/*
  ==========================================================================
  wsmail.c by Frank Wang, Copyright 1995

  Functions:

    1. Post reply packets created by wsOMR.
    2. Retrieve mails from system mail box

  Usage:

    Compile this program in the internet side using ff. commands:
      cc wsmail.c
      mv a.out wsmail

    To send replies:
      wsmail r file_name

    To send replies and delete the reply file after sending
      wsmail r- file_name

    To retrieve mails from system mail box and move to a new file:
      wsmail m file_name

    To retrieve mails from system mail box and append to a new/existing file
      wsmail m+ file_name

    To retrieve mails from system mail box without deleting:
      wsmail M file_name

      wsmail M+ file_name

    Note: This program assumes max character per line is 512.
  ==========================================================================
*/

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <memory.h>
#include <sys/types.h>
#include <pwd.h>

#define MAX_NUM 512
#define BUF_SIZE 512
/*#define MAIL_SPOOL  "c:\\usenet\\"*/
#define MAIL_SPOOL  "/usr/spool/mail/"

char *send_cmd  = "sendmail -t ";   /* change this in case different */
char *temp_msg  = "temp.msg";       /* Temporary file for mail processed */
char *wsomr_tag = "$WSOMR$";        /* Message seperating string         */

char user_mail[128];
char home_dir[128];

/* -------------------------------- */
/*  Read next line from the buffer  */
/* -------------------------------- */
next_line( f, buf, buf_siz, cnt, offset, ret_buf )
FILE *f;
char *buf;
int buf_siz, *cnt, *offset;
char *ret_buf;
{
  int ret = 0;

  memset( ret_buf, 0, buf_siz );
  if (*offset < 0)                        /* first pass */
  {
    fseek( f, 0L, 0 );
    *offset = *cnt = 0;
  }
  if (*offset == *cnt)                    /* at end of buffer ? */
  {
    memset( buf, 0, buf_siz );
    *cnt = fread( buf, 1, buf_siz, f );   /* read the next block into buffer */
    *offset = 0;
  }
  while ( *cnt > 0 )
  {
    int k, n;
    char *p = buf + *offset;
    for ( k = *offset, n = 0; *p && *p != '\n' && k < buf_siz; k ++, p++ )
      n ++;

    /* If end of line or block */

    if ( k < buf_siz && (*p == '\n' || *p == 0) ) 
    {
      memcpy( ret_buf, buf + *offset, n );
      ret_buf[n] = 0;
      *offset = ++k;
      ret = 1;
      break;
    }
    else                                  /* The line is not ended in */
    {                                     /* block, read the next block if any */
      int new_siz = buf_siz - n;
      memcpy( buf, buf + *offset, n );
      memset( buf + n, 0, new_siz );
      *cnt = fread( buf + n, 1, new_siz, f );
      if ( *cnt == 0 )                    /* no more left in the file */
      {                                   /* copy whatever left in the prv.blk*/
        memcpy( ret_buf, buf + *offset, n );
        ret_buf[n] = 0;
      }
      else
      {
        *cnt += n;
        *offset = 0;
      }
    }
  }
  return ret;
}

/* ------------------------------------------- */
/*  Send mail using internet sendmail command  */
/* ------------------------------------------- */
send_mail( msg_no, to )
int msg_no;
char *to;
{
  int status;  char cmd[128];
  sprintf( cmd, "%s <%s", send_cmd, temp_msg );
  status  = system( cmd );
  printf("\nMail # %2d, Status: %d, To:%s", msg_no, status, to );
}

/* ------------------------------------------------------------- */
/*  Scan wsOMR created reply file and send one mail at one time  */
/* ------------------------------------------------------------- */
post_all_mails( fname )
char *fname;
{
  int ret = 0;
  FILE *rep = fopen (fname, "rt");
  if (NULL == rep )
    fprintf (stderr, "can't open %s\n", fname );
  else
  {
    FILE *out;
    char buffer[MAX_NUM], ret_buf[MAX_NUM], name[128];
    int cnt, offset = -1, done, msg_no, valid_msg, apnd, end_of_msg;
    cnt = done = apnd = msg_no = valid_msg = end_of_msg = 0;
    while (!done)
    {
      if (!apnd)
      {
        if (NULL == (out = fopen (temp_msg, "wt")))
        {
          fprintf (stderr, "can't create %s\n", temp_msg );
          exit (0);
        }
        apnd = 1;
        end_of_msg = valid_msg = 0;
        memset( name, 0, sizeof(name) );
      }
      done = !next_line( rep, buffer, sizeof(buffer), &cnt, &offset, ret_buf );
      if (!done)
      {
        if ( strncmp( ret_buf, wsomr_tag, strlen(wsomr_tag) ) )
        {
          fwrite( ret_buf, 1, strlen(ret_buf), out );
          fwrite( "\n", 1, 1, out );
          if (!valid_msg)
          {
            valid_msg = strncmp( ret_buf, "To:", 3 ) == 0;
            if (valid_msg)
              strcpy( name, ret_buf + 3 );
          }
        }
        else
          end_of_msg = 1;
      }
      if ( (apnd && valid_msg) && (done || end_of_msg) )
      {
        fclose( out );
        msg_no ++;
        send_mail( msg_no, name );
        apnd = end_of_msg = valid_msg = 0;
      }
    }
    if ( apnd )      /* invalid message encountered */
      fclose( out );
    printf("\n");
    fclose( rep );
  }
  return ret;
}

/*
  ---------------------------------------
    Retrieve user info from UNIX system
  ---------------------------------------
*/
set_param()
{
  struct passwd *pw;
  if (NULL == (pw = getpwuid(getuid())))
  {
    fprintf ( stderr, "can't determin user info\n");
    return 0;
  }
  else
  {
    strcpy ( user_mail, MAIL_SPOOL );
    strcat ( user_mail, pw -> pw_name );
    strcpy ( home_dir,  pw -> pw_dir );
    return 1;
  }
}

/*
  --------------------------------------------------------
    Move personal mail from system mail box to file_name
  --------------------------------------------------------
*/
get_mail( file_name, read_only, is_append )
char *file_name;
int read_only, is_append;
{
  int  done = 0;
  long fsize = 0;
  FILE *mail, *folder;
  char *mode = is_append ? "ab" : "wb";

  /* Open user's mail file */
  if (NULL == (mail = fopen (user_mail, "rb")))
  {
    fprintf ( stderr, "\ncan't open %s\n", user_mail );
    return 0;
  }
  else
  {
    fseek( mail, 0L, 2 );
    if ( !ftell(mail) )
    {
      fprintf ( stderr, "\nmail box is empty\n" );
      fclose(mail);
      return 0;
    }
    else
      rewind(mail);
  }

  if (NULL == (folder = fopen (file_name, mode )))
  {
    fprintf ( stderr, "\ncan't create %s\n", file_name );
    return 0;
  }

  /* Copy */
  while (!done)
  {
    unsigned char buffer[BUF_SIZE];
    int  rcount, wcount;
    rcount = fread( buffer, 1, sizeof(buffer), mail );
    done = rcount < sizeof(buffer);
    wcount = fwrite( buffer,1, rcount, folder );
    if ( wcount != rcount )
    {
      fprintf (stderr, "Error in writing file \n", file_name );
      return 0;
    }
    fsize += wcount;
  }
  fclose (mail);
  fclose (folder);

  if (!read_only)
  {
    if (NULL == (mail = fopen (user_mail, "wb")))
      fprintf (stderr, "can't write %s\n", user_mail );
    else
      fclose (mail);
  }
  return (fsize);
}

void syntax()
{
  printf( "Postman for wsOMR by Frank Wang\n" );
  printf( "\nSyntax: wsmail [rm] file_name" );
  printf( "\n        r  post reply(file_name)" );
  printf( "\n        r- post reply(file_name) and delete afterwards" );
  printf( "\n        m  copy mails to file_name" );
  printf( "\n        m+ append mails to file_name" );
  printf( "\n        M  copy mails(read only) to file_name" );
  printf( "\n        M+ append mails(read only) to file_name" );
  printf( "\n" );
}

main( argc, argv )
int argc;
char *argv[];
{
  int ret = 1;
  char *param, *file_name;

  if ( argc > 2 )
  {
    char optn, mode;
    param     = argv[1];
    file_name = argv[2];

    optn = param[0];
    mode = param[1];    /* optional switch */

    if ( optn == 'r' )
    {
      post_all_mails( file_name );
      if ( mode == '-' )
        unlink( file_name );
      ret = 0;
    }
    else if ( optn == 'm' || optn == 'M' )
    {
      if ( set_param() )
      {
        long siz = get_mail(file_name, optn == 'M', mode == '+' );
        if ( siz > 0 )
        {
          printf( "\nmails packed into %s (%u characters)\n", file_name, siz );
          ret = 0;
        }
      }
    }
    else
      syntax();
  }
  else
    syntax();
  exit(ret);
}