// ==============================================================
//	This file is part of Glest Shared Library (www.glest.org)
//
//	Copyright (C) 2001-2010 Martiño Figueroa and others
//
//	You can redistribute this code and/or modify it under 
//	the terms of the GNU General Public License as published 
//	by the Free Software Foundation; either version 2 of the 
//	License, or (at your option) any later version
// ==============================================================

#include "BMPReader.h"
#include "types.h"
#include "pixmap.h"
#include <stdexcept>

using std::runtime_error;

namespace Shared{ namespace Graphics{

/**Copied from pixmap.cpp*/
// =====================================================
//	Structs used for BMP-reading
// =====================================================
#pragma pack(push, 1)

struct BitmapFileHeader{
	uint8 type1;
	uint8 type2;
	uint32 size;
	uint16 reserved1;
	uint16 reserved2;
	uint32 offsetBits;
};

struct BitmapInfoHeader{
	uint32 size;
	int32 width;
	int32 height;
	uint16 planes;
	uint16 bitCount;
	uint32 compression;
	uint32 sizeImage;
	int32 xPelsPerMeter;
	int32 yPelsPerMeter;
	uint32 clrUsed;
	uint32 clrImportant;
};

#pragma pack(pop)

/**Returns a string containing the extensions we want, intitialisation is guaranteed*/
static inline const string* getExtensionsBmp() {
	static const string extensions[] = {"bmp", ""};
	return extensions;
}

// =====================================================
//	class BMPReader
// =====================================================

BMPReader::BMPReader(): FileReader<Pixmap2D>(getExtensionsBmp()) {}

/**Reads a Pixmap2D-object
  *This function reads a Pixmap2D-object from the given ifstream utilising the already existing Pixmap2D* ret.
  *Path is used for printing error messages
  *@return <code>NULL</code> if the Pixmap2D could not be read, else the pixmap*/
Pixmap2D* BMPReader::read(ifstream& in, const string& path, Pixmap2D* ret) const {
	//read file header
	BitmapFileHeader fileHeader;
	in.read((char*)&fileHeader, sizeof(BitmapFileHeader));
	if(fileHeader.type1!='B' || fileHeader.type2!='M'){
		throw runtime_error(path +" is not a bitmap");
	}
		//read info header
	BitmapInfoHeader infoHeader;
	in.read((char*)&infoHeader, sizeof(BitmapInfoHeader));
	if(infoHeader.bitCount!=24){
		throw runtime_error(path+" is not a 24 bit bitmap");
	}
	int h= infoHeader.height;
	int w= infoHeader.width;
	int components= (ret->getComponents() == -1)?3:ret->getComponents();
	//std::cout << "BMP-Components: Pic: " << components << " old: " << (ret->getComponents()) << " File: " << 3 << std::endl;
	ret->init(w,h,components);
	uint8* pixels = ret->getPixels();
	for(int i=0; i<h*w*components; i+=components){
		uint8 r, g, b;
		in.read((char*)&b, 1);
		in.read((char*)&g, 1);
		in.read((char*)&r, 1);
		if (!in.good()) {
			return NULL;
		}
		switch(components){
		case 1:
			pixels[i]= (r+g+b)/3;
			break;
		case 3:
			pixels[i]= r;
			pixels[i+1]= g;
			pixels[i+2]= b;
			break;
		case 4:
			pixels[i]= r;
			pixels[i+1]= g;
			pixels[i+2]= b;
			pixels[i+3]= 255;
			break;
		}
	}
	return ret;
}

}} //end namespace