#pragma once

#include <ATen/core/ivalue.h>

namespace c10 {

template<class T> TypePtr getTypePtr();
std::string toString(TypePtr typePtr);

namespace impl {
inline bool shallowEquals(const IValue& lhs, const IValue& rhs) {
  if (lhs.isNone()) {
    return rhs.isNone();
  } else if (lhs.isInt()) {
    return rhs.isInt() && lhs.toInt() == rhs.toInt();
  } else if (lhs.isString()) {
    return rhs.isString() && lhs.toStringRef() == rhs.toStringRef();
  } else if (lhs.isDouble()) {
    return rhs.isDouble() && lhs.toDouble() == rhs.toDouble();
  } else if (lhs.isBool()) {
    return rhs.isBool() && lhs.toBool() == rhs.toBool();
  } else if (lhs.isList()) {
    if (!rhs.isList()) {
      return false;
    }
    auto l = lhs.toListRef();
    auto r = rhs.toListRef();
    if (l.size() != r.size()) {
      return false;
    }
    for (size_t i = 0, N = l.size(); i < N; ++i) {
      if (!shallowEquals(l[i], r[i])) {
        return false;
      }
    }
    return true;
  } else if (lhs.isTensor()) {
    return lhs.toTensor().is_same(rhs.toTensor());
  } else {
    AT_ERROR("shallowEquals(IValue, IValue) not implemented for type ", lhs.tagKind());
  }
}


template<class Key, class Value>
Dict<Key, Value> toTypedDict(GenericDict dict) {
  TORCH_INTERNAL_ASSERT(*getTypePtr<Key>() == *dict.impl_->elementTypes.keyType, "Tried to cast a Dict<", toString(dict.impl_->elementTypes.keyType), ", ", toString(dict.impl_->elementTypes.valueType) ,"> to a Dict<", toString(getTypePtr<Key>()), ", ", toString(getTypePtr<Value>()), ">. Key types mismatch.");
  TORCH_INTERNAL_ASSERT(*getTypePtr<Value>() == *dict.impl_->elementTypes.valueType, "Tried to cast a Dict<", toString(dict.impl_->elementTypes.keyType), ", ", toString(dict.impl_->elementTypes.valueType) ,"> to a Dict<", toString(getTypePtr<Key>()), ", ", toString(getTypePtr<Value>()), ">. Value types mismatch.");

  return Dict<Key, Value>(std::move(dict.impl_));
}

template<class Key, class Value>
GenericDict toGenericDict(Dict<Key, Value> dict) {
  return GenericDict(std::move(dict.impl_));
}
}

namespace detail {

inline size_t DictKeyHash::operator()(const IValue& ivalue) const {
  if (ivalue.isInt()) {
    return std::hash<int>()(ivalue.toInt());
  } else if (ivalue.isString()) {
    return std::hash<std::string>()(ivalue.toStringRef());
  } else if (ivalue.isDouble()) {
    return std::hash<double>()(ivalue.toDouble());
  } else if (ivalue.isBool()) {
    return std::hash<bool>()(ivalue.toBool());
  } else if (ivalue.isTensor()) {
    return std::hash<TensorImpl*>()(ivalue.toTensor().unsafeGetTensorImpl());
  } else {
    throw std::runtime_error(
        "Can't hash IValues with tag '" + ivalue.tagKind() + "'");
  }
}

inline intrusive_ptr<DictImpl> DictImpl::copy() const {
  return make_intrusive<DictImpl>(dict, elementTypes);
}

}

template<class Key, class Value>
Dict<Key, Value>::Dict()
  :Dict(make_intrusive<detail::DictImpl>(
      detail::DictImpl::dict_map_type(),
      detail::DictImpl::DictElementTypes{getTypePtr<Key>(), getTypePtr<Value>()})) {
  static_assert(!std::is_same<Key, IValue>::value, "This constructor is not valid for Dict<IValue, _>. Please use c10::impl::GenericDict(keyType, valueType) instead, or if you absolutely have to, use c10::impl::GenericDict(c10::impl::deprecatedUntypedDict()).");
  static_assert(!std::is_same<Value, IValue>::value, "This constructor is not valid for Dict<_, IValue>. Please use c10::impl::GenericDict(keyType, valueType) instead, or if you absolutely have to, use c10::impl::GenericDict(c10::impl::deprecatedUntypedDict()).");
}

template<class Key, class Value>
Dict<Key, Value>::Dict(TypePtr keyType, TypePtr valueType)
: Dict(make_intrusive<detail::DictImpl>(
    detail::DictImpl::dict_map_type(),
    detail::DictImpl::DictElementTypes {std::move(keyType), std::move(valueType)})) {
  static_assert(std::is_same<Key, IValue>::value, "This constructor is only valid for c10::impl::GenericDict.");
  static_assert(std::is_same<Value, IValue>::value, "This constructor is only valid for c10::impl::GenericDict.");
}

template<class Key, class Value>
Dict<Key, Value>::Dict(Dict&& rhs) noexcept: impl_(std::move(rhs.impl_)) {
  rhs.impl_ = make_intrusive<detail::DictImpl>(detail::DictImpl::dict_map_type(), impl_->elementTypes);
}

template<class Key, class Value>
Dict<Key, Value>::Dict(c10::intrusive_ptr<detail::DictImpl>&& impl): impl_(std::move(impl)) {}

template<class Key, class Value>
Dict<Key, Value>& Dict<Key, Value>::operator=(Dict&& rhs) noexcept {
  impl_ = std::move(rhs.impl_);
  rhs.impl_ = make_intrusive<detail::DictImpl>(detail::DictImpl::dict_map_type(), impl_->elementTypes);
  return *this;
}

template<class Key, class Value>
Dict<Key, Value> Dict<Key, Value>::copy() const {
  return Dict<Key, Value>(impl_->copy());
}

template<class Key, class Value>
typename Dict<Key, Value>::iterator Dict<Key, Value>::begin() const {
  return iterator{impl_->dict.begin()};
}

template<class Key, class Value>
typename Dict<Key, Value>::iterator Dict<Key, Value>::end() const {
  return iterator{impl_->dict.end()};
}

template<class Key, class Value>
bool Dict<Key, Value>::empty() const {
  return impl_->dict.empty();
}

template<class Key, class Value>
typename Dict<Key, Value>::size_type Dict<Key, Value>::size() const {
  return impl_->dict.size();
}

template<class Key, class Value>
void Dict<Key, Value>::clear() const {
  impl_->dict.clear();
}

template<class Key, class Value>
template<class Key_, class Value_>
std::pair<typename Dict<Key, Value>::iterator, bool> Dict<Key, Value>::insert(Key_&& key, Value_&& value) const {
  static_assert(std::is_constructible<Key, Key_>::value, "Wrong type for the key argument of Dict::insert");
  static_assert(std::is_constructible<Value, Value_>::value, "Wrong type for the value argument of Dict::insert");
  auto inserted = impl_->dict.insert(std::pair<IValue, IValue>{
    Key(std::forward<Key_>(key)),
    Value(std::forward<Value_>(value))});
  return {iterator{inserted.first}, inserted.second};
}

template<class Key, class Value>
template<class Key_, class Value_>
std::pair<typename Dict<Key, Value>::iterator, bool> Dict<Key, Value>::insert_or_assign(Key_&& key, Value_&& value) const {
  static_assert(std::is_constructible<Key, Key_>::value, "Wrong type for the key argument of Dict::insert_or_assign");
  static_assert(std::is_constructible<Value, Value_>::value, "Wrong type for the value argument of Dict::insert_or_assign");
  auto inserted = impl_->dict.insert_or_assign(
    Key(std::forward<Key_>(key)),
    Value(std::forward<Value_>(value)));
  return {iterator{inserted.first}, inserted.second};
}

template<class Key, class Value>
void Dict<Key, Value>::erase(iterator iter) const {
  impl_->dict.erase(iter.entryRef_.iterator_);
}

template<class Key, class Value>
C10_NODISCARD size_t Dict<Key, Value>::erase(const Key& key) const {
  return impl_->dict.erase(key);
}

template<class Key, class Value>
Value Dict<Key, Value>::at(const Key& key) const {
  return impl_->dict.at(key).template to<Value>();
}

template<class Key, class Value>
typename Dict<Key, Value>::iterator Dict<Key, Value>::find(const Key& key) const {
  return iterator{impl_->dict.find(key)};
}

template<class Key, class Value>
bool Dict<Key, Value>::contains(const Key& key) const {
  return end() != find(key);
}

template<class Key, class Value>
void Dict<Key, Value>::reserve(size_type count) const {
  impl_->dict.reserve(count);
}

template<class Key, class Value>
TypePtr Dict<Key, Value>::keyType() const {
  return impl_->elementTypes.keyType;
}

template<class Key, class Value>
TypePtr Dict<Key, Value>::valueType() const {
  return impl_->elementTypes.valueType;
}
template <class Key, class Value>
void Dict<Key, Value>::unsafeSetKeyType(TypePtr t) {
  impl_->elementTypes.keyType = std::move(t);
}

template <class Key, class Value>
void Dict<Key, Value>::unsafeSetValueType(TypePtr t) {
  impl_->elementTypes.valueType = std::move(t);
}

template <class Key_, class Value_>
bool operator==(const Dict<Key_, Value_>& lhs, const Dict<Key_, Value_>& rhs) {
  if (lhs.impl_ == rhs.impl_) {
    // Dicts with the same identity trivially compare equal.
    return true;
  }

  // TODO: when we define equality on IValue, we can just defer to the
  // operator== implementation of the underlying map.
  // For now, do the comparison manually to avoid invoking the template
  // specialization for IValue equality
  if (lhs.size() != rhs.size()) {
    return false;
  }
  for (const auto& pr : lhs) {
    auto it = rhs.find(pr.key());
    if (it == rhs.end()) {
      return false;
    }
    if (it->value() != pr.value()) {
      return false;
    }
  }
  return true;
}

template <class Key_, class Value_>
bool operator!=(const Dict<Key_, Value_>& lhs, const Dict<Key_, Value_>& rhs) {
  return !(lhs == rhs);
}

template <class Key, class Value>
bool Dict<Key, Value>::is(const Dict& rhs) const {
  return this->impl_ == rhs.impl_;
}
}
