#pragma once

#include <iostream>
#include <utility>

#include "arguments.h"
#include "exception.h"
#include "utilities.h"

#ifndef PROGRAM_ARGS_NOEXIT_ON_HELP
#define PROGRAM_ARGS_EXIT(X) std::exit(X)
#else
#define PROGRAM_ARGS_EXIT(X) (void)X
#endif

namespace program {

template <typename Impl>
template <typename T>
Arguments<Impl>::Action::operator T() const {
  static_assert(std::is_base_of_v<Arguments<T>, T>,
                "Action can only bind to Arguments");
  if (!primed()) {
    self->actions.emplace(name, [](int argc, char const * const *argv) {
      return [action = T(argc, argv)](Arguments<Impl> const &args){
        return typed_main(args, action);
      };
    });
  }
  return T();
}

template <typename Impl> Arguments<Impl>::Action::operator bool() const {
  return primed() && self->arguments.size() > 0;
}

template <typename Impl> bool Arguments<Impl>::Action::primed() const {
  if (self->primed_) { return true; }
  if (!self->argument_names.empty()) { throw ArgumentMixingError(); }
  self->action_descriptions.emplace(name, description);
  return false;
}

}

namespace program {

template <typename Impl>
template <typename T>
Arguments<Impl>::Argument::operator T() const {
  if (!primed()) {
    return T();
  } else if (self->arguments.size() > index) {
    return convert<T>(name, self->arguments.at(index));
  }
  throw IllegalPositionError("No argument provided", index);
}

template <typename Impl> Arguments<Impl>::Argument::operator bool() const {
  return primed() && self->arguments.size() > index;
}

template <typename Impl>
template <typename T>
auto Arguments<Impl>::Argument::operator=(T && value) {
  is_optional = true;
  if (description.size()) {
    using ::program::to_string;
    description += "\n    Default Value: " + to_string(value);
  }
  return WithDefault<Argument, T>{*this, std::forward<T>(value)};
}

template <typename Impl> bool Arguments<Impl>::Argument::primed() const {
  if (self->primed_) { return true; }
  if (!self->actions.empty()) { throw ArgumentMixingError(); }
  if (is_optional) {
    self->optional_from = std::min(self->optional_from, index);
  } else if (self->optional_from < index) {
    throw ArgumentStructureError{"Required positional after optional", name};
  }
  if (!self->argument_names.emplace(index, name).second) {
    throw IllegalPositionError("Duplicate positional", index);
  }
  self->argument_descriptions.emplace(name, description);
  return false;
}

}

namespace program {

template <typename Impl>
template <typename T>
Arguments<Impl>::Flag::operator T() const {
  return primed(false) ? static_cast<T>(self->flags.at(name)) : T();
}

template <typename Impl> Arguments<Impl>::Flag::operator bool() const {
  return primed(true) ? static_cast<bool>(self->flags.at(name)) : default_value;
}

template <typename Impl> auto Arguments<Impl>::Flag::operator=(bool && value) {
  if (description.size()) {
    description += "\n    Default Value: ";
    description += (value ? "true" : "false");
  }
  default_value = value;
  return *this;
}

template <typename Impl> bool Arguments<Impl>::Flag::primed(bool inv) const {
  if (self->primed_) { return self->flags.count(name); }
  std::vector<std::string> aliases;
  if (name.size() > 1 && inv) {
    aliases.push_back("no-" + name);
  }
  self->add_options(name, abbrev, description, aliases);
  self->flag_names.emplace(name);
  return false;
}

}

namespace program {

template <typename Impl>
template <typename T>
Arguments<Impl>::Option::operator T() const {
  return (*this) ? convert<T>(name, self->options.at(name)) : T();
}

template <typename Impl> Arguments<Impl>::Option::operator bool() const {
  return primed() && self->options.count(name);
}

template <typename Impl>
template <typename T>
auto Arguments<Impl>::Option::operator=(T && value) {
  if (description.size()) {
    using ::program::to_string;
    description += "\n    Default Value: " + to_string(value);
  }
  return WithDefault<Option, T>{*this, std::forward<T>(value)};
}


template <typename Impl>
template <typename T>
auto Arguments<Impl>::Option::operator=(std::initializer_list<T> value) {
  if (description.size()) {
    using ::program::to_string;
    description += "\n    Default Value: " + to_string(value);
  }
  return WithDefault<Option, std::initializer_list<T>>{*this, value};
}

template <typename Impl> bool Arguments<Impl>::Option::primed() const {
  if (self->primed_) { return true; }
  self->add_options(name, abbrev, description);
  return false;
}

}

namespace program {

template <typename Impl>
Arguments<Impl>::Arguments(int argc, char const * const * const argv) {
  Impl generator;
  *this = static_cast<Arguments const &>(generator);
  if (argument_names.size() &&
      argument_names.rbegin()->first != argument_names.size() - 1) {
    throw IllegalPositionError("Higher positional than number recorded",
                               argument_names.rbegin()->first);
  }

  primed_ = true;
  program = argv[0];
  for (size_t i = 1; i < argc; ++i) {
    std::string arg = argv[i];
    char const * const next = argv[i + 1];
    char abbrev = arg[1];
    if (arg == "--help") {
      usage();
      PROGRAM_ARGS_EXIT(0);
    } else if (arg == "--") {
      arguments.insert(arguments.end(), &next, &argv[argc]);
      break;
    } else if (auto hook = actions[arg]) {
      main_callback = hook(argc - i, argv + i);
      return;
    } else if (arg == "help" && next && actions[next]) {
      char const * const help[] = {next, "--help"};
      main_callback = actions[next](2, help);
      return;
    } else if (arg[0] != '-') {
      arguments.emplace_back(arg);
    } else if (is_flag(arg)) {
      if (arg.substr(0, 5) == "--no-") {
        flags[id(arg)] = 0;
      } else {
        ++flags[id(arg)];
      }
    } else if (is_option(arg)) {
      options[id(arg)].emplace_back(argv[++i]);
    } else if (is_flag(abbrev) && arg.find_last_not_of("0123456789") == 1) {
      flags[id(abbrev)] = std::stoi(arg.substr(2));
    } else if (is_flag(abbrev)) {
      for (auto c : arg.substr(1)) {
        if (!is_flag(c)) { throw NotAnArgumentError({'-', c}); }
        ++flags[id(c)];
      }
    } else if (is_option(abbrev)) {
      options[id(abbrev)].emplace_back(arg.substr(2));
    } else {
      throw NotAnArgumentError(arg);
    }
  }
}

template <typename Impl> void Arguments<Impl>::usage() const {
  std::cout << program << " [options...]";
  for (auto & [index, name] : argument_names) {
    std::cout << " " << (index == optional_from ? "[" : "") << name;
  }
  if (rest_name_.size()) {
    std::cout << " [" << rest_name_ << "...]";
  }
  if (optional_from != no_optional_args) { std::cout << "]"; }
  std::cout << "\nArgument Arguments:\n";
  for (auto & [name, desc] : argument_descriptions) {
    std::cout << "  " << name << ": " << desc << "\n";
  }
  std::cout << "Options:\n";
  for (auto & [opt, desc] : option_descriptions) {
    std::cout << "  " << opt << ": " << desc << "\n";
  }
}

template <typename Impl>
void Arguments<Impl>::add_options(std::string const & name, char abbrev,
                                  std::string const & description,
                                  std::vector<std::string> aliases) {
  for (auto & str : aliases) {
    str = "--" + str;
  }
  if (name.size() > 1) { aliases.push_back("--" + name); }
  if (abbrev) { aliases.push_back(std::string{'-', abbrev}); }
  for (auto & str : aliases) {
    if (!option_names.emplace(str, name).second) {
      throw ArgumentStructureError("Duplicate option string", str);
    }
  }
  option_descriptions.emplace(join(",", aliases), description);
}

template <typename Impl>
auto Arguments<Impl>::id(std::string const & arg) const -> option_id {
  if (!is_option(arg)) { throw NotAnArgumentError(arg); }
  return option_names.at(arg);
}

template <typename Impl>
bool Arguments<Impl>::is_option(std::string const & arg) const {
  return option_names.count(arg);
}

template <typename Impl>
bool Arguments<Impl>::is_flag(std::string const & arg) const {
  return is_option(arg) && flag_names.count(id(arg));
}

template <typename Impl>
auto Arguments<Impl>::action(LongArg name, std::string const & description) {
  return Action{this, name, description};
}

template <typename Impl>
auto Arguments<Impl>::argument(size_t index, LongArg name,
                               std::string const & description) {
  return Argument{this, index, false, name, description};
}

template <typename Impl>
auto Arguments<Impl>::flag(LongArg name, std::string const & description) {
  return Flag{this, name, 0, description, false};
}

template <typename Impl>
auto Arguments<Impl>::flag(LongArg name, char abbrev,
                           std::string const & description) {
  return Flag{this, name, abbrev, description, false};
}

template <typename Impl>
auto Arguments<Impl>::flag(char abbrev, std::string const & description) {
  return Flag{this, {abbrev}, abbrev, description, false};
}

template <typename Impl>
auto Arguments<Impl>::option(LongArg name, std::string const & description) {
  return Option{this, name, 0, description};
}

template <typename Impl>
auto Arguments<Impl>::option(LongArg name, char abbrev,
                             std::string const & description) {
  return Option{this, name, abbrev, description};
}

template <typename Impl>
auto Arguments<Impl>::option(char abbrev, std::string const & description) {
  return Option{this, {abbrev}, abbrev, description};
}

}