#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include "commands.h"
#include "sig.h"
#include "getln.h"
#include "stralloc.h"
#include "buffer.h"
#include "alloc.h"
#include "open.h"
#include "prioq.h"
#include "scan.h"
#include "fmt.h"
#include "str.h"
#include "exit.h"
#include "maildir.h"
#include "timeout.h"
#include "qmail.h"

#define FDIN 0
#define FDOUT 1
#define POP3_TIMEOUT 1200

int rename(const char *,const char *); // stdio.h

void die() { _exit(0); }

ssize_t saferead(int fd,char *buf,int len)
{
  int r;
  r = timeoutread(POP3_TIMEOUT,fd,buf,len);
  if (r <= 0) die();
  return r;
}

ssize_t safewrite(int fd,char *buf,int len)
{
  int r;
  r = timeoutwrite(POP3_TIMEOUT,fd,buf,len);
  if (r <= 0) die();
  return r;
}

char inbuf[BUFSIZE_LINE];
buffer bi = BUFFER_INIT(saferead,FDIN,inbuf,sizeof(inbuf));
char outbuf[BUFSIZE_LINE];
buffer bo = BUFFER_INIT(safewrite,FDOUT,outbuf,sizeof(outbuf));

void out(char *buf,int len)
{
  buffer_put(&bo,buf,len);
}
void outs(char *s)
{
  buffer_puts(&bo,s);
}
void flush()
{
  buffer_flush(&bo);
}
void err(char *s)
{
  outs("-ERR ");
  outs(s);
  outs("\r\n");
  flush();
}

void die_nomem() { err("out of memory"); die(); }
void die_nomaildir() { err("this user has no $HOME/Maildir"); die(); }
void die_scan() { err("unable to scan $HOME/Maildir"); die(); }

void err_syntax() { err("syntax error"); }
void err_unimpl() { err("unimplemented"); }
void err_deleted() { err("already deleted"); }
void err_nozero() { err("messages are counted from 1"); }
void err_toobig() { err("not that many messages"); }
void err_nosuch() { err("unable to open that message"); }
void err_nounlink() { err("unable to unlink all deleted messages"); }

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

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

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

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;

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;
  }
}

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();
}

void pop3_rset()
{
  int i;

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

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

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();
}

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;
}

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();
}

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");
}

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();
}

void pop3_uidl(char *arg) { dolisting(arg,1); }
void pop3_list(char *arg) { dolisting(arg,0); }

char msgbuf[BUFSIZE_MESS];
buffer bm; 

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();
}