import { initialWaveState, step, wavePalette, waveScale, type WaveState } from '@pipu/core';
import { Canvas, createPicture, Picture } from '@shopify/react-native-skia';
import { useFocusEffect } from 'expo-router';
import { useCallback, useEffect, useMemo, useState, type ReactNode } from 'react';
import { AppState, Pressable, View } from 'react-native';
import Animated, { useAnimatedStyle, useDerivedValue, useFrameCallback, useReducedMotion, useSharedValue } from 'react-native-reanimated';

import { useThemeName } from '../../theme';
import { drawLiquid, drawOrb } from './draw';

export interface WaveOrbProps {
  variant: 'orb' | 'liquid';
  playing: boolean;
  bpm?: number;
  energy?: number;
  colors?: readonly string[];
  size: number;
  label?: string;
  onPress?: () => void;
  children?: ReactNode;
}

/**
 * «Моя волна» на Skia (docs/design.md#3): в покое «дышит», при игре пульсирует в такт BPM с силой от energy,
 * при нажатии сжимается с отскоком. Кадры считаются в UI-потоке; вне экрана и в фоне анимация стоит.
 * Без `onPress` — декоративная визуализация (полноэкранный плеер в виде «волна»).
 */
export function WaveOrb({ variant, playing, bpm = 100, energy = 0.6, colors, size, label, onPress, children }: WaveOrbProps) {
  const dark = useThemeName() === 'dark';
  const reduced = useReducedMotion();
  const [focused, setFocused] = useState(true);
  useFocusEffect(
    useCallback(() => {
      setFocused(true);
      return () => setFocused(false);
    }, []),
  );
  const [foreground, setForeground] = useState(AppState.currentState === 'active');
  const palette = useMemo(() => wavePalette(colors), [colors]);

  const props = useSharedValue({ variant, playing, bpm, energy, colors: palette, dark, reduced });
  const state = useSharedValue<WaveState>(initialWaveState(size));
  const pressT = useSharedValue(0);
  // Новый объект на каждом кадре — пересчёт картинки (одно и то же число могло бы не вызвать его).
  const time = useSharedValue({ ts: 0, dt: 0 });

  useEffect(() => {
    props.value = { variant, playing, bpm, energy, colors: palette, dark, reduced };
  }, [variant, playing, bpm, energy, palette[0], palette[1], palette[2], dark, reduced]);

  useEffect(() => {
    const sub = AppState.addEventListener('change', (st) => setForeground(st === 'active'));
    return () => sub.remove();
  }, []);

  const frame = useFrameCallback((info) => {
    time.value = { ts: info.timestamp, dt: Math.min(0.05, (info.timeSincePreviousFrame ?? 16) / 1000) };
  }, false);
  useEffect(() => {
    frame.setActive(focused && foreground);
  }, [focused, foreground]);

  const S = size * 1.6;
  const picture = useDerivedValue(() => {
    const dt = time.value.dt;
    const s = state.value;
    Object.assign(s, props.value);
    s.size = size;
    if (pressT.value === 0 && s.pressT === 1) s.pressV -= 0.12; // отпустили — отскок
    s.pressT = pressT.value;
    step(s, dt);
    const r = size * 0.5 * waveScale(s);
    return createPicture(
      (canvas) => {
        if (s.variant === 'liquid') drawLiquid(canvas, S / 2, S / 2, r, s);
        else drawOrb(canvas, S / 2, S / 2, r, s);
      },
      { width: S, height: S },
    );
  });
  const labelStyle = useAnimatedStyle(() => {
    void time.value.ts; // пересчёт на каждом кадре
    const s = state.value;
    return { transform: [{ scale: waveScale(s) + s.pulse * 0.03 }] };
  });

  const body = (
    <View style={{ width: size, height: size, alignItems: 'center', justifyContent: 'center' }}>
      <Canvas style={{ position: 'absolute', width: S, height: S, left: (size - S) / 2, top: (size - S) / 2 }} pointerEvents="none">
        <Picture picture={picture} />
      </Canvas>
      <Animated.View style={[{ alignItems: 'center', justifyContent: 'center', gap: 4 }, labelStyle]} pointerEvents="none">
        {children}
      </Animated.View>
    </View>
  );
  if (!onPress) return <View accessibilityElementsHidden importantForAccessibility="no-hide-descendants">{body}</View>;
  return (
    <Pressable
      onPress={onPress}
      onPressIn={() => (pressT.value = 1)}
      onPressOut={() => (pressT.value = 0)}
      accessibilityRole="button"
      accessibilityLabel={label}
      accessibilityState={{ selected: playing }}
    >
      {body}
    </Pressable>
  );
}