/* Compile with:
   gcc -o commenteraser main.c
   
   if you want to use the debug mode, compile with -D_DEBUG
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void printHelp( char* prog );
void checkFile( FILE* fStream, char* filename );
void eraseComment( char* filename, size_t uiCommentBytes, size_t ulCommentOffset );

int main( int argc, char *argv[] )
{
	FILE*						fsCurFile						= NULL;
	
	if( argc < 2 )
	{
		printHelp( *argv );
	}

	while( *(++argv) )
	{
		fsCurFile = fopen( *argv, "r+" );

		if( fsCurFile == NULL )
		{
			printf( "[ERROR] %s: file not found\n", *argv );
			continue;
		}
		else
		{
			printf( "File %s opened..\n", *argv );
			
			checkFile( fsCurFile, *argv );

			fclose( fsCurFile );

			printf( "File %s cleared of comments..\n", *argv );
		}
	}

	return EXIT_SUCCESS;
}

void printHelp( char* prog )
{
	printf( "usage: %s <file>,..", prog );
	
	return;
}

void checkFile( FILE* fStream, char* filename )
{
	char						curChar						= 0;
	char						lastChar						= 0;

	int							commentStarted		= 0;
	int							iCnt								= 0;

	size_t						uiCommentBytes		= 1;
	size_t						ulCommentOffset	= 0;

	while( ( curChar = fgetc( fStream ) ) != EOF )
	{		
		if( lastChar == '/' && curChar == '/' )
		{
#			if defined _DEBUG
			printf( "\nComment found at byte %d\n", ulCommentOffset );
#			endif			

			commentStarted = 1;
		}

		if( lastChar == '\n' && commentStarted == 1 )
		{
			commentStarted = 0;
			
			printf("erasing content from %d to %d\n", ulCommentOffset, ulCommentOffset+uiCommentBytes );
			eraseComment( filename, uiCommentBytes, ulCommentOffset );

			// We couldn't continue count, because we had lost the comment beginning
			//ulCommentOffset += uiCommentBytes; 
			
			fseek( fStream, ulCommentOffset, SEEK_SET );

			uiCommentBytes = 1;
		}

		if( commentStarted == 0 && curChar != '/' )
		{
#			if defined _DEBUG
			printf("Offset: %x(%c)\n", curChar, curChar );
#			endif

			++ulCommentOffset;
		}
		else if( commentStarted == 1 )
		{
#			if defined _DEBUG
			printf("Byte: %x(%c)\n", curChar, curChar );
#			endif

			++uiCommentBytes;
		}

		lastChar = curChar;
	}

	return;
}


void eraseComment( char* filename, size_t uiCommentBytes, size_t ulCommentOffset )
{
	int		iVal = 0x90;
	size_t	iCnt = 0;

	FILE*	fStream = fopen( filename, "r+" ); 

#	if defined _DEBUG
	printf( "deleting %d bytes\n", uiCommentBytes );
#	endif

	for( iCnt = 0; iCnt != uiCommentBytes; iCnt++ )
	{
		fseek( fStream, ulCommentOffset+iCnt, SEEK_SET );
		fwrite( &iVal, 1, 1, fStream );
	}

	iVal = 0x0D;

	fwrite( &iVal, 1, 1, fStream );

	fclose( fStream );

	return;
}