/****************************************************************************
 * drivers/syslog/syslog_write.c
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.  The
 * ASF licenses this file to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the
 * License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 ****************************************************************************/

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

#include <nuttx/config.h>

#include <sys/types.h>
#include <assert.h>

#include <nuttx/arch.h>
#include <nuttx/sched.h>
#include <nuttx/syslog/syslog.h>

#include "syslog.h"

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

/****************************************************************************
 * Name: syslog_safe_to_block
 *
 * Description:
 *   Check if it is safe to block for write. If not, the write  defaults to a
 *   non-blocking method.
 *
 * Input Parameters:
 *   None.
 *
 * Returned Value:
 *   true if it is safe to block; false otherwise.
 *
 ****************************************************************************/

static bool syslog_safe_to_block(void)
{
  FAR const struct tcb_s *rtcb;

  /* It's not safe to block in interrupts or when executing the idle loop */

  if (up_interrupt_context() || sched_idletask())
    {
      return false;
    }

  /* It's not safe to block if a signal is being delivered */

  rtcb = nxsched_self();
  if (rtcb->sigdeliver != NULL)
    {
      return false;
    }

  return true;
}

/****************************************************************************
 * Name: syslog_default_write
 *
 * Description:
 *   This provides a default write method for syslog devices that do not
 *   support multiple byte writes  This functions simply loops, outputting
 *   one character at a time.
 *
 * Input Parameters:
 *   buffer - The buffer containing the data to be output
 *   buflen - The number of bytes in the buffer
 *
 * Returned Value:
 *   On success, the number of characters written is returned.  A negated
 *   errno value is returned on any failure.
 *
 ****************************************************************************/

static ssize_t syslog_default_write(FAR const char *buffer, size_t buflen)
{
  size_t nwritten;

  if (!syslog_safe_to_block())
    {
#ifdef CONFIG_SYSLOG_INTBUFFER
      if (up_interrupt_context())
        {
          for (nwritten = 0; nwritten < buflen; nwritten++)
            {
              syslog_add_intbuffer(buffer[nwritten]);
            }
        }
      else
#endif
        {
          int i;

          for (i = 0; i < CONFIG_SYSLOG_MAX_CHANNELS; i++)
            {
              FAR syslog_channel_t *channel = g_syslog_channel[i];
              nwritten = 0;

              if (channel == NULL)
                {
                  break;
                }

#ifdef CONFIG_SYSLOG_IOCTL
              if (channel->sc_state & SYSLOG_CHANNEL_DISABLE)
                {
                  continue;
                }
#endif

              if (channel->sc_ops->sc_write_force != NULL)
                {
#ifdef CONFIG_SYSLOG_CRLF
                  if (!(channel->sc_state & SYSLOG_CHANNEL_DISABLE_CRLF))
                    {
                      size_t head;

                      for (head = 0; head < buflen; head++)
                        {
                          ssize_t ret;

                          /* Check for LF */

                          if (buffer[head] != '\n')
                            {
                              continue;
                            }

                          ret = channel->sc_ops->sc_write_force(channel,
                                                          buffer + nwritten,
                                                          head - nwritten);
                          if (ret < 0)
                            {
                              return ret;
                            }

                          ret = channel->sc_ops->sc_write_force(channel,
                                                                "\r\n", 2);
                          if (ret < 0)
                            {
                              return ret;
                            }

                          nwritten = head + 1;
                        }
                    }
#endif

                  if (nwritten < buflen)
                    {
                      ssize_t ret;

                      ret = channel->sc_ops->sc_write_force(channel,
                                                          buffer + nwritten,
                                                          buflen - nwritten);
                      if (ret < 0)
                        {
                          return ret;
                        }
                      else
                        {
                          nwritten += ret;
                        }
                    }
                }
              else
                {
                  DEBUGASSERT(channel->sc_ops->sc_force != NULL);
                  for (nwritten = 0; nwritten < buflen; nwritten++)
                    {
#ifdef CONFIG_SYSLOG_CRLF
                      /* Check for LF */

                      if (buffer[nwritten] == '\n' &&
                          !(channel->sc_state & SYSLOG_CHANNEL_DISABLE_CRLF))
                        {
                          /* Add CR */

                          channel->sc_ops->sc_force(channel, '\r');
                        }
#endif

                      channel->sc_ops->sc_force(channel, buffer[nwritten]);
                    }
                }
            }
        }
    }
  else
    {
      int i;

      for (i = 0; i < CONFIG_SYSLOG_MAX_CHANNELS; i++)
        {
          FAR syslog_channel_t *channel = g_syslog_channel[i];
          nwritten = 0;

          if (channel == NULL)
            {
              break;
            }

#ifdef CONFIG_SYSLOG_IOCTL
          if (channel->sc_state & SYSLOG_CHANNEL_DISABLE)
            {
              continue;
            }
#endif

          if (channel->sc_ops->sc_write != NULL)
            {
#ifdef CONFIG_SYSLOG_CRLF
              if (!(channel->sc_state & SYSLOG_CHANNEL_DISABLE_CRLF))
                {
                  size_t head;

                  for (head = 0; head < buflen; head++)
                    {
                      size_t ret;

                      /* Check for LF */

                      if (buffer[head] != '\n')
                        {
                          continue;
                        }

                      ret = channel->sc_ops->sc_write(channel,
                                                      buffer + nwritten,
                                                      head - nwritten);
                      if (ret < 0)
                        {
                          return ret;
                        }

                      /* Add CR */

                      ret = channel->sc_ops->sc_write(channel, "\r\n", 2);
                      if (ret < 0)
                        {
                          return ret;
                        }

                      nwritten = head + 1;
                    }
                }
#endif

              if (nwritten < buflen)
                {
                  ssize_t ret;

                  ret = channel->sc_ops->sc_write(channel,
                                                  buffer + nwritten,
                                                  buflen - nwritten);
                  if (ret < 0)
                    {
                      return ret;
                    }
                  else
                    {
                      nwritten += ret;
                    }
                }
            }
          else
            {
              DEBUGASSERT(channel->sc_ops->sc_putc != NULL);
              for (nwritten = 0; nwritten < buflen; nwritten++)
                {
#ifdef CONFIG_SYSLOG_CRLF
                  /* Check for LF */

                  if (buffer[nwritten] == '\n' &&
                      !(channel->sc_state & SYSLOG_CHANNEL_DISABLE_CRLF))
                    {
                      /* Add CR */

                      channel->sc_ops->sc_putc(channel, '\r');
                    }
#endif

                  channel->sc_ops->sc_putc(channel, buffer[nwritten]);
                }
            }
        }
    }

  return nwritten;
}

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

/****************************************************************************
 * Name: syslog_write
 *
 * Description:
 *   This is the low-level, multiple character, system logging interface.
 *
 * Input Parameters:
 *   buffer - The buffer containing the data to be output
 *   buflen - The number of bytes in the buffer
 *
 * Returned Value:
 *   On success, the number of characters written is returned.  A negated
 *   errno value is returned on any failure.
 *
 ****************************************************************************/

ssize_t syslog_write(FAR const char *buffer, size_t buflen)
{
#ifdef CONFIG_SYSLOG_INTBUFFER
  if (!up_interrupt_context() && !sched_idletask())
    {
      /* Flush any characters that may have been added to the interrupt
       * buffer.
       */

      syslog_flush_intbuffer(false);
    }
#endif

  return syslog_default_write(buffer, buflen);
}