// Copyright (c) 2018 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 <memory>
#include <unordered_map>
#include <unordered_set>
#include <vector>
#include "paddle/fluid/framework/details/op_handle_base.h"

namespace paddle {
namespace framework {
namespace details {

class OpHandleGraph {
 public:
  enum Relation { kSame = 0, kBefore = 1, kAfter = 2, kNoDeps = 3 };

  explicit OpHandleGraph(const std::vector<std::unique_ptr<OpHandleBase>> &ops);

  size_t OpNumber() const;

  std::unordered_set<OpHandleBase *> AllOps() const;

  const std::unordered_set<OpHandleBase *> &PrecedingOps(
      OpHandleBase *op) const;

  const std::unordered_set<OpHandleBase *> &PendingOps(OpHandleBase *op) const;

  std::vector<std::unordered_set<OpHandleBase *>> AllPrecedingOps(
      OpHandleBase *op) const;

  std::vector<std::unordered_set<OpHandleBase *>> AllPendingOps(
      OpHandleBase *op) const;

  bool HasOp(OpHandleBase *op) const;

  Relation RelationBetween(OpHandleBase *op1, OpHandleBase *op2) const;

  bool IsSame(OpHandleBase *op1, OpHandleBase *op2) const;

  bool IsBeforeOrSame(OpHandleBase *op1, OpHandleBase *op2) const;

  bool IsBefore(OpHandleBase *op1, OpHandleBase *op2) const;

  bool IsAfterOrSame(OpHandleBase *op1, OpHandleBase *op2) const;

  bool IsAfter(OpHandleBase *op1, OpHandleBase *op2) const;

  bool IsNoDeps(OpHandleBase *op1, OpHandleBase *op2) const;

  OpHandleBase *NearestCommonParent(OpHandleBase *op1, OpHandleBase *op2) const;

  // Find an operator that is after op and before op1, op2
  OpHandleBase *NearestCommonParentAfter(OpHandleBase *op, OpHandleBase *op1,
                                         OpHandleBase *op2) const;

  std::unordered_set<OpHandleBase *> NoPendingOpSet() const;

  std::unordered_set<OpHandleBase *> NoPrecedingOpSet() const;

 private:
  void BuildGraph(const std::vector<std::unique_ptr<OpHandleBase>> &ops);
  void EnforceHasOp(OpHandleBase *op) const;
  bool IsBeforeOrSameImpl(OpHandleBase *op1, OpHandleBase *op2) const;

  std::unordered_map<OpHandleBase *, std::unordered_set<OpHandleBase *>>
      preceding_ops_;
  std::unordered_map<OpHandleBase *, std::unordered_set<OpHandleBase *>>
      pending_ops_;
};

}  // namespace details
}  // namespace framework
}  // namespace paddle