#include <unistd.h>

#include "alloc.h"
#include "buffer.h"
#include "env.h"
#include "error.h"
#include "exit.h"
#include "getln.h"
#include "open.h"
#include "sig.h"
#include "str.h"
#include "stralloc.h"

#include "headerbody.h"
#include "hfield.h"
#include "qmail.h"
#include "quote.h"
#include "token822.h"

#define WHO "qreceipt"

static void die_noreceipt()
{
  _exit(0);
}

static void die()
{
  _exit(100);
}

static void die_temp()
{
  _exit(111);
}

static void die_nomem()
{
  buffer_putsflush(buffer_2, "qreceipt: fatal: out of memory\n");
  die_temp();
}

static void die_fork()
{
  buffer_putsflush(buffer_2, "qreceipt: fatal: unable to fork\n");
  die_temp();
}

static void die_qqperm()
{
  buffer_putsflush(buffer_2, "qreceipt: fatal: permanent qmail-queue error\n");
  die();
}

static void die_qqtemp()
{
  buffer_putsflush(buffer_2, "qreceipt: fatal: temporary qmail-queue error\n");
  die_temp();
}

static void die_usage()
{
  buffer_putsflush(buffer_2, "qreceipt: usage: qreceipt deliveryaddress\n");
  die();
}

static void die_read()
{
  if (errno == ENOMEM) die_nomem();
  buffer_putsflush(buffer_2, "qreceipt: fatal: read error\n");
  die_temp();
}

static void doordie(stralloc *sa, int r)
{
  if (r == 1) return;
  if (r == -1) die_nomem();
  buffer_putsflush(buffer_2, "qreceipt: fatal: unable to parse this: ");
  buffer_putflush(buffer_2, sa->s, sa->len);
  die();
}

char *target;

int flagreceipt = 0;

char *returnpath;
stralloc messageid = {0};
stralloc sanotice = {0};

static int rwnotice(token822_alloc *addr)
{
  token822_reverse(addr);
  if (token822_unquote(&sanotice, addr) != 1) die_nomem();
  if (sanotice.len == str_len(target))
    if (!str_diffn(sanotice.s, target, sanotice.len)) flagreceipt = 1;
  token822_reverse(addr);
  return 1;
}

struct qmail qqt;

stralloc quoted = {0};

static void finishheader()
{
  char *qqx;

  if (!flagreceipt) die_noreceipt();
  if (str_equal(returnpath, "")) die_noreceipt();
  if (str_equal(returnpath, "#@[]")) die_noreceipt();

  if (!quote2(&quoted, returnpath)) die_nomem();

  if (qmail_open(&qqt) == -1) die_fork();

  qmail_puts(&qqt, "From: DELIVERY NOTICE SYSTEM <");
  qmail_put(&qqt, quoted.s, quoted.len);
  qmail_puts(&qqt, ">\n");
  qmail_puts(&qqt, "To: <");
  qmail_put(&qqt, quoted.s, quoted.len);
  qmail_puts(&qqt, ">\n");
  qmail_puts(
      &qqt,
      "Subject: success notice\n\n"
      "Hi! This is the qreceipt program. Your message was delivered to the\n"
      "following address: ");
  qmail_puts(&qqt, target);
  qmail_puts(&qqt, ". Thanks for asking.\n");
  if (messageid.s) {
    qmail_puts(&qqt, "Your ");
    qmail_put(&qqt, messageid.s, messageid.len);
  }

  qmail_from(&qqt, "");
  qmail_to(&qqt, returnpath);
  qqx = qmail_close(&qqt);

  if (*qqx) {
    if (*qqx == 'D')
      die_qqperm();
    else
      die_qqtemp();
  }
}

stralloc hfbuf = {0};
token822_alloc hfin = {0};
token822_alloc hfrewrite = {0};
token822_alloc hfaddr = {0};

static void doheaderfield(stralloc *h)
{
  switch (hfield_known(h->s, h->len)) {
    case H_MESSAGEID:
      if (!stralloc_copy(&messageid, h)) die_nomem();
      break;
    case H_NOTICEREQUESTEDUPONDELIVERYTO:
      doordie(h, token822_parse(&hfin, h, &hfbuf));
      doordie(h, token822_addrlist(&hfrewrite, &hfaddr, &hfin, rwnotice));
      break;
  }
}

static void dobody(stralloc *h) {}

int main(int argc, char **argv)
{
  sig_pipeignore();
  if (!(target = argv[1])) die_usage();
  if (!(returnpath = env_get("SENDER"))) die_usage();
  if (headerbody(buffer_0, doheaderfield, finishheader, dobody) == -1) die_read();
  die_noreceipt();
}