// Copyright (c) 2023 Dominic Masters
// 
// This software is released under the MIT License.
// https://opensource.org/licenses/MIT

#pragma once
#include "assert/assert.hpp"

namespace Dawn {
  class IStateProperty {
    public:
      std::vector<std::function<void()>> _effectListners;
  };

  template<class V>
  class StateProperty : public IStateProperty {
    private:
      /**
       * Method that is invoked every time that the value of this state property
       * is updated.
       * 
       * @param val Value that is to be used for this property.
       */
      void setInternal(V val) {
        if(val == this->_realValue) return;// TODO: can I omit this? kinda bad tbh.
        this->previous = this->_realValue;
        this->_realValue = val;

        // Notify the effect listeners
        auto itEffect = this->_effectListners.begin();
        while(itEffect != this->_effectListners.end()) {
          (*itEffect)();
          ++itEffect;
        }
      }

    public:
      V _realValue;
      V previous;

      /**
       * Creates a new state property and listens for its change.
       */
      StateProperty() {}

      /**
       * Creates a new state property and listens for its change.
       * @param initial The initial value of this state.
       */
      StateProperty(V initial) : _realValue(initial) {}

      const StateProperty& operator += (const V &value) {
        this->setInternal(this->_realValue + value);
        return *this;
      }

      const bool_t operator != (const V &value) {
        return value != this->_realValue;
      }

      const bool_t operator == (const V &value) {
        return value == this->_realValue;
      }

      const StateProperty& operator = (const V &val) {
        this->setInternal(val);
        return *this;
      }

      operator V() const {
        return this->_realValue;
      }

      /**
       * Destructor for StateProperty.
       */
      ~StateProperty() {}

      friend class StateOwner;
  };
}