/**
 * @author sciecode / https://github.com/sciecode
 *
 * EXR format references:
 * 	https://www.openexr.com/documentation/openexrfilelayout.pdf
 */

import {
	FloatType,
	HalfFloatType,
	RGBAFormat,
	DataUtils,
} from 'three';
import * as fflate from '../libs/fflate.module.js';

const textEncoder = new TextEncoder();

const NO_COMPRESSION = 0;
const ZIPS_COMPRESSION = 2;
const ZIP_COMPRESSION = 3;

class EXRExporter {

	parse( renderer, renderTarget, options ) {

		if ( ! supported( renderer, renderTarget ) ) return undefined;

		const info = buildInfo( renderTarget, options ),
			dataBuffer = getPixelData( renderer, renderTarget, info ),
			rawContentBuffer = reorganizeDataBuffer( dataBuffer, info ),
			chunks = compressData( rawContentBuffer, info );

		return fillData( chunks, info );

	}

}

function supported( renderer, renderTarget ) {

	if ( ! renderer || ! renderer.isWebGLRenderer ) {

		console.error( 'EXRExporter.parse: Unsupported first parameter, expected instance of WebGLRenderer.' );

		return false;

	}

	if ( ! renderTarget || ! renderTarget.isWebGLRenderTarget ) {

		console.error( 'EXRExporter.parse: Unsupported second parameter, expected instance of WebGLRenderTarget.' );

		return false;

	}

	if ( renderTarget.texture.type !== FloatType && renderTarget.texture.type !== HalfFloatType ) {

		console.error( 'EXRExporter.parse: Unsupported WebGLRenderTarget texture type.' );

		return false;

	}

	if ( renderTarget.texture.format !== RGBAFormat ) {

		console.error( 'EXRExporter.parse: Unsupported WebGLRenderTarget texture format, expected RGBAFormat.' );

		return false;

	}


	return true;

}

function buildInfo( renderTarget, options = {} ) {

	const compressionSizes = {
		0: 1,
		2: 1,
		3: 16
	};

	const WIDTH = renderTarget.width,
		HEIGHT = renderTarget.height,
		TYPE = renderTarget.texture.type,
		FORMAT = renderTarget.texture.format,
		COLOR_SPACE = renderTarget.texture.colorSpace,
		COMPRESSION = ( options.compression !== undefined ) ? options.compression : ZIP_COMPRESSION,
		EXPORTER_TYPE = ( options.type !== undefined ) ? options.type : HalfFloatType,
		OUT_TYPE = ( EXPORTER_TYPE === FloatType ) ? 2 : 1,
		COMPRESSION_SIZE = compressionSizes[ COMPRESSION ],
		NUM_CHANNELS = 4;

	return {
		width: WIDTH,
		height: HEIGHT,
		type: TYPE,
		format: FORMAT,
		colorSpace: COLOR_SPACE,
		compression: COMPRESSION,
		blockLines: COMPRESSION_SIZE,
		dataType: OUT_TYPE,
		dataSize: 2 * OUT_TYPE,
		numBlocks: Math.ceil( HEIGHT / COMPRESSION_SIZE ),
		numInputChannels: 4,
		numOutputChannels: NUM_CHANNELS,
	};

}

function getPixelData( renderer, rtt, info ) {

	let dataBuffer;

	if ( info.type === FloatType ) {

		dataBuffer = new Float32Array( info.width * info.height * info.numInputChannels );

	} else {

		dataBuffer = new Uint16Array( info.width * info.height * info.numInputChannels );

	}

	renderer.readRenderTargetPixels( rtt, 0, 0, info.width, info.height, dataBuffer );

	return dataBuffer;

}

function reorganizeDataBuffer( inBuffer, info ) {

	const w = info.width,
		h = info.height,
		dec = { r: 0, g: 0, b: 0, a: 0 },
		offset = { value: 0 },
		cOffset = ( info.numOutputChannels == 4 ) ? 1 : 0,
		getValue = ( info.type == FloatType ) ? getFloat32 : getFloat16,
		setValue = ( info.dataType == 1 ) ? setFloat16 : setFloat32,
		outBuffer = new Uint8Array( info.width * info.height * info.numOutputChannels * info.dataSize ),
		dv = new DataView( outBuffer.buffer );

	for ( let y = 0; y < h; ++ y ) {

		for ( let x = 0; x < w; ++ x ) {

			const i = y * w * 4 + x * 4;

			const r = getValue( inBuffer, i );
			const g = getValue( inBuffer, i + 1 );
			const b = getValue( inBuffer, i + 2 );
			const a = getValue( inBuffer, i + 3 );

			const line = ( h - y - 1 ) * w * ( 3 + cOffset ) * info.dataSize;

			decodeLinear( dec, r, g, b, a );

			offset.value = line + x * info.dataSize;
			setValue( dv, dec.a, offset );

			offset.value = line + ( cOffset ) * w * info.dataSize + x * info.dataSize;
			setValue( dv, dec.b, offset );

			offset.value = line + ( 1 + cOffset ) * w * info.dataSize + x * info.dataSize;
			setValue( dv, dec.g, offset );

			offset.value = line + ( 2 + cOffset ) * w * info.dataSize + x * info.dataSize;
			setValue( dv, dec.r, offset );

		}

	}

	return outBuffer;

}

function compressData( inBuffer, info ) {

	let compress,
		tmpBuffer,
		sum = 0;

	const chunks = { data: new Array(), totalSize: 0 },
		size = info.width * info.numOutputChannels * info.blockLines * info.dataSize;

	switch ( info.compression ) {

		case 0:
			compress = compressNONE;
			break;

		case 2:
		case 3:
			compress = compressZIP;
			break;

	}

	if ( info.compression !== 0 ) {

		tmpBuffer = new Uint8Array( size );

	}

	for ( let i = 0; i < info.numBlocks; ++ i ) {

		const arr = inBuffer.subarray( size * i, size * ( i + 1 ) );

		const block = compress( arr, tmpBuffer );

		sum += block.length;

		chunks.data.push( { dataChunk: block, size: block.length } );

	}

	chunks.totalSize = sum;

	return chunks;

}

function compressNONE( data ) {

	return data;

}

function compressZIP( data, tmpBuffer ) {

	//
	// Reorder the pixel data.
	//

	let t1 = 0,
		t2 = Math.floor( ( data.length + 1 ) / 2 ),
		s = 0;

	const stop = data.length - 1;

	while ( true ) {

		if ( s > stop ) break;
		tmpBuffer[ t1 ++ ] = data[ s ++ ];

		if ( s > stop ) break;
		tmpBuffer[ t2 ++ ] = data[ s ++ ];

	}

	//
	// Predictor.
	//

	let p = tmpBuffer[ 0 ];

	for ( let t = 1; t < tmpBuffer.length; t ++ ) {

		const d = tmpBuffer[ t ] - p + ( 128 + 256 );
		p = tmpBuffer[ t ];
		tmpBuffer[ t ] = d;

	}

	const deflate = fflate.zlibSync( tmpBuffer );

	return deflate;

}

function fillHeader( outBuffer, chunks, info ) {

	const offset = { value: 0 };
	const dv = new DataView( outBuffer.buffer );

	setUint32( dv, 20000630, offset ); // magic
	setUint32( dv, 2, offset ); // mask

	// = HEADER =

	setString( dv, 'compression', offset );
	setString( dv, 'compression', offset );
	setUint32( dv, 1, offset );
	setUint8( dv, info.compression, offset );

	setString( dv, 'screenWindowCenter', offset );
	setString( dv, 'v2f', offset );
	setUint32( dv, 8, offset );
	setUint32( dv, 0, offset );
	setUint32( dv, 0, offset );

	setString( dv, 'screenWindowWidth', offset );
	setString( dv, 'float', offset );
	setUint32( dv, 4, offset );
	setFloat32( dv, 1.0, offset );

	setString( dv, 'pixelAspectRatio', offset );
	setString( dv, 'float', offset );
	setUint32( dv, 4, offset );
	setFloat32( dv, 1.0, offset );

	setString( dv, 'lineOrder', offset );
	setString( dv, 'lineOrder', offset );
	setUint32( dv, 1, offset );
	setUint8( dv, 0, offset );

	setString( dv, 'dataWindow', offset );
	setString( dv, 'box2i', offset );
	setUint32( dv, 16, offset );
	setUint32( dv, 0, offset );
	setUint32( dv, 0, offset );
	setUint32( dv, info.width - 1, offset );
	setUint32( dv, info.height - 1, offset );

	setString( dv, 'displayWindow', offset );
	setString( dv, 'box2i', offset );
	setUint32( dv, 16, offset );
	setUint32( dv, 0, offset );
	setUint32( dv, 0, offset );
	setUint32( dv, info.width - 1, offset );
	setUint32( dv, info.height - 1, offset );

	setString( dv, 'channels', offset );
	setString( dv, 'chlist', offset );
	setUint32( dv, info.numOutputChannels * 18 + 1, offset );

	setString( dv, 'A', offset );
	setUint32( dv, info.dataType, offset );
	offset.value += 4;
	setUint32( dv, 1, offset );
	setUint32( dv, 1, offset );

	setString( dv, 'B', offset );
	setUint32( dv, info.dataType, offset );
	offset.value += 4;
	setUint32( dv, 1, offset );
	setUint32( dv, 1, offset );

	setString( dv, 'G', offset );
	setUint32( dv, info.dataType, offset );
	offset.value += 4;
	setUint32( dv, 1, offset );
	setUint32( dv, 1, offset );

	setString( dv, 'R', offset );
	setUint32( dv, info.dataType, offset );
	offset.value += 4;
	setUint32( dv, 1, offset );
	setUint32( dv, 1, offset );

	setUint8( dv, 0, offset );

	// null-byte
	setUint8( dv, 0, offset );

	// = OFFSET TABLE =

	let sum = offset.value + info.numBlocks * 8;

	for ( let i = 0; i < chunks.data.length; ++ i ) {

		setUint64( dv, sum, offset );

		sum += chunks.data[ i ].size + 8;

	}

}

function fillData( chunks, info ) {

	const TableSize = info.numBlocks * 8,
		HeaderSize = 259 + ( 18 * info.numOutputChannels ), // 259 + 18 * chlist
		offset = { value: HeaderSize + TableSize },
		outBuffer = new Uint8Array( HeaderSize + TableSize + chunks.totalSize + info.numBlocks * 8 ),
		dv = new DataView( outBuffer.buffer );

	fillHeader( outBuffer, chunks, info );

	for ( let i = 0; i < chunks.data.length; ++ i ) {

		const data = chunks.data[ i ].dataChunk;
		const size = chunks.data[ i ].size;

		setUint32( dv, i * info.blockLines, offset );
		setUint32( dv, size, offset );

		outBuffer.set( data, offset.value );
		offset.value += size;

	}

	return outBuffer;

}

function decodeLinear( dec, r, g, b, a ) {

	dec.r = r;
	dec.g = g;
	dec.b = b;
	dec.a = a;

}

// function decodeSRGB( dec, r, g, b, a ) {

// 	dec.r = r > 0.04045 ? Math.pow( r * 0.9478672986 + 0.0521327014, 2.4 ) : r * 0.0773993808;
// 	dec.g = g > 0.04045 ? Math.pow( g * 0.9478672986 + 0.0521327014, 2.4 ) : g * 0.0773993808;
// 	dec.b = b > 0.04045 ? Math.pow( b * 0.9478672986 + 0.0521327014, 2.4 ) : b * 0.0773993808;
// 	dec.a = a;

// }


function setUint8( dv, value, offset ) {

	dv.setUint8( offset.value, value );

	offset.value += 1;

}

function setUint32( dv, value, offset ) {

	dv.setUint32( offset.value, value, true );

	offset.value += 4;

}

function setFloat16( dv, value, offset ) {

	dv.setUint16( offset.value, DataUtils.toHalfFloat( value ), true );

	offset.value += 2;

}

function setFloat32( dv, value, offset ) {

	dv.setFloat32( offset.value, value, true );

	offset.value += 4;

}

function setUint64( dv, value, offset ) {

	dv.setBigUint64( offset.value, BigInt( value ), true );

	offset.value += 8;

}

function setString( dv, string, offset ) {

	const tmp = textEncoder.encode( string + '\0' );

	for ( let i = 0; i < tmp.length; ++ i ) {

		setUint8( dv, tmp[ i ], offset );

	}

}

function decodeFloat16( binary ) {

	const exponent = ( binary & 0x7C00 ) >> 10,
		fraction = binary & 0x03FF;

	return ( binary >> 15 ? - 1 : 1 ) * (
		exponent ?
			(
				exponent === 0x1F ?
					fraction ? NaN : Infinity :
					Math.pow( 2, exponent - 15 ) * ( 1 + fraction / 0x400 )
			) :
			6.103515625e-5 * ( fraction / 0x400 )
	);

}

function getFloat16( arr, i ) {

	return decodeFloat16( arr[ i ] );

}

function getFloat32( arr, i ) {

	return arr[ i ];

}

export { EXRExporter, NO_COMPRESSION, ZIP_COMPRESSION, ZIPS_COMPRESSION };
