#include <iostream>
#include <cstdlib>

//class structure for bmpFile

class BmpFile {
	public:
		// properties...
		int bmpIdentifier;												//BM identifier
		long bmpFilesize;												//File size
		unsigned short int bmpres1,bmpres2;
		long bmpPixoff;
		long bmpiSize;
		long bmpWidth;													//BMP width
		long bmpHeight;													//BMP height
		unsigned short int bmpPlanes;
		unsigned short int bmpBitsPixel;
		long bmpCompression;											//if BMP is compressed
		long bmpImageSize;
		long bmpXscale;
		long bmpYScale;
		long bmpColor;													//BMP color depth
		long bmpImpCol;
		long bmpTotalStuffablechar;										//ASCII stuffable character in bitmap

		//	methods...
		BmpFile(char *filename);                                		//constructor #
		~BmpFile();                                             		//destructor
		int isFileExist(char *filename);								//checking file existence
		int getDimension(char *filename, long *width, long *height);	//get height & width
		int readHeader(char *filename);									//get the header info #
		int hide(char *bmpfile, char *txtfile, char *output);			//hidding job *
		int unhide(char *bmpfile,char *txtfile);						//unhidding job *
		int checkFilesForHiding(char *bmpfile, char *txtfile);			//gets file ready
		int printFileInfo();
};


// checks for existence of file, returns 0 if ok, returns -1 on error
int BmpFile::isFileExist(char *filename)
{
    FILE *bmpFilename;
    bmpFilename = fopen(filename,"rb");

    if(bmpFilename == NULL)
    {
        throw("File doesn't exits or wrong Filename.\n");
        return (-1);
    }

    fclose(bmpFilename);
    return 0;
}

// read header of file and other stuff, important method.
int BmpFile::readHeader(char *filename)
{
    char m1,m2;
    unsigned long width, height, fileSize;

    if(isFileExist(filename) == 0)
    {
        FILE *bmpFilename = fopen(filename,"rb");

        // reading first two part of file.
        fread((char *)&m1,1,1,bmpFilename);
        fread((char *)&m2,1,1,bmpFilename);

        if(m1 != 'B' || m2 != 'M')	//B 42 & M 4D
        {
            throw ("error: not a valid bitmap file");
            fclose(bmpFilename);
            return -1;
        }

        bmpIdentifier = m1 * 100 + m2;

        fread((long *)&bmpFilesize,4,1,bmpFilename);

        fread((unsigned short int *)&bmpres1,2,1,bmpFilename);

        fread((unsigned short int *)&bmpres2,2,1,bmpFilename);

        fread((long *)&bmpPixoff,4,1,bmpFilename);

        fread((long *)&bmpiSize,4,1,bmpFilename);

        fread((long *)&bmpWidth,4,1,bmpFilename);

        fread((long *)&bmpHeight,4,1,bmpFilename);

        fread((unsigned short int *)&bmpPlanes,2,1,bmpFilename);

        fread((unsigned short int *)&(bmpBitsPixel),2,1,bmpFilename);

        fread((long *)&bmpCompression,4,1,bmpFilename);

        fread((long *)&bmpImageSize,4,1,bmpFilename);

        fread((long *)&bmpXscale,4,1,bmpFilename);

        fread((long *)&bmpYScale,4,1,bmpFilename);

        fread((long *)&bmpColor,4,1,bmpFilename);

        fread((long *)&bmpImpCol,4,1,bmpFilename);

        fclose(bmpFilename);

        width = bmpWidth;
        height = bmpHeight;
        fileSize = width * height * 3;
        bmpTotalStuffablechar = (fileSize/8)-54;

        return 0;
    }
    return -1;
}

//0 if ok , -1 on err
int BmpFile::getDimension(char *filename, long *width, long *height)
{
    if(isFileExist(filename) == 0)
    {
        readHeader(filename);
        *width = bmpWidth;
        *height = bmpHeight;
        return 0;
    }
    return -1;
}

// class contructor
BmpFile::BmpFile(char *filename)
{
    if(isFileExist(filename) == 0)
    {
        readHeader(filename);
    }
}

// checking for file existence and compability.
int BmpFile::checkFilesForHiding(char *bmpfile, char *txtfile)
{
    FILE *bfile, *tfile;
    long l = 0;

    // check and Initialize files...
    bfile = fopen(bmpfile,"rb");

    if(isFileExist(bmpfile) == -1)
    {
        throw("BMP file doesn't exist");
        return -1;
    }

    tfile = fopen(txtfile,"rb");
    if(isFileExist(txtfile)== -1)
    {
        throw("txt file doesn't exist");
        return -1;
    }

    while( ! feof(tfile) )				// read the length of txt file...
    {
        fgetc(tfile);
        l++;
    }

    readHeader(bmpfile);

    if(l >= bmpTotalStuffablechar)
    {
        throw "length of text file too big , select bigger bmp file";
        return -1;
    }

    fclose(bfile);
    fclose(tfile);
    return 0;
}

// encoding implementation...
int BmpFile::hide(char *bmpfile, char *txtfile, char *output)
{

    FILE *bfile, *tfile, *outfile;
    unsigned char header[54];
    char bmpbuffer, txtbuffer;
    int i;
    char txtTerminatorIndicator = '*';

    // check and Initialize bmp & txt files...
    if(checkFilesForHiding(bmpfile, txtfile) == -1)
    {
        throw "error!, initialization failed...";
        return -1;
    }

    bfile = fopen(bmpfile,"rb");
    tfile = fopen(txtfile,"rb");
    outfile = fopen(output,"w+b");

    fread(header,54,1,bfile);		//read BMP header
    fwrite(header,54,1,outfile);	//write BMP header
    bmpFilesize = bmpFilesize - 54;

    // main hiding/encoding process
    while(!feof(tfile))
    {
        txtbuffer = fgetc(tfile);
        for(i = 0; i<8; i++)
        {
            bmpbuffer = fgetc(bfile);
            bmpbuffer &= 0xFE;		//FE, to make sure LSB is always zero
            bmpbuffer |= (char)((txtbuffer >> i) & 1);
            fputc(bmpbuffer,outfile);

            bmpTotalStuffablechar--;
            bmpFilesize--;
        }
    }

    // stuffing txt terminator indicator.
    for(i = 0; i < 8; i++)
    {
            bmpbuffer = fgetc(bfile);
            bmpbuffer &= 0xFE;
            bmpbuffer |= (char)((txtTerminatorIndicator >> i) & 1);
            fputc(bmpbuffer,outfile);
            bmpTotalStuffablechar--;
            bmpFilesize--;
    }

    // write remaing bmp bytes into the new bmp file.
    if(bmpFilesize != 0)
    {
        while( ! feof(bfile) )
        {
            fputc(fgetc(bfile), outfile);
        }
    }

    // close all file handlers
    fclose(bfile);
    fclose(tfile);
    fclose(outfile);

    return 0;
}

// encoding implementation...
int BmpFile::unhide (char *bmpfile, char *txtfile)
{
    if(readHeader(bmpfile) == -1)
        return -1;

    FILE *bfile, *tfile;
    char ch, bmpBuffer[8];
    int i;
    bfile = fopen(bmpfile,"rb");
    tfile = fopen(txtfile,"w+b");

    fseek(bfile, 54, SEEK_SET);				//skip the BMP header part
    ch = 0;

    while(!feof(bfile))
    {
            //read the last bit from BMP file
        ch = 0;
        for(i=0; i<=7; i++)
        {
            bmpBuffer[i] = fgetc(bfile);
        }

        for(i=7; i>=0; i--)
        {
            ch += (bmpBuffer[i] & 1);
            if(i != 0)
                ch <<= 1;
        }

        if(ch == EOF || ch == '*')
        {
            break;
        }
        else
        {
            fputc(ch,tfile);
        }
    }

    fclose(bfile);
    fclose(tfile);

    return 0;
}

// destructor implementation
BmpFile::~BmpFile ()
{}

// bmp header information
int BmpFile::printFileInfo()
{
    //readHeader(filename)
    std::cout<<"identifier      : "<<bmpIdentifier<<std::endl;
    std::cout<<"filesize        : "<<bmpFilesize<<std::endl;
    std::cout<<"res1            : "<<bmpres1<<std::endl;
    std::cout<<"res2            : "<<bmpres2<<std::endl;
    std::cout<<"pixoff          : "<<bmpPixoff<<std::endl;
    std::cout<<"isize           : "<<bmpiSize<<std::endl;
    std::cout<<"Width           : "<<bmpWidth<<std::endl;
    std::cout<<"Height          : "<<bmpHeight<<std::endl;
    std::cout<<"Plane           : "<<bmpPlanes<<std::endl;
    std::cout<<"BitPixel        : "<<bmpBitsPixel<<std::endl;
    std::cout<<"compression     : "<<bmpCompression<<std::endl;
    std::cout<<"imageSize       : "<<bmpImageSize<<std::endl;
    std::cout<<"Xscale          : "<<bmpXscale<<std::endl;
    std::cout<<"YScale          : "<<bmpYScale<<std::endl;
    std::cout<<"color           : "<<bmpColor<<std::endl;
    std::cout<<"ImpCol          : "<<bmpImpCol<<std::endl;
    std::cout<<"---------------------------------------"<<std::endl;
    std::cout<<"Width           : " << bmpWidth << std::endl;
    std::cout<<"Height          : " << bmpHeight << std::endl;
    std::cout<<"comprss         : "<< bmpCompression<<std::endl;
    std::cout<<"FileSize        : " << bmpFilesize <<std::endl;
    std::cout<<"Stuffable ASCII : " << bmpTotalStuffablechar << std::endl;

    return 0;
}