import { useEffect, useRef, type MouseEvent as ReactMouseEvent, type ReactNode } from 'react';

import { drawLiquid, drawOrb, step, type WaveState } from './draw';

export interface WaveButtonProps {
  variant?: 'orb' | 'liquid';
  playing?: boolean;
  readAudio?: () => { bass: number; mid: number; treble: number };
  bpm?: number;
  energy?: number;
  colors?: [string, string, string];
  theme?: 'dark' | 'light';
  interactive?: boolean;
  size?: number;
  label: string;
  onClick?: () => void;
  children?: ReactNode;
}

const DEFAULT_COLORS: [string, string, string] = ['#2F80FF', '#7C5CFF', '#35D3FF'];

function prefersReducedMotion(): boolean {
  return typeof window !== 'undefined' && !!window.matchMedia?.('(prefers-reduced-motion: reduce)').matches;
}

/**
 * Кнопка «Моя волна» (docs/design.md#3): в покое «дышит», при игре пульсирует в такт BPM с силой от energy,
 * тянется к курсору, при нажатии сжимается с отскоком. Enter / пробел — то же, что клик.
 */
export function WaveButton(props: WaveButtonProps) {
  const size = props.size ?? 320;
  const audioRef = useRef(props.readAudio);
  audioRef.current = props.readAudio;
  const canvasRef = useRef<HTMLCanvasElement>(null);
  const labelRef = useRef<HTMLDivElement>(null);
  const wrapRef = useRef<HTMLDivElement>(null);
  const st = useRef<WaveState>({
    hover: 0, hoverT: 0, press: 0, pressV: 0, pressT: 0, mx: 0, my: 0, ang: 0, t: 0, amp: 0, pulse: 0,
    speed: 1, phase: 0, variant: 'orb', playing: false, bpm: 100, energy: 0.6, colors: DEFAULT_COLORS,
    dark: true, reduced: false, size,
  });
  // Пропсы читаются в цикле анимации через ref — перерисовка React не нужна.
  const s = st.current;
  s.variant = props.variant ?? 'orb';
  s.playing = !!props.playing;
  s.bpm = props.bpm ?? 100;
  s.energy = props.energy ?? 0.6;
  s.colors = props.colors ?? DEFAULT_COLORS;
  s.dark = props.theme !== 'light';
  s.size = size;

  useEffect(() => {
    const cv = canvasRef.current;
    const ctx = cv?.getContext('2d');
    if (!cv || !ctx) return;
    const mq = window.matchMedia?.('(prefers-reduced-motion: reduce)');
    st.current.reduced = prefersReducedMotion();
    const onMq = () => (st.current.reduced = prefersReducedMotion());
    mq?.addEventListener?.('change', onMq);
    let raf = 0;
    let livePulse = 0;
    let last = performance.now();
    const loop = (now: number) => {
      const dt = Math.min(0.05, (now - last) / 1000);
      last = now;
      const w = st.current;
      const S = w.size * 1.6;
      const dpr = window.devicePixelRatio || 1;
      if (cv.width !== Math.round(S * dpr)) {
        cv.width = Math.round(S * dpr);
        cv.height = Math.round(S * dpr);
      }
      step(w, dt);
      const audio = !w.reduced && w.playing ? audioRef.current?.() : undefined;
      if (audioRef.current && !w.reduced) {
        const target = audio ? Math.min(1, audio.bass * 0.7 + audio.mid * 0.2) : 0;
        livePulse += (target - livePulse) * (1 - Math.exp(-dt * (target > livePulse ? 35 : 9)));
        w.pulse = livePulse;
        w.amp = audio ? Math.min(1, audio.mid * 0.8 + audio.treble * 0.7) : 0;
      }
      ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
      ctx.clearRect(0, 0, S, S);
      const sc = 1 - w.press * 0.07 + w.hover * 0.02;
      const r = w.size * 0.5 * sc * (1 + w.pulse * 0.055);
      const cx = S / 2 + w.mx * w.hover * 6;
      const cy = S / 2 + w.my * w.hover * 6;
      const ripple = audio ? w.amp * 0.025 * Math.sin(w.t * 13) : 0;
      ctx.translate(cx, cy);
      ctx.scale(1 + ripple, 1 - ripple);
      ctx.translate(-cx, -cy);
      if (w.variant === 'liquid') drawLiquid(ctx, cx, cy, r, w, w.t);
      else drawOrb(ctx, cx, cy, r, w, w.t);
      if (labelRef.current) labelRef.current.style.transform = `scale(${sc + w.pulse * 0.03})`;
      raf = requestAnimationFrame(loop);
    };
    // Во фоновой вкладке анимация не нужна — останавливаемся до возвращения.
    const onVisibility = () => {
      cancelAnimationFrame(raf);
      if (document.visibilityState === 'visible') {
        last = performance.now();
        raf = requestAnimationFrame(loop);
      }
    };
    raf = requestAnimationFrame(loop);
    document.addEventListener('visibilitychange', onVisibility);
    return () => {
      cancelAnimationFrame(raf);
      document.removeEventListener('visibilitychange', onVisibility);
      mq?.removeEventListener?.('change', onMq);
    };
  }, []);

  const interactive = props.interactive !== false;
  const onMove = (e: ReactMouseEvent) => {
    const b = wrapRef.current!.getBoundingClientRect();
    const x = ((e.clientX - b.left) / b.width) * 2 - 1;
    const y = ((e.clientY - b.top) / b.height) * 2 - 1;
    s.mx = x;
    s.my = y;
    s.ang = Math.atan2(y, x);
  };

  return (
    <div
      ref={wrapRef}
      role={interactive ? 'button' : undefined}
      tabIndex={interactive ? 0 : undefined}
      aria-label={interactive ? props.label : undefined}
      aria-pressed={interactive ? !!props.playing : undefined}
      aria-hidden={interactive ? undefined : true}
      onMouseMove={interactive ? onMove : undefined}
      onMouseEnter={interactive ? () => (s.hoverT = 1) : undefined}
      onMouseLeave={
        interactive
          ? () => {
              s.hoverT = 0;
              s.pressT = 0;
            }
          : undefined
      }
      onMouseDown={interactive ? () => (s.pressT = 1) : undefined}
      onMouseUp={
        interactive
          ? () => {
              s.pressT = 0;
              s.pressV -= 0.12;
            }
          : undefined
      }
      onClick={interactive ? props.onClick : undefined}
      onKeyDown={
        interactive
          ? (e) => {
              if (e.key === 'Enter' || e.key === ' ') {
                e.preventDefault();
                e.stopPropagation(); // пробел здесь — кнопка волны, а не пауза плеера
                props.onClick?.();
              }
            }
          : undefined
      }
      style={{
        position: 'relative',
        width: size,
        height: size,
        maxWidth: '78vw',
        maxHeight: '78vw',
        borderRadius: '50%',
        cursor: interactive ? 'pointer' : 'default',
        flexShrink: 0,
        pointerEvents: interactive ? 'auto' : 'none',
      }}
    >
      <canvas
        ref={canvasRef}
        style={{
          position: 'absolute',
          left: '-30%',
          top: '-30%',
          width: '160%',
          height: '160%',
          pointerEvents: 'none',
        }}
      />
      <div
        ref={labelRef}
        style={{
          position: 'absolute',
          inset: 0,
          display: 'flex',
          flexDirection: 'column',
          alignItems: 'center',
          justifyContent: 'center',
          pointerEvents: 'none',
          color: '#fff',
          textAlign: 'center',
        }}
      >
        {props.children}
      </div>
    </div>
  );
}