#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <GL/glew.h>

#include <GLFW/glfw3.h>


GLuint loadBMP_custom(const char * imagepath){

	printf("Reading image %s\n", imagepath);

	// Data read from the header of the BMP file
	unsigned char header[54];
	unsigned int dataPos;
	unsigned int imageSize;
	unsigned int width, height;
	// Actual RGB data
	unsigned char * data;

	// Open the file
	FILE * file = fopen(imagepath,"rb");
	if (!file)							    {printf("%s could not be opened. Are you in the right directory ? Don't forget to read the FAQ !\n", imagepath); getchar(); return 0;}

	// Read the header, i.e. the 54 first bytes

	// If less than 54 bytes are read, problem
	if ( fread(header, 1, 54, file)!=54 ){
		printf("Not a correct BMP file\n");
		return 0;
	}
	// A BMP files always begins with "BM"
	if ( header[0]!='B' || header[1]!='M' ){
		printf("Not a correct BMP file\n");
		return 0;
	}
	// Make sure this is a 24bpp file
	if ( *(int*)&(header[0x1E])!=0  )         {printf("Not a correct BMP file\n");    return 0;}
	if ( *(int*)&(header[0x1C])!=24 )         {printf("Not a correct BMP file\n");    return 0;}

	// Read the information about the image
	dataPos    = *(int*)&(header[0x0A]);
	imageSize  = *(int*)&(header[0x22]);
	width      = *(int*)&(header[0x12]);
	height     = *(int*)&(header[0x16]);

	// Some BMP files are misformatted, guess missing information
	if (imageSize==0)    imageSize=width*height*3; // 3 : one byte for each Red, Green and Blue component
	if (dataPos==0)      dataPos=54; // The BMP header is done that way

	// Create a buffer
	data = new unsigned char [imageSize];

	// Read the actual data from the file into the buffer
	fread(data,1,imageSize,file);

	// Everything is in memory now, the file wan be closed
	fclose (file);

	// Create one OpenGL texture
	GLuint textureID;
	glGenTextures(1, &textureID);

	// "Bind" the newly created texture : all future texture functions will modify this texture
	glBindTexture(GL_TEXTURE_2D, textureID);

	// Give the image to OpenGL
	glTexImage2D(GL_TEXTURE_2D, 0,GL_RGB, width, height, 0, GL_BGR, GL_UNSIGNED_BYTE, data);

	// OpenGL has now copied the data. Free our own version
	delete [] data;

	// Poor filtering, or ...
	//glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	//glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

	// ... nice trilinear filtering.
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
	glGenerateMipmap(GL_TEXTURE_2D);

	// Return the ID of the texture we just created
	return textureID;
}

// Since GLFW 3, glfwLoadTexture2D() has been removed. You have to use another texture loading library,
// or do it yourself (just like loadBMP_custom and loadDDS)
//GLuint loadTGA_glfw(const char * imagepath){
//
//	// Create one OpenGL texture
//	GLuint textureID;
//	glGenTextures(1, &textureID);
//
//	// "Bind" the newly created texture : all future texture functions will modify this texture
//	glBindTexture(GL_TEXTURE_2D, textureID);
//
//	// Read the file, call glTexImage2D with the right parameters
//	glfwLoadTexture2D(imagepath, 0);
//
//	// Nice trilinear filtering.
//	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
//	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
//	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
//	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
//	glGenerateMipmap(GL_TEXTURE_2D);
//
//	// Return the ID of the texture we just created
//	return textureID;
//}



#define FOURCC_DXT1 0x31545844 // Equivalent to "DXT1" in ASCII
#define FOURCC_DXT3 0x33545844 // Equivalent to "DXT3" in ASCII
#define FOURCC_DXT5 0x35545844 // Equivalent to "DXT5" in ASCII

GLuint loadDDS(const char * imagepath){

	unsigned char header[124];

	FILE *fp;

	/* try to open the file */
	fp = fopen(imagepath, "rb");
	if (fp == NULL){
		printf("%s could not be opened. Are you in the right directory ? Don't forget to read the FAQ !\n", imagepath); getchar();
		return 0;
	}

	/* verify the type of file */
	char filecode[4];
	fread(filecode, 1, 4, fp);
	if (strncmp(filecode, "DDS ", 4) != 0) {
		fclose(fp);
		return 0;
	}

	/* get the surface desc */
	fread(&header, 124, 1, fp);

	unsigned int height      = *(unsigned int*)&(header[8 ]);
	unsigned int width	     = *(unsigned int*)&(header[12]);
	unsigned int linearSize	 = *(unsigned int*)&(header[16]);
	unsigned int mipMapCount = *(unsigned int*)&(header[24]);
	unsigned int fourCC      = *(unsigned int*)&(header[80]);


	unsigned char * buffer;
	unsigned int bufsize;
	/* how big is it going to be including all mipmaps? */
	bufsize = mipMapCount > 1 ? linearSize * 2 : linearSize;
	buffer = (unsigned char*)malloc(bufsize * sizeof(unsigned char));
	fread(buffer, 1, bufsize, fp);
	/* close the file pointer */
	fclose(fp);

	// unsigned int components  = (fourCC == FOURCC_DXT1) ? 3 : 4;
	unsigned int format;
	switch(fourCC)
	{
	case FOURCC_DXT1:
		format = GL_COMPRESSED_RGBA_S3TC_DXT1_EXT;
		break;
	case FOURCC_DXT3:
		format = GL_COMPRESSED_RGBA_S3TC_DXT3_EXT;
		break;
	case FOURCC_DXT5:
		format = GL_COMPRESSED_RGBA_S3TC_DXT5_EXT;
		break;
	default:
		free(buffer);
		return 0;
	}

	// Create one OpenGL texture
	GLuint textureID;
	glGenTextures(1, &textureID);

	// "Bind" the newly created texture : all future texture functions will modify this texture
	glBindTexture(GL_TEXTURE_2D, textureID);
	glPixelStorei(GL_UNPACK_ALIGNMENT,1);

	unsigned int blockSize = (format == GL_COMPRESSED_RGBA_S3TC_DXT1_EXT) ? 8 : 16;
	unsigned int offset = 0;

	/* load the mipmaps */
	for (unsigned int level = 0; level < mipMapCount && (width || height); ++level)
	{
		unsigned int size = ((width+3)/4)*((height+3)/4)*blockSize;
		glCompressedTexImage2D(GL_TEXTURE_2D, level, format, width, height,
			0, size, buffer + offset);

		offset += size;
		width  /= 2;
		height /= 2;

		// Deal with Non-Power-Of-Two textures. This code is not included in the webpage to reduce clutter.
		if(width < 1) width = 1;
		if(height < 1) height = 1;

	}

	free(buffer);

	return textureID;


}