// https://wwwimages2.adobe.com/content/dam/acom/en/products/speedgrade/cc/pdfs/cube-lut-specification-1.0.pdf

import {
	ClampToEdgeWrapping,
	Data3DTexture,
	FileLoader,
	FloatType,
	LinearFilter,
	Loader,
	UnsignedByteType,
	Vector3,
} from 'three';

export class LUTCubeLoader extends Loader {

	constructor( manager ) {

		super( manager );

		this.type = UnsignedByteType;

	}

	setType( type ) {

		if ( type !== UnsignedByteType && type !== FloatType ) {

			throw new Error( 'LUTCubeLoader: Unsupported type' );

		}

		this.type = type;

		return this;

	}

	load( url, onLoad, onProgress, onError ) {

		const loader = new FileLoader( this.manager );
		loader.setPath( this.path );
		loader.setResponseType( 'text' );
		loader.load( url, text => {

			try {

				onLoad( this.parse( text ) );

			} catch ( e ) {

				if ( onError ) {

					onError( e );

				} else {

					console.error( e );

				}

				this.manager.itemError( url );

			}

		}, onProgress, onError );

	}

	parse( input ) {

		const regExpTitle = /TITLE +"([^"]*)"/;
		const regExpSize = /LUT_3D_SIZE +(\d+)/;
		const regExpDomainMin = /DOMAIN_MIN +([\d.]+) +([\d.]+) +([\d.]+)/;
		const regExpDomainMax = /DOMAIN_MAX +([\d.]+) +([\d.]+) +([\d.]+)/;
		const regExpDataPoints = /^([\d.e+-]+) +([\d.e+-]+) +([\d.e+-]+) *$/gm;

		let result = regExpTitle.exec( input );
		const title = ( result !== null ) ? result[ 1 ] : null;

		result = regExpSize.exec( input );

		if ( result === null ) {

			throw new Error( 'LUTCubeLoader: Missing LUT_3D_SIZE information' );

		}

		const size = Number( result[ 1 ] );
		const length = size ** 3 * 4;
		const data = this.type === UnsignedByteType ? new Uint8Array( length ) : new Float32Array( length );

		const domainMin = new Vector3( 0, 0, 0 );
		const domainMax = new Vector3( 1, 1, 1 );

		result = regExpDomainMin.exec( input );

		if ( result !== null ) {

			domainMin.set( Number( result[ 1 ] ), Number( result[ 2 ] ), Number( result[ 3 ] ) );

		}

		result = regExpDomainMax.exec( input );

		if ( result !== null ) {

			domainMax.set( Number( result[ 1 ] ), Number( result[ 2 ] ), Number( result[ 3 ] ) );

		}

		if ( domainMin.x > domainMax.x || domainMin.y > domainMax.y || domainMin.z > domainMax.z ) {

			throw new Error( 'LUTCubeLoader: Invalid input domain' );

		}

		const scale = this.type === UnsignedByteType ? 255 : 1;
		let i = 0;

		while ( ( result = regExpDataPoints.exec( input ) ) !== null ) {

			data[ i ++ ] = Number( result[ 1 ] ) * scale;
			data[ i ++ ] = Number( result[ 2 ] ) * scale;
			data[ i ++ ] = Number( result[ 3 ] ) * scale;
			data[ i ++ ] = scale;

		}

		const texture3D = new Data3DTexture();
		texture3D.image.data = data;
		texture3D.image.width = size;
		texture3D.image.height = size;
		texture3D.image.depth = size;
		texture3D.type = this.type;
		texture3D.magFilter = LinearFilter;
		texture3D.minFilter = LinearFilter;
		texture3D.wrapS = ClampToEdgeWrapping;
		texture3D.wrapT = ClampToEdgeWrapping;
		texture3D.wrapR = ClampToEdgeWrapping;
		texture3D.generateMipmaps = false;
		texture3D.needsUpdate = true;

		return {
			title,
			size,
			domainMin,
			domainMax,
			texture3D,
		};

	}

}