/* Copyright 1996 by Eric S. Raymond
 * All rights reserved.
 * For license terms, see the file COPYING in this directory.
 */

/***********************************************************************
  module:       imap.c
  project:      popclient
  programmer:   Eric S. Raymond
  description:  IMAP client code

 ***********************************************************************/

#include  <config.h>
#include  <varargs.h>

#include  <stdio.h>
#if defined(STDC_HEADERS)
#include  <string.h>
#endif
#if defined(HAVE_UNISTD_H)
#include  <unistd.h>
#endif

#include  <sys/time.h>
#include  <ctype.h>
#include  <errno.h>

#include  "socket.h"
#include  "popclient.h"

#define	  IMAP_PORT	143

#ifdef HAVE_PROTOTYPES
/* prototypes for internal functions */
int IMAP_OK (char *buf, int socket);
void IMAP_send ();
int IMAP_cmd ();
int IMAP_readmsg (int socket, int mboxfd, int len,
       char *host, int topipe, int rewrite);
#endif

#define TAGLEN	5
static char tag[TAGLEN];
static int tagnum;
#define GENSYM	(sprintf(tag, "a%04d", ++tagnum), tag)

static int exists;
static int unseen;
static int recent;

/*********************************************************************
  function:      doIMAP
  description:   retrieve messages from the specified mail server
                 using IMAP Version 2bis or Version 4.

  arguments:     
    queryctl     fully-specified options (i.e. parsed, defaults invoked,
                 etc).

  return value:  exit code from the set of PS_.* constants defined in 
                 popclient.h
  calls:
  globals:       reads outlevel.
 *********************************************************************/

int doIMAP (queryctl)
struct hostrec *queryctl;
{
    int ok, num, len;
    int mboxfd;
    char buf [POPBUFSIZE];
    int socket;
    int first,number,count;

    tagnum = 0;

    /* open stdout or the mailbox, locking it if it is a folder */
    if (queryctl->output == TO_FOLDER || queryctl->output == TO_STDOUT) 
	if ((mboxfd = openuserfolder(queryctl)) < 0) 
	    return(PS_IOERR);
    
    /* open the socket */
    if ((socket = Socket(queryctl->servername,IMAP_PORT)) < 0) {
	perror("doIMAP: socket");
	ok = PS_SOCKET;
	goto closeUp;
    }

    /* accept greeting message from IMAP server */
    ok = IMAP_OK(buf,socket);
    if (ok != 0) {
	if (ok != PS_SOCKET)
	    IMAP_cmd(socket, "LOGOUT");
	close(socket);
	goto closeUp;
    }

    /* print the greeting */
    if (outlevel > O_SILENT && outlevel < O_VERBOSE) 
	fprintf(stderr,"IMAP greeting: %s\n",buf);

    /* try to get authorized */
    ok = IMAP_cmd(socket,
		  "LOGIN %s %s",
		  queryctl->remotename, queryctl->password);
    if (ok == PS_ERROR)
	ok = PS_AUTHFAIL;
    if (ok != 0)
	goto cleanUp;

    /* find out how many messages are waiting */
    exists = unseen = recent = -1;
    ok = IMAP_cmd(socket,
		  "SELECT %s",
		  queryctl->remotefolder[0] ? queryctl->remotefolder : "INBOX");
    if (ok != 0)
	goto cleanUp;

    /* compute size of message run */
    count = exists;
    if (queryctl->fetchall)
	first = 1;
    else {
	if (exists > 0 && unseen == -1) {
	    fprintf(stderr,
		    "no UNSEEN response; assuming all %d RECENT messages are unseen\n",
		    recent);
	    first = exists - recent + 1;
	} else {
	    first = unseen;
	}
    }

    /* show them how many messages we'll be downloading */
    if (outlevel > O_SILENT && outlevel < O_VERBOSE)
	if (first > 1) 
	    fprintf(stderr,"%d messages in folder, %d new messages.\n", 
		    count, count - first + 1);
	else
	    fprintf(stderr,"%d %smessages in folder.\n", count, ok ? "" : "new ");

    if (count > 0) { 
	for (number = queryctl->flush ? 1 : first;  number<=count; number++) {

	    char *cp;

	    /* open the mail pipe if we're using an MDA */
	    if (queryctl->output == TO_MDA
		&& (queryctl->fetchall || number >= first)) {
		ok = (mboxfd = openmailpipe(queryctl)) < 0 ? -1 : 0;
		if (ok != 0)
		    goto cleanUp;
	    }
           
	    if (queryctl->flush && number < first && !queryctl->fetchall) 
		ok = 0;  /* no command to send here, will delete message below */
	    else if (linelimit) 
		IMAP_send(socket,
			  "PARTIAL %d RFC822 0 %d",
			  number, linelimit);
	    else 
		IMAP_send(socket,
			  "FETCH %d RFC822",
			  number);

	    if (number >= first || queryctl->fetchall) {
		/* looking for FETCH response */
		do {
		    if (SockGets(socket, buf,sizeof(buf)) < 0)
			return(PS_SOCKET);
		} while
		       (sscanf(buf+2, "%d FETCH (RFC822 {%d}", &num, &len)!=2);
		if (outlevel == O_VERBOSE)
		    fprintf(stderr,"fetching message %d (%d bytes)\n",num,len);
		ok = IMAP_readmsg(socket,mboxfd, len,
				  queryctl->servername,
				  queryctl->output == TO_MDA, 
				  queryctl->rewrite);
		/* discard tail of FETCH response */
		if (SockGets(socket, buf,sizeof(buf)) < 0)
		    return(PS_SOCKET);
	    }
	    else
		ok = 0;

	    if (ok != 0)
		goto cleanUp;

	    /* maybe we delete this message now? */
	    if ((number < first && queryctl->flush) || !queryctl->keep) {
		if (outlevel > O_SILENT && outlevel < O_VERBOSE) 
		    fprintf(stderr,"flushing message %d\n", number);
		else
		    ;
		ok = IMAP_cmd(socket,
			      "STORE %d +FLAGS (\\Deleted)",
			      number);
		if (ok != 0)
		    goto cleanUp;
	    }

	    /* close the mail pipe, we'll reopen before next message */
	    if (queryctl->output == TO_MDA
		&& (queryctl->fetchall || number >= first)) {
		ok = closemailpipe(mboxfd);
		if (ok != 0)
		    goto cleanUp;
	    }
	}

	/* remove all messages flagged for deletion */
        if (!queryctl->keep)
	{
	    ok = IMAP_cmd(socket, "EXPUNGE");
	    if (ok != 0)
		goto cleanUp;
        }

	ok = IMAP_cmd(socket, "LOGOUT");
	if (ok == 0)
	    ok = PS_SUCCESS;
	close(socket);
	goto closeUp;
    }
    else {
	ok = IMAP_cmd(socket, "LOGOUT");
	if (ok == 0)
	    ok = PS_NOMAIL;
	close(socket);
	goto closeUp;
    }

cleanUp:
    if (ok != 0 && ok != PS_SOCKET)
	IMAP_cmd(socket, "LOGOUT");

closeUp:
    if (queryctl->output == TO_FOLDER)
	if (closeuserfolder(mboxfd) < 0 && ok == 0)
	    ok = PS_IOERR;
    
    if (ok == PS_IOERR || ok == PS_SOCKET) 
	perror("doIMAP: cleanUp");

    return(ok);
}

/*********************************************************************
  function:      IMAP_OK
  description:   get the server's response to a command, and return
                 the extra arguments sent with the response.
  arguments:     
    argbuf       buffer to receive the argument string.
    socket       socket to which the server is connected.

  return value:  zero if okay, else return code.
  calls:         SockGets
  globals:       reads outlevel.
 *********************************************************************/

int IMAP_OK (argbuf,socket)
char *argbuf;
int socket;
{
  int ok;
  char buf [POPBUFSIZE];
  char *bufp;
  int n;

  do {
    if (SockGets(socket, buf, sizeof(buf)) < 0)
      return(PS_SOCKET);

    if (outlevel == O_VERBOSE)
      fprintf(stderr,"%s\n",buf);

    /* interpret untagged status responses */
    if (strstr(buf, "EXISTS"))
	exists = atoi(buf+2);
    if (strstr(buf, "RECENT"))
	recent = atoi(buf+2);
    if (sscanf(buf + 2, "OK [UNSEEN %d]", &n) == 1)
	unseen = n;

  } while
      (tag[0] != '\0' && strncmp(buf, tag, strlen(tag)));

  if (tag[0] == '\0')
    return(0); 
  else {
    if (strncmp(buf + TAGLEN + 1, "OK", 2) == 0) {
      strcpy(argbuf, buf + TAGLEN);
      return(0);
    }
    else if (strncmp(buf + TAGLEN + 1, "BAD", 2) == 0)
      return(PS_ERROR);
    else
      return(PS_PROTOCOL);
  }
}

/*********************************************************************
  function:      IMAP_send
  description:   Assemble command in print style and send to the server

  arguments:     
    socket       socket to which the server is connected.
    fmt          printf-style format

  return value:  none.
  calls:         SockPuts.
  globals:       reads outlevel.
 *********************************************************************/

void IMAP_send(socket, fmt, va_alist)
int socket;
const char *fmt;
va_dcl {

  char buf [POPBUFSIZE];
  va_list ap;

  (void) sprintf(buf, "%s ", GENSYM);

  va_start(ap);
  vsprintf(buf + strlen(buf), fmt, ap);
  va_end(ap);

  SockPuts(socket, buf);

  if (outlevel == O_VERBOSE)
    fprintf(stderr,"> %s\n", buf);
}

/*********************************************************************
  function:      IMAP_cmd
  description:   Assemble command in print style and send to the server

  arguments:     
    socket       socket to which the server is connected.
    fmt          printf-style format

  return value:  none.
  calls:         SockPuts, IMAP_OK.
  globals:       reads outlevel.
 *********************************************************************/

int IMAP_cmd(socket, fmt, va_alist)
int socket;
const char *fmt;
va_dcl {

  int ok;
  char buf [POPBUFSIZE];
  va_list ap;

  (void) sprintf(buf, "%s ", GENSYM);

  va_start(ap);
  vsprintf(buf + strlen(buf), fmt, ap);
  va_end(ap);

  SockPuts(socket, buf);

  if (outlevel == O_VERBOSE)
    fprintf(stderr,"> %s\n", buf);

  ok = IMAP_OK(buf,socket);
  if (ok != 0 && outlevel > O_SILENT && outlevel < O_VERBOSE)
    fprintf(stderr,"%s\n",buf);

  return(ok);
}

/*********************************************************************
  function:      IMAP_readmsg
  description:   Read the message content 

 as described in RFC 1225.
  arguments:     
    socket       ... to which the server is connected.
    mboxfd       open file descriptor to which the retrieved message will
                 be written.
    len          lrength of text 
    pophost      name of the POP host 
    topipe       true if we're writing to the system mailbox pipe.

  return value:  zero if success else PS_* return code.
  calls:         SockGets.
  globals:       reads outlevel. 
 *********************************************************************/

int IMAP_readmsg (socket,mboxfd,len,pophost,topipe,rewrite)
int socket;
int mboxfd;
int len;
char *pophost;
int topipe;
int rewrite;
{ 
  char buf [MSGBUFSIZE]; 
  char *bufp;
  char savec;
  char fromBuf[MSGBUFSIZE];
  int n;
  int needFrom;
  int inheaders;
  int lines,sizeticker;
  time_t now;
  /* This keeps the retrieved message count for display purposes */
  static int msgnum = 0;  

  /* set up for status message if outlevel allows it */
  if (outlevel > O_SILENT && outlevel < O_VERBOSE) {
    fprintf(stderr,"reading message %d",++msgnum);
    /* won't do the '...' if retrieved messages are being sent to stdout */
    if (mboxfd == 1)
      fputs(".\n",stderr);
    else
      ;
  }
  else
    ;

  /* read the message content from the server */
  inheaders = 1;
  lines = 0;
  sizeticker = MSGBUFSIZE;
  while (len > 0) {
    if ((n = SockGets(socket,buf,sizeof(buf))) < 0)
      return(PS_SOCKET);
    len -= n;
    bufp = buf;
    if (buf[0] == '\r' || buf[0] == '\n')
      inheaders = 0;
    if (*bufp == '.') {
      bufp++;
    }
    strcat(bufp,"\n");
     
    /* Check for Unix 'From' header, and add a bogus one if it's not
       present -- only if not using an MDA.
       XXX -- should probably parse real From: header and use its 
              address field instead of bogus 'POPmail' string. 
    */
    if (!topipe && lines == 0) {
      if (strlen(bufp) >= strlen("From ")) {
        savec = *(bufp + 5);
        *(bufp + 5) = 0;
        needFrom = strcmp(bufp,"From ") != 0;
        *(bufp + 5) = savec;
      }
      else
        needFrom = 1;
      if (needFrom) {
        now = time(NULL);
        sprintf(fromBuf,"From POPmail %s",ctime(&now));
        if (write(mboxfd,fromBuf,strlen(fromBuf)) < 0) {
          perror("IMAP_readmsg: write");
          return(PS_IOERR);
        }
      }
    }

    /*
     * Edit some headers so that replies will work properly.
     */
    if (inheaders && rewrite)
      reply_hack(bufp, pophost);

    /* write this line to the file */
    if (write(mboxfd,bufp,strlen(bufp)) < 0) {
      perror("IMAP_readmsg: write");
      return(PS_IOERR);
    }

    sizeticker -= strlen(bufp);
    if (sizeticker <= 0) {
      if (outlevel > O_SILENT && outlevel < O_VERBOSE && mboxfd != 1)
        fputc('.',stderr);
      sizeticker = MSGBUFSIZE;
    }
    lines++;
  }

  if (!topipe) {
    /* The server may not write the extra newline required by the Unix
       mail folder format, so we write one here just in case */
    if (write(mboxfd,"\n",1) < 0) {
      perror("IMAP_readmsg: write");
      return(PS_IOERR);
    }
  }
  else {
    /* The mail delivery agent may require a terminator.  Write it if
       it has been defined */
#ifdef BINMAIL_TERM
    if (write(mboxfd,BINMAIL_TERM,strlen(BINMAIL_TERM)) < 0) {
      perror("IMAP_readmsg: write");
      return(PS_IOERR);
    }
#endif
    }

  /* finish up display output */
  if (outlevel == O_VERBOSE)
    fprintf(stderr,"(%d lines of message content)\n",lines);
  else if (outlevel > O_SILENT && mboxfd != 1) 
    fputs(".\n",stderr);
  else
    ;
  return(0);
}