#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>

#include "buffer.h"
#include "byte.h"
#include "env.h"
#include "exit.h"
#include "open.h"
#include "str.h"
#include "stralloc.h"

#include "hasutmp.h"
#include "headerbody.h"
#include "hfield.h"


#ifdef HASUTMP
  #include <utmp.h>
  #ifndef UTMP_FILE
    #ifdef _PATH_UTMP
      #define UTMP_FILE _PATH_UTMP
    #else
      #define UTMP_FILE "/etc/utmp"
    #endif
  #endif
#else
  #include <utmpx.h>
#endif

buffer b;
#ifdef HASUTMP
char bufutmp[sizeof(struct utmp) * 16];
int fdutmp;
#endif
char buftty[1024];
int fdtty;

#ifdef HASUTMP
struct utmp ut;
char line[sizeof(ut.ut_line) + 1];
#else
struct utmpx *ut;
char line[sizeof(ut->ut_line) + 1];
#endif

stralloc woof = {0};
stralloc tofrom = {0};
stralloc text = {0};

void doit(char *s, int n)
{
  if (!stralloc_catb(&text, s, n)) _exit(0);
  if (text.len > 78) text.len = 78;
}

void dobody(stralloc *h)
{
  doit(h->s, h->len);
}

void doheader(stralloc *h)
{
  int i;

  if (hfield_known(h->s, h->len) == H_SUBJECT) {
    i = hfield_skipname(h->s, h->len);
    doit(h->s + i, h->len - i);
  }
}

void finishheader() {}

int main()
{
  char *user;
  char *sender;
  char *userext;
  struct stat st;
  int i;

  if (chdir("/dev") == -1) _exit(0);

  if (!(user = env_get("USER"))) _exit(0);
  if (!(sender = env_get("SENDER"))) _exit(0);
  if (!(userext = env_get("LOCAL"))) _exit(0);
#ifdef HASUTMP
  if (str_len(user) > sizeof(ut.ut_name)) _exit(0);
#else
  if (str_len(user) > sizeof(ut->ut_user)) _exit(0);
#endif

  if (!stralloc_copys(&tofrom, "*** TO <")) _exit(0);
  if (!stralloc_cats(&tofrom, userext)) _exit(0);
  if (!stralloc_cats(&tofrom, "> FROM <")) _exit(0);
  if (!stralloc_cats(&tofrom, sender)) _exit(0);
  if (!stralloc_cats(&tofrom, ">")) _exit(0);

  for (i = 0; i < tofrom.len; ++i)
    if ((tofrom.s[i] < 32) || (tofrom.s[i] > 126)) tofrom.s[i] = '_';

  if (!stralloc_copys(&text, "    ")) _exit(0);
  if (headerbody(buffer_0, doheader, finishheader, dobody) == -1) _exit(0);

  for (i = 0; i < text.len; ++i)
    if ((text.s[i] < 32) || (text.s[i] > 126)) text.s[i] = '/';

  if (!stralloc_copys(&woof, "\015\n\007")) _exit(0);
  if (!stralloc_cat(&woof, &tofrom)) _exit(0);
  if (!stralloc_cats(&woof, "\015\n")) _exit(0);
  if (!stralloc_cat(&woof, &text)) _exit(0);
  if (!stralloc_cats(&woof, "\015\n")) _exit(0);

#ifdef HASUTMP
  fdutmp = open_read(UTMP_FILE);
  if (fdutmp == -1) _exit(0);
  buffer_init(&b, read, fdutmp, bufutmp, sizeof(bufutmp));

  while (buffer_get(&b, &ut, sizeof(ut)) == sizeof(ut)) {
    if (!str_diffn(ut.ut_name, user, sizeof(ut.ut_name))) {
#else
  while ((ut = getutxent()) != 0) {
    if (ut->ut_type == USER_PROCESS && !str_diffn(ut->ut_user, user, sizeof(ut->ut_user))) {
#endif
#ifdef HASUTMP
      byte_copy(line, sizeof(ut.ut_line), ut.ut_line);
      line[sizeof(ut.ut_line)] = 0;
#else
      byte_copy(line, sizeof(ut->ut_line), ut->ut_line);
      line[sizeof(ut->ut_line)] = 0;
#endif
      if (line[0] == '/') continue;
      if (!line[0]) continue;
      if (line[str_chr(line, '.')]) continue;

      fdtty = open_append(line);
      if (fdtty == -1) continue;
      if (fstat(fdtty, &st) == -1) {
        close(fdtty);
        continue;
      }
      if (!(st.st_mode & 0100)) {
        close(fdtty);
        continue;
      }
      if (st.st_uid != getuid()) {
        close(fdtty);
        continue;
      }
      buffer_init(&b, write, fdtty, buftty, sizeof(buftty));
      buffer_putflush(&b, woof.s, woof.len);
      close(fdtty);
    }
  }
  _exit(0);
}