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

#include <stdio.h>

#include "alloc.h"
#include "buffer.h"
#include "exit.h"
#include "fmt.h"
#include "getln.h"
#include "open.h"
#include "scan.h"
#include "sig.h"
#include "str.h"
#include "stralloc.h"
#include "timeout.h"

#include "commands.h"
#include "maildir.h"
#include "prioq.h"

#define FDIN  0
#define FDOUT 1

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

static ssize_t saferead(int fd, char *buf, int len)
{
  int r;
  r = timeoutread(1200, fd, buf, len);
  if (r <= 0) die();
  return r;
}

static ssize_t safewrite(int fd, char *buf, int len)
{
  int r;
  r = timeoutwrite(1200, fd, buf, len);
  if (r <= 0) die();
  return r;
}

char outbuf[1024];
buffer bo = BUFFER_INIT(safewrite, FDOUT, outbuf, sizeof(outbuf));

char inbuf[128];
buffer bi = BUFFER_INIT(saferead, FDIN, inbuf, sizeof(inbuf));

static void out(char *buf, int len)
{
  buffer_put(&bo, buf, len);
}

static void outs(char *s)
{
  buffer_puts(&bo, s);
}

static void flush()
{
  buffer_flush(&bo);
}

static void err(char *s)
{
  outs("-ERR ");
  outs(s);
  outs("\r\n");
  flush();
}

static void die_nomem()
{
  err("out of memory");
  die();
}

static void die_nomaildir()
{
  err("this user has no $HOME/Maildir");
  die();
}

static void die_scan()
{
  err("unable to scan $HOME/Maildir");
  die();
}

static void err_syntax()
{
  err("syntax error");
}

static void err_unimpl()
{
  err("unimplemented");
}

static void err_deleted()
{
  err("already deleted");
}

static void err_nozero()
{
  err("messages are counted from 1");
}

static void err_toobig()
{
  err("not that many messages");
}

static void err_nosuch()
{
  err("unable to open that message");
}

static void err_nounlink()
{
  err("unable to unlink all deleted messages");
}

static void okay()
{
  outs("+OK \r\n");
  flush();
}

static void printfn(char *fn)
{
  fn += 4;
  out(fn, str_chr(fn, ':'));
}

char strnum[FMT_ULONG];
stralloc line = {0};

static void blast(buffer *bf, unsigned long limit)
{
  int match;
  int inheaders = 1;

  for (;;) {
    if (getln(bf, &line, &match, '\n') != 0) die();
    if (!match && !line.len) break;
    if (match) --line.len; /* no way to pass this info over POP */
    if (limit)
      if (!inheaders)
        if (!--limit) break;
    if (!line.len)
      inheaders = 0;
    else if (line.s[0] == '.')
      out(".", 1);
    out(line.s, line.len);
    out("\r\n", 2);

    if (!match) break;
  }
  out("\r\n.\r\n", 5);
  flush();
}

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

struct message {
  int flagdeleted;
  unsigned long size;
  char *fn;
} *m;

int numm;
int last = 0;

static void getlist()
{
  struct prioq_elt pe;
  struct stat st;
  int i;

  maildir_clean(&line);
  if (maildir_scan(&pq, &filenames, 1, 1) == -1) die_scan();

  numm = pq.p ? pq.len : 0;
  m = (struct message *)alloc(numm * sizeof(struct message));
  if (!m) die_nomem();

  for (i = 0; i < numm; ++i) {
    if (!prioq_min(&pq, &pe)) {
      numm = i;
      break;
    }
    prioq_delmin(&pq);
    m[i].fn = filenames.s + pe.id;
    m[i].flagdeleted = 0;
    if (stat(m[i].fn, &st) == -1)
      m[i].size = 0;
    else
      m[i].size = st.st_size;
  }
}

static void pop3_stat()
{
  int i;
  unsigned long total;

  total = 0;
  for (i = 0; i < numm; ++i)
    if (!m[i].flagdeleted) total += m[i].size;

  outs("+OK ");
  out(strnum, fmt_uint(strnum, numm));
  outs(" ");
  out(strnum, fmt_ulong(strnum, total));
  outs("\r\n");
  flush();
}

static void pop3_rset()
{
  int i;

  for (i = 0; i < numm; ++i) m[i].flagdeleted = 0;
  last = 0;
  okay();
}

static void pop3_last()
{
  outs("+OK ");
  out(strnum, fmt_uint(strnum, last));
  outs("\r\n");
  flush();
}

static void pop3_quit()
{
  int i;

  for (i = 0; i < numm; ++i) {
    if (m[i].flagdeleted) {
      if (unlink(m[i].fn) == -1) err_nounlink();
    } else {
      if (str_start(m[i].fn, "new/")) {
        if (!stralloc_copys(&line, "cur/")) die_nomem();
        if (!stralloc_cats(&line, m[i].fn + 4)) die_nomem();
        if (!stralloc_cats(&line, ":2,")) die_nomem();
        if (!stralloc_0(&line)) die_nomem();
        rename(m[i].fn, line.s); /* if it fails, bummer */
      }
    }
  }
  okay();
  die();
}

static int msgno(char *arg)
{
  unsigned long u;

  if (!scan_ulong(arg, &u)) {
    err_syntax();
    return -1;
  }
  if (!u) {
    err_nozero();
    return -1;
  }
  --u;
  if (u >= numm) {
    err_toobig();
    return -1;
  }
  if (m[u].flagdeleted) {
    err_deleted();
    return -1;
  }
  return u;
}

static void pop3_dele(char *arg)
{
  int i;

  i = msgno(arg);
  if (i == -1) return;
  m[i].flagdeleted = 1;
  if (i + 1 > last) last = i + 1;
  okay();
}

static void list(int i, int flaguidl)
{
  out(strnum, fmt_uint(strnum, i + 1));
  outs(" ");
  if (flaguidl)
    printfn(m[i].fn);
  else
    out(strnum, fmt_ulong(strnum, m[i].size));
  outs("\r\n");
}

static void dolisting(char *arg, int flaguidl)
{
  unsigned int i;

  if (*arg) {
    i = msgno(arg);
    if (i == -1) return;

    outs("+OK ");
    list(i, flaguidl);
  } else {
    okay();
    for (i = 0; i < numm; ++i)
      if (!m[i].flagdeleted) list(i, flaguidl);
    outs(".\r\n");
  }
  flush();
}

static void pop3_uidl(char *arg)
{
  dolisting(arg, 1);
}

static void pop3_list(char *arg)
{
  dolisting(arg, 0);
}

char msgbuf[1024];
buffer bm;

static void pop3_top(char *arg)
{
  int i;
  unsigned long limit;
  int fd;

  i = msgno(arg);
  if (i == -1) return;

  arg += scan_ulong(arg, &limit);
  while (*arg == ' ') ++arg;
  if (scan_ulong(arg, &limit))
    ++limit;
  else
    limit = 0;

  fd = open_read(m[i].fn);
  if (fd == -1) {
    err_nosuch();
    return;
  }
  okay();
  buffer_init(&bm, read, fd, msgbuf, sizeof(msgbuf));
  blast(&bm, limit);
  close(fd);
}

struct commands pop3commands[] = {
    {"quit",  pop3_quit, 0},
    {"stat",  pop3_stat, 0},
    {"list",  pop3_list, 0},
    {"uidl",  pop3_uidl, 0},
    {"dele",  pop3_dele, 0},
    {"retr",   pop3_top, 0},
    {"rset",  pop3_rset, 0},
    {"last",  pop3_last, 0},
    { "top",   pop3_top, 0},
    {"noop",       okay, 0},
    {     0, err_unimpl, 0}
};

int main(int argc, char **argv)
{
  sig_alarmcatch(die);
  sig_pipeignore();

  if (!argv[1]) die_nomaildir();
  if (chdir(argv[1]) == -1) die_nomaildir();

  getlist();

  okay();
  commands(&bi, pop3commands);
  die();
}