/****************************************************************************
 * apps/system/readline/readline.c
 *
 *   Copyright (C) 2007-2008, 2011-2013 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <sys/types.h>
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <assert.h>

#include "system/readline.h"
#include "readline.h"

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

/****************************************************************************
 * Private Type Declarations
 ****************************************************************************/

struct readline_s
{
  struct rl_common_s vtbl;
  int infd;
#ifdef CONFIG_READLINE_ECHO
  int outfd;
#endif
};

/****************************************************************************
 * Private Function Prototypes
 ****************************************************************************/

/****************************************************************************
 * Public Data
 ****************************************************************************/

/****************************************************************************
 * Private Data
 ****************************************************************************/

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: readline_getc
 ****************************************************************************/

static int readline_getc(FAR struct rl_common_s *vtbl)
{
  FAR struct readline_s *priv = (FAR struct readline_s *)vtbl;
  char buffer;
  ssize_t nread;

  DEBUGASSERT(priv);

  /* Loop until we successfully read a character (or until an unexpected
   * error occurs).
   */

  do
    {
      /* Read one character from the incoming stream */

      nread = read(priv->infd, &buffer, 1);

      /* Check for end-of-file. */

      if (nread == 0)
        {
          /* Return EOF on end-of-file */

          return EOF;
        }

      /* Check if an error occurred */

      else if (nread < 0)
        {
          /* EINTR is not really an error; it simply means that a signal we
           * received while watiing for intput.
           */

          int errcode = errno;
          if (errcode != EINTR)
            {
              /* Return EOF on any errors that we cannot handle */

              return EOF;
            }
        }
    }
  while (nread < 1);

  /* On success, return the character that was read */

  return (int)buffer;
}

/****************************************************************************
 * Name: readline_putc
 ****************************************************************************/

#ifdef CONFIG_READLINE_ECHO
static void readline_putc(FAR struct rl_common_s *vtbl, int ch)
{
  FAR struct readline_s *priv = (FAR struct readline_s *)vtbl;
  char buffer = ch;
  ssize_t nwritten;

  DEBUGASSERT(priv);

  /* Loop until we successfully write a character (or until an unexpected
   * error occurs).
   */

  do
    {
      /* Write the character to the outgoing stream */

      nwritten = write(priv->outfd, &buffer, 1);

      /* Check for irrecoverable write errors. */

      if (nwritten < 0 && errno != EINTR)
        {
          break;
        }
    }
  while (nwritten < 1);
}
#endif

/****************************************************************************
 * Name: readline_write
 ****************************************************************************/

#ifdef CONFIG_READLINE_ECHO
static void readline_write(FAR struct rl_common_s *vtbl,
                           FAR const char *buffer, size_t buflen)
{
  FAR struct readline_s *priv = (FAR struct readline_s *)vtbl;
  DEBUGASSERT(priv && buffer && buflen > 0);

  (void)write(priv->outfd, buffer, buflen);
}
#endif

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: readline
 *
 *   readline() reads in at most one less than 'buflen' characters from
 *   'instream' and stores them into the buffer pointed to by 'buf'.
 *   Characters are echoed on 'outstream'.  Reading stops after an EOF or a
 *   newline.  If a newline is read, it is stored into the buffer.  A null
 *   terminator is stored after the last character in the buffer.
 *
 *   This version of realine assumes that we are reading and writing to
 *   a VT100 console.  This will not work well if 'instream' or 'outstream'
 *   corresponds to a raw byte steam.
 *
 *   This function is inspired by the GNU readline but is an entirely
 *   different creature.
 *
 * Input Parameters:
 *   buf       - The user allocated buffer to be filled.
 *   buflen    - the size of the buffer.
 *   instream  - The stream to read characters from
 *   outstream - The stream to each characters to.
 *
 * Returned values:
 *   On success, the (positive) number of bytes transferred is returned.
 *   EOF is returned to indicate either an end of file condition or a
 *   failure.
 *
 ****************************************************************************/

ssize_t readline(FAR char *buf, int buflen, FILE *instream, FILE *outstream)
{
  struct readline_s vtbl;

  /* Sanity checks */

  DEBUGASSERT(instream && outstream);

  /* Set up the vtbl structure */

  vtbl.vtbl.rl_getc  = readline_getc;
  vtbl.infd          = instream->fs_fd;

#ifdef CONFIG_READLINE_ECHO
  vtbl.vtbl.rl_putc  = readline_putc;
  vtbl.vtbl.rl_write = readline_write;
  vtbl.outfd         = outstream->fs_fd;
#endif

  /* The let the common readline logic do the work */

  return readline_common(&vtbl.vtbl, buf, buflen);
}
