#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <getopt.h>
#include <openssl/rand.h>
#include <unistd.h>
#include <errno.h>
#include <error.h>

void xor (int ed, char* mess, char* keyf, char* outp);		/* operates the bitwise XOR between mess and keyf and puts the output to outp */
void keyrand (int nb, char* outp);				/* generates random numbers using RAND_bytes from openssl and puts them into outp */
void bluh (int c, char* mess, char* outp, char* ch);		/* performs the binary dump of the input file and prints that to outp */
void help (char* av[]);						/* prints the help message */

int main (int argc, char* argv[]) {

	int opt = 1;
	int command = 0;
	int comm = 0;
	int tear = 0;
	char* chars = "01";
	char* message = NULL;
	char* keyfile = NULL;
	char* output = NULL;
	int nbytes = -1;	// must be resolved temporary workaround (ho sonno)

	/* The following while cycle parses the argv vector to find commands, options and relative arguments
	   using the function getopt_long */

	while (opt) {
		int option_index = 0;
		static struct option options[] = {
			{"bluh",	required_argument,	0,	'b'},
			{"char",	required_argument,	0,	'c'},
			{"decrypt",	required_argument,	0,	'd'},
			{"encrypt",	required_argument,	0,	'e'},
			{"key-file",	required_argument,	0,	'k'},
			{"gen-key",	no_argument,		0,	'g'},
			{"help",	no_argument,		0,	'h'},
			{"nbytes",	required_argument,	0,	'n'},
			{"output",	required_argument,	0,	'o'},
			{"tear-page",	no_argument,		0,	't'},
			{"uhbluh",	required_argument,	0,	'u'},
			{0,		0,			0,	0},
		};

		if ((opt = getopt_long (argc, argv, "b:c:d:e:ghk:n:o:tu:", options, &option_index)) == -1)
			break;

		switch (opt) {
		case 'b':
			message = argv[optind-1];
			if (access (message, F_OK) == -1) {		/* look at next comment */
				error (errno, errno, message);
			}
			command ++;
			comm = 'b';
			break;
		case 'c':
			if (strlen (argv[optind - 1]) != 2){
				printf ("Too much or too many characters inserted!");
				exit (EXIT_FAILURE);
			}
			chars = argv[optind - 1];
			break;
		case 'd':
			message = argv[optind-1];
			command ++;
			comm = 'r';
			break;
		case 'e':
			message = argv[optind-1];
			if (access (message, F_OK) == -1) {		/* checks the existence of the file and eventually exits */
				error (errno, errno, message);
			}
			command ++;
			comm = 'e';
			break;
		case 'g':
			command++;
			comm = 'g';
			break;
		case 'h':
			help (argv);
			command ++;
			break;
		case 'k':
			keyfile = argv[optind-1];
			if (access (keyfile, F_OK) == -1) {		/* look at the previous comment */
				error (errno, errno, keyfile);
			}
			break;
		case 'n':
			nbytes = atoi (argv[optind-1]);
			break;
		case 'o':
			output = argv[optind-1];
			break;
		case 't':
			tear = 1;
			break;
		case 'u':
			message = argv[optind-1];
			if (access (message, F_OK) == -1) {		/* just guess */
				error (errno, errno, message);
			}
			command ++;
			comm = 'u';
			break;
		case '?':
			break;
		default:
			printf ("carachter code returned 0%o \n", opt);
		}
	}

	/* Next section performs some input checks */

	if (command == 0) {
		printf ("%s: No command called\n", argv[0]);
		exit (EXIT_FAILURE);
	} else if (command > 1) {
		printf ("Multiple commands called\n");
		printf ("%s [COMMAND] [OPTIONS] ...\n", argv[0]);
		exit (EXIT_FAILURE);
	}

	if (optind < argc) {
		printf ("%s: Too many arguments\n", argv[0]);
		exit (EXIT_FAILURE);
	}

	/* Next section detects the functions to call */

	if (comm == 'e' || comm == 'r') {
		if (keyfile == NULL) {
			printf ("%s: No key specified: exit!\n", argv[0]);
			exit (EXIT_FAILURE);
		}
		if (tear == 1) {
			comm++;
		}
		xor (comm, message, keyfile, output);
	} else if (comm == 'g') {
		keyrand (nbytes, output);
	} else if (comm == 'b' || comm == 'u') {
		bluh (comm, message, output, chars);
	}

	exit (EXIT_SUCCESS);
}

void xor (int ed, char* mess, char* keyf, char* outp) {

	char* defenoutp = "critt";
	char* defdeoutp = "decritt";

	/* In absence of input by users next block sets the default values */

	if (outp == NULL) {
		if (ed == 'e' || ed == 'f') {
			printf ("WARNING no output name specified using default value 'critt' \n");
			outp = defenoutp;
		} else if (ed == 'r' || ed == 's') {
			printf ("WARNING no output name specified usign default value 'decritt' \n");
			outp = defdeoutp;
		}
	}

	FILE* mex = fopen (mess, "r");
	FILE* keyx = fopen (keyf, "r+");
	FILE* critt = fopen (outp, "w");

	long mess_size;
	long pad_size;

	fseek (mex, 0L, SEEK_END);
	mess_size = ftell (mex);
	rewind (mex);
	fseek (keyx, 0L, SEEK_END);
	pad_size = ftell (keyx);
	fseek (keyx, (pad_size - mess_size), SEEK_SET);

	char* bytes = malloc (mess_size);

	long i;
	char a, b;

	for (i = 0; i < mess_size; i ++) {
		fscanf (mex, "%c", &a);
		fscanf (keyx, "%c", &b);
		bytes[i] = a ^ b;
	}

	fwrite (bytes, sizeof(char), mess_size, critt);

	if (ed == 'f' || ed == 's') {
		ftruncate (fileno (keyx), (pad_size - mess_size));
		fseek (keyx, 0L, SEEK_END);
		long new_pad_size = ftell (keyx);
		printf ("Your pad is now %li bytes shorter \n", mess_size);
		printf ("You now have %li bytes left \n", new_pad_size);
	}

	free (bytes);

	fclose (mex);
	fclose (keyx);
	fclose (critt);

	if (ed == 'e' || ed == 'f') {
		printf ("Message successfully encrypted \n");
	} else if (ed == 'r' || ed == 's') {
		printf ("Message successfully decrypted \n");
	}

	return;
}

void keyrand (int nb, char* outp) {

	char* defoutp = "default.key";

	/* Next block controls the inputs and eventually sets the default values */

	if((nb == -1) && (outp == NULL)) {
		printf ("WARNING no option specified usign default values... \n");
		nb = 1048576;
		outp = defoutp;
	}
	if (nb < -1) {		// orribile
		printf ("Negative byte value inserted! \n");
		printf ("Exiting... \n");
		exit (EXIT_FAILURE);
	} else if (nb != 0) {
		if(nb == -1) {
			printf ("No byte number specified... using default value: 1MB \n");
			nb = 1048576;
		}

		unsigned char* key = malloc (nb);
		RAND_bytes (key, nb);

		if (outp == NULL) {
			outp = defoutp;
			printf ("No output name specified... using default value: default.key \n");
		}

		FILE* file = fopen (outp, "w");
		fwrite (key, sizeof(char), nb, file);
		fclose (file);
		free (key);
		printf ("Created key file %s of %d bytes \n", outp, nb);
	} else {
		printf ("Byte number specified is 0. \n");
		printf ("Doing nothing! \n");
	}

	return;
}

void bluh (int c, char* mess, char* outp, char* ch) {

	char* defbluh = "bluhed";
	char* defunbluh = "unbluhed";
	char a = ch[0];
	char b = ch[1];

	/* In absence of input by users next block sets the default values */

	if (outp == NULL) {
		if (c == 'b') {
			printf ("WARNING no output name specified using default value 'bluhed' \n");
			outp = defbluh;
		} else if (c == 'u') {
			printf ("WARNING no output name specified usign default value 'unbluhed' \n");
			outp = defunbluh;
		}
	}

	FILE* mex = fopen (mess, "r");
	FILE* bluh = fopen (outp, "w");

	long len;

	fseek (mex, 0L, SEEK_END);
	len = ftell (mex);
	rewind (mex);

	if (c == 'b') {
		char* bytes = malloc (len);
		char* bits = malloc (8 * len);

		fread (bytes, sizeof(char), len, mex);

		int i,j;

		for (i = 0; i < len; i ++) {
			for (j = 0; j < 8; j ++) {
				bits[8 * i + j] = (bytes[i] & (1 << (7 -j))) ? b : a;
			}
		}

		fwrite (bits, sizeof(char), (8 * len), bluh);
		free (bytes);
		free (bits);

		printf ("Message successfully bluhed!\n");

	} else if (c == 'u') {
		char* comp = malloc ((len / 8) + 1);
		char* bits = malloc (len);

		fread (bits, sizeof(char), len, mex);
		memset (comp, 0, ((len / 8) + 1));

		int i, j;

		for (i = 0; i < (len / 8); i ++) {
			for (j = 0; j < 8; j ++) {
				if (bits[8 * i + j] == b) {
					comp[i] |= 1 << (7 - j);
				}
			}
		}

		fwrite (comp, sizeof(char), (len / 8), bluh);
		free (comp);
		free (bits);

		printf ("Message successfully unbluhed!\n");
	}

	fclose (mex);
	fclose (bluh);

	return;
}

void help (char* av[]) {
	fprintf (stdout,"ONETIMEBLUH USAGE:\n"
	"%s [COMMAND] [OPTIONS]\n\n"
	"COMMANDS:\n\n"
	"-b, --bluh=FILE            bluhes your message or in other words performs a binary dump\n"
	"-d, --decrypt=FILE         decrypt message (input) same ad --encrypt, just for the feeling\n"
	"-e, --encrypt=FILE         encrypt message (input)\n"
	"-g, --gen-key              create key file\n"
	"-h, --help                 print this help\n"
	"-u, --unbluh=FILE          unbluhes your message (gets the orginal message from the binary dump)\n\n"
	"OPTIONS\n\n"
	"-c, --char=CAHRS           reads two cahracters as argument and uses them to bluh your message\n"
	"-k, --key-file=KEY_FILE    use key (input)\n"
	"-n, --nbytes=NUM           number of bytes\n"
	"-o, --output=FILE          output name\n"
	"-t, --tear-page            deletes from the pad file the bytes used to encrypt/decrypt\n\n"
	"Onetimebluh project repository at https://git.eigenlab.org/seppia/onetimebluh\n", av[0]);

	return;
}