#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <unistd.h>
#include <string.h>
#include <time.h>
#include <sys/types.h>
#include <signal.h>


void sigpipe (int sig)
{
	char * s = "Client terminated prematurly\n";
	write (2, s, strlen (s));
	_exit (1);
}

int readline (char * buf, int len)
{
	int i=0;
	int cridx = -1;
	assert (len > 3);
	while (i < len-1) {
		int ret = read (0, buf+i, 1);
		if (ret < 0) {
			perror ("read");
			exit (1);
		}
		if (ret == 0) {
			fprintf (stderr, "At least they could say goodbye\n");
			exit (1);
		}
		i++;
		if (buf[i-1] == '\n')
			break;
		if (cridx < 0 || buf[i-1] == '\r')
			cridx = i-1;
	}
	buf[i] = 0;
	if (i < 2 || buf[i-1] != '\n' || buf[i-2] != '\r') {
		return 0;
	}
	if (cridx != i-2) {
		return 0;
	}
	return 1;
}

void writeline (char * buf)
{
	int len = strlen (buf);
	assert (len >= 2 && buf[len-1] == '\n' && buf[len-2] == '\r');
	while (len) {
		int off = 1+rand()%5;
		if (off > len)
			off = len;
		int done = write (1, buf, off);
		if (done < 0) {
			perror ("write");
			exit (1);
		}
		len -= done;
		buf += done;
		yield();
	}
}

int main ()
{
	static char buf[1000];
	static char code[20];
	static int cols[20];
	int colmax, lenmax;
	int len, col, unique;
	int running = 0;
	int i;
	struct sigaction act;
	act.sa_flags = 0;
	sigemptyset (&act.sa_mask);
	act.sa_handler = sigpipe;
	if (sigaction (SIGPIPE, &act, NULL) < 0) {
		perror ("sigaction");
		exit (1);
	}
	srand (time(0) + getpid ());
	colmax = 3+rand()%10;
	lenmax = 3+rand()%10;
	sprintf (buf, "200 MMSERVER colmax=%d lenmax=%d\r\n", colmax, lenmax);
	writeline (buf);
	while (1) {
		int ret = readline (buf, 1000);
		if (!ret) {
			writeline ("300 Line Format Error\r\n");
			continue;
		}
		if (strncasecmp (buf, "GAME ", 5) == 0) {
			char * p = buf+5;
			int add;
			if (running) {
				writeline ("400 Game already running\r\n");
				continue;
			}
			unique = -1;
			if (strncasecmp (p, "UNIQUE ", 7) == 0) {
				unique = 1;
				p += 7;
			} else if (strncasecmp (p, "FREE ", 5) == 0) {
				unique = 0;
				p += 5;
			}
			if (unique < 0) {
				writeline ("301 FREE/UNIQUE missing\r\n");
				continue;
			}
			if (sscanf (p, "%d %d%n", &col, &len, &add) < 2) {
				writeline ("302 Can't parse col/len\r\n");
				continue;
			}
			p += add;
			if (col>colmax || len>lenmax || col<1 || len<1) {
				writeline ("500 Parameters out of range\r\n");
				continue;
			}
			if (unique && col < len) {
				writeline ("501 Impossible parameters\r\n");
				continue;
			}
			if (p[0] != '\r' || p[1] != '\n') {
				writeline ("303 Chunk at end of line\r\n");
				continue;
			}
			running = 1;
			for (i=0; i<col; ++i)
				cols[i] = 0;
			for (i=0; i<len; ++i) {
				int c = rand() % col;
				if (unique) {
					while (cols[c]) {
						c = rand() % col;
					}
				}
				cols[c]++;
				code[i] = 'A' + c;
			}
			code[len] = 0;
			writeline ("201 Ok. Start guessing\r\n");
			continue;
		}
		if (strcasecmp (buf, "HELLO\r\n") == 0) {
			sprintf (buf, "202 MMSERVER colmax=%d lenmax=%d\r\n", colmax, lenmax);
			writeline (buf);
			continue;
		}
		if (strcasecmp (buf, "RESET\r\n") == 0) {
			sprintf (buf, "203 Communication reset\r\n");
			writeline (buf);
			running = 0;
			continue;
		}
		if (strcasecmp (buf, "SOLVE\r\n") == 0) {
			if (!running) {
				writeline ("401 No game running\r\n");
				continue;
			}
			sprintf (buf, "204 Solution was %s\r\n", code);
			writeline (buf);
			running = 0;
			continue;
		}
		if (strncasecmp (buf, "GUESS ", 6) == 0) {
			char * p = buf+6;
			int mcol[20];
			int badc, badun,blacks, whites;
			if (!running) {
				writeline ("401 No game running\r\n");
				continue;
			}
			if (strlen (p) != len + 2 || p[len] != '\r'
			    || p[len+1] != '\n') {
			    	writeline ("304 Syntax error in Guess\r\n");
				continue;
			}
			for (i=0; i<col; ++i)
				mcol[i] = 0;
			badc = 0;
			badun = 0;
			blacks = 0;
			for (i=0; i<len; ++i) {
				int c = p[i] - 'A';
				if (c < 0 || c >= col) {
					badc = 1;
					break;
				}
				if (unique && mcol[c]) {
					badun = 1;
					break;
				}
				mcol[c]++;
				if (code[i] == 'A' + c)
					blacks++;
			}
			if (badc) {
				writeline ("502 Colour out of range\r\n");
				continue;
			}
			if (badun) {
				writeline ("503 Colours not unique\r\n");
				continue;
			}
			whites = 0;
			for (i=0; i<col; ++i) {
				if (mcol[i] < cols[i]) {
					whites += mcol[i];
				} else {
					whites += cols[i];
				}
			}
			whites -= blacks;
			assert (whites >= 0);
			if (blacks == len) {
				writeline ("205 Congratulations\r\n");
				running = 0;
				continue;
			}
			sprintf (buf, "206 Blacks=%d Whites=%d\r\n",blacks, whites);
			writeline (buf);
			continue;
		}
		if (strcasecmp (buf, "QUIT\r\n") == 0) {
			yield();
			yield();
			yield();
			writeline ("207 Good Bye\r\n");
			exit (0);
		}
		writeline ("310 Unknown command\r\n");
	}
	return 0;
}