/* Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License. */

#pragma once

#include "paddle/phi/core/dense_tensor.h"

namespace phi {

/// \brief The TensorArray store a list of tensor and it is designed for
/// compatible with LodTensorArray in Fluid. It shouldn't be used widely
/// in PHI. If you want to store a list of tensor in PHI, please use std::vector
/// when ever possible.
class TensorArray : public TensorBase,
                    public TypeInfoTraits<TensorBase, TensorArray> {
 public:
  /// \brief Construct a TensorArray.
  /// \param vec The vector DenseTensor used to init TensorArray.
  explicit TensorArray(const std::vector<DenseTensor>& vec);

  explicit TensorArray(size_t n) {
    for (size_t i = 0; i < n; i++) {
      tensors_.emplace_back();
    }
  }

  TensorArray() = default;

  TensorArray(TensorArray&& other) = default;

  TensorArray(const TensorArray& other) = default;

  /// \brief TensorArray shallow copy assignment.
  TensorArray& operator=(const TensorArray& other) = default;

  TensorArray& operator=(TensorArray&& other) = default;

  /// \brief Destroy the tensor object and release exclusive resources.
  virtual ~TensorArray() = default;

 public:
  /// \brief Returns the name of the class for type traits.
  /// \return The name of the class.
  static const char* name() { return "TensorArray"; }

  /// \brief This overrided function is not used in TensorArray.
  int64_t numel() const override;

  /// \brief This overrided function is not used in TensorArray.
  const DDim& dims() const override;

  /// \brief This overrided function is not used in TensorArray.
  const Place& place() const override;

  /// \brief This overrided function is not used in TensorArray.
  DataType dtype() const override;

  /// \brief This overrided function is not used in TensorArray.
  DataLayout layout() const override;

  /// \brief This overrided function is not used in TensorArray.
  bool valid() const override;

  /// \brief Test whether the tensor's storage in TensorArray is allocated.
  /// return Whether all tensors in TensorArray is allocated.
  bool initialized() const override;

  /// \brief Clear all tensors in TensorArray.
  void clear() { tensors_.clear(); }

  /// \brief Allocate memory with requested size for all tensors from allocator.
  /// \return Void pointer
  void* AllocateFrom(Allocator* allocator,
                     DataType dtype,
                     size_t requested_size = 0);

  bool empty() const { return tensors_.empty(); }

  /// \brief Returns the number of tensors in TensorArray.
  size_t size() const { return tensors_.size(); }

  /// \brief Resizes the TensorArray so that it contains n tensors.
  void resize(size_t n) { tensors_.resize(n); }

  /// \brief Requests that the TensorArray capacity be at least enough to
  /// contain n tensors.
  void reserve(size_t n) { tensors_.reserve(n); }

  /// \brief Add the tensor to the end of TensorArray
  void push_back(const DenseTensor& tensor);

  void emplace_back();

  void emplace_back(const DenseTensor& tensor);

  /// \brief Return the last tensor in TensorArray
  DenseTensor& back() { return tensors_.back(); }

  DenseTensor& at(size_t index) { return tensors_.at(index); }

  const DenseTensor& at(size_t index) const { return tensors_.at(index); }

  const DenseTensor& operator[](size_t index) const { return tensors_[index]; }

  DenseTensor& operator[](size_t index) { return tensors_[index]; }

  std::vector<DenseTensor>::iterator begin() { return tensors_.begin(); }

  std::vector<DenseTensor>::const_iterator begin() const {
    return tensors_.begin();
  }

  std::vector<DenseTensor>::iterator end() { return tensors_.end(); }

  std::vector<DenseTensor>::const_iterator end() const {
    return tensors_.end();
  }

 private:
  std::vector<DenseTensor> tensors_;
};

}  // namespace phi