import {
	FrontSide,
	BackSide,
	DoubleSide,
	RGBAFormat,
	NearestFilter,
	LinearFilter,
	PCFShadowMap,
	VSMShadowMap,
	RGBADepthPacking,
	NoBlending,
} from '../../constants.js';
import { WebGLRenderTarget } from '../WebGLRenderTarget.js';
import { MeshDepthMaterial } from '../../materials/MeshDepthMaterial.js';
import { MeshDistanceMaterial } from '../../materials/MeshDistanceMaterial.js';
import { ShaderMaterial } from '../../materials/ShaderMaterial.js';
import { BufferAttribute } from '../../core/BufferAttribute.js';
import { BufferGeometry } from '../../core/BufferGeometry.js';
import { Mesh } from '../../objects/Mesh.js';
import { Vector4 } from '../../math/Vector4.js';
import { Vector2 } from '../../math/Vector2.js';
import { Frustum } from '../../math/Frustum.js';

import * as vsm from '../shaders/ShaderLib/vsm.glsl.js';

function WebGLShadowMap(_renderer, _objects, _capabilities) {
	let _frustum = new Frustum();

	const _shadowMapSize = new Vector2(),
		_viewportSize = new Vector2(),
		_viewport = new Vector4(),
		_depthMaterial = new MeshDepthMaterial({ depthPacking: RGBADepthPacking }),
		_distanceMaterial = new MeshDistanceMaterial(),
		_materialCache = {},
		_maxTextureSize = _capabilities.maxTextureSize;

	const shadowSide = { 0: BackSide, 1: FrontSide, 2: DoubleSide };

	const shadowMaterialVertical = new ShaderMaterial({
		defines: {
			VSM_SAMPLES: 8,
		},
		uniforms: {
			shadow_pass: { value: null },
			resolution: { value: new Vector2() },
			radius: { value: 4.0 },
		},

		vertexShader: vsm.vertex,
		fragmentShader: vsm.fragment,
	});

	const shadowMaterialHorizontal = shadowMaterialVertical.clone();
	shadowMaterialHorizontal.defines.HORIZONTAL_PASS = 1;

	const fullScreenTri = new BufferGeometry();
	fullScreenTri.setAttribute('position', new BufferAttribute(new Float32Array([-1, -1, 0.5, 3, -1, 0.5, -1, 3, 0.5]), 3));

	const fullScreenMesh = new Mesh(fullScreenTri, shadowMaterialVertical);

	const scope = this;

	this.enabled = false;

	this.autoUpdate = true;
	this.needsUpdate = false;

	this.type = PCFShadowMap;

	this.render = function (lights, scene, camera) {
		if (scope.enabled === false) return;
		if (scope.autoUpdate === false && scope.needsUpdate === false) return;

		if (lights.length === 0) return;

		const currentRenderTarget = _renderer.getRenderTarget();
		const activeCubeFace = _renderer.getActiveCubeFace();
		const activeMipmapLevel = _renderer.getActiveMipmapLevel();

		const _state = _renderer.state;

		// Set GL state for depth map.
		_state.setBlending(NoBlending);
		_state.buffers.color.setClear(1, 1, 1, 1);
		_state.buffers.depth.setTest(true);
		_state.setScissorTest(false);

		// render depth map

		for (let i = 0, il = lights.length; i < il; i++) {
			const light = lights[i];
			const shadow = light.shadow;

			if (shadow === undefined) {
				console.warn('THREE.WebGLShadowMap:', light, 'has no shadow.');
				continue;
			}

			if (shadow.autoUpdate === false && shadow.needsUpdate === false) continue;

			_shadowMapSize.copy(shadow.mapSize);

			const shadowFrameExtents = shadow.getFrameExtents();

			_shadowMapSize.multiply(shadowFrameExtents);

			_viewportSize.copy(shadow.mapSize);

			if (_shadowMapSize.x > _maxTextureSize || _shadowMapSize.y > _maxTextureSize) {
				if (_shadowMapSize.x > _maxTextureSize) {
					_viewportSize.x = Math.floor(_maxTextureSize / shadowFrameExtents.x);
					_shadowMapSize.x = _viewportSize.x * shadowFrameExtents.x;
					shadow.mapSize.x = _viewportSize.x;
				}

				if (_shadowMapSize.y > _maxTextureSize) {
					_viewportSize.y = Math.floor(_maxTextureSize / shadowFrameExtents.y);
					_shadowMapSize.y = _viewportSize.y * shadowFrameExtents.y;
					shadow.mapSize.y = _viewportSize.y;
				}
			}

			if (shadow.map === null && !shadow.isPointLightShadow && this.type === VSMShadowMap) {
				const pars = { minFilter: LinearFilter, magFilter: LinearFilter, format: RGBAFormat };

				shadow.map = new WebGLRenderTarget(_shadowMapSize.x, _shadowMapSize.y, pars);
				shadow.map.texture.name = light.name + '.shadowMap';

				shadow.mapPass = new WebGLRenderTarget(_shadowMapSize.x, _shadowMapSize.y, pars);

				shadow.camera.updateProjectionMatrix();
			}

			if (shadow.map === null) {
				const pars = { minFilter: NearestFilter, magFilter: NearestFilter, format: RGBAFormat };

				shadow.map = new WebGLRenderTarget(_shadowMapSize.x, _shadowMapSize.y, pars);
				shadow.map.texture.name = light.name + '.shadowMap';

				shadow.camera.updateProjectionMatrix();
			}

			_renderer.setRenderTarget(shadow.map);
			_renderer.clear();

			const viewportCount = shadow.getViewportCount();

			for (let vp = 0; vp < viewportCount; vp++) {
				const viewport = shadow.getViewport(vp);

				_viewport.set(_viewportSize.x * viewport.x, _viewportSize.y * viewport.y, _viewportSize.x * viewport.z, _viewportSize.y * viewport.w);

				_state.viewport(_viewport);

				shadow.updateMatrices(light, vp);

				_frustum = shadow.getFrustum();

				renderObject(scene, camera, shadow.camera, light, this.type);
			}

			// do blur pass for VSM

			if (!shadow.isPointLightShadow && this.type === VSMShadowMap) {
				VSMPass(shadow, camera);
			}

			shadow.needsUpdate = false;
		}

		scope.needsUpdate = false;

		_renderer.setRenderTarget(currentRenderTarget, activeCubeFace, activeMipmapLevel);
	};

	function VSMPass(shadow, camera) {
		const geometry = _objects.update(fullScreenMesh);

		if (shadowMaterialVertical.defines.VSM_SAMPLES !== shadow.blurSamples) {
			shadowMaterialVertical.defines.VSM_SAMPLES = shadow.blurSamples;
			shadowMaterialHorizontal.defines.VSM_SAMPLES = shadow.blurSamples;

			shadowMaterialVertical.needsUpdate = true;
			shadowMaterialHorizontal.needsUpdate = true;
		}

		// vertical pass

		shadowMaterialVertical.uniforms.shadow_pass.value = shadow.map.texture;
		shadowMaterialVertical.uniforms.resolution.value = shadow.mapSize;
		shadowMaterialVertical.uniforms.radius.value = shadow.radius;
		_renderer.setRenderTarget(shadow.mapPass);
		_renderer.clear();
		_renderer.renderBufferDirect(camera, null, geometry, shadowMaterialVertical, fullScreenMesh, null);

		// horizontal pass

		shadowMaterialHorizontal.uniforms.shadow_pass.value = shadow.mapPass.texture;
		shadowMaterialHorizontal.uniforms.resolution.value = shadow.mapSize;
		shadowMaterialHorizontal.uniforms.radius.value = shadow.radius;
		_renderer.setRenderTarget(shadow.map);
		_renderer.clear();
		_renderer.renderBufferDirect(camera, null, geometry, shadowMaterialHorizontal, fullScreenMesh, null);
	}

	function getDepthMaterial(object, geometry, material, light, shadowCameraNear, shadowCameraFar, type) {
		let result = null;

		const customMaterial = light.isPointLight === true ? object.customDistanceMaterial : object.customDepthMaterial;

		if (customMaterial !== undefined) {
			result = customMaterial;
		} else {
			result = light.isPointLight === true ? _distanceMaterial : _depthMaterial;
		}

		if (
			(_renderer.localClippingEnabled && material.clipShadows === true && material.clippingPlanes.length !== 0) ||
			(material.displacementMap && material.displacementScale !== 0) ||
			(material.alphaMap && material.alphaTest > 0)
		) {
			// in this case we need a unique material instance reflecting the
			// appropriate state

			const keyA = result.uuid,
				keyB = material.uuid;

			let materialsForVariant = _materialCache[keyA];

			if (materialsForVariant === undefined) {
				materialsForVariant = {};
				_materialCache[keyA] = materialsForVariant;
			}

			let cachedMaterial = materialsForVariant[keyB];

			if (cachedMaterial === undefined) {
				cachedMaterial = result.clone();
				materialsForVariant[keyB] = cachedMaterial;
			}

			result = cachedMaterial;
		}

		result.visible = material.visible;
		result.wireframe = material.wireframe;

		if (type === VSMShadowMap) {
			result.side = material.shadowSide !== null ? material.shadowSide : material.side;
		} else {
			result.side = material.shadowSide !== null ? material.shadowSide : shadowSide[material.side];
		}

		result.alphaMap = material.alphaMap;
		result.alphaTest = material.alphaTest;

		result.clipShadows = material.clipShadows;
		result.clippingPlanes = material.clippingPlanes;
		result.clipIntersection = material.clipIntersection;

		result.displacementMap = material.displacementMap;
		result.displacementScale = material.displacementScale;
		result.displacementBias = material.displacementBias;

		result.wireframeLinewidth = material.wireframeLinewidth;
		result.linewidth = material.linewidth;

		if (light.isPointLight === true && result.isMeshDistanceMaterial === true) {
			result.referencePosition.setFromMatrixPosition(light.matrixWorld);
			result.nearDistance = shadowCameraNear;
			result.farDistance = shadowCameraFar;
		}

		return result;
	}

	function renderObject(object, camera, shadowCamera, light, type) {
		if (object.visible === false) return;

		const visible = object.layers.test(camera.layers);

		if (visible && (object.isMesh || object.isLine || object.isPoints)) {
			if ((object.castShadow || (object.receiveShadow && type === VSMShadowMap)) && (!object.frustumCulled || _frustum.intersectsObject(object))) {
				object.modelViewMatrix.multiplyMatrices(shadowCamera.matrixWorldInverse, object.matrixWorld);

				const geometry = _objects.update(object);
				const material = object.material;

				if (Array.isArray(material)) {
					const groups = geometry.groups;

					for (let k = 0, kl = groups.length; k < kl; k++) {
						const group = groups[k];
						const groupMaterial = material[group.materialIndex];

						if (groupMaterial && groupMaterial.visible) {
							const depthMaterial = getDepthMaterial(object, geometry, groupMaterial, light, shadowCamera.near, shadowCamera.far, type);

							_renderer.renderBufferDirect(shadowCamera, null, geometry, depthMaterial, object, group);
						}
					}
				} else if (material.visible) {
					const depthMaterial = getDepthMaterial(object, geometry, material, light, shadowCamera.near, shadowCamera.far, type);

					_renderer.renderBufferDirect(shadowCamera, null, geometry, depthMaterial, object, null);
				}
			}
		}

		const children = object.children;

		for (let i = 0, l = children.length; i < l; i++) {
			renderObject(children[i], camera, shadowCamera, light, type);
		}
	}
}

export { WebGLShadowMap };