/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.

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. */

#include "paddle/framework/grad_op_builder.h"
#include "paddle/framework/op_proto.pb.h"
#include "paddle/framework/op_registry.h"

namespace paddle {
namespace framework {

class OpRegistry;

using VarIndexMap = std::unordered_map<std::string, int>;

enum OpArgType { IN, OUT };

static std::vector<int>* GetOpFormat(OperatorBase* op, const OpArgType& type) {
  std::string key = type == IN ? "input_format" : "output_name";
  return op->attrs_.count(key)
             ? &boost::get<std::vector<int>>(op->attrs_.at(key))
             : nullptr;
}

static const std::vector<int>* GetOpFormat(const OperatorBase* op,
                                           const OpArgType& type) {
  std::string key = type == IN ? "input_format" : "output_name";
  return op->attrs_.count(key)
             ? &boost::get<std::vector<int>>(op->attrs_.at(key))
             : nullptr;
}

static void TransOpArg(const OperatorBase* src_op, OperatorBase* dst_op,
                       const OpArgType& src_type, const OpArgType& dst_type,
                       int& idx, bool is_grad) {
  const std::vector<std::string>& src_inout =
      src_type == IN ? src_op->inputs_ : src_op->outputs_;
  const std::vector<int>* src_format = GetOpFormat(src_op, src_type);

  std::vector<std::string>& dst_inout =
      dst_type == IN ? dst_op->inputs_ : dst_op->outputs_;
  std::vector<int>* dst_format = GetOpFormat(dst_op, dst_type);
  const OpProto& proto = OpRegistry::protos().at(src_op->type_);
  const auto& src_arg_list = src_type == IN ? proto.inputs() : proto.outputs();

  for (const auto& arg : src_arg_list) {
    std::string src_name = arg.name();
    std::string dst_name =
        is_grad ? src_name + OperatorBase::GRAD_VAR_SUFFIX() : src_name;
    (*dst_op->in_out_idxs_)[dst_name] = idx++;
    int src_arg_idx = src_op->in_out_idxs_->at(src_name);
    int src_begin =
        src_format == nullptr ? src_arg_idx : src_format->at(src_arg_idx);
    int src_end = src_format == nullptr ? src_arg_idx + 1
                                        : src_format->at(src_arg_idx + 1);
    for (int i = src_begin; i < src_end; ++i) {
      std::string s = is_grad ? src_inout[i] + OperatorBase::GRAD_VAR_SUFFIX()
                              : arg.ignore_gradient()
                                    ? OperatorBase::EMPTY_VAR_NAME()
                                    : src_inout[i];
      dst_inout.emplace_back(s);
    }
    if (dst_format != nullptr) {
      dst_format->push_back(dst_inout.size());
    }
  }
}

OperatorBase* BuildGradOp(const OperatorBase* op) {
  std::string grad_op_type = OpRegistry::grad_ops().at(op->type_);
  OperatorBase* grad_op = OpRegistry::op_creators().at(grad_op_type)();
  grad_op->type_ = grad_op_type;
  grad_op->attrs_ = op->attrs_;
  grad_op->attrs_.erase("input_format");
  grad_op->attrs_.erase("output_format");
  if (GetOpFormat(op, OUT) != nullptr) {
    grad_op->attrs_["output_format"] = std::vector<int>({0});
  }
  if (GetOpFormat(op, IN) != nullptr || GetOpFormat(op, OUT) != nullptr) {
    grad_op->attrs_["input_format"] = std::vector<int>({0});
  }
  grad_op->in_out_idxs_.reset(new VarIndexMap());
  int in_idx = 0;
  int out_idx = 0;
  TransOpArg(op, grad_op, IN, IN, in_idx, false);   // I
  TransOpArg(op, grad_op, OUT, IN, in_idx, false);  // G
  TransOpArg(op, grad_op, OUT, IN, in_idx, true);   // OG
  TransOpArg(op, grad_op, IN, OUT, out_idx, true);  // IG
  return grad_op;
}

}  // namespace framework
}  // namespace paddle