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

#include <queue>

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();
}

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;
  std::vector<std::string> vars1;  // input vars from delete ops
  for (auto it = ops_.begin() + s; it != ops_.begin() + e; it++) {
    // delete all output vars
    auto out_names = (*it)->OutputArgumentNames();
    for (auto n : out_names) {
      vars_.erase(vars_.find(n));
    }
    // collect all input vars from remove ops
    auto in_names = (*it)->InputArgumentNames();
    vars1.insert(vars1.end(), in_names.begin(), in_names.end());
  }
  ops_.erase(ops_.begin() + s, ops_.begin() + e);

  // collect input and output vars from remain ops
  std::vector<std::string> vars2;
  for (auto it = ops_.begin(); it != ops_.end(); it++) {
    auto in_names = (*it)->InputArgumentNames();
    auto out_names = (*it)->OutputArgumentNames();
    vars2.insert(vars2.end(), in_names.begin(), in_names.end());
    vars2.insert(vars2.end(), out_names.begin(), out_names.end());
  }

  // delete input vars if no other op use it.
  std::vector<std::string> del_vars;
  std::sort(vars1.begin(), vars1.end());
  std::unique(vars1.begin(), vars1.end());
  std::sort(vars2.begin(), vars2.end());
  std::unique(vars2.begin(), vars2.end());
  // del_vars = vars1 -  vars1 ^ vars2
  std::set_difference(vars1.begin(), vars1.end(), vars2.begin(), vars2.end(),
                      std::inserter(del_vars, del_vars.end()));
  for (auto it = del_vars.begin(); it != del_vars.end(); it++) {
    vars_.erase(vars_.find(*it));
  }
}

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() {
  for (auto &op_desc : ops_) {
    op_desc->Flush();
  }

  if (need_update_) {
    auto &op_field = *this->desc_->mutable_ops();
    this->ClearPBOps();
    op_field.Reserve(static_cast<int>(ops_.size()));
    for (auto &op_desc : ops_) {
      op_field.AddAllocated(op_desc->Proto());
    }
    auto &var_field = *this->desc_->mutable_vars();
    this->ClearPBVars();
    var_field.Reserve(static_cast<int>(vars_.size()));
    for (auto &var_desc : vars_) {
      var_field.AddAllocated(var_desc.second->Proto());
    }
    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, prog, this));
  }
}

BlockDesc::BlockDesc(const BlockDesc &other, proto::BlockDesc *desc,
                     ProgramDesc *prog)
    : prog_(prog), desc_(desc) {
  need_update_ = true;
  for (auto &op : other.ops_) {
    ops_.emplace_back(new OpDesc(*op->Proto(), prog, this));
  }
  for (auto &it : other.vars_) {
    auto *var = new VarDesc(*it.second);
    vars_[it.first].reset(var);
  }
}

void BlockDesc::ClearPBOps() {
  auto ops = this->desc_->mutable_ops();
  while (!ops->empty()) {
    // we do not own the OpDesc, so release the ownership.
    ops->ReleaseLast();
  }
}

void BlockDesc::ClearPBVars() {
  auto vars = this->desc_->mutable_vars();
  while (!vars->empty()) {
    // we do not own the VarDesc, so release the ownership.
    vars->ReleaseLast();
  }
}

void BlockDesc::SetForwardBlockID(int32_t forward_block_id) {
  PADDLE_ENFORCE(!desc_->has_forward_block_idx(),
                 "Parent block ID has been set to %d. Cannot set to %d",
                 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()));
}

}  // namespace framework
}  // namespace paddle