/*
 *
 *  The code assumes that the message to hide and the recovered message
 *  are both short enough to store and retrieve within the dimensions of the image
 *
 */
void decode(char image[]){
	
	string recoveredMessage;
	
	// Recover the message
	int maxMessageLength = width*height*3 / 8;	// Determine the max length of the message (It can't be larger than the file itself)
	
	for (int i = 0; i < maxMessageLength; i++){
		
		char ch = '\0'; // set the internal value of ch to 00000000
		
		// There are 8 bits per character in the message we want to recover,
		// so lets read 8 bits at a time.  Each individual bit will come from one element
		// of the image character array.  That is to say, every 8 elements of image will comprise
		// a single character in our output message
		for( int bit = 0; bit < 8; bit++){
			ch <<= 1;
			ch |= image[i * 8 + bit] & 1 ? 1 : 0;
		}
		// If after reading 8 bits the value of ch is still 00000000
		// then we've reached the null character signaling the end of our message
		if (ch == '\0') break;
		
		// Add the newly recovered character to our recovered message string
		recoveredMessage += (unsigned char)ch;
	}
}

void hideData(char image[], string messageToHide){
	
	// Hide the data, one character at a time
	for (int i = 0; i < messageToHide.size(); i++){
		image[i * 8 + 0] >>= 1; image[i * 8 + 0] <<= 1; image[i * 8 + 0] |= (messageToHide[i] & 1<<7) ? 1 : 0;
		image[i * 8 + 1] >>= 1; image[i * 8 + 1] <<= 1; image[i * 8 + 1] |= (messageToHide[i] & 1<<6) ? 1 : 0;
		image[i * 8 + 2] >>= 1; image[i * 8 + 2] <<= 1; image[i * 8 + 2] |= (messageToHide[i] & 1<<5) ? 1 : 0;
		image[i * 8 + 3] >>= 1; image[i * 8 + 3] <<= 1; image[i * 8 + 3] |= (messageToHide[i] & 1<<4) ? 1 : 0;
		image[i * 8 + 4] >>= 1; image[i * 8 + 4] <<= 1; image[i * 8 + 4] |= (messageToHide[i] & 1<<3) ? 1 : 0;
		image[i * 8 + 5] >>= 1; image[i * 8 + 5] <<= 1; image[i * 8 + 5] |= (messageToHide[i] & 1<<2) ? 1 : 0;
		image[i * 8 + 6] >>= 1; image[i * 8 + 6] <<= 1; image[i * 8 + 6] |= (messageToHide[i] & 1<<1) ? 1 : 0;
		image[i * 8 + 7] >>= 1; image[i * 8 + 7] <<= 1; image[i * 8 + 7] |= (messageToHide[i] & 1<<0) ? 1 : 0;
	}
	
	// Set the null character
	int i = messageToHide.size();
	
	image[i * 8 + 0] >>= 1; image[i * 8 + 0];
	image[i * 8 + 1] >>= 1; image[i * 8 + 1];
	image[i * 8 + 2] >>= 1; image[i * 8 + 2];
	image[i * 8 + 3] >>= 1; image[i * 8 + 3];
	image[i * 8 + 4] >>= 1; image[i * 8 + 4];
	image[i * 8 + 5] >>= 1; image[i * 8 + 5];
	image[i * 8 + 6] >>= 1; image[i * 8 + 6];
	image[i * 8 + 7] >>= 1; image[i * 8 + 7];
	
}