import { useRef, useMemo } from 'react';
import { useFrame } from '@react-three/fiber';
import * as THREE from 'three';

function Particles({ count = 10000 }) {
  const points = useRef<THREE.Points>(null!);
  
  const positions = useMemo(() => {
    const pos = new Float32Array(count * 3);
    for (let i = 0; i < count; i++) {
      pos[i * 3] = (Math.random() - 0.5) * 10;
      pos[i * 3 + 1] = (Math.random() - 0.5) * 10;
      pos[i * 3 + 2] = (Math.random() - 0.5) * 10;
    }
    return pos;
  }, [count]);
  
  return (
    <points ref={points}>
      <bufferGeometry>
        <bufferAttribute
          attach="attributes-position"
          count={count}
          array={positions}
          itemSize={3}
        />
      </bufferGeometry>
      <pointsMaterial size={0.05} color="#ffffff" />
    </points>
  );
}

function BasicPoints({ count = 5000 }) {
  const positions = useMemo(() => {
    const pos = new Float32Array(count * 3);
    for (let i = 0; i < count; i++) {
      const theta = Math.random() * Math.PI * 2;
      const phi = Math.acos(2 * Math.random() - 1);
      const r = Math.cbrt(Math.random()) * 5;
      
      pos[i * 3] = r * Math.sin(phi) * Math.cos(theta);
      pos[i * 3 + 1] = r * Math.sin(phi) * Math.sin(theta);
      pos[i * 3 + 2] = r * Math.cos(phi);
    }
    return pos;
  }, [count]);
  
  return (
    <points>
      <bufferGeometry>
        <bufferAttribute
          attach="attributes-position"
          count={count}
          array={positions}
          itemSize={3}
        />
      </bufferGeometry>
      <pointsMaterial
        size={0.1}
        sizeAttenuation={true}
        transparent={true}
        opacity={0.8}
        depthWrite={false}
        blending={THREE.AdditiveBlending}
      />
    </points>
  );
}

function TexturedPoints({ count = 5000 }) {
  const texture = useTexture('/particle.png');
  
  return (
    <points>
      <bufferGeometry>
        {/* ... positions ... */}
      </bufferGeometry>
      <pointsMaterial
        size={0.5}
        map={texture}
        transparent={true}
        alphaTest={0.01}
        depthWrite={false}
        blending={THREE.AdditiveBlending}
      />
    </points>
  );
}

function ColoredParticles({ count = 10000 }) {
  const { positions, colors, sizes } = useMemo(() => {
    const pos = new Float32Array(count * 3);
    const col = new Float32Array(count * 3);
    const siz = new Float32Array(count);
    
    for (let i = 0; i < count; i++) {
      // Position
      pos[i * 3] = (Math.random() - 0.5) * 10;
      pos[i * 3 + 1] = (Math.random() - 0.5) * 10;
      pos[i * 3 + 2] = (Math.random() - 0.5) * 10;
      
      // Color (HSL to RGB)
      const color = new THREE.Color();
      color.setHSL(Math.random(), 0.8, 0.5);
      col[i * 3] = color.r;
      col[i * 3 + 1] = color.g;
      col[i * 3 + 2] = color.b;
      
      // Size
      siz[i] = 0.05 + Math.random() * 0.1;
    }
    
    return { positions: pos, colors: col, sizes: siz };
  }, [count]);
  
  return (
    <points>
      <bufferGeometry>
        <bufferAttribute
          attach="attributes-position"
          count={count}
          array={positions}
          itemSize={3}
        />
        <bufferAttribute
          attach="attributes-color"
          count={count}
          array={colors}
          itemSize={3}
        />
        <bufferAttribute
          attach="attributes-size"
          count={count}
          array={sizes}
          itemSize={1}
        />
      </bufferGeometry>
      <pointsMaterial
        vertexColors
        size={0.1}
        sizeAttenuation
        transparent
        depthWrite={false}
      />
    </points>
  );
}

const vertexShader = `
  attribute float aSize;
  attribute vec3 aColor;
  attribute float aAlpha;
  
  uniform float uTime;
  uniform float uPixelRatio;
  
  varying vec3 vColor;
  varying float vAlpha;
  
  void main() {
    vColor = aColor;
    vAlpha = aAlpha;
    
    vec4 mvPosition = modelViewMatrix * vec4(position, 1.0);
    
    // Size attenuation
    gl_PointSize = aSize * uPixelRatio * (300.0 / -mvPosition.z);
    gl_Position = projectionMatrix * mvPosition;
  }
`;

const fragmentShader = `
  varying vec3 vColor;
  varying float vAlpha;
  
  void main() {
    // Circular particle
    float dist = length(gl_PointCoord - 0.5);
    if (dist > 0.5) discard;
    
    // Soft edge
    float alpha = 1.0 - smoothstep(0.4, 0.5, dist);
    
    gl_FragColor = vec4(vColor, alpha * vAlpha);
  }
`;

function ShaderParticles({ count = 50000 }) {
  const points = useRef<THREE.Points>(null!);
  
  const { positions, sizes, colors, alphas } = useMemo(() => {
    const pos = new Float32Array(count * 3);
    const siz = new Float32Array(count);
    const col = new Float32Array(count * 3);
    const alp = new Float32Array(count);
    
    for (let i = 0; i < count; i++) {
      pos[i * 3] = (Math.random() - 0.5) * 20;
      pos[i * 3 + 1] = (Math.random() - 0.5) * 20;
      pos[i * 3 + 2] = (Math.random() - 0.5) * 20;
      
      siz[i] = 10 + Math.random() * 20;
      
      const color = new THREE.Color();
      color.setHSL(0.6 + Math.random() * 0.2, 0.8, 0.5);
      col[i * 3] = color.r;
      col[i * 3 + 1] = color.g;
      col[i * 3 + 2] = color.b;
      
      alp[i] = 0.3 + Math.random() * 0.7;
    }
    
    return { positions: pos, sizes: siz, colors: col, alphas: alp };
  }, [count]);
  
  useFrame(({ clock }) => {
    points.current.material.uniforms.uTime.value = clock.elapsedTime;
  });
  
  return (
    <points ref={points}>
      <bufferGeometry>
        <bufferAttribute attach="attributes-position" count={count} array={positions} itemSize={3} />
        <bufferAttribute attach="attributes-aSize" count={count} array={sizes} itemSize={1} />
        <bufferAttribute attach="attributes-aColor" count={count} array={colors} itemSize={3} />
        <bufferAttribute attach="attributes-aAlpha" count={count} array={alphas} itemSize={1} />
      </bufferGeometry>
      <shaderMaterial
        vertexShader={vertexShader}
        fragmentShader={fragmentShader}
        uniforms={{
          uTime: { value: 0 },
          uPixelRatio: { value: Math.min(window.devicePixelRatio, 2) }
        }}
        transparent
        depthWrite={false}
        blending={THREE.AdditiveBlending}
      />
    </points>
  );
}

// Vertex shader with animation
attribute vec3 aVelocity;
attribute float aPhase;

uniform float uTime;

void main() {
  vec3 pos = position;
  
  // Simple oscillation
  pos.y += sin(uTime * 2.0 + aPhase) * 0.5;
  
  // Velocity-based movement
  pos += aVelocity * uTime;
  
  // Wrap around bounds
  pos = mod(pos + 10.0, 20.0) - 10.0;
  
  vec4 mvPosition = modelViewMatrix * vec4(pos, 1.0);
  gl_PointSize = 10.0 * (300.0 / -mvPosition.z);
  gl_Position = projectionMatrix * mvPosition;
}

function AnimatedParticles({ count = 10000 }) {
  const points = useRef<THREE.Points>(null!);
  
  const velocities = useMemo(() => {
    const vel = new Float32Array(count * 3);
    for (let i = 0; i < count; i++) {
      vel[i * 3] = (Math.random() - 0.5) * 0.02;
      vel[i * 3 + 1] = (Math.random() - 0.5) * 0.02;
      vel[i * 3 + 2] = (Math.random() - 0.5) * 0.02;
    }
    return vel;
  }, [count]);
  
  useFrame(() => {
    const positions = points.current.geometry.attributes.position.array as Float32Array;
    
    for (let i = 0; i < count; i++) {
      positions[i * 3] += velocities[i * 3];
      positions[i * 3 + 1] += velocities[i * 3 + 1];
      positions[i * 3 + 2] += velocities[i * 3 + 2];
      
      // Wrap around
      for (let j = 0; j < 3; j++) {
        if (positions[i * 3 + j] > 5) positions[i * 3 + j] = -5;
        if (positions[i * 3 + j] < -5) positions[i * 3 + j] = 5;
      }
    }
    
    points.current.geometry.attributes.position.needsUpdate = true;
  });
  
  // ... geometry setup
}

function InstancedParticles({ count = 1000 }) {
  const mesh = useRef<THREE.InstancedMesh>(null!);
  const dummy = useMemo(() => new THREE.Object3D(), []);
  
  useEffect(() => {
    for (let i = 0; i < count; i++) {
      dummy.position.set(
        (Math.random() - 0.5) * 10,
        (Math.random() - 0.5) * 10,
        (Math.random() - 0.5) * 10
      );
      dummy.rotation.set(
        Math.random() * Math.PI,
        Math.random() * Math.PI,
        0
      );
      dummy.scale.setScalar(0.05 + Math.random() * 0.1);
      dummy.updateMatrix();
      mesh.current.setMatrixAt(i, dummy.matrix);
    }
    mesh.current.instanceMatrix.needsUpdate = true;
  }, [count, dummy]);
  
  useFrame(({ clock }) => {
    for (let i = 0; i < count; i++) {
      mesh.current.getMatrixAt(i, dummy.matrix);
      dummy.matrix.decompose(dummy.position, dummy.quaternion, dummy.scale);
      
      dummy.rotation.x += 0.01;
      dummy.rotation.y += 0.01;
      
      dummy.updateMatrix();
      mesh.current.setMatrixAt(i, dummy.matrix);
    }
    mesh.current.instanceMatrix.needsUpdate = true;
  });
  
  return (
    <instancedMesh ref={mesh} args={[undefined, undefined, count]}>
      <icosahedronGeometry args={[1, 0]} />
      <meshStandardMaterial color="#ff6b6b" />
    </instancedMesh>
  );
}

function spherePositions(count: number, radius: number) {
  const positions = new Float32Array(count * 3);
  
  for (let i = 0; i < count; i++) {
    const theta = Math.random() * Math.PI * 2;
    const phi = Math.acos(2 * Math.random() - 1);
    const r = Math.cbrt(Math.random()) * radius;  // Cube root for uniform volume
    
    positions[i * 3] = r * Math.sin(phi) * Math.cos(theta);
    positions[i * 3 + 1] = r * Math.sin(phi) * Math.sin(theta);
    positions[i * 3 + 2] = r * Math.cos(phi);
  }
  
  return positions;
}

function galaxyPositions(count: number, arms: number, spin: number) {
  const positions = new Float32Array(count * 3);
  
  for (let i = 0; i < count; i++) {
    const armIndex = i % arms;
    const armAngle = (armIndex / arms) * Math.PI * 2;
    
    const radius = Math.random() * 5;
    const spinAngle = radius * spin;
    const angle = armAngle + spinAngle;
    
    // Add randomness
    const randomX = (Math.random() - 0.5) * 0.5 * radius;
    const randomY = (Math.random() - 0.5) * 0.2;
    const randomZ = (Math.random() - 0.5) * 0.5 * radius;
    
    positions[i * 3] = Math.cos(angle) * radius + randomX;
    positions[i * 3 + 1] = randomY;
    positions[i * 3 + 2] = Math.sin(angle) * radius + randomZ;
  }
  
  return positions;
}

function gridPositions(countPerAxis: number, spacing: number) {
  const count = countPerAxis ** 3;
  const positions = new Float32Array(count * 3);
  const offset = (countPerAxis - 1) * spacing * 0.5;
  
  let index = 0;
  for (let x = 0; x < countPerAxis; x++) {
    for (let y = 0; y < countPerAxis; y++) {
      for (let z = 0; z < countPerAxis; z++) {
        positions[index * 3] = x * spacing - offset;
        positions[index * 3 + 1] = y * spacing - offset;
        positions[index * 3 + 2] = z * spacing - offset;
        index++;
      }
    }
  }
  
  return positions;
}

<pointsMaterial
  transparent
  depthWrite={false}           // Faster blending
  blending={THREE.AdditiveBlending}  // Good for glowing particles
  sizeAttenuation              // Perspective-correct size
/>

particles-gpu/
├── SKILL.md
├── references/
│   ├── buffer-patterns.md     # Distribution patterns
│   └── shader-examples.md     # Complete shader examples
└── scripts/
    ├── particles/
    │   ├── basic-points.tsx   # Simple points setup
    │   ├── shader-points.tsx  # Custom shader particles
    │   └── instanced.tsx      # Instanced mesh particles
    └── distributions/
        ├── sphere.ts          # Sphere distribution
        ├── galaxy.ts          # Galaxy spiral
        └── grid.ts            # Grid distribution