/* Copyright (c) 2016 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. */

#include "paddle/fluid/framework/block_desc.h"

#include <queue>

#include "paddle/fluid/framework/operator.h"
#include "paddle/fluid/framework/program_desc.h"

namespace paddle {
namespace framework {

VarDesc *BlockDesc::Var(const std::string &name) {
  auto it = vars_.find(name);
  if (it != vars_.end()) {
    return it->second.get();
  }
  need_update_ = true;
  auto *var = new VarDesc(name);
  vars_[name].reset(var);
  return var;
}

VarDesc *BlockDesc::FindVar(const std::string &name) const {
  auto it = vars_.find(name);
  if (it == vars_.end()) {
    return nullptr;
  }
  return it->second.get();
}

bool BlockDesc::HasVar(const std::string &name) const {
  return vars_.find(name) != vars_.end();
}

VarDesc *BlockDesc::RenameVar(const std::string &old_name,
                              const std::string &new_name) {
  if (!this->HasVar(old_name)) {
    return nullptr;
  }
  need_update_ = true;
  auto *var = this->Var(old_name);
  VarDesc *new_var = new VarDesc(*(var->Proto()));
  new_var->SetName(new_name);
  vars_[new_name].reset(new_var);
  // rename inputs and outputs
  for (const auto &op : ops_) {
    auto *it = op.get();
    it->Rename(old_name, new_name);
  }
  vars_.erase(old_name);
  return new_var;
}

VarDesc *BlockDesc::FindVarRecursive(const std::string &name) const {
  if (name == kEmptyVarName) return nullptr;

  std::queue<const BlockDesc *> frontier;
  std::unordered_set<const BlockDesc *> visited;

  frontier.push(this);

  while (!frontier.empty()) {  // BFS
    auto cur = frontier.front();
    frontier.pop();
    if (visited.count(cur) != 0) {
      continue;
    }
    auto var = cur->FindVar(name);
    if (var != nullptr) {
      return var;
    }

    auto fwd = cur->ForwardBlock();
    auto parent = cur->ParentBlock();

    if (fwd != nullptr) {
      frontier.push(fwd);
    }
    if (parent != nullptr) {
      frontier.push(parent);
    }

    visited.insert(cur);
  }

  return nullptr;
}

VarDesc &BlockDesc::FindRecursiveOrCreateVar(const std::string &name_bytes) {
  VarDesc *res = FindVarRecursive(name_bytes);
  if (res == nullptr) {
    res = Var(name_bytes);
  }
  return *res;
}

bool BlockDesc::HasVarRecursive(const std::string &name) const {
  return FindVarRecursive(name) != nullptr;
}

std::vector<VarDesc *> BlockDesc::AllVars() const {
  std::vector<VarDesc *> res;
  for (const auto &p : vars_) {
    res.push_back(p.second.get());
  }
  return res;
}

OpDesc *BlockDesc::AppendOp() {
  need_update_ = true;
  ops_.emplace_back(new OpDesc(this));
  return ops_.back().get();
}

void BlockDesc::AppendAllocatedOp(std::unique_ptr<OpDesc> &&op_desc) {
  need_update_ = true;
  ops_.emplace_back(std::move(op_desc));
}

OpDesc *BlockDesc::PrependOp() {
  need_update_ = true;
  ops_.emplace_front(new OpDesc(this));
  return ops_.front().get();
}

void BlockDesc::PrependAllocatedOp(std::unique_ptr<OpDesc> &&op_desc) {
  need_update_ = true;
  ops_.emplace_front(std::move(op_desc));
}

OpDesc *BlockDesc::InsertOp(size_t index) {
  need_update_ = true;
  auto it = ops_.begin() + index;
  std::unique_ptr<OpDesc> new_op(new OpDesc(this));
  it = ops_.insert(it, std::move(new_op));
  return (*it).get();
}

void BlockDesc::RemoveOp(size_t s, size_t e) {
  if (ops_.begin() + s >= ops_.end() || ops_.begin() + e > ops_.end()) {
    return;
  }
  need_update_ = true;
  ops_.erase(ops_.begin() + s, ops_.begin() + e);
}

void BlockDesc::RemoveOpInternal(const OpDesc *op_desc) {
  // TODO(minqiyang): make this faster
  for (auto it = ops_.begin(); it != ops_.end(); ++it) {
    if (it->get() == op_desc) {
      ops_.erase(it);
      break;
    }
  }
}

std::vector<OpDesc *> BlockDesc::AllOps() const {
  std::vector<OpDesc *> res;
  for (const auto &op : ops_) {
    res.push_back(op.get());
  }
  return res;
}

void BlockDesc::Flush() {
  auto need_update = NeedUpdate(true);
  for (auto &op_desc : ops_) {
    op_desc->Flush();
  }
  // no flush for var_desc? or is op_desc flush really needed?
  VLOG(10) << "Flush " << NeedUpdate(true) << " " << need_update << std::endl;
  if (need_update) {
    this->desc_->mutable_ops()->Clear();
    for (auto &op_desc : ops_) {
      this->desc_->mutable_ops()->Add()->CopyFrom(*op_desc->Proto());
      // op_desc's need_update is set to false in op_desc->Flush();
    }

    std::vector<std::string> var_names;
    std::set<std::string> var_names_set;

    // keep order
    for (const auto &var : this->desc_->vars()) {
      var_names.emplace_back(var.name());
      var_names_set.insert(var.name());
    }

    this->desc_->mutable_vars()->Clear();
    for (const auto &name : var_names) {
      if (vars_.count(name)) {
        this->desc_->mutable_vars()->Add()->CopyFrom(*vars_[name]->Proto());
        vars_[name]->SetNeedUpdate(false);
      }
    }

    for (auto &var_desc : vars_) {
      if (var_names_set.count(var_desc.first) != 1) {
        this->desc_->mutable_vars()->Add()->CopyFrom(*var_desc.second->Proto());
        var_desc.second->SetNeedUpdate(false);
      }
    }

    // this->desc_->mutable_vars()->Clear();
    // for (auto &var_desc : vars_) {
    //   this->desc_->mutable_vars()->Add()->CopyFrom(*var_desc.second->Proto());
    //   var_desc.second->SetNeedUpdate(false);
    // }
    need_update_ = false;
  }
}

BlockDesc *BlockDesc::ParentBlock() const {
  return prog_->MutableBlock(static_cast<size_t>(desc_->parent_idx()));
}

proto::BlockDesc *BlockDesc::Proto() {
  Flush();
  return desc_;
}

BlockDesc::BlockDesc(ProgramDesc *prog, proto::BlockDesc *desc)
    : prog_(prog), desc_(desc), need_update_(false) {
  for (const proto::VarDesc &var_desc : desc_->vars()) {
    vars_[var_desc.name()].reset(new VarDesc(var_desc));
  }

  for (const proto::OpDesc &op_desc : desc_->ops()) {
    ops_.emplace_back(new OpDesc(op_desc, this));
  }
}

BlockDesc::BlockDesc(const BlockDesc &other,
                     proto::BlockDesc *desc,
                     ProgramDesc *prog)
    : prog_(prog), desc_(desc) {
  need_update_ = true;
  // NOTE(dev): Init vars_ firstly so we can find them
  // while constructing OpDesc.
  for (auto &it : other.vars_) {
    auto *var = new VarDesc(*it.second);
    vars_[it.first].reset(var);
  }
  for (auto &op : other.ops_) {
    ops_.emplace_back(new OpDesc(*op, this));
  }
}

void BlockDesc::SetForwardBlockID(int32_t forward_block_id) {
  PADDLE_ENFORCE_EQ(
      desc_->has_forward_block_idx(),
      false,
      platform::errors::PreconditionNotMet(
          "Block %d's parent block ID has been set to %d, cannot be set to %d.",
          desc_->idx(),
          desc_->forward_block_idx(),
          forward_block_id));
  desc_->set_forward_block_idx(forward_block_id);
}

BlockDesc *BlockDesc::ForwardBlock() const {
  return prog_->MutableBlock(static_cast<size_t>(desc_->forward_block_idx()));
}

void BlockDesc::MoveFrom(BlockDesc *block) {
  PADDLE_ENFORCE_NOT_NULL(
      block, platform::errors::InvalidArgument("Block must be provided."));
  if (this == block) {
    return;
  }

  for (auto &pair : block->vars_) {
    const auto &name = pair.first;
    auto &var_ptr = pair.second;
    auto &old_var_ptr = vars_[name];
    if (old_var_ptr == nullptr) {
      VLOG(10) << "Create new variable " << var_ptr->Name();
      old_var_ptr = std::move(var_ptr);
    } else {
      // NOTE(zjl): cannot release old_var_ptr, because Python
      // Variable holds the reference of the C++ VarDesc object.
      // If the C++ VarDesc object is destructed, any call to the
      // methods of Python Variable may raise segmentation fault.
      VLOG(10) << "Update old variable " << var_ptr->Name();
      *old_var_ptr = *var_ptr;
    }
  }
  ops_.clear();
  for (const auto &src_op : block->ops_) {
    auto *dst_op = AppendOp();
    dst_op->CopyFrom(*src_op);
    for (const auto &pair : src_op->GetAttrMap()) {
      const auto &attr_name = pair.first;
      const auto &attr_value = pair.second;
      auto attr_type = static_cast<proto::AttrType>(attr_value.index() - 1);
      if (attr_type == proto::AttrType::VAR ||
          attr_type == proto::AttrType::VARS) {
        dst_op->UpdateVarAttr(attr_name, attr_value);
      } else if (attr_type == proto::AttrType::BLOCK) {
        auto block_id = PADDLE_GET_CONST(BlockDesc *, attr_value)->ID();
        dst_op->SetBlockAttr(attr_name, prog_->MutableBlock(block_id));
        VLOG(10) << "Set block attr " << attr_name << " id " << block_id;
      } else if (attr_type == proto::AttrType::BLOCKS) {
        auto old_blocks =
            PADDLE_GET_CONST(std::vector<BlockDesc *>, attr_value);
        std::vector<BlockDesc *> new_blocks;
        new_blocks.reserve(old_blocks.size());
        for (auto *b : old_blocks) {
          VLOG(10) << "Set block attr " << attr_name << " id " << b->ID();
          new_blocks.push_back(prog_->MutableBlock(b->ID()));
        }
        dst_op->SetBlocksAttr(attr_name, new_blocks);
      }
    }
  }
  need_update_ = true;
  Flush();

  block->ops_.clear();
  block->vars_.clear();
  block->need_update_ = true;
  block->Flush();
}

bool BlockDesc::NeedUpdate(bool include_subs) {
  bool need = need_update_;
  if (include_subs) {
    for (const auto &op : ops_) {
      if (op->NeedUpdate()) {
        need = true;
        break;
      }
    }
    for (const auto &pair : vars_) {
      if (pair.second->NeedUpdate()) {
        need = true;
        break;
      }
    }
  }
  return need;
}

}  // namespace framework
}  // namespace paddle