import { ShaderChunk } from 'three';

const CSMShader = {
	lights_fragment_begin: /* glsl */`
GeometricContext geometry;

geometry.position = - vViewPosition;
geometry.normal = normal;
geometry.viewDir = ( isOrthographic ) ? vec3( 0, 0, 1 ) : normalize( vViewPosition );

#ifdef CLEARCOAT

	geometry.clearcoatNormal = clearcoatNormal;

#endif

IncidentLight directLight;

#if ( NUM_POINT_LIGHTS > 0 ) && defined( RE_Direct )

	PointLight pointLight;
	#if defined( USE_SHADOWMAP ) && NUM_POINT_LIGHT_SHADOWS > 0
	PointLightShadow pointLightShadow;
	#endif

	#pragma unroll_loop_start
	for ( int i = 0; i < NUM_POINT_LIGHTS; i ++ ) {

		pointLight = pointLights[ i ];

		getPointLightInfo( pointLight, geometry, directLight );

		#if defined( USE_SHADOWMAP ) && ( UNROLLED_LOOP_INDEX < NUM_POINT_LIGHT_SHADOWS )
		pointLightShadow = pointLightShadows[ i ];
		directLight.color *= all( bvec2( directLight.visible, receiveShadow ) ) ? getPointShadow( pointShadowMap[ i ], pointLightShadow.shadowMapSize, pointLightShadow.shadowBias, pointLightShadow.shadowRadius, vPointShadowCoord[ i ], pointLightShadow.shadowCameraNear, pointLightShadow.shadowCameraFar ) : 1.0;
		#endif

		RE_Direct( directLight, geometry, material, reflectedLight );

	}
	#pragma unroll_loop_end

#endif

#if ( NUM_SPOT_LIGHTS > 0 ) && defined( RE_Direct )

	SpotLight spotLight;
	#if defined( USE_SHADOWMAP ) && NUM_SPOT_LIGHT_SHADOWS > 0
	SpotLightShadow spotLightShadow;
	#endif

	#pragma unroll_loop_start
	for ( int i = 0; i < NUM_SPOT_LIGHTS; i ++ ) {

		spotLight = spotLights[ i ];

		getSpotLightInfo( spotLight, geometry, directLight );

		#if defined( USE_SHADOWMAP ) && ( UNROLLED_LOOP_INDEX < NUM_SPOT_LIGHT_SHADOWS )
		spotLightShadow = spotLightShadows[ i ];
		directLight.color *= all( bvec2( directLight.visible, receiveShadow ) ) ? getShadow( spotShadowMap[ i ], spotLightShadow.shadowMapSize, spotLightShadow.shadowBias, spotLightShadow.shadowRadius, vSpotShadowCoord[ i ] ) : 1.0;
		#endif

		RE_Direct( directLight, geometry, material, reflectedLight );

	}
	#pragma unroll_loop_end

#endif

#if ( NUM_DIR_LIGHTS > 0) && defined( RE_Direct ) && defined( USE_CSM ) && defined( CSM_CASCADES )

	DirectionalLight directionalLight;
	float linearDepth = (vViewPosition.z) / (shadowFar - cameraNear);
	#if defined( USE_SHADOWMAP ) && NUM_DIR_LIGHT_SHADOWS > 0
	DirectionalLightShadow directionalLightShadow;
	#endif

	#if defined( USE_SHADOWMAP ) && defined( CSM_FADE )
	vec2 cascade;
	float cascadeCenter;
	float closestEdge;
	float margin;
	float csmx;
	float csmy;

	#pragma unroll_loop_start
	for ( int i = 0; i < NUM_DIR_LIGHTS; i ++ ) {

		directionalLight = directionalLights[ i ];
		getDirectionalLightInfo( directionalLight, geometry, directLight );

	  	#if defined( USE_SHADOWMAP ) && ( UNROLLED_LOOP_INDEX < NUM_DIR_LIGHT_SHADOWS )
			// NOTE: Depth gets larger away from the camera.
			// cascade.x is closer, cascade.y is further
			cascade = CSM_cascades[ i ];
			cascadeCenter = ( cascade.x + cascade.y ) / 2.0;
			closestEdge = linearDepth < cascadeCenter ? cascade.x : cascade.y;
			margin = 0.25 * pow( closestEdge, 2.0 );
			csmx = cascade.x - margin / 2.0;
			csmy = cascade.y + margin / 2.0;
			if( linearDepth >= csmx && ( linearDepth < csmy || UNROLLED_LOOP_INDEX == CSM_CASCADES - 1 ) ) {

				float dist = min( linearDepth - csmx, csmy - linearDepth );
				float ratio = clamp( dist / margin, 0.0, 1.0 );

				vec3 prevColor = directLight.color;
				directionalLightShadow = directionalLightShadows[ i ];
				directLight.color *= all( bvec2( directLight.visible, receiveShadow ) ) ? getShadow( directionalShadowMap[ i ], directionalLightShadow.shadowMapSize, directionalLightShadow.shadowBias, directionalLightShadow.shadowRadius, vDirectionalShadowCoord[ i ] ) : 1.0;

				bool shouldFadeLastCascade = UNROLLED_LOOP_INDEX == CSM_CASCADES - 1 && linearDepth > cascadeCenter;
				directLight.color = mix( prevColor, directLight.color, shouldFadeLastCascade ? ratio : 1.0 );

				ReflectedLight prevLight = reflectedLight;
				RE_Direct( directLight, geometry, material, reflectedLight );

				bool shouldBlend = UNROLLED_LOOP_INDEX != CSM_CASCADES - 1 || UNROLLED_LOOP_INDEX == CSM_CASCADES - 1 && linearDepth < cascadeCenter;
				float blendRatio = shouldBlend ? ratio : 1.0;

				reflectedLight.directDiffuse = mix( prevLight.directDiffuse, reflectedLight.directDiffuse, blendRatio );
				reflectedLight.directSpecular = mix( prevLight.directSpecular, reflectedLight.directSpecular, blendRatio );
				reflectedLight.indirectDiffuse = mix( prevLight.indirectDiffuse, reflectedLight.indirectDiffuse, blendRatio );
				reflectedLight.indirectSpecular = mix( prevLight.indirectSpecular, reflectedLight.indirectSpecular, blendRatio );

			}
	  	#endif

	}
	#pragma unroll_loop_end
	#else

		#pragma unroll_loop_start
		for ( int i = 0; i < NUM_DIR_LIGHTS; i ++ ) {

			directionalLight = directionalLights[ i ];
			getDirectionalLightInfo( directionalLight, geometry, directLight );

			#if defined( USE_SHADOWMAP ) && ( UNROLLED_LOOP_INDEX < NUM_DIR_LIGHT_SHADOWS )

			directionalLightShadow = directionalLightShadows[ i ];
			if(linearDepth >= CSM_cascades[UNROLLED_LOOP_INDEX].x && linearDepth < CSM_cascades[UNROLLED_LOOP_INDEX].y) directLight.color *= all( bvec2( directLight.visible, receiveShadow ) ) ? getShadow( directionalShadowMap[ i ], directionalLightShadow.shadowMapSize, directionalLightShadow.shadowBias, directionalLightShadow.shadowRadius, vDirectionalShadowCoord[ i ] ) : 1.0;

			if(linearDepth >= CSM_cascades[UNROLLED_LOOP_INDEX].x && (linearDepth < CSM_cascades[UNROLLED_LOOP_INDEX].y || UNROLLED_LOOP_INDEX == CSM_CASCADES - 1)) RE_Direct( directLight, geometry, material, reflectedLight );

			#endif

		}
		#pragma unroll_loop_end

	#endif

	#if ( NUM_DIR_LIGHTS > NUM_DIR_LIGHT_SHADOWS)
		// compute the lights not casting shadows (if any)

		#pragma unroll_loop_start
		for ( int i = NUM_DIR_LIGHT_SHADOWS; i < NUM_DIR_LIGHTS; i ++ ) {

			directionalLight = directionalLights[ i ];

			getDirectionalLightInfo( directionalLight, geometry, directLight );

			RE_Direct( directLight, geometry, material, reflectedLight );

		}
		#pragma unroll_loop_end

	#endif

#endif


#if ( NUM_DIR_LIGHTS > 0 ) && defined( RE_Direct ) && !defined( USE_CSM ) && !defined( CSM_CASCADES )

	DirectionalLight directionalLight;
	#if defined( USE_SHADOWMAP ) && NUM_DIR_LIGHT_SHADOWS > 0
	DirectionalLightShadow directionalLightShadow;
	#endif

	#pragma unroll_loop_start
	for ( int i = 0; i < NUM_DIR_LIGHTS; i ++ ) {

		directionalLight = directionalLights[ i ];

		getDirectionalLightInfo( directionalLight, geometry, directLight );

		#if defined( USE_SHADOWMAP ) && ( UNROLLED_LOOP_INDEX < NUM_DIR_LIGHT_SHADOWS )
		directionalLightShadow = directionalLightShadows[ i ];
		directLight.color *= all( bvec2( directLight.visible, receiveShadow ) ) ? getShadow( directionalShadowMap[ i ], directionalLightShadow.shadowMapSize, directionalLightShadow.shadowBias, directionalLightShadow.shadowRadius, vDirectionalShadowCoord[ i ] ) : 1.0;
		#endif

		RE_Direct( directLight, geometry, material, reflectedLight );

	}
	#pragma unroll_loop_end

#endif

#if ( NUM_RECT_AREA_LIGHTS > 0 ) && defined( RE_Direct_RectArea )

	RectAreaLight rectAreaLight;

	#pragma unroll_loop_start
	for ( int i = 0; i < NUM_RECT_AREA_LIGHTS; i ++ ) {

		rectAreaLight = rectAreaLights[ i ];
		RE_Direct_RectArea( rectAreaLight, geometry, material, reflectedLight );

	}
	#pragma unroll_loop_end

#endif

#if defined( RE_IndirectDiffuse )

	vec3 iblIrradiance = vec3( 0.0 );

	vec3 irradiance = getAmbientLightIrradiance( ambientLightColor );

	irradiance += getLightProbeIrradiance( lightProbe, geometry.normal );

	#if ( NUM_HEMI_LIGHTS > 0 )

		#pragma unroll_loop_start
		for ( int i = 0; i < NUM_HEMI_LIGHTS; i ++ ) {

			irradiance += getHemisphereLightIrradiance( hemisphereLights[ i ], geometry.normal );

		}
		#pragma unroll_loop_end

	#endif

#endif

#if defined( RE_IndirectSpecular )

	vec3 radiance = vec3( 0.0 );
	vec3 clearcoatRadiance = vec3( 0.0 );

#endif
`,
	lights_pars_begin: /* glsl */`
#if defined( USE_CSM ) && defined( CSM_CASCADES )
uniform vec2 CSM_cascades[CSM_CASCADES];
uniform float cameraNear;
uniform float shadowFar;
#endif
	` + ShaderChunk.lights_pars_begin
};

export { CSMShader };