/* file: daemon.c		G. Moody		24 February 2012
				Last revised:		  15 May 2017
main() and other functions for the PhysioBank Simple Query Server daemon
*/

#include "pbsqs.h"

#include <errno.h>
#include <signal.h>
#include <syslog.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define SERV_TCP_PORT	9967
#define SERV_HOST_ADDR	"127.0.0.1"	/* localhost */

void newline() { fprintf(ofile, "\n"); }

int reload = 1;

void reload_handler(int dummy) { reload = 1; }

static void fatal(const char *message)
{
    syslog(LOG_ERR, "pbsqs: %s: %s", message, strerror(errno));
    exit(1);
}

main(int argc, char **argv)
{
    int sockfd, newsockfd, clilen, childpid;
    struct sockaddr_in cli_addr, serv_addr;
    int matches, qc = 0, status = 1;

    /* Drop into the background, close stdio, detach from terminal. */
    daemon(0, 0);

    /* Open a TCP socket */
    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
	fatal("can't open stream socket");
    clilen = sizeof(cli_addr);

    /* Bind our local address so that the client can send to us */
    bzero((char *)&serv_addr, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_addr.sin_port = htons(SERV_TCP_PORT);

    if (bind(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
	fatal("can't bind local address");

    ofile = efile = fdopen(sockfd, "w+");

    signal(SIGHUP, &reload_handler);
    signal(SIGCHLD, SIG_IGN);
    if (listen(sockfd, 5) < 0)
        fatal("can't listen on local port");

    while (1) {
	static char *p, *r, qbuf[64];
	Query q;

	if (reload) {
	    cleanup();
	    (void)geturl(PBI_URL, &indeximg); /* (re)read the index */
	    (void)parsepbi();		      /* ... and parse it */
	    reload = 0;
	}

	/* wait for a connection from a client process */
	newsockfd = accept(sockfd, (struct sockaddr *)&cli_addr, &clilen);
	if (newsockfd < 0)
	    fatal("accept error");
	if ((childpid = fork()) < 0)
	    fatal("fork error");
	else if (childpid == 0) { /* child process */
	    close(sockfd);
	    
	    signal(SIGCHLD, SIG_DFL);
	    /* Set up for stream I/O via the socket. */
	    ofile = efile = fdopen(newsockfd, "w+");
	    ifile = fdopen(dup(newsockfd), "r+");
    
	    fprintf(ofile, "pbs>\n"); fflush(ofile);
	    p = r = fgets(qbuf, sizeof(qbuf), ifile);
	    while (r && r < p + sizeof(qbuf) && *r != '\r' && *r != '\n')
		r++;
	    if (r && *r) *r = '\0';
	    q = parsequery(p);
	    matches = -1; verbose = 1;
	    switch (q.type) {
	      case qt_count: showlist = 0; matches = search(q); qc++; break;
	      case qt_list:  showlist = 1; matches = search(q); qc++; break;
	      case qt_long:  showlist = 2; matches = search(q); qc++; break;
	      case qt_help:  help(q); break;
	      case qt_exit:
	      case qt_null:
	      default: break;
	    }
	    if (matches >= 0 && showlist == 0)
		fprintf(ofile, "%d match%s for query: %s %s %s\n",
		       matches, (matches == 1 ? "" : "es"),
		       q.iname, rn[q.comp].name, q.sval);
	    fprintf(ofile, "pbs>\n"); fflush(ofile);
	    close(newsockfd);
	    exit(0);
	}
	
	close(newsockfd); /* parent process */
    }

    /* We should never get here!  Child processes take one trip through
       the code and exit, and the parent process loops indefinitely. */
    cleanup();
    exit(0);
}