#pragma once

#include <string>
#include <utility>
#include <vector>
#include <optional>
#include <unordered_map>

// for clangd
#include "error_handling.hpp"
#include "utils.hpp"

namespace info {

template<typename Value, typename ValueManager>
class ContextManager {
public:
  ContextManager() {
    contexts_.emplace_back(true); // no difference ??
  }

  template<typename T>
  utils::IdType AddValue(const T& value, utils::ValueType value_type) {
    return value_manager_.AddValue(value, value_type);
  }

  utils::IdType AddAnyValue(Value&& value, utils::ValueType value_type) {
    return value_manager_.AddAnyValue(std::move(value), value_type);
  }

  template<typename T>
  std::optional<T*> GetValue(utils::IdType value_id) {
    return value_manager_.template GetValue<T>(value_id);
  }

  Value* GetAnyValue(utils::IdType value_id) {
    return  value_manager_.GetAnyValue(value_id);
  }

  bool AddValueRequirement(utils::IdType type, utils::IdType requrement) {
    return value_manager_.AddValueRequirement(type, requrement);
  }

  bool EqualValues(utils::IdType first_type, utils::IdType second_type) {
    return value_manager_.EqualValues(first_type, second_type);
  }

  utils::ValueType GetValueType(utils::IdType value_id) {
    return  value_manager_.GetValueType(value_id);
  }

  utils::IdType ToModifiedValue(utils::IdType value_id, utils::ValueType new_value_type) {
    Value value = *GetAnyValue(value_id);
    return AddAnyValue(std::move(value), new_value_type);
  }

  ValueManager* GetValueManager() {
    return &value_manager_;
  }

  void EnterContext(bool is_hiding_previous = false) {
    contexts_.emplace_back(is_hiding_previous);
  }

  void ExitContext() {
    if (contexts_.empty()) {
      error_handling::HandleInternalError("contexts_ is empty",
                                          "ContextManager.ExitContext",
                                          std::nullopt);
    }

    contexts_.pop_back();
  }

  void ChangeHidingOfCurrentContextTo(bool is_hiding_previous) {
    contexts_.back().ChangeHidingTo(is_hiding_previous);
  }

  bool DefineVariable(const std::string& name, utils::IdType value_id) {
    return contexts_.back().DefineVariable(name, value_id);
  }

  bool DefineLocalType(const std::string& name, utils::IdType type_id) {
    return contexts_.back().DefineLocalType(name, type_id);
  }

  bool AssignVariable(const std::string& name, utils::IdType value_id) {
    for (ssize_t i = (ssize_t)contexts_.size() - 1; i >= 0; --i) {
      if (contexts_[i].AssignVariable(name, value_id)) {
        return true;
      }

      if (contexts_[i].IsHidingPrevious()) {
        break;
      }
    }
    return false;
  }

  bool AssignLocalType(const std::string& name, utils::IdType type_id) {
    for (ssize_t i = (ssize_t)contexts_.size() - 1; i >= 0; --i) {
      if (contexts_[i].AssignLocalType(name, type_id)) {
        return true;
      }

      if (contexts_[i].IsHidingPrevious()) {
        break;
      }
    }
    return false;
  }

  bool RemoveVariable(const std::string& name) {
    for (ssize_t i = (ssize_t)contexts_.size() - 1; i >= 0; --i) {
      if (contexts_[i].RemoveVariable(name)) {
        return true;
      }

      if (contexts_[i].IsHidingPrevious()) {
        break;
      }
    }
    return false;
  }

  void EnterVariableContext(const std::string& name,
                            utils::IdType value_id,
                            bool is_hiding_previous = false) {
    EnterContext(is_hiding_previous);

    DefineVariable(name, value_id);
  }

  std::optional<utils::IdType> FindVariable(const std::string& name) {
    for (ssize_t i = (ssize_t)contexts_.size() - 1; i >= 0; --i) {
      auto maybe_variable = contexts_[i].FindVariable(name);
      if (maybe_variable.has_value()) {
        return maybe_variable.value();
      }

      if (contexts_[i].IsHidingPrevious()) {
        break;
      }
    }
    return std::nullopt;
  }

  std::optional<utils::IdType> FindLocalType(const std::string& name) {
    for (ssize_t i = (ssize_t)contexts_.size() - 1; i >= 0; --i) {
      auto maybe_type = contexts_[i].FindLocalType(name);
      if (maybe_type.has_value()) {
        return maybe_type.value();
      }

      if (contexts_[i].IsHidingPrevious()) {
        break;
      }
    }
    return std::nullopt;
  }

private:
  class Context {
  public:
    explicit Context(bool is_hiding_previous) : is_hiding_previous_(is_hiding_previous) {}

    bool DefineVariable(const std::string& name, utils::IdType value_id) {
      if (name == "_") { // placeholder
        return true;
      }

      if (variables_.count(name) != 0) {
        return false;
      }
      variables_[name] = value_id;
      return true;
    }

    bool DefineLocalType(const std::string& name, utils::IdType type_id) {
      if (local_types_.count(name) != 0) {
        return false;
      }
      local_types_[name] = type_id;
      return true;
    }

    bool AssignVariable(const std::string& name, utils::IdType value_id) {
      if (name == "_") { // placeholder
        return true;
      }

      auto variable_iter = variables_.find(name);
      if (variable_iter == variables_.end()) {
        return false;
      }
      variable_iter->second = value_id;
      return true;
    }

    bool AssignLocalType(const std::string& name, utils::IdType type_id) {
      auto local_type_iter = local_types_.find(name);
      if (local_type_iter == local_types_.end()) {
        return false;
      }
      local_type_iter->second = type_id;
      return true;
    }

    bool RemoveVariable(const std::string& name) {
      return variables_.erase(name);
    }

    std::optional<utils::IdType> FindVariable(const std::string& name) {
      auto variable_iter = variables_.find(name);

      if (variable_iter == variables_.end()) {
        return std::nullopt;
      }

      return variable_iter->second;
    }

    std::optional<utils::IdType> FindLocalType(const std::string& name) {
      auto local_abstract_type_iter = local_types_.find(name);

      if (local_abstract_type_iter == local_types_.end()) {
        return std::nullopt;
      }

      return local_abstract_type_iter->second;
    }

    bool IsHidingPrevious() {
      return is_hiding_previous_;
    }

    void ChangeHidingTo(bool is_hiding_previous) {
      is_hiding_previous_ = is_hiding_previous;
    }

  private:
    std::unordered_map<std::string, utils::IdType> variables_;
    std::unordered_map<std::string, utils::IdType> local_types_;

    bool is_hiding_previous_ = false;
  };

  std::vector<Context> contexts_;
  ValueManager value_manager_;
};

} // namespace info