#include "utils.h"
unsigned char* DecodeBMP(unsigned char*bmpFileData, int&width, int&height) {
	if (0x4D42 == *((unsigned short*)bmpFileData)) {
		int pixelDataOffset = *((int*)(bmpFileData + 10));
		width = *((int*)(bmpFileData + 18));
		height = *((int*)(bmpFileData + 22));
		unsigned char*pixelData = bmpFileData + pixelDataOffset;
		for (int i = 0; i < width*height * 3; i += 3) {
			unsigned char temp = pixelData[i];
			pixelData[i] = pixelData[i + 2];
			pixelData[i + 2] = temp;
		}
		return pixelData;
	}
	return nullptr;
}
GLuint CreateTexture2D(unsigned char*pixelData, int width, int height, GLenum type) {
	GLuint texture;
	glGenTextures(1, &texture);
	glBindTexture(GL_TEXTURE_2D, texture);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glTexImage2D(GL_TEXTURE_2D, 0, type, width, height, 0, type, GL_UNSIGNED_BYTE, pixelData);
	glBindTexture(GL_TEXTURE_2D, 0);
	return texture;
}
GLuint CreateTexture2DFromBMP(const char*bmpPath) {
	int nFileSize = 0;
	unsigned char *bmpFileContent = LoadFileContent(bmpPath, nFileSize);
	if (bmpFileContent == nullptr) {
		return 0;
	}
	int bmpWidth = 0, bmpHeight = 0;
	unsigned char*pixelData = DecodeBMP(bmpFileContent, bmpWidth, bmpHeight);
	if (bmpWidth == 0) {
		delete bmpFileContent;
		return 0;
	}
	GLuint texture = CreateTexture2D(pixelData, bmpWidth, bmpHeight, GL_RGB);
	delete bmpFileContent;
	return texture;
}
GLuint CreateTextureCubeFromBMP(const char *front, const char *back, const char *left,
	const char *right, const char *top, const char *bottom) {
	GLuint texture;
	glGenTextures(1, &texture);
	glBindTexture(GL_TEXTURE_CUBE_MAP, texture);
	int nFileSize = 0, width = 0, height = 0;
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
	unsigned char *bmpFileContent = LoadFileContent(front, nFileSize);
	unsigned char*pixelData = DecodeBMP(bmpFileContent, width, height);
	glTexImage2D(GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, pixelData);
	delete bmpFileContent;
	bmpFileContent = LoadFileContent(back, nFileSize);
	pixelData = DecodeBMP(bmpFileContent, width, height);
	glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_Z, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, pixelData);
	delete bmpFileContent;
	bmpFileContent = LoadFileContent(left, nFileSize);
	pixelData = DecodeBMP(bmpFileContent, width, height);
	glTexImage2D(GL_TEXTURE_CUBE_MAP_NEGATIVE_X, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, pixelData);
	delete bmpFileContent;
	bmpFileContent = LoadFileContent(right, nFileSize);
	pixelData = DecodeBMP(bmpFileContent, width, height);
	glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, pixelData);
	delete bmpFileContent;
	bmpFileContent = LoadFileContent(top, nFileSize);
	pixelData = DecodeBMP(bmpFileContent, width, height);
	glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_Y, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, pixelData);
	delete bmpFileContent;
	bmpFileContent = LoadFileContent(bottom, nFileSize);
	pixelData = DecodeBMP(bmpFileContent, width, height);
	glTexImage2D(GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, pixelData);
	glBindTexture(GL_TEXTURE_CUBE_MAP, 0);
	delete bmpFileContent;
	return texture;
}