Lofi_Generator/components/timeline/Playhead.tsx

'use client';

import { useCallback, useState } from 'react';
import { cn } from '@/lib/utils';

interface PlayheadProps {
  bar: number;
  beat: number;
  pixelsPerBar: number;
  height: number;
  durationBars: number;
  onSeek?: (bar: number, beat: number) => void;
  className?: string;
}

export function Playhead({
  bar,
  beat,
  pixelsPerBar,
  height,
  durationBars,
  onSeek,
  className,
}: PlayheadProps) {
  const [isDragging, setIsDragging] = useState(false);
  const pixelsPerBeat = pixelsPerBar / 4;
  const position = bar * pixelsPerBar + beat * pixelsPerBeat;

  const handleDrag = useCallback(
    (clientX: number, containerLeft: number) => {
      if (!onSeek) return;

      const x = clientX - containerLeft;
      const totalBeats = x / pixelsPerBeat;
      const newBar = Math.floor(totalBeats / 4);
      const newBeat = Math.floor(totalBeats % 4);

      if (newBar >= 0 && newBar < durationBars) {
        onSeek(newBar, Math.max(0, Math.min(3, newBeat)));
      }
    },
    [onSeek, pixelsPerBeat, durationBars]
  );

  const handleMouseDown = useCallback(
    (e: React.MouseEvent) => {
      if (!onSeek) return;
      e.preventDefault();
      e.stopPropagation();
      setIsDragging(true);

      const container = (e.currentTarget as HTMLElement).parentElement;
      if (!container) return;
      const containerRect = container.getBoundingClientRect();

      const handleMouseMove = (e: MouseEvent) => {
        handleDrag(e.clientX, containerRect.left);
      };

      const handleMouseUp = () => {
        setIsDragging(false);
        window.removeEventListener('mousemove', handleMouseMove);
        window.removeEventListener('mouseup', handleMouseUp);
      };

      window.addEventListener('mousemove', handleMouseMove);
      window.addEventListener('mouseup', handleMouseUp);
    },
    [onSeek, handleDrag]
  );

  return (
    <div
      className={cn(
        'absolute top-0 z-20',
        'flex flex-col items-center',
        className
      )}
      style={{ left: position, height }}
    >
      <div
        className={cn(
          'w-4 h-3 bg-lofi-orange rounded-sm -mt-0.5 cursor-grab',
          isDragging && 'cursor-grabbing scale-110'
        )}
        style={{
          clipPath: 'polygon(50% 100%, 0% 0%, 100% 0%)',
        }}
        onMouseDown={handleMouseDown}
      />
      <div className="w-0.5 flex-1 bg-lofi-orange shadow-[0_0_8px_var(--lofi-orange)] pointer-events-none" />
    </div>
  );
}