#include <stdio.h>
#include <errno.h>
#include <fcntl.h>
#include <strings.h>

extern const char *__progname;

#include "system.h"
#include "context.h"
#include "profile.h"

static int ctxfd = -1;

const char context_always_flag;

static void get_ctxfd(void)
{
 if (ctxfd < 0)
  { const char *ctxname;
    ctxname = profile_relative_to(system_get_profile(),"statefile","state",system_mmdir());
    ctxfd = open(ctxname,O_RDWR|O_CREAT,0600);
    if (ctxfd < 0)
     { fprintf(stderr,"%s: can't open context file %s: %s\n",__progname,ctxname,strerror(errno));
       exit(1);
     }
    fcntl(ctxfd,F_SETFD,1);
  }
}

char *context_lookup(const char *tag)
{
 PROFILE *p;
 const char *v;
 char *rv;

 get_ctxfd();
 flock(ctxfd,LOCK_SH);
 lseek(ctxfd,0,SEEK_SET);
 p = profile_read_fd(ctxfd);
 flock(ctxfd,LOCK_UN);
 v = profile_lookup(p,tag);
 rv = v ? strdup(v) : 0;
 profile_free(p);
 return(rv);
}

int context_set(const char *tag, const char *newval, const char *oldval)
{
 PROFILE *p;

 get_ctxfd();
 flock(ctxfd,LOCK_EX);
 lseek(ctxfd,0,SEEK_SET);
 p = profile_read_fd(ctxfd);
 if (oldval != CONTEXT_ALWAYS)
  { const char *ov;
    ov = profile_lookup(p,tag);
    if ( (ov && !oldval) ||
	 (oldval && !ov) ||
	 (ov && oldval && strcmp(ov,oldval)) )
     { profile_free(p);
       flock(ctxfd,LOCK_UN);
       return(0);
     }
  }
 profile_set(p,tag,newval);
 lseek(ctxfd,0,SEEK_SET);
 if ( (profile_write_fd(p,ctxfd) < 0) ||
      (ftruncate(ctxfd,lseek(ctxfd,0,SEEK_CUR)) < 0) )
  { fprintf(stderr,"%s: can't save context: %s\n",__progname,strerror(errno));
  }
 profile_free(p);
 return(1);
}