/* http://www.mrwadlo.com */
#include <stdio.h>
#include <conio.h>

void showpercent(int percent);
void createfilename();

void loadfile();
void writetodisk();

void readfile();
void writefile();

void selectoper();
void crypt();

int mark;
long filesize;
char oper;

char iofile[15];
char crypttext[2000];

int main()
{
	
	int i;
	char reply = '?';

	clrscr();

	selectoper();

	while ( oper == 'D' )
	{
		
		gotoxy(8,24);
		printf("Please Enter Output Filename Using 8.3 limit: ");
        	scanf("%12s", &iofile);

		if ( fopen(iofile,"rb") )
		{
			break;
                }
		else
		{
                        clrscr();
			gotoxy(10,25);
			printf("%s - No Such File, Try Again.",iofile);
		}

	}

        if ( oper == 'E' )
	{
		writefile();
		crypt();
		writetodisk();
	}

	if ( oper == 'D' )
        {
		loadfile();
		crypt();
		readfile();

		gotoxy(19,25);
		printf("Would you like to write a reply? [Y]es [N]o");

		do {
                        reply = getch();
		} while ( reply != 'y' && reply != 'Y' && reply != 'n' && reply != 'N');

		if ( reply == 'y' || reply == 'Y')
		{
			clrscr();
			oper = 'E';
			writefile();
			crypt();
			writetodisk();
		}
	}
	return 0;
}
void showpercent(int percent)
{
	if( percent % 2 == 0) 
	{
        		mark++;
		
			if ( mark % 2 == 0)
			{
				printf("%c",223);
                	}
			else
			{
				printf("%c",220);
			}

		printf(" %3d%%", percent);
		printf("\b\b\b\b\b");
        }
}
void loadfile()
{
	int i;
	FILE *fpREAD;
	
	fpREAD = fopen(iofile,"rb");

        fseek(fpREAD, 0, SEEK_END);
	filesize = ftell(fpREAD);
	rewind(fpREAD);

	for ( i=0 ; ( i<filesize && i<2000) ; i++ )
		fread(&crypttext[i], 1, 1, fpREAD);

	fclose(fpREAD);
}
void readfile()
{
	int i;
	char sym;
        int line = 2;
        int para = 2;

	clrscr();

	printf("\n ");

	for ( i=0 ; ( i<filesize && line<24 ) ; i++ )
	{
		sym = crypttext[i];
	
		if ( sym == 13 )
		{
			printf("%c\n ",170);
			para = 2;
                        line++;
		       
		}
		else if (sym == 10 )
			;
		else if ( sym == 9 )
                	printf("%c",29);
		else
			printf("%c", sym);

		if ( para > 78 )
		{
			printf("\n ");
			para = 2;
			line++;
                }
		else
			para++;

	}
	if ( i == 0 )
	{
		printf("(Loaded File is Empty)");
	}
}
void writefile()
{
	int i = 0;
	char sym;
	int col = 2;
	int colcount;
	int line = 2;

	gotoxy(8,24);
	printf("Please Enter Output Filename Using 8.3 limit: ");
	scanf("%12s", &iofile);

	clrscr();
	gotoxy(19,25);
	printf("Enter Message. Press [ESC] to save and exit.");
	gotoxy(2,2);

        sym = getch();
	while ( sym != 27 && i<2000 ) {

                if ( col == 79 && sym != '\b' )
		{
			if ( line == 23 )
			{
				printf("\b \b\a");
				i--;
				col--;
                        }
			else
			{
				printf("%c\n ",170);
				crypttext[i] = 13;
				line++;
				col = 2;
				i++;
                        }
		}


		if (sym == 9)
		{
			crypttext[i] = 29;
			printf("%c",29);
			col++;
		}
		else if ( sym == 13 )
		{
			if ( line == 23 )
			{
				printf("\a");
				i--;
			}
			else
			{
				printf("%c\n ",170);
				crypttext[i] = 13;
				line++;
				col = 2;
                        }
		}
		else if ( sym == '\b' )
		{
			if ( col == 2 && line == 2 )
			{
				printf("\a");
				i--;
                        }
			else if ( col == 2 )
			{
				colcount = i-2;
				while ( crypttext[colcount] != 13 && colcount != -1 )
				{
					colcount--;
				}
				
				col = i - colcount;
				gotoxy(col,--line);
				printf(" \b");
				i-=2;

			}
			else
			{
				printf("\b \b");
				i--;
				crypttext[i] = '\0';
				i--;
				col--;
			}
		}
                else
		{
			crypttext[i] = sym;
			printf("%c", sym);
			col++;
                }

		i++;
                sym = getch();
	}
	filesize = i;
}
void selectoper()
{

	gotoxy(19,25);
        printf("Please Select Operation: [E]ncrypt [D]ecrypt");

	do {
		oper = getch();

		if ( oper == 'e' || oper == 'E' || oper == 'd' || oper == 'D' )
		     break;
		else
			printf("\a");

	} while ( 1 );

	if ( oper == 'e' )
		oper = 'E';
	else if ( oper == 'd' )
		oper = 'D';
        clrscr();
}
void crypt()
{
	long i;
	
	char sym;
	int percent;
	long start, end;

	long fib = 1;
	long last = 0;
	long temp;
	int fib_mod;

	if (oper == 'E' )
                printf("\n Encrypting ");
        if ( oper == 'D' )
		printf("\n Decrypting ");


	percent = 0;

	for ( i=0 ; i < filesize ; i++ )
	{
		temp = fib;
		fib = fib + last;
		last = temp;

		fib_mod = fib % 254;

                fib = fib % 9000000000;
                last = last % 9000000000;

		sym = crypttext[i];

		if ( oper == 'E' )
			sym = sym + fib_mod;
		if ( oper == 'D' )
			sym = sym - fib_mod;

		if ( sym > 253 )
			sym % 254;
		if ( sym < 0 )
			sym + 254;

		crypttext[i] = sym;

		if ( 100*i/filesize > percent )
		{
			percent++;
			showpercent(percent);
		}
                
	}

	while (percent < 100 )
		showpercent(++percent);

	printf("\n Done");

}
void writetodisk()
{
	int i;
	FILE *fpWRITE;

	fpWRITE = fopen(iofile,"wb");

	for ( i=0 ; i<filesize ; i++ )
		fwrite(&crypttext[i], 1, 1, fpWRITE);

	fclose(fpWRITE);
}