaying, setIsPlaying] = useState(false);
    const [playingSegment, setPlayingSegment] = useState<number | null>(null);
    const [zoom, setZoom] = useState(1); // 1 = full view, higher = zoomed in
    const [viewOffset, setViewOffset] = useState(0); // Offset in seconds for panning
    const [playbackPosition, setPlaybackPosition] = useState<number | null>(null); // Current playback position in seconds
    const audioContextRef = useRef<AudioContext | null>(null);
    const sourceRef = useRef<AudioBufferSourceNode | null>(null);
    const playbackStartTimeRef = useRef<number>(0); // When playback started
    const playbackOffsetRef = useRef<number>(0); // Offset in the audio file
    const animationFrameRef = useRef<number | null>(null);

    useEffect(() => {
        const loadAudio = async () => {
            try {
                const response = await fetch(audioUrl);
                const arrayBuffer = await response.arrayBuffer();

                const audioContext = new (window.AudioContext || (window as any).webkitAudioContext)();
                audioContextRef.current = audioContext;

                const buffer = await audioContext.decodeAudioData(arrayBuffer);
                setAudioBuffer(buffer);
                setAudioDuration(buffer.duration);
            } catch (error) {
                console.error('Error loading audio:', error);
            }
        };

        loadAudio();

        return () => {
            if (sourceRef.current) {
                sourceRef.current.stop();
            }
            if (animationFrameRef.current) {
                cancelAnimationFrame(animationFrameRef.current);
            }
        };
    }, [audioUrl]);

    useEffect(() => {
        if (!audioBuffer || !canvasRef.current) return;

        const canvas = canvasRef.current;
        const ctx = canvas.getContext('2d');
        if (!ctx) return;

        const width = canvas.width;
        const height = canvas.height;

        // Calculate visible range based on zoom and offset
        const visibleDuration = audioDuration / zoom;
        const visibleStart = Math.max(0, Math.min(viewOffset, audioDuration - visibleDuration));
        const visibleEnd = Math.min(audioDuration, visibleStart + visibleDuration);

        // Clear canvas
        ctx.fillStyle = '#f3f4f6';
        ctx.fillRect(0, 0, width, height);

        // Draw waveform for visible range
        const data = audioBuffer.getChannelData(0);
        const samplesPerPixel = Math.ceil((data.length * visibleDuration / audioDuration) / width);
        const startSample = Math.floor(data.length * visibleStart / audioDuration);
        const amp = height / 2;

        ctx.fillStyle = '#4f46e5';
        for (let i = 0; i < width; i++) {
            let min = 1.0;
            let max = -1.0;
            const sampleIndex = startSample + (i * samplesPerPixel);
            for (let j = 0; j < samplesPerPixel && sampleIndex + j < data.length; j++) {
                const datum = data[sampleIndex + j];
                if (datum < min) min = datum;
                if (datum > max) max = datum;
            }
            ctx.fillRect(i, (1 + min) * amp, 1, Math.max(1, (max - min) * amp));
        }

        // Draw selection overlay
        const selectionStartPx = ((startTime - visibleStart) / visibleDuration) * width;
        const selectionWidthPx = (duration / visibleDuration) * width;

        if (selectionStartPx + selectionWidthPx > 0 && selectionStartPx < width) {
            ctx.fillStyle = 'rgba(79, 70, 229, 0.3)';
            ctx.fillRect(Math.max(0, selectionStartPx), 0, Math.min(selectionWidthPx, width - selectionStartPx), height);

            // Draw selection borders
            ctx.strokeStyle = '#4f46e5';
            ctx.lineWidth = 2;
            ctx.strokeRect(Math.max(0, selectionStartPx), 0, Math.min(selectionWidthPx, width - selectionStartPx), height);
        }

        // Draw segment markers (vertical lines)
        ctx.strokeStyle = '#ef4444';
        ctx.lineWidth = 1;
        ctx.setLineDash([5, 5]);

        let cumulativeTime = 0;
        unlockSteps.forEach((step, index) => {
            const segmentTime = startTime + cumulativeTime;
            const segmentPx = ((segmentTime - visibleStart) / visibleDuration) * width;

            if (segmentPx >= 0 && segmentPx <= width) {
                ctx.beginPath();
                ctx.moveTo(segmentPx, 0);
                ctx.lineTo(segmentPx, height);
                ctx.stroke();

                // Draw segment number
                ctx.setLineDash([]);
                ctx.fillStyle = '#ef4444';
                ctx.font = 'bold 12px sans-serif';
                ctx.fillText(`${index + 1}`, segmentPx + 3, 15);
                ctx.setLineDash([5, 5]);
            }

            cumulativeTime = step;
        });
        ctx.setLineDash([]);

        // Draw playback cursor
        if (playbackPosition !== null) {
            const cursorPx = ((playbackPosition - visibleStart) / visibleDuration) * width;
            if (cursorPx >= 0 && cursorPx <= width) {
                ctx.strokeStyle = '#10b981'; // Green
                ctx.lineWidth = 2;
                ctx.beginPath();
                ctx.moveTo(cursorPx, 0);
                ctx.lineTo(cursorPx, height);
                ctx.stroke();

                // Draw playhead triangle
                ctx.fillStyle = '#10b981';
                ctx.beginPath();
                ctx.moveTo(cursorPx, 0);
                ctx.lineTo(cursorPx - 5, 10);
                ctx.lineTo(cursorPx + 5, 10);
                ctx.closePath();
                ctx.fill();
            }
        }

    }, [audioBuffer, startTime, duration, audioDuration, zoom, viewOffset, unlockSteps, playbackPosition]);

    const handleCanvasClick = (e: React.MouseEvent<HTMLCanvasElement>) => {
        if (!canvasRef.current || !audioDuration) return;

        const rect = canvasRef.current.getBoundingClientRect();
        const x = e.clientX - rect.left;
        const visibleDuration = audioDuration / zoom;
        const visibleStart = Math.max(0, Math.min(viewOffset, audioDuration - visibleDuration));
        const clickedTime = visibleStart + (x / rect.width) * visibleDuration;

        // Center the selection on the clicked point
        let newStartTime = clickedTime - (duration / 2);

        // Clamp to valid range
        newStartTime = Math.max(0, Math.min(newStartTime, audioDuration - duration));

        onStartTimeChange(Math.floor(newStartTime));
    };

    const stopPlayback = () => {
        sourceRef.current?.stop();
        setIsPlaying(false);
        setPlayingSegment(null);
        setPlaybackPosition(null);
        if (animationFrameRef.current) {
            cancelAnimationFrame(animationFrameRef.current);
            animationFrameRef.current = null;
        }
    };

    // Animation loop for playback cursor
    useEffect(() => {
        if (!isPlaying || !audioContextRef.current) {
            return;
        }

        const animate = () => {
            if (!audioContextRef.current || !isPlaying) return;

            const elapsed = audioContextRef.current.currentTime - playbackStartTimeRef.current;
            const currentPos = playbackOffsetRef.current + elapsed;
            setPlaybackPosition(currentPos);

            animationFrameRef.current = requestAnimationFrame(animate);
        };

        animationFrameRef.current = requestAnimationFrame(animate);

        return () => {
            if (animationFrameRef.current) {
                cancelAnimationFrame(animationFrameRef.current);
            }
        };
    }, [isPlaying]);

    const handlePlaySegment = (segmentIndex: number) => {
        if (!audioBuffer || !audioContextRef.current) return;

        stopPlayback();

        const source = audioContextRef.current.createBufferSource();
        source.buffer = audioBuffer;
        source.connect(audioContextRef.current.destination);

        // Calculate segment start and duration
        const segmentStart = startTime + (segmentIndex > 0 ? unlockSteps[segmentIndex - 1] : 0);
        const segmentDuration = unlockSteps[segmentIndex] - (segmentIndex > 0 ? unlockSteps[segmentIndex - 1] : 0);

        playbackStartTimeRef.current = audioContextRef.current.currentTime;
        playbackOffsetRef.current = segmentStart;

        source.start(0, segmentStart, segmentDuration);
        sourceRef.current = source;
        setIsPlaying(true);
        setPlayingSegment(segmentIndex);
        setPlaybackPosition(segmentStart);

        source.onended = () => {
            setIsPlaying(false);
            setPlayingSegment(null);
            setPlaybackPosition(null);
            if (animationFrameRef.current) {
                cancelAnimationFrame(animationFrameRef.current);
                animationFrameRef.current = null;
            }
        };
    };

    const handlePlayFull = () => {
        if (!audioBuffer || !audioContextRef.current) return;

        if (isPlaying) {
            stopPlayback();
        } else {
            const source = audioContextRef.current.createBufferSource();
            source.buffer = audioBuffer;
            source.connect(audioContextRef.current.destination);

            playbackStartTimeRef.current = audioContextRef.current.currentTime;
            playbackOffsetRef.current = startTime;

            source.start(0, startTime, duration);
            sourceRef.current = source;
            setIsPlaying(true);
            setPlaybackPosition(startTime);

            source.onended = () => {
                setIsPlaying(false);
                setPlaybackPosition(null);
                if (animationFrameRef.current) {
                    cancelAnimationFrame(animationFrameRef.current);
                    animationFrameRef.current = null;
                }
            };
        }
    };

    const handleZoomIn = () => setZoom(prev => Math.min(prev * 1.5, 10));
    const handleZoomOut = () => setZoom(prev => Math.max(prev / 1.5, 1));
    const handlePanLeft = () => {
        const visibleDuration = audioDuration / zoom;
        setViewOffset(prev => Math.max(0, prev - visibleDuration * 0.2));
    };
    const handlePanRight = () => {
        const visibleDuration = audioDuration / zoom;
        setViewOffset(prev => Math.min(audioDuration - visibleDuration, prev + visibleDuration * 0.2));
    };

    return (
        <div style={{ marginTop: '1rem' }}>
            {/* Zoom and Pan Controls */}
            <div style={{ marginBottom: '0.5rem', display: 'flex', gap: '0.5rem', alignItems: 'center' }}>
                <button
                    onClick={handleZoomOut}
                    disabled={zoom <= 1}
                    style={{
                        padding: '0.25rem 0.5rem',
                        background: zoom <= 1 ? '#e5e7eb' : '#4f46e5',
                        color: zoom <= 1 ? '#9ca3af' : 'white',
                        border: 'none',
                        borderRadius: '0.25rem',
                        cursor: zoom <= 1 ? 'not-allowed' : 'pointer',
                        fontSize: '0.875rem'
                    }}
                >
                    🔍−
                </button>
                <button
                    onClick={handleZoomIn}
                    disabled={zoom >= 10}
                    style={{
                        padding: '0.25rem 0.5rem',
                        background: zoom >= 10 ? '#e5e7eb' : '#4f46e5',
                        color: zoom >= 10 ? '#9ca3af' : 'white',
                        border: 'none',
                        borderRadius: '0.25rem',
                        cursor: zoom >= 10 ? 'not-allowed' : 'pointer',
                        fontSize: '0.875rem'
                    }}
                >
                    🔍+
                </button>
                <span style={{ fontSize: '0.75rem', color: '#666' }}>Zoom: {zoom.toFixed(1)}x</span>
                {zoom > 1 && (
                    <>
                        <button onClick={handlePanLeft} style={{ padding: '0.25rem 0.5rem', background: '#4f46e5', color: 'white', border: 'none', borderRadius: '0.25rem', cursor: 'pointer', fontSize: '0.875rem' }}>
                            ←
                        </button>
                        <button onClick={handlePanRight} style={{ padding: '0.25rem 0.5rem', background: '#4f46e5', color: 'white', border: 'none', borderRadius: '0.25rem', cursor: 'pointer', fontSize: '0.875rem' }}>
                            →
                        </button>
                    </>
                )}
            </div>

            <canvas
                ref={canvasRef}
                width={800}
                height={150}
                onClick={handleCanvasClick}
                style={{
                    width: '100%',
                    height: 'auto',
                    cursor: 'pointer',
                    border: '1px solid #e5e7eb',
                    borderRadius: '0.5rem'
                }}
            />

            {/* Playback Controls */}
            <div style={{ marginTop: '1rem', display: 'flex', gap: '1rem', alignItems: 'center', flexWrap: 'wrap' }}>
                <button
                    onClick={handlePlayFull}
                    style={{
                        padding: '0.5rem 1rem',
                        background: '#4f46e5',
                        color: 'white',
                        border: 'none',
                        borderRadius: '0.5rem',
                        cursor: 'pointer',
                        fontWeight: 'bold'
                    }}
                >
                    {isPlaying && playingSegment === null ? '⏸ Pause' : '▶ Play Full Selection'}
                </button>

                <div style={{ fontSize: '0.875rem', color: '#666' }}>
                    Start: {startTime}s | Duration: {duration}s | Total: {Math.floor(audioDuration)}s
                </div>
            </div>

            {/* Segment Playback Buttons */}
            <div style={{ marginTop: '1rem', display: 'flex', gap: '0.5rem', flexWrap: 'wrap' }}>
                <span style={{ fontSize: '0.875rem', color: '#666', marginRight: '0.5rem' }}>Play Segments:</span>
                {unlockSteps.map((step, index) => {
                    const segmentStart = index > 0 ? unlockSteps[index - 1] : 0;
                    const segmentDuration = step - segmentStart;
                    return (
                        <button
                            key={index}
                            onClick={() => handlePlaySegment(index)}
                            style={{
                                padding: '0.25rem 0.75rem',
                                background: playingSegment === index ? '#ef4444' : '#f3f4f6',
                                color: playingSegment === index ? 'white' : '#374151',
                                border: '1px solid #e5e7eb',
                                borderRadius: '0.25rem',
                                cursor: 'pointer',
                                fontSize: '0.75rem',
                                fontWeight: playingSegment === index ? 'bold' : 'normal'
                            }}
                        >
                            {index + 1} ({segmentDuration}s)
                        </button>
                    );
                })}
            </div>
        </div>
    );
}