/*
 * Copyright (c) 2017-2019 Cisco and/or its affiliates.
 * Licensed 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.
 */

#ifndef _WIN32
#include <unistd.h>
#endif
#include <ctype.h>
#include <errno.h>
#include <hicn/hicn-light/config.h>
#include <stdio.h>
#include <string.h>

#include <parc/algol/parc_ArrayList.h>
#include <parc/algol/parc_List.h>
#include <parc/algol/parc_Memory.h>
#include <parc/algol/parc_Object.h>
#include <parc/assert/parc_Assert.h>
#include <hicn/config/configuration.h>
#include <hicn/config/configurationFile.h>
#include <hicn/config/controlRoot.h>
#include <hicn/config/controlState.h>

struct configuration_file {
  Forwarder *forwarder;
  const char *filename;
  FILE *fh;

  size_t linesRead;

  // our custom state machine.
  ControlState *controlState;
};

/*
 * Called by a command to dispatch the correct command
 */
struct iovec *_writeRead(ControlState *state, struct iovec *msg) {
  ConfigurationFile *configFile =
      (ConfigurationFile *)controlState_GetUserdata(state);

  parcAssertNotNull(msg, "Parameter msg must be non-null");
  struct iovec *response = configuration_DispatchCommand(
      forwarder_GetConfiguration(configFile->forwarder),
      ((header_control_message *)msg[0].iov_base)->commandID, msg, 0);

  return response;
}

/**
 * Removes leading whitespace (space + tab).
 *
 * If the string is all whitespace, the return value will point to the
 * terminating '\0'.
 *
 * @param [in] str A null-terminated c-string
 *
 * @retval non-null A pointer in to string of the first non-whitespace
 *
 *
 * Example:
 * @code
 * <#example#>
 * @endcode
 */
static char *_stripLeadingWhitespace(char *str) {
  while (isspace(*str)) {
    str++;
  }
  return str;
}

/**
 * Removes trailing whitespace
 *
 * Inserts a NULL after the last non-whitespace character, modiyfing the input
 * string.
 *
 * @param [in] str A null-terminated c-string
 *
 * @return non-null A pointer to the input string
 *
 * Example:
 * @code
 * {
 *     <#example#>
 * }
 * @endcode
 */
static char *_stripTrailingWhitespace(char *str) {
  char *p = str + strlen(str) - 1;
  while (p > str && isspace(*p)) {
    p--;
  }

  // cap it.  If no whitespace, p+1 == str + strlen(str), so will overwrite the
  // current null.  If all whitespace p+1 == str+1.  For an empty string, p+1 =
  // str.
  *(p + 1) = 0;

  // this does not catch the case where the entire string is whitespace
  if (p == str && isspace(*p)) {
    *p = 0;
  }

  return str;
}

/**
 * Removed leading and trailing whitespace
 *
 * Modifies the input string (may add a NULL at the end).  Will return
 * a pointer to the first non-whitespace character or the terminating NULL.
 *
 * @param [in] str A null-terminated c-string
 *
 * @return non-null A pointer in to the input string
 *
 * Example:
 * @code
 * {
 *     <#example#>
 * }
 * @endcode
 */
static char *_trim(char *str) {
  return _stripTrailingWhitespace(_stripLeadingWhitespace(str));
}

/**
 * Parse a string in to a PARCList with one word per element
 *
 * The string passed will be modified by inserting NULLs after each token.
 *
 * @param [in] str A c-string (will be modified)
 *
 * @retval non-null A PARCList where each item is a single word
 *
 * Example:
 * @code
 * <#example#>
 * @endcode
 */
static PARCList *_parseArgs(char *str) {
  PARCList *list =
      parcList(parcArrayList_Create(NULL), PARCArrayListAsPARCList);

  const char delimiters[] = " \t";

  char *token;
  token = strtok(str, delimiters);
  while (token != NULL) {
    if (strlen(token) > 0) {
      parcList_Add(list, strdup(token));
    }
    token = strtok(NULL, delimiters);
  }
  // while ((token = strsep(&str, delimiters)) != NULL) {
  //	  parcList_Add(list, token);
  //  }

  return list;
}

// =============================================================

static void _destroy(ConfigurationFile **configFilePtr) {
  ConfigurationFile *configFile = *configFilePtr;
  parcMemory_Deallocate((void **)&configFile->filename);

  if (configFile->fh != NULL) {
    fclose(configFile->fh);
  }

  controlState_Destroy(&configFile->controlState);
}

parcObject_ExtendPARCObject(ConfigurationFile, _destroy, NULL, NULL, NULL, NULL,
                            NULL, NULL);

parcObject_ImplementRelease(configurationFile, ConfigurationFile);

ConfigurationFile *configurationFile_Create(Forwarder *forwarder,
                                            const char *filename) {
  parcAssertNotNull(forwarder, "Parameter hicn-fwd must be non-null");
  parcAssertNotNull(filename, "Parameter filename must be non-null");

  ConfigurationFile *configFile = parcObject_CreateInstance(ConfigurationFile);

  if (configFile) {
    configFile->linesRead = 0;
    configFile->forwarder = forwarder;
    configFile->filename =
        parcMemory_StringDuplicate(filename, strlen(filename));
    parcAssertNotNull(configFile->filename, "Could not copy string '%s'",
                      filename);

    // setup the control state for the command parser: last parameter NULL
    // because
    // writeRead still not implemented from configuration file.
    configFile->controlState =
        controlState_Create(configFile, _writeRead, false,
                            SRV_CTRL_IP, SRV_CTRL_PORT);

    // we do not register Help commands
    controlState_RegisterCommand(configFile->controlState,
                                 controlRoot_Create(configFile->controlState));

    // open the file and make sure we can read it
    configFile->fh = fopen(configFile->filename, "r");

    if (configFile->fh) {
      if (logger_IsLoggable(forwarder_GetLogger(forwarder),
                            LoggerFacility_Config, PARCLogLevel_Debug)) {
        logger_Log(forwarder_GetLogger(forwarder), LoggerFacility_Config,
                   PARCLogLevel_Debug, __func__, "Open config file %s",
                   configFile->filename);
      }
    } else {
      if (logger_IsLoggable(forwarder_GetLogger(forwarder),
                            LoggerFacility_Config, PARCLogLevel_Error)) {
        logger_Log(forwarder_GetLogger(forwarder), LoggerFacility_Config,
                   PARCLogLevel_Error, __func__,
                   "Could not open config file %s: (%d) %s",
                   configFile->filename, errno, strerror(errno));
      }

      // failure cleanup the object -- this nulls it so final return null be
      // NULL
      configurationFile_Release(&configFile);
    }
  }
  return configFile;
}

bool configurationFile_Process(ConfigurationFile *configFile) {
  parcAssertNotNull(configFile, "Parameter configFile must be non-null");

  // default to a "true" return value and only set to false if we encounter an
  // error.
  bool success = true;

#define BUFFERLEN 2048
  char buffer[BUFFERLEN];

  configFile->linesRead = 0;

  // always clear errors and fseek to start of file in case we get called
  // multiple times.
  clearerr(configFile->fh);
  rewind(configFile->fh);

  while (success && fgets(buffer, BUFFERLEN, configFile->fh) != NULL) {
    configFile->linesRead++;

    char *stripedBuffer = _trim(buffer);
    if (strlen(stripedBuffer) > 0) {
      if (stripedBuffer[0] != '#') {
        // not empty and not a comment

        // _parseArgs will modify the string
        char *copy =
            parcMemory_StringDuplicate(stripedBuffer, strlen(stripedBuffer));
        PARCList *args = _parseArgs(copy);
        char output[8192];
        CommandReturn result =
            controlState_DispatchCommand(configFile->controlState, args, output, sizeof(output));

        // we ignore EXIT from the configuration file
        if (result == CommandReturn_Failure) {
          if (logger_IsLoggable(forwarder_GetLogger(configFile->forwarder),
                                LoggerFacility_Config, PARCLogLevel_Error)) {
            logger_Log(forwarder_GetLogger(configFile->forwarder),
                       LoggerFacility_Config, PARCLogLevel_Error, __func__,
                       "Error on input file %s line %d: %s",
                       configFile->filename, configFile->linesRead,
                       stripedBuffer);
          }
          success = false;
        }
        for(int i = 0; i < parcList_Size(args); i++){
          free(parcList_GetAtIndex(args, i));
        }
        parcList_Release(&args);
        parcMemory_Deallocate((void **)&copy);
      }
    }
  }

  if (ferror(configFile->fh)) {
    if (logger_IsLoggable(forwarder_GetLogger(configFile->forwarder),
                          LoggerFacility_Config, PARCLogLevel_Error)) {
      logger_Log(forwarder_GetLogger(configFile->forwarder),
                 LoggerFacility_Config, PARCLogLevel_Error, __func__,
                 "Error on input file %s line %d: (%d) %s",
                 configFile->filename, configFile->linesRead, errno,
                 strerror(errno));
    }
    success = false;
  }

  return success;
}