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

#include "alloc.h"
#include "buffer.h"
#include "byte.h"
#include "case.h"
#include "cdbread.h"
#include "env.h"
#include "exit.h"
#include "fmt.h"
#include "getoptb.h"
#include "logmsg.h"
#include "open.h"
#include "readclose.h"
#include "seek.h"
#include "sig.h"
#include "str.h"
#include "stralloc.h"
#include "wait.h"

#include "qmail.h"
#include "strset.h"

#define WHO "fastforward"

static void usage()
{
  logmsg(WHO, 100, USAGE, "fastforward [ -nNpP ] data.cdb");
}
static void nomem()
{
  logmsg(WHO, 111, FATAL, "out of memory");
}

static void print(char *s)
{
  char ch;
  while ((ch = *s++)) {
    buffer_put(buffer_2, &ch, 1);
  }
}

static void printsafe(char *s)
{
  char ch;
  while ((ch = *s++)) {
    if (ch < 32) ch = '_';
    buffer_put(buffer_2, &ch, 1);
  }
}

struct qmail qq;
char qp[FMT_ULONG];
char qqbuf[1];

static ssize_t qqwrite(int fd, char *buf, int len)
{
  qmail_put(&qq, buf, len);
  return len;
}

buffer bufq = BUFFER_INIT(qqwrite, -1, qqbuf, sizeof(qqbuf));

char messbuf[4096];
buffer mess = BUFFER_INIT(read, 0, messbuf, sizeof(messbuf));

int flagdeliver = 1;
int flagpassthrough = 0;

char *dtline;
stralloc sender = {0};
stralloc programs = {0};
stralloc forward = {0};

strset done;
stralloc todo = {0};

stralloc mailinglist = {0};

static void dofile(char *fn)
{
  int fd;
  struct stat st;
  int i;
  int j;

  if (!stralloc_copys(&mailinglist, "")) nomem();

  fd = open_read(fn);
  if (fd == -1) logmsg(WHO, 111, FATAL, B("unable to read: ", fn));
  if (fstat(fd, &st) == -1) logmsg(WHO, 111, FATAL, B("unable to read: ", fn));
  if ((st.st_mode & 0444) != 0444) logmsg(WHO, 111, FATAL, B(fn, " is not world-readable"));
  if (readclose_append(fd, &mailinglist, 1024) == -1) logmsg(WHO, 111, FATAL, B("unable to read: ", fn));

  i = 0;
  for (j = 0; j < mailinglist.len; ++j) {
    if (!mailinglist.s[j]) {
      if ((mailinglist.s[i] == '.') || (mailinglist.s[i] == '/')) {
        if (!stralloc_cats(&todo, mailinglist.s + i)) nomem();
        if (!stralloc_0(&todo)) nomem();
      } else if ((mailinglist.s[i] == '&') && (j - i < 900)) {
        if (!stralloc_cats(&todo, mailinglist.s + i)) nomem();
        if (!stralloc_0(&todo)) nomem();
      }
      i = j + 1;
    }
  }
}

char *fncdb;
int fdcdb;
stralloc key = {0};
uint32 dlen;
stralloc data = {0};
struct cdb cdb;

static void cdbreaderror()
{
  logmsg(WHO, 111, FATAL, B("unable to read: ", fncdb));
}

static int findtarget(int flagwild, char *prepend, char *addr)
{
  int r;
  int at;

  if (!stralloc_copys(&key, prepend)) nomem();
  if (!stralloc_cats(&key, addr)) nomem();
  case_lowerb(key.s, key.len);

  r = cdb_find(&cdb, key.s, key.len);
  if (r == -1) cdbreaderror();
  if (r) return 1;

  if (!flagwild) return 0;
  at = str_rchr(addr, '@');
  if (!addr[at]) return 0;

  if (!stralloc_copys(&key, prepend)) nomem();
  if (!stralloc_cats(&key, addr + at)) nomem();
  case_lowerb(key.s, key.len);

  r = cdb_find(&cdb, key.s, key.len);
  if (r == -1) cdbreaderror();
  if (r) return 1;

  if (!stralloc_copys(&key, prepend)) nomem();
  if (!stralloc_catb(&key, addr, at + 1)) nomem();
  case_lowerb(key.s, key.len);

  r = cdb_find(&cdb, key.s, key.len);
  if (r == -1) cdbreaderror();
  if (r) return 1;

  return 0;
}

static int gettarget(int flagwild, char *prepend, char *addr)
{
  if (!findtarget(flagwild, prepend, addr)) return 0;
  dlen = cdb_datalen(&cdb);
  if (!stralloc_ready(&data, (unsigned int)dlen)) nomem();
  data.len = dlen;
  if (cdb_read(&cdb, data.s, data.len, cdb_datapos(&cdb)) == -1) cdbreaderror();

  return 1;
}

static void doprogram(char *arg)
{
  char *args[5];
  int child;
  int wstat;

  if (!flagdeliver) {
    print("run ");
    printsafe(arg);
    print("\n");
    buffer_flush(buffer_2);
    return;
  }

  if (*arg == '!') {
    args[0] = "preline";
    args[1] = "sh";
    args[2] = "-c";
    args[3] = arg + 1;
    args[4] = 0;
  } else {
    args[0] = "sh";
    args[1] = "-c";
    args[2] = arg + 1;
    args[3] = 0;
  }

  switch (child = vfork()) {
    case -1: logmsg(WHO, 111, FATAL, "unable to fork: ");
    case 0:
      sig_pipedefault();
      execvp(*args, args);
      logmsg(WHO, 111, FATAL, B("unable to run: ", arg));
  }

  wait_pid(&wstat, child);
  if (wait_crashed(wstat)) logmsg(WHO, 111, FATAL, B("child crashed in: ", arg));

  switch (wait_exitcode(wstat)) {
    case 64:
    case 65:
    case 70:
    case 76:
    case 77:
    case 78:
    case 112:
    case 100: _exit(100);
    case 0:   break;
    default:  _exit(111);
  }

  if (seek_begin(0) == -1) logmsg(WHO, 111, FATAL, "unable to rewind input: ");
}

static void dodata()
{
  int i;
  int j;
  i = 0;

  for (j = 0; j < data.len; ++j) {
    if (!data.s[j]) {
      if ((data.s[i] == '|') || (data.s[i] == '!')) {
        doprogram(data.s + i);
      } else if ((data.s[i] == '.') || (data.s[i] == '/')) {
        if (!stralloc_cats(&todo, data.s + i)) nomem();
        if (!stralloc_0(&todo)) nomem();
      } else if ((data.s[i] == '&') && (j - i < 900)) {
        if (!stralloc_cats(&todo, data.s + i)) nomem();
        if (!stralloc_0(&todo)) nomem();
      }
      i = j + 1;
    }
  }
}

static void dorecip(char *addr)
{

  if (!findtarget(0, "?", addr)) {
    if (gettarget(0, ":", addr)) {
      dodata();
      return;
    }
  }
  if (!stralloc_cats(&forward, addr)) nomem();
  if (!stralloc_0(&forward)) nomem();
}

static void doorigrecip(char *addr)
{
  if (sender.len)
    if ((sender.len != 4) || byte_diff(sender.s, 4, "#@[]"))
      if (gettarget(1, "?", addr))
        if (!stralloc_copy(&sender, &data)) nomem();
  if (!gettarget(1, ":", addr)) {
    if (flagpassthrough)
      _exit(0);
    else
      logmsg(WHO, 100, ERROR, "Sorry, no mailbox here by that name. (#5.1.1)");
  }
  dodata();
}

stralloc recipient = {0};
int flagdefault = 0;

int main(int argc, char **argv)
{
  int opt;
  char *x;
  int i;

  sig_pipeignore();

  dtline = env_get("DTLINE");
  if (!dtline) dtline = "";

  x = env_get("SENDER");
  if (!x) x = "original envelope sender";
  if (!stralloc_copys(&sender, x)) nomem();

  if (!stralloc_copys(&forward, "")) nomem();
  if (!strset_init(&done)) nomem();

  while ((opt = getopt(argc, argv, "nNpPdD")) != opteof) {
    switch (opt) {
      case 'n': flagdeliver = 0; break;
      case 'N': flagdeliver = 1; break;
      case 'p': flagpassthrough = 1; break;
      case 'P': flagpassthrough = 0; break;
      case 'd': flagdefault = 1; break;
      case 'D': flagdefault = 0; break;
      default:  usage();
    }
  }
  argv += optind;

  fncdb = *argv;
  if (!fncdb) usage();
  fdcdb = open_read(fncdb);
  if (fdcdb == -1) cdbreaderror();
  cdb_init(&cdb, fdcdb);

  if (flagdefault) {
    x = env_get("DEFAULT");
    if (!x) x = env_get("EXT");
    if (!x) logmsg(WHO, 100, FATAL, "$DEFAULT or $EXT must be set");
    if (!stralloc_copys(&recipient, x)) nomem();
    if (!stralloc_cats(&recipient, "@")) nomem();
    x = env_get("HOST");
    if (!x) logmsg(WHO, 100, FATAL, "$HOST must be set");
    if (!stralloc_cats(&recipient, x)) nomem();
    if (!stralloc_0(&recipient)) nomem();
    x = recipient.s;
  } else {
    x = env_get("RECIPIENT");
    if (!x) logmsg(WHO, 100, FATAL, "$RECIPIENT must be set");
  }
  if (!strset_add(&done, x)) nomem();
  doorigrecip(x);

  while (todo.len) {
    i = todo.len - 1;
    while ((i > 0) && todo.s[i - 1]) --i;
    todo.len = i;

    if (strset_in(&done, todo.s + i)) continue;

    x = alloc(str_len(todo.s + i) + 1);
    if (!x) nomem();
    str_copy(x, todo.s + i);
    if (!strset_add(&done, x)) nomem();

    x = todo.s + i;
    if (*x == 0)
      continue;
    else if ((*x == '.') || (*x == '/'))
      dofile(x);
    else
      dorecip(x + 1);
  }

  if (!forward.len) {
    if (!flagdeliver) {
      print("no forwarding\n");
      buffer_flush(buffer_2);
    }
    _exit(flagpassthrough ? 99 : 0);
  }

  if (!stralloc_0(&sender)) nomem();

  if (!flagdeliver) {
    print("from <");
    printsafe(sender.s);
    print(">\n");
    while (forward.len) {
      i = forward.len - 1;
      while ((i > 0) && forward.s[i - 1]) --i;
      forward.len = i;
      print("to <");
      printsafe(forward.s + i);
      print(">\n");
    }
    buffer_flush(buffer_2);
    _exit(flagpassthrough ? 99 : 0);
  }

  if (qmail_open(&qq) == -1) logmsg(WHO, 111, FATAL, "unable to fork: ");
  qmail_puts(&qq, dtline);
  if (buffer_copy(&bufq, &mess) != 0) logmsg(WHO, 111, FATAL, "unable to read message: ");
  buffer_flush(&bufq);
  qp[fmt_ulong(qp, qmail_qp(&qq))] = 0;

  qmail_from(&qq, sender.s);

  while (forward.len) {
    i = forward.len - 1;
    while ((i > 0) && forward.s[i - 1]) --i;
    forward.len = i;
    qmail_to(&qq, forward.s + i);
  }

  x = qmail_close(&qq);
  if (*x) logmsg(WHO, *x == 'D' ? 100 : 111, FATAL, x + 1);
  logmsg(WHO, flagpassthrough ? 99 : 0, LOG, B("qp ", qp));
}