#include <sys/types.h>
#include <sys/stat.h>
#include "sgetopt.h"
#include "scan.h"
#include "stralloc.h"
#include "fd.h"
#include "open.h"
#include "getln.h"
#include "subfd.h"
#include "strerr.h"
#include "substdio.h"
#include "readwrite.h"
#include "maildir.h"
#include "prioq.h"
#include "wait.h"
#include "fork.h"
#include "sig.h"
#include "now.h"
#include "str.h"
#include "fmt.h"
#include "date822fmt.h"
#include "control.h"
#include "qmail.h"
#include "auto_qmail.h"

#define FATAL "maildirserial: fatal: "
#define WARNING "maildirserial: warning: "
#define INFO "maildirserial: info: "

void die_usage() {
  strerr_die1x(100,"maildirserial: usage: maildirserial [ -b ] [ -t lifetime ] dir prefix client [ arg ... ]");
}
void die_readclient()
{
  strerr_die2sys(111,FATAL,"unable to read from client: ");
}
void die_nomem()
{
  strerr_die2x(111,FATAL,"out of memory");
}
void die_control()
{
  strerr_die2sys(111,FATAL,"unable to read controls: ");
}
void die_qq()
{
  strerr_die2sys(111,FATAL,"unable to run qq: ");
}

char *prefix;
char **client;

char messbuf[256];
substdio ssmess;

stralloc line = {0};
stralloc recipient = {0};

char buf[1024];
substdio ss; /* in parent, reading from child; in scanner, writing to child */

int pid; /* in parent, pid of scanner; in scanner, pid of child */
int wstat;

stralloc deadfiles = {0};


/* ---------------------------------------------------------------- BOUNCING */

stralloc me = {0};
stralloc bouncefrom = {0};
stralloc bouncehost = {0};
stralloc doublebounceto = {0};
stralloc doublebouncehost = {0};

void readcontrols()
{
  int r;
  int fddir;

  fddir = open_read(".");
  if (fddir == -1)
    strerr_die2sys(111,FATAL,"unable to open current directory: ");

  if (chdir(auto_qmail) == -1)
    strerr_die4sys(111,FATAL,"unable to chdir to ",auto_qmail,": ");

  r = control_readline(&me,"control/me");
  if (r == -1) die_control();
  if (!r) if (!stralloc_copys(&me,"me")) die_nomem();

  r = control_readline(&bouncefrom,"control/bouncefrom");
  if (r == -1) die_control();
  if (!r) if (!stralloc_copys(&bouncefrom,"MAILER-DAEMON")) die_nomem();

  r = control_readline(&bouncehost,"control/bouncehost");
  if (r == -1) die_control();
  if (!r) if (!stralloc_copy(&bouncehost,&me)) die_nomem();

  r = control_readline(&doublebouncehost,"control/doublebouncehost");
  if (r == -1) die_control();
  if (!r) if (!stralloc_copy(&doublebouncehost,&me)) die_nomem();

  r = control_readline(&doublebounceto,"control/doublebounceto");
  if (r == -1) die_control();
  if (!r) if (!stralloc_copys(&doublebounceto,"postmaster")) die_nomem();

  if (!stralloc_cats(&doublebounceto,"@")) die_nomem();
  if (!stralloc_cat(&doublebounceto,&doublebouncehost)) die_nomem();
  if (!stralloc_0(&doublebounceto)) die_nomem();

  if (fchdir(fddir) == -1)
    strerr_die2sys(111,FATAL,"unable to set current directory: ");
}

struct qmail qq;

void put(buf,len) char *buf; int len; { qmail_put(&qq,buf,len); }
void puts(buf) char *buf; { qmail_puts(&qq,buf); }

char *qqx;
unsigned long qp;
char num[FMT_ULONG];

struct datetime dt;
char datestr[DATE822FMT];

stralloc sender = {0};
stralloc quoted = {0};

int bounce(fd,why,flagtimeout)
int fd;
stralloc *why; /* must end with \n; must not contain \n\n */
int flagtimeout;
{
  int match;
  char *bouncesender;
  char *bouncerecip;
  char *x;
  int n;

  substdio_fdbuf(&ssmess,read,fd,messbuf,sizeof messbuf);

  if (getln(&ssmess,&line,&match,'\n') == -1) return -1;
  if (!match) return -3;
  if (!stralloc_starts(&line,"Return-Path: <")) return -3;
  if (line.s[line.len - 2] != '>') return -3;
  if (line.s[line.len - 1] != '\n') return -3;
  if (!stralloc_copyb(&sender,line.s + 14,line.len - 16)) die_nomem();
  if (byte_chr(sender.s,sender.len,'\0') < sender.len) return -3;
  if (!stralloc_0(&sender)) die_nomem();

  if (getln(&ssmess,&line,&match,'\n') == -1) return -1;
  if (!match) return -3;
  if (!stralloc_starts(&line,"Delivered-To: ")) return -3;
  if (line.s[line.len - 1] != '\n') return -3;
  if (!stralloc_copyb(&recipient,line.s + 14,line.len - 15)) die_nomem();

  if (!str_diff(sender.s,"#@[]")) return 2;

  if (qmail_open(&qq) == -1) die_qq();
  qp = qmail_qp(&qq);

  if (*sender.s) { bouncesender = ""; bouncerecip = sender.s; }
  else { bouncesender = "#@[]"; bouncerecip = doublebounceto.s; }

  puts("Date: ");
  datetime_tai(&dt,now());
  put(datestr,date822fmt(datestr,&dt));
  puts("From: ");
  if (!quote(&quoted,&bouncefrom)) die_nomem();
  put(quoted.s,quoted.len);
  puts("@");
  put(bouncehost.s,bouncehost.len);
  puts("\nTo: ");
  if (!quote2(&quoted,bouncerecip)) die_nomem();
  put(quoted.s,quoted.len);

  puts("\n\
Subject: failure notice\n\
\n\
Hi. This is the maildirbounce program at ");
  put(bouncehost.s,bouncehost.len);

  puts(*sender.s ? ".\n\
I'm afraid I wasn't able to deliver your message to the following address.\n\
This is a permanent error; I've given up. Sorry it didn't work out.\n\
\n\
" : ".\n\
I tried to deliver a bounce message to this address, but the bounce bounced!\n\
\n\
");

  puts("<");
  if (stralloc_starts(&recipient,prefix))
    put(recipient.s + str_len(prefix),recipient.len - str_len(prefix));
  else
    put(recipient.s,recipient.len);
  puts(">:\n");
  put(why->s,why->len);
  if (flagtimeout)
    puts("This message is too old. Giving up.\n");
  puts("\n");

  puts(*sender.s ? "--- Below this line is a copy of the message.\n\n" : "--- Below this line is the original bounce.\n\n");
  puts("Return-Path: <");
  if (!quote2(&quoted,sender.s)) die_nomem();
  put(quoted.s,quoted.len);
  puts(">\n");

  for (;;) {
    n = substdio_feed(&ssmess);
    if (n < 0) strerr_die2sys(111,FATAL,"unable to read message: ");
    if (!n) break;
    x = substdio_PEEK(&ssmess);
    put(x,n);
    substdio_SEEK(&ssmess,n);
  }

  qmail_from(&qq,bouncesender);
  qmail_to(&qq,bouncerecip);
  qqx = qmail_close(&qq);
  if (qqx) return -2;

  return 1;
}


/* ----------------------------------------------------------------- SCANNER */

int hasprefix(fd)
int fd;
{
  int match;

  substdio_fdbuf(&ssmess,read,fd,messbuf,sizeof messbuf);

  if (getln(&ssmess,&line,&match,'\n') == -1) return -1;
  if (!match) return 0;
 
  if (getln(&ssmess,&line,&match,'\n') == -1) return -1;
  if (!match) return 0;
  if (!stralloc_starts(&line,"Delivered-To: ")) return 0;
  if (line.s[line.len - 1] != '\n') return 0;
  if (!stralloc_copyb(&recipient,line.s + 14,line.len - 15)) return -1;

  return stralloc_starts(&recipient,prefix);
}

int usable(fn)
char *fn;
{
  int i;
  int fd;

  i = 0;
  while (i < deadfiles.len) {
    if (str_equal(fn,deadfiles.s + i)) return 0;
    i += str_len(deadfiles.s + i);
    ++i;
  }

  if (!*prefix) return 1; /* optimization */

  fd = open_read(fn);
  if (fd == -1) {
    strerr_warn4(WARNING,"unable to open ",fn,": ",&strerr_sys);
    return 0;
  }

  i = hasprefix(fd);
  if (i == -1)
    strerr_warn4(WARNING,"unable to read ",fn,": ",&strerr_sys);
  close(fd);
  return i == 1;
}

stralloc filenames = {0};
prioq pq = {0};

int pis2c[2];

void scanner()
{
  struct prioq_elt pe;
  char *fn;

  if (pipe(pis2c) == -1)
    strerr_die2sys(111,FATAL,"unable to create pipe: ");

  substdio_fdbuf(&ss,write,pis2c[1],buf,sizeof buf);

  maildir_clean(&filenames);

  if (maildir_scan(&pq,&filenames,1,1) == -1)
    strerr_die1(111,FATAL,&maildir_scan_err);

  while (prioq_min(&pq,&pe)) {
    prioq_delmin(&pq);
    fn = filenames.s + pe.id;
    if (usable(fn)) {
      if (!pid) {
	pid = fork();
	if (pid == -1)
	  strerr_die2sys(111,FATAL,"unable to fork: ");
	if (pid == 0) {
	  close(pis2c[1]);
	  fd_move(0,pis2c[0]);
	  sig_pipedefault();
	  execvp(*client,client);
	  strerr_die4sys(111,FATAL,"unable to run ",*client,": ");
	}
	close(pis2c[0]);
      }
      substdio_put(&ss,fn,str_len(fn) + 1); /* ignore errors */
    }
  }

  if (!pid) _exit(0);

  substdio_flush(&ss); /* ignore errors */
  close(pis2c[1]);

  if (wait_pid(&wstat,pid) == -1)
    strerr_die2sys(111,FATAL,"unable to get client status: ");
  if (wait_crashed(wstat))
    strerr_die2x(111,FATAL,"client crashed");
  if (wait_exitcode(wstat) == 100)
    _exit(100); /* client has produced error message */

  _exit(30);
}


/* ------------------------------------------------------------------ PARENT */

int flagbounce = 0;
int flaglifetime = 0;
unsigned long lifetime;
int flagtimeout;

int pic2p[2];

stralloc fn = {0};
stralloc err = {0};
int match;

void info(result)
char *result;
{
  substdio_puts(subfderr,INFO);
  substdio_puts(subfderr,fn.s);
  substdio_puts(subfderr,result);
  substdio_put(subfderr,err.s,err.len);
  substdio_flush(subfderr);
}

void main(argc,argv)
int argc;
char **argv;
{
  int opt;
  char *dir;
  int r;
  char status;
  struct stat st;
  int progress;

  sig_pipeignore();

  while ((opt = getopt(argc,argv,"bt:")) != opteof)
    switch(opt) {
      case 'b':
	flagbounce = 1;
	break;
      case 't':
	scan_ulong(optarg,&lifetime);
	flaglifetime = 1;
	break;
      default:
	die_usage();
    }

  argv += optind;
  dir = *argv++;
  if (!dir) die_usage();
  prefix = *argv++;
  if (!prefix) die_usage();
  client = argv;
  if (!*client) die_usage();

  if (chdir(dir) == -1)
    strerr_die4sys(111,FATAL,"unable to chdir to ",dir,": ");

  readcontrols();

  if (!stralloc_copys(&deadfiles,"")) die_nomem();

  progress = 3;

  for (;;) {
    if (pipe(pic2p) == -1)
      strerr_die2sys(111,FATAL,"unable to create pipe: ");

    pid = fork();
    if (pid == -1)
      strerr_die2sys(111,FATAL,"unable to fork: ");
  
    if (!pid) {
      close(pic2p[0]);
      fd_move(1,pic2p[1]);
      scanner();
    }

    close(pic2p[1]);
    substdio_fdbuf(&ss,read,pic2p[0],buf,sizeof buf);

    --progress;

    for (;;) {
      if (getln(&ss,&fn,&match,'\0') == -1) die_readclient();
      if (!match) break;
      r = substdio_get(&ss,&status,1);
      if (r == -1) die_readclient();
      if (!match) break;
      if (getln(&ss,&err,&match,'\n') == -1) die_readclient();
      if (!match) break;

      progress = 3;

      if (status == 'K') {
	info(" succeeded: ");

	if (unlink(fn.s) == -1) {
	  strerr_warn4(WARNING,"message will be delivered twice! unable to unlink ",fn.s,": ",&strerr_sys);
          if (!stralloc_cat(&deadfiles,&fn)) die_nomem();
	}
	continue;
      }

      flagtimeout = 0;

      if (flaglifetime && (status != 'D')) {
	if (stat(fn.s,&st) == -1)
	  strerr_warn4(WARNING,"assuming message is still alive; unable to stat ",fn.s,": ",&strerr_sys);
	else
	  if (now() > st.st_mtime + lifetime) {
	    status = 'D';
	    flagtimeout = 1;
	  }
      }

      if (flagbounce)
        if (status == 'D') {
	  int fd;
	  int r;

	  info(" bounced: ");

	  fd = open_read(fn.s);
	  if (fd == -1) {
	    strerr_warn4(WARNING,"unable to read ",fn.s,": ",&strerr_sys);
            if (!stralloc_cat(&deadfiles,&fn)) die_nomem();
	    continue;
	  }

	  r = bounce(fd,&err,flagtimeout);
	  if (r == -1)
	    strerr_warn4(WARNING,"unable to bounce ",fn.s,": ",&strerr_sys);
	  if (r == -2)
	    strerr_warn5(WARNING,"unable to bounce ",fn.s,": qq failed: ",qqx + 1,0);
	  if (r == -3)
	    strerr_warn4(WARNING,"unable to bounce ",fn.s,": bad file format",0);
	  if (r == 2)
	    strerr_warn4(INFO,"discarding ",fn.s,": triple bounce",0);
	  if (r == 1) {
	    substdio_puts(subfderr,INFO);
	    substdio_puts(subfderr,"returned ");
	    substdio_puts(subfderr,fn.s);
	    substdio_puts(subfderr,": qp ");
	    substdio_put(subfderr,num,fmt_ulong(num,qp));
	    substdio_puts(subfderr,"\n");
	    substdio_flush(subfderr);
	  }

	  close(fd);

	  if (r > 0) {
	    if (unlink(fn.s) == 0)
	      continue;
	    strerr_warn4(WARNING,"message has been bounced but not removed! unable to unlink ",fn.s,": ",&strerr_sys);
	  }
          if (!stralloc_cat(&deadfiles,&fn)) die_nomem();
	  continue;
        }

      info(status == 'D' ? " failed: " : " failed temporarily: ");
      if (!stralloc_cat(&deadfiles,&fn)) die_nomem();
    }

    close(pic2p[0]);

    if (wait_pid(&wstat,pid) == -1)
      strerr_die2sys(111,FATAL,"unable to get scanner status: ");
    if (wait_crashed(wstat))
      strerr_die2x(111,FATAL,"scanner crashed");
    switch(wait_exitcode(wstat)) {
      case 0: _exit(deadfiles.len ? 111 : 0); /* scanner says no files */
      case 100: _exit(100); /* scanner has produced error message */
      case 111: _exit(111); /* scanner has produced error message */
    }

    if (!progress)
      strerr_die2x(111,FATAL,"making no progress, giving up");
  }
}