audio-ui/components/analysis/FrequencyAnalyzer.tsx

'use client';

import * as React from 'react';
import { cn } from '@/lib/utils/cn';

export interface FrequencyAnalyzerProps {
  analyserNode: AnalyserNode | null;
  className?: string;
}

export function FrequencyAnalyzer({ analyserNode, className }: FrequencyAnalyzerProps) {
  const canvasRef = React.useRef<HTMLCanvasElement>(null);
  const animationFrameRef = React.useRef<number>();

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

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

    // Set canvas size
    const dpr = window.devicePixelRatio || 1;
    const rect = canvas.getBoundingClientRect();
    canvas.width = rect.width * dpr;
    canvas.height = rect.height * dpr;
    ctx.scale(dpr, dpr);

    const bufferLength = analyserNode.frequencyBinCount;
    const dataArray = new Uint8Array(bufferLength);

    const draw = () => {
      animationFrameRef.current = requestAnimationFrame(draw);

      analyserNode.getByteFrequencyData(dataArray);

      // Clear canvas
      ctx.fillStyle = 'rgb(15, 15, 15)';
      ctx.fillRect(0, 0, rect.width, rect.height);

      const barWidth = rect.width / bufferLength;
      let x = 0;

      for (let i = 0; i < bufferLength; i++) {
        const barHeight = (dataArray[i] / 255) * rect.height;

        // Color gradient based on frequency
        const hue = (i / bufferLength) * 120; // 0 (red) to 120 (green)
        ctx.fillStyle = `hsl(${180 + hue}, 70%, 50%)`;

        ctx.fillRect(x, rect.height - barHeight, barWidth, barHeight);
        x += barWidth;
      }

      // Draw frequency labels
      ctx.fillStyle = 'rgba(255, 255, 255, 0.5)';
      ctx.font = '10px monospace';
      ctx.textAlign = 'left';
      ctx.fillText('20Hz', 5, rect.height - 5);
      ctx.textAlign = 'center';
      ctx.fillText('1kHz', rect.width / 2, rect.height - 5);
      ctx.textAlign = 'right';
      ctx.fillText('20kHz', rect.width - 5, rect.height - 5);
    };

    draw();

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

  return (
    <div className={cn('w-full h-full bg-card/50 border-2 border-accent/50 rounded-lg p-2', className)}>
      <div className="text-[10px] font-bold text-accent uppercase tracking-wider mb-2">
        Frequency Analyzer
      </div>
      <canvas
        ref={canvasRef}
        className="w-full h-[calc(100%-24px)] rounded"
      />
    </div>
  );
}