/*
 * Copyright (c) 2015 Balabit
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * As an additional exemption you are allowed to compile & link against the
 * OpenSSL libraries as published by the OpenSSL project. See the file
 * COPYING for details.
 */

#include "filter/filter-expr.h"
#include "filter/filter-expr-parser.h"
#include "cfg.h"
#include "value-pairs/value-pairs.h"
#include "value-pairs/cmdline.h"
#include "syslog-ng.h"
#include "str-utils.h"
#include "format-cef-extension.h"

typedef struct _TFCefState
{
  TFSimpleFuncState super;
  ValuePairs *vp;
} TFCefState;

static gboolean
tf_cef_prepare(LogTemplateFunction *self, gpointer s, LogTemplate *parent,
               gint argc, gchar *argv[],
               GError **error)
{
  TFCefState *state = (TFCefState *)s;

  state->vp = value_pairs_new_from_cmdline(parent->cfg, &argc, &argv, NULL, NULL, error);
  if (!state->vp)
    return FALSE;

  return TRUE;
}

typedef struct
{
  gboolean need_separator;
  GString *buffer;
  const LogTemplateOptions *template_options;
} CefWalkerState;

static gboolean
tf_cef_is_valid_key(const gchar *str)
{
  size_t end = strspn(str, "0123456789"
                      "abcdefghijklmnopqrstuvwxyz"
                      "ABCDEFGHIJKLMNOPQRSTUVWXYZ");
  return str[end] == '\0';
}

static inline void
tf_cef_append_escaped(GString *escaped_string, const gchar *str, gsize str_len)
{
  const gchar *char_ptr;
  gunichar uchar;

  while (str_len)
    {
      uchar = g_utf8_get_char_validated(str, str_len);

      switch (uchar)
        {
        case (gunichar) -1:
        case (gunichar) -2:
          g_string_append_printf(escaped_string, "\\x%02x", *(guint8 *) str++);
          str_len--;
          continue;
          break;
        case '=':
          g_string_append(escaped_string, "\\=");
          break;
        case '\n':
          g_string_append(escaped_string, "\\n");
          break;
        case '\r':
          g_string_append(escaped_string, "\\r");
          break;
        case '\\':
          g_string_append(escaped_string, "\\\\");
          break;
        default:
          if (uchar < 32)
            g_string_append_printf(escaped_string, "\\u%04x", uchar);
          else
            g_string_append_unichar_optimized(escaped_string, uchar);
          break;
        }
      char_ptr = g_utf8_next_char(str);
      str_len -= char_ptr - str;
      str = char_ptr;
    }
}

static gboolean
tf_cef_append_value(const gchar *name, const gchar *value, gsize value_len,
                    CefWalkerState *state)
{
  if (state->need_separator)
    g_string_append_c(state->buffer, ' ');

  g_string_append(state->buffer, name);

  g_string_append_c(state->buffer, '=');

  tf_cef_append_escaped(state->buffer, value, value_len);

  return TRUE;
}

static gint
tf_cef_walk_cmp(const gchar *s1, const gchar *s2)
{
  return strcmp(s1, s2);
}

static gboolean
tf_cef_walker(const gchar *name, LogMessageValueType type, const gchar *value, gsize value_len,
              gpointer user_data)
{
  CefWalkerState *state = (CefWalkerState *)user_data;
  gint on_error = state->template_options->on_error;

  if (!tf_cef_is_valid_key(name))
    {
      if (!(on_error & ON_ERROR_SILENT))
        {
          msg_error("Invalid CEF key",
                    evt_tag_str("key", name));
        }
      return !!(on_error & ON_ERROR_DROP_MESSAGE);
    }

  tf_cef_append_value(name, value, value_len, state);

  state->need_separator = TRUE;

  return FALSE;
}

static gboolean
tf_cef_append(GString *result, ValuePairs *vp, LogMessage *msg, LogTemplateEvalOptions *options)
{
  CefWalkerState state;

  state.need_separator = FALSE;
  state.buffer = result;
  state.template_options = options->opts;

  return value_pairs_foreach_sorted(vp, tf_cef_walker,
                                    (GCompareFunc) tf_cef_walk_cmp, msg,
                                    options, &state);
}

static void
tf_cef_call(LogTemplateFunction *self, gpointer s,
            const LogTemplateInvokeArgs *args, GString *result, LogMessageValueType *type)
{
  TFCefState *state = (TFCefState *)s;
  gint i;
  gboolean r = TRUE;
  gsize orig_size = result->len;

  *type = LM_VT_STRING;
  for (i = 0; i < args->num_messages; i++)
    r &= tf_cef_append(result, state->vp, args->messages[i], args->options);

  if (!r && (args->options->opts->on_error & ON_ERROR_DROP_MESSAGE))
    g_string_set_size(result, orig_size);
}

static void
tf_cef_free_state(gpointer s)
{
  TFCefState *state = (TFCefState *)s;

  if (state->vp)
    value_pairs_unref(state->vp);
  tf_simple_func_free_state(&state->super);
}

TEMPLATE_FUNCTION(TFCefState, tf_cef, tf_cef_prepare, NULL, tf_cef_call,
                  tf_cef_free_state, NULL);
