/*************************************************************************/
/*  image_loader_tinyexr.cpp                                             */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
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/* Copyright (c) 2007-2019 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2019 Godot Engine contributors (cf. AUTHORS.md)    */
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#include "image_loader_tinyexr.h"

#include "os/os.h"
#include "print_string.h"

#include "thirdparty/tinyexr/tinyexr.h"

Error ImageLoaderTinyEXR::load_image(Ref<Image> p_image, FileAccess *f, bool p_force_linear, float p_scale) {

	PoolVector<uint8_t> src_image;
	int src_image_len = f->get_len();
	ERR_FAIL_COND_V(src_image_len == 0, ERR_FILE_CORRUPT);
	src_image.resize(src_image_len);

	PoolVector<uint8_t>::Write w = src_image.write();

	f->get_buffer(&w[0], src_image_len);

	f->close();

	// Re-implementation of tinyexr's LoadEXRFromMemory using Godot types to store the Image data
	// and Godot's error codes.
	// When debugging after updating the thirdparty library, check that we're still in sync with
	// their API usage in LoadEXRFromMemory.

	EXRVersion exr_version;
	EXRImage exr_image;
	EXRHeader exr_header;
	const char *err = NULL;

	InitEXRHeader(&exr_header);

	int ret = ParseEXRVersionFromMemory(&exr_version, w.ptr(), src_image_len);
	if (ret != TINYEXR_SUCCESS) {

		return ERR_FILE_CORRUPT;
	}

	ret = ParseEXRHeaderFromMemory(&exr_header, &exr_version, w.ptr(), src_image_len, &err);
	if (ret != TINYEXR_SUCCESS) {
		if (err) {
			ERR_PRINTS(String(err));
		}
		return ERR_FILE_CORRUPT;
	}

	// Read HALF channel as FLOAT. (GH-13490)
	for (int i = 0; i < exr_header.num_channels; i++) {
		if (exr_header.pixel_types[i] == TINYEXR_PIXELTYPE_HALF) {
			exr_header.requested_pixel_types[i] = TINYEXR_PIXELTYPE_FLOAT;
		}
	}

	InitEXRImage(&exr_image);
	ret = LoadEXRImageFromMemory(&exr_image, &exr_header, w.ptr(), src_image_len, &err);
	if (ret != TINYEXR_SUCCESS) {
		if (err) {
			ERR_PRINTS(String(err));
		}
		return ERR_FILE_CORRUPT;
	}

	// RGBA
	int idxR = -1;
	int idxG = -1;
	int idxB = -1;
	int idxA = -1;
	for (int c = 0; c < exr_header.num_channels; c++) {
		if (strcmp(exr_header.channels[c].name, "R") == 0) {
			idxR = c;
		} else if (strcmp(exr_header.channels[c].name, "G") == 0) {
			idxG = c;
		} else if (strcmp(exr_header.channels[c].name, "B") == 0) {
			idxB = c;
		} else if (strcmp(exr_header.channels[c].name, "A") == 0) {
			idxA = c;
		}
	}

	if (idxR == -1) {
		ERR_PRINT("TinyEXR: R channel not found.");
		// @todo { free exr_image }
		return ERR_FILE_CORRUPT;
	}

	if (idxG == -1) {
		ERR_PRINT("TinyEXR: G channel not found.")
		// @todo { free exr_image }
		return ERR_FILE_CORRUPT;
	}

	if (idxB == -1) {
		ERR_PRINT("TinyEXR: B channel not found.")
		// @todo { free exr_image }
		return ERR_FILE_CORRUPT;
	}

	// EXR image data loaded, now parse it into Godot-friendly image data

	PoolVector<uint8_t> imgdata;
	Image::Format format;

	if (idxA > 0) {

		imgdata.resize(exr_image.width * exr_image.height * 8); //RGBA16
		format = Image::FORMAT_RGBAH;
	} else {

		imgdata.resize(exr_image.width * exr_image.height * 6); //RGB16
		format = Image::FORMAT_RGBH;
	}

	{
		PoolVector<uint8_t>::Write wd = imgdata.write();
		uint16_t *iw = (uint16_t *)wd.ptr();

		// Assume `out_rgba` have enough memory allocated.
		for (int i = 0; i < exr_image.width * exr_image.height; i++) {

			Color color(
					reinterpret_cast<float **>(exr_image.images)[idxR][i],
					reinterpret_cast<float **>(exr_image.images)[idxG][i],
					reinterpret_cast<float **>(exr_image.images)[idxB][i]);

			if (p_force_linear)
				color = color.to_linear();

			*iw++ = Math::make_half_float(color.r);
			*iw++ = Math::make_half_float(color.g);
			*iw++ = Math::make_half_float(color.b);

			if (idxA > 0) {
				*iw++ = Math::make_half_float(reinterpret_cast<float **>(exr_image.images)[idxA][i]);
			}
		}
	}

	p_image->create(exr_image.width, exr_image.height, false, format, imgdata);

	w = PoolVector<uint8_t>::Write();

	FreeEXRHeader(&exr_header);
	FreeEXRImage(&exr_image);

	return OK;
}

void ImageLoaderTinyEXR::get_recognized_extensions(List<String> *p_extensions) const {

	p_extensions->push_back("exr");
}

ImageLoaderTinyEXR::ImageLoaderTinyEXR() {
}