/**
 * @project      The CERN Tape Archive (CTA)
 * @copyright    Copyright © 2019-2022 CERN
 * @license      This program is free software, distributed under the terms of the GNU General Public
 *               Licence version 3 (GPL Version 3), copied verbatim in the file "COPYING". You can
 *               redistribute it and/or modify it under the terms of the GPL Version 3, 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.
 *
 *               In applying this licence, CERN does not waive the privileges and immunities
 *               granted to it by virtue of its status as an Intergovernmental Organization or
 *               submit itself to any jurisdiction.
 */

#include <fstream>
#include <sstream>
#include <vector>
#include <map>
#include <limits>

#include "common/exception/UserError.hpp"
#include "Config.hpp"

namespace cta::frontend {

//! Configuration option list type
using optionlist_t = std::vector<std::string>;

Config::Config(const std::string& filename) {
  // Open the config file for reading
  std::ifstream file(filename);
  if(!file) {
    throw exception::UserError("Failed to open " + filename);
  }
  // Parse the config file
  try {
    parse(file);
  } catch(std::exception &ex) {
    throw exception::UserError("Failed to parse configuration file " + filename + ": " + ex.what());
  }
}

const optionlist_t& Config::getOptionList(const std::string& key) const {
  auto it = m_configuration.find(key);
  return it == m_configuration.end() ? m_nulloptionlist : it->second;
}

std::optional<std::string> Config::getOptionValueStr(const std::string &key) const {
  auto optionlist = getOptionList(key);

  return optionlist.empty() ? std::nullopt : std::optional<std::string>(optionlist.at(0));
}

std::optional<int> Config::getOptionValueInt(const std::string &key) const {
  auto optionlist = getOptionList(key);

  return optionlist.empty() ? std::nullopt : std::optional<int>(std::stoi(optionlist.at(0)));
}

std::optional<uint32_t> Config::getOptionValueUInt(const std::string &key) const {

  auto optionlist = getOptionList(key);

  return optionlist.empty() ? std::nullopt : std::optional<uint32_t>(stou<uint32_t>(optionlist.at(0)));

}

void Config::parse(std::ifstream &file) {
  std::string line;

  while(std::getline(file, line)) {
    // Strip out comments
    auto pos = line.find('#');
    if(pos != std::string::npos) {
      line.resize(pos);
    }

    // Extract the key
    std::istringstream ss(line);
    std::string key;
    ss >> key;

    // Extract and store the config options
    if(!key.empty()) {
      optionlist_t values = tokenize(ss);

      if(!values.empty()) {
        m_configuration[key] = values;
      }
    }
  }
}

optionlist_t Config::tokenize(std::istringstream &input) {
  optionlist_t values;

  while(!input.eof()) {
    std::string value;
    input >> value;
    if(!value.empty()) values.push_back(value);
  }

  return values;
}

template<class T>
T Config::stou(const std::string &strVal) const {
    
  try {
    std::size_t uiPos = 0;
    auto lVal = stoll(strVal, &uiPos);
    // Do not accept value like: 123abc
    if (uiPos != strVal.size()) {
      throw std::invalid_argument("Invalid argument");
    }
    if (lVal < 0) {
      throw std::out_of_range("Negative value");
    }
    if(static_cast<uint64_t>(lVal) > std::numeric_limits<T>::max()) {
      throw std::out_of_range("Above maximum value");
    }
  } catch (std::invalid_argument const& ex) {
    std::ostringstream strErrMsg;
    strErrMsg << "stou(" << strVal << "): Invalid argument";
    throw std::invalid_argument(strErrMsg.str());
  } catch (std::out_of_range const& ex) {
    std::ostringstream strErrMsg;
    strErrMsg << "stou(" << strVal << "): " << ex.what();
    if(std::numeric_limits<int64_t>::max() < std::numeric_limits<T>::max()) {
      strErrMsg << ", expected correct value is in the range [0, " << std::numeric_limits<int64_t>::max() << "]";
    } else {
      strErrMsg << ", expected correct value is in the range [0, " << std::numeric_limits<T>::max() << "]";
    }
    throw std::out_of_range(strErrMsg.str());
  }

  auto ulVal = std::stoul(strVal);

  return static_cast<T>(ulVal);
}

} // namespace cta::frontend