import { Matrix4 } from '../math/Matrix4.js';
import { Vector2 } from '../math/Vector2.js';
import { Vector3 } from '../math/Vector3.js';
import { Vector4 } from '../math/Vector4.js';
import { Frustum } from '../math/Frustum.js';

const _projScreenMatrix = /*@__PURE__*/ new Matrix4();
const _lightPositionWorld = /*@__PURE__*/ new Vector3();
const _lookTarget = /*@__PURE__*/ new Vector3();

class LightShadow {

	constructor( camera ) {

		this.camera = camera;

		this.bias = 0;
		this.normalBias = 0;
		this.radius = 1;

		this.mapSize = new Vector2( 512, 512 );

		this.map = null;
		this.mapPass = null;
		this.matrix = new Matrix4();

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

		this._frustum = new Frustum();
		this._frameExtents = new Vector2( 1, 1 );

		this._viewportCount = 1;

		this._viewports = [

			new Vector4( 0, 0, 1, 1 )

		];

	}

	getViewportCount() {

		return this._viewportCount;

	}

	getFrustum() {

		return this._frustum;

	}

	updateMatrices( light ) {

		const shadowCamera = this.camera;
		const shadowMatrix = this.matrix;

		_lightPositionWorld.setFromMatrixPosition( light.matrixWorld );
		shadowCamera.position.copy( _lightPositionWorld );

		_lookTarget.setFromMatrixPosition( light.target.matrixWorld );
		shadowCamera.lookAt( _lookTarget );
		shadowCamera.updateMatrixWorld();

		_projScreenMatrix.multiplyMatrices( shadowCamera.projectionMatrix, shadowCamera.matrixWorldInverse );
		this._frustum.setFromProjectionMatrix( _projScreenMatrix );

		shadowMatrix.set(
			0.5, 0.0, 0.0, 0.5,
			0.0, 0.5, 0.0, 0.5,
			0.0, 0.0, 0.5, 0.5,
			0.0, 0.0, 0.0, 1.0
		);

		shadowMatrix.multiply( shadowCamera.projectionMatrix );
		shadowMatrix.multiply( shadowCamera.matrixWorldInverse );

	}

	getViewport( viewportIndex ) {

		return this._viewports[ viewportIndex ];

	}

	getFrameExtents() {

		return this._frameExtents;

	}

	dispose() {

		if ( this.map ) {

			this.map.dispose();

		}

		if ( this.mapPass ) {

			this.mapPass.dispose();

		}

	}

	copy( source ) {

		this.camera = source.camera.clone();

		this.bias = source.bias;
		this.radius = source.radius;

		this.mapSize.copy( source.mapSize );

		return this;

	}

	clone() {

		return new this.constructor().copy( this );

	}

	toJSON() {

		const object = {};

		if ( this.bias !== 0 ) object.bias = this.bias;
		if ( this.normalBias !== 0 ) object.normalBias = this.normalBias;
		if ( this.radius !== 1 ) object.radius = this.radius;
		if ( this.mapSize.x !== 512 || this.mapSize.y !== 512 ) object.mapSize = this.mapSize.toArray();

		object.camera = this.camera.toJSON( false ).object;
		delete object.camera.matrix;

		return object;

	}

}

export { LightShadow };