/* Loesung von Jan Siersch */

#include <sys/types.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "morse.h"

#define DIT '.'
#define DAH '-'
#define LETTER_SIZE 8

volatile int sig = 0;
volatile pid_t pid = 0;

void sigAction(int _sig, siginfo_t *info, void *context) {
	sig = _sig;
	pid = info->si_pid;
}

int main(void) {
	// register action for the necessary signals
	int signals[] = {SIGUSR1, SIGUSR2, SIGTERM};
	struct sigaction sigAct = {{0}};
	sigAct.sa_sigaction = sigAction;
	sigAct.sa_flags = SA_SIGINFO;
	for (int i = 0; i < (sizeof(signals) / sizeof(int)); ++i) {
		sigaction(signals[i], &sigAct, 0);
	}
	
	// stores the currently received letter
	char letter[LETTER_SIZE] = {'\0'};
	int index = 0;
	
	// wait for signals
	for(;;) {
		// try to avoid losing signals
		if (!sig)
			pause();
		
		// make sure that letters are terminated at some point
		if (index > LETTER_SIZE - 1) {
			puts("input too long for a letter");
			fflush(stdout);
			exit(EXIT_FAILURE);
		}
		
		// interprete the signal
		switch(sig) {
		case SIGUSR1:
			letter[index++] = DIT;
			break;
		case SIGUSR2:
			letter[index++] = DAH;
			break;
		case SIGTERM:
			letter[index++] = '\0';
			index = 0;
			
			// decode and show letter
			unsigned char result = decode(letter);
			if (!result) {
				perror("could not decode letter");
				exit(EXIT_FAILURE);
			}
			putchar(result);
			break;
		default:
			perror("unknown signal");
			exit(EXIT_FAILURE);
			break;
		}
		fflush(stdout);
		sig = 0;
		
		// signal that we are ready for the next part of the letter
		if (kill(pid, SIGINT)) {
			perror("could not send receipt");
			exit(EXIT_FAILURE);
		}
		
	}
	
	return EXIT_SUCCESS;
}