/**
 * @file utils/StateMachine.hpp
 * @author The ARTIS Development Team
 * See the AUTHORS or Authors.txt file
 */

/*
 * ARTIS - the multimodeling and simulation environment
 * This file is a part of the ARTIS environment
 *
 * Copyright (C) 2013-2023 ULCO http://www.univ-littoral.fr
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, 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, see <http://www.gnu.org/licenses/>.
 */

#ifndef ARTIS_STAR_ADDONS_UTILS_STATE_MACHINE_HPP
#define ARTIS_STAR_ADDONS_UTILS_STATE_MACHINE_HPP

#include <artis-star/common/event/Value.hpp>

#include <map>
#include <memory>
#include <vector>

namespace artis::addons::utils {

template<class Time, class Types, class Parameters, class StateMachineTypes>
class RootStateMachine;

template<class Time, class Types>
class AbstractStateMachine {
public:
  struct Event {
    int id;
    artis::common::event::Value data;
  };

  struct InternalEvent : Event {
    int machine_id;
  };

  struct ExternalEvent : Event {
  };

  struct Events {
    std::vector <InternalEvent> internals;
    std::vector <ExternalEvent> externals;
  };

  struct AbstractState {
    int _id;

    AbstractState(int id) : _id(id) {}

    virtual typename Time::type ta(const typename Time::type & /* t */) const = 0;

    virtual ~AbstractState() = default;
  };

  template<class Machine>
  struct State : AbstractState {
    std::shared_ptr <Machine> _machine;

    State(int id, const std::shared_ptr <Machine> &machine) :
      AbstractState(id), _machine(machine) {}

    typename Time::type ta(const typename Time::type & /* t */) const override { return Time::infinity; }
  };

  struct AbstractTransition {
    virtual void action(const typename Time::type & /* t */,
                        const artis::common::event::Value & /* value */) = 0;

    virtual bool event(const typename Time::type & /* t */, int  /* event */) = 0;

    virtual bool guard(const typename Time::type & /* t */,
                       const artis::common::event::Value & /* value */) const = 0;

    virtual bool no_event() const = 0;

    virtual Events output(const typename Time::type & /* t */) const = 0;

    virtual ~AbstractTransition() = default;
  };

  template<class Machine>
  struct Transition : AbstractTransition {
    std::shared_ptr <Machine> _machine;

    Transition(const std::shared_ptr <Machine> &machine) : _machine(machine) {}

    void action(const typename Time::type & /* t */,
                const artis::common::event::Value & /* value */) override {}

    bool event(const typename Time::type & /* t */,
               int  /* event */) override { return false; }

    bool guard(const typename Time::type & /* t */,
               const artis::common::event::Value & /* value */) const override { return true; }

    bool no_event() const override { return false; }

    Events output(const typename Time::type & /* t */) const override { return {}; }
  };

  AbstractStateMachine(const typename Types::root_state_machine_type &root) : _root(root) {}

  virtual ~AbstractStateMachine() = default;

//  virtual void build(const std::shared_ptr<StateMachine<Types>> &machine) = 0;

  const std::unique_ptr <AbstractState> &current_state() const {
    return _states.at(_current_state);
  }

  int current_state(int machine_id) const {
    return _root.current_state(machine_id);
  }

  void initial_state(int state) {
    _initial_state = state;
  }

  bool is_ready(const typename Time::type &t) const {
    return std::abs(_sigma - (t - _last_time)) < 1e-6;
  }

  const typename Types::root_state_machine_type &root() const { return _root; }

  void start(const typename Time::type &t) {
    _current_state = _initial_state;
    _last_time = t;
    compute_sigma(t);
  }

  void state(AbstractState *state) {
    _states.insert(std::make_pair(state->_id, std::unique_ptr<AbstractState>(state)));
    _transitions.insert(std::make_pair(state->_id, _transitions_type{}));
  }

  void switch_transition(int state, int next_state, size_t index, AbstractTransition *transition) {
    auto it = std::find_if(_transitions[state].begin(), _transitions[state].end(), [next_state](const auto &e) {
      return e.second == next_state;
    });

    assert(it != _transitions[state].end());

    while (it + 1 != _transitions[state].end() and index > 0) {
      it = std::find_if(it + 1, _transitions[state].end(), [next_state](const auto &e) {
        return e.second == next_state;
      });
      --index;
    }

    assert(it != _transitions[state].end());

    it->first.reset(transition);
  }

  typename Time::type ta(const typename Time::type & /* t */) const {
    return _sigma;
  }

  void transition(int state, int next_state, AbstractTransition *transition) {
    _transitions[state].push_back(std::make_pair(std::unique_ptr<AbstractTransition>(transition), next_state));
  }

  // without event
  Events transition(const typename Time::type &t) {
    typename std::map<int, _transitions_type>::const_iterator it = _transitions.find(_current_state);
    Events events{};
    uint unique = 0;

    if (it != _transitions.cend()) {
      AbstractTransition *select = nullptr;
      int stateID{};

      std::for_each(it->second.cbegin(), it->second.cend(),
                    [t, &unique, &select, &stateID](
                      const std::pair<std::unique_ptr<AbstractTransition>, int> &e) {
                      if (e.first->no_event() and e.first->guard(t, {})) {
                        select = e.first.get();
                        stateID = e.second;
                        ++unique;
                      }
                    });

      assert(unique <= 1);

      if (select != nullptr) {
        select->action(t, {});
        events = select->output(t);
        _current_state = stateID;
        compute_sigma(t);
      } else {
        update_sigma(t);
      }
    }
    return events;
  }

  // with external event
  Events transition(const typename Time::type &t, const ExternalEvent &event) {
    typename std::map<int, _transitions_type>::const_iterator it = _transitions.find(_current_state);
    Events events{};
    uint unique = 0;

    if (it != _transitions.cend()) {
      AbstractTransition *select = nullptr;
      int stateID{};

      std::for_each(it->second.cbegin(), it->second.cend(),
                    [t, event, &unique, &select, &stateID](
                      const std::pair<std::unique_ptr<AbstractTransition>, int> &e) {
                      if (e.first->guard(t, event.data) and e.first->event(t, event.id)) {
                        select = e.first.get();
                        stateID = e.second;
                        ++unique;
                      }
                    });

      assert(unique <= 1);

      if (select != nullptr) {
        select->action(t, event.data);
        events = select->output(t);
        _current_state = stateID;
        compute_sigma(t);
      } else {
        update_sigma(t);
      }
    }
    return events;
  }

  // with internal event
  Events transition(const typename Time::type &t, const InternalEvent &event) {
    typename std::map<int, _transitions_type>::const_iterator it = _transitions.find(_current_state);
    Events events{};
    uint unique = 0;

    if (it != _transitions.cend()) {
      AbstractTransition *select = nullptr;
      int stateID{};

      std::for_each(it->second.cbegin(), it->second.cend(),
                    [t, event, &unique, &select, &stateID](
                      const std::pair<std::unique_ptr<AbstractTransition>, int> &e) {
                      if (e.first->guard(t, event.data) and e.first->event(t, event.id)) {
                        select = e.first.get();
                        stateID = e.second;
                        ++unique;
                      }
                    });

      assert(unique <= 1);

      if (select != nullptr) {
        select->action(t, event.data);
        events = select->output(t);
        _current_state = stateID;
        compute_sigma(t);
      } else {
        update_sigma(t);
      }
    }
    return events;
  }

  void update_sigma(const typename Time::type &t) {
    _sigma -= t - _last_time;
    _last_time = t;
  }

private:
  void compute_sigma(const typename Time::type &t) {
    _sigma = current_state()->ta(t);
    _last_time = t;
  }

  typedef std::vector<std::pair<std::unique_ptr < AbstractTransition>, int >> _transitions_type;

  std::map<int, std::unique_ptr<AbstractState>> _states;
  std::map<int, _transitions_type> _transitions;
  int _initial_state;
  const typename Types::root_state_machine_type &_root;

  int _current_state;
  typename Time::type _last_time{};
  typename Time::type _sigma{};
};

template<class Time, class Types, class StateType>
class StateMachine : public AbstractStateMachine<Time, Types> {
public:
  StateMachine(const typename Types::root_state_machine_type &root, StateType state)
    : AbstractStateMachine<Time, Types>(root), _state(state) {}

  virtual ~StateMachine() = default;

  const StateType &state_() const { return _state; }

  StateType &state_() { return _state; }

protected:
  StateType _state;
};

}

#define DECLARE_STATE_TRANSITION_TYPES(StateMachineClassName) \
  typedef typename StateMachineClassName<Types, Parameters, StateType>::template State<StateMachineClassName<Types, Parameters, StateType>> State_t; \
  typedef typename StateMachineClassName<Types, Parameters, StateType>::template Transition<StateMachineClassName<Types, Parameters, StateType>> Transition_t;

#define DEFINE_STATE_MACHINE_STATE(StateClassName, StateID, StateMachineClassName) \
  template<class Types, class Parameters, class StateType>                         \
    struct StateClassName : StateMachineClassName<Types, Parameters, StateType>::State_t { \
      StateClassName(const std::shared_ptr<StateMachineClassName<Types, Parameters, StateType>> &machine) : \
      StateMachineClassName<Types, Parameters, StateType>::State_t(StateID, machine) {}    \
    };

#define DEFINE_STATE_MACHINE_STATE_WITH_NULL_TA(StateClassName, StateID, StateMachineClassName) \
  template<class Types, class Parameters, class StateType>                                      \
    struct StateClassName : StateMachineClassName<Types, Parameters, StateType>::State_t {      \
      StateClassName(const std::shared_ptr<StateMachineClassName<Types, Parameters, StateType>> &machine) : \
      StateMachineClassName<Types, Parameters, StateType>::State_t(StateID, machine) {}         \
      artis::traffic::core::Time ta(const artis::traffic::core::Time & /* t */) const override { return 0; }\
    };

#define DEFINE_STATE_MACHINE_STATE_WITH_TA(StateClassName, StateID, StateMachineClassName) \
  template<class Types, class Parameters, class StateType>                                      \
    struct StateClassName : StateMachineClassName<Types, Parameters, StateType>::State_t {      \
      StateClassName(const std::shared_ptr<StateMachineClassName<Types, Parameters, StateType>> &machine) : \
      StateMachineClassName<Types, Parameters, StateType>::State_t(StateID, machine) {}         \
      artis::traffic::core::Time ta(const artis::traffic::core::Time & /* t */) const override; \
    };

#define DEFINE_STATE_MACHINE_TRANSITION_HEADER(TransitionClassName, StateMachineClassName) \
  template<class Types, class Parameters, class StateType>                                 \
    struct TransitionClassName : StateMachineClassName<Types, Parameters, StateType>::Transition_t { \
     TransitionClassName(                                                                  \
        const std::shared_ptr<StateMachineClassName<Types, Parameters, StateType>> &machine) :       \
        StateMachineClassName<Types, Parameters, StateType>::Transition_t(machine) {}

#define ATTRIBUTE(Type, Var) Type Var;

#define NO_ATTRIBUTE

#define DEFINE_STATE_MACHINE_TRANSITION_FOOTER(Attribute) \
  Attribute                                               \
  };

#define DEFINE_STATE_MACHINE_TRANSITION_ACTION_true void action(const artis::traffic::core::Time & /* t */, const artis::common::event::Value & /* value */) override;
#define DEFINE_STATE_MACHINE_TRANSITION_ACTION_false
#define DEFINE_STATE_MACHINE_TRANSITION_EVENT_true bool event(const artis::traffic::core::Time & /* t */, int event) override;
#define DEFINE_STATE_MACHINE_TRANSITION_EVENT_false
#define DEFINE_STATE_MACHINE_TRANSITION_GUARD_true bool guard(const artis::traffic::core::Time & /* t */, const artis::common::event::Value & /* value */) const override;
#define DEFINE_STATE_MACHINE_TRANSITION_GUARD_false
#define DEFINE_STATE_MACHINE_TRANSITION_NO_EVENT_true bool no_event() const override { return true; }
#define DEFINE_STATE_MACHINE_TRANSITION_NO_EVENT_false
#define DEFINE_STATE_MACHINE_TRANSITION_OUTPUT_true(StateMachineClassName) typename StateMachineClassName<Types, Parameters, StateType>::Events output(const artis::traffic::core::Time & /* t */) const override;
#define DEFINE_STATE_MACHINE_TRANSITION_OUTPUT_false(StateMachineClassName)

#define DEFINE_STATE_MACHINE_TRANSITION(TransitionClassName, StateMachineClassName, Attribute, ActionMethod, EventMethod, GuardMethod, NoEventMethod, OutputMethod) \
  DEFINE_STATE_MACHINE_TRANSITION_HEADER(TransitionClassName, StateMachineClassName)                                                                    \
  DEFINE_STATE_MACHINE_TRANSITION_ACTION_##ActionMethod                                                                                                 \
  DEFINE_STATE_MACHINE_TRANSITION_EVENT_##EventMethod                                                                                                   \
  DEFINE_STATE_MACHINE_TRANSITION_GUARD_##GuardMethod                                                                                                   \
  DEFINE_STATE_MACHINE_TRANSITION_NO_EVENT_##NoEventMethod                                                                                              \
  DEFINE_STATE_MACHINE_TRANSITION_OUTPUT_##OutputMethod(StateMachineClassName)                                                                          \
  DEFINE_STATE_MACHINE_TRANSITION_FOOTER(Attribute)

#endif //ARTIS_STAR_ADDONS_UTILS_STATE_MACHINE_HPP