// 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.

#include "paddle/fluid/framework/ir/conv_bn_fuse_pass.h"
#include <functional>
#include <string>
#include <vector>
#include "paddle/fluid/framework/lod_tensor.h"
#include "paddle/fluid/operators/math/cpu_vec.h"
#include "paddle/fluid/platform/enforce.h"

namespace paddle {
namespace framework {
namespace ir {

#define GET_CONV_BN_NODES(pattern_name)                                      \
  /* OPERATORS */                                                            \
  GET_IR_NODE_FROM_SUBGRAPH(conv, conv, pattern_name);                       \
  GET_IR_NODE_FROM_SUBGRAPH(batch_norm, batch_norm, pattern_name);           \
  /* CONV inputs */                                                          \
  GET_IR_NODE_FROM_SUBGRAPH(conv_weight, conv_weight, pattern_name);         \
  /* CONV outputs */                                                         \
  GET_IR_NODE_FROM_SUBGRAPH(conv_out, conv_out, pattern_name);               \
  /* BN inputs */                                                            \
  GET_IR_NODE_FROM_SUBGRAPH(bn_scale, bn_scale, pattern_name);               \
  GET_IR_NODE_FROM_SUBGRAPH(bn_bias, bn_bias, pattern_name);                 \
  GET_IR_NODE_FROM_SUBGRAPH(bn_mean, bn_mean, pattern_name);                 \
  GET_IR_NODE_FROM_SUBGRAPH(bn_variance, bn_variance, pattern_name);         \
  /* BN outputs */                                                           \
  GET_IR_NODE_FROM_SUBGRAPH(bn_out, bn_out, pattern_name); /* Out */         \
  GET_IR_NODE_FROM_SUBGRAPH(bn_mean_out, bn_mean_out, pattern_name);         \
  GET_IR_NODE_FROM_SUBGRAPH(bn_variance_out, bn_variance_out, pattern_name); \
  GET_IR_NODE_FROM_SUBGRAPH(bn_saved_mean, bn_saved_mean, pattern_name);     \
  GET_IR_NODE_FROM_SUBGRAPH(bn_saved_variance, bn_saved_variance, pattern_name)

template <typename UnaryOperation>
LoDTensor tensor_apply(const LoDTensor& vec, UnaryOperation f) {
  LoDTensor vec_y;
  vec_y.Resize(vec.dims());
  const float* x = vec.data<float>();
  float* y = vec_y.mutable_data<float>(platform::CPUPlace());
  for (int64_t i = 0; i < vec.numel(); i++) {
    y[i] = f(x[i]);
  }
  return vec_y;
}

void tensor_apply_inplace(LoDTensor* vec, float (*f)(float)) {
  float* data = vec->mutable_data<float>(platform::CPUPlace());
  for (int64_t i = 0; i < vec->numel(); i++) {
    data[i] = f(data[i]);
  }
}

template <typename BinaryOperation>
LoDTensor tensor_apply_eltwise(const LoDTensor& vec_a, const LoDTensor& vec_b,
                               BinaryOperation f) {
  PADDLE_ENFORCE_EQ(vec_a.dims(), vec_b.dims());
  LoDTensor vec_y;
  vec_y.Resize(vec_a.dims());
  const float* a = vec_a.data<float>();
  const float* b = vec_b.data<float>();
  float* y = vec_y.mutable_data<float>(platform::CPUPlace());
  for (int64_t i = 0; i < vec_a.numel(); i++) {
    y[i] = f(a[i], b[i]);
  }
  return vec_y;
}

template <typename BinaryOperation>
LoDTensor tensor_apply_eltwise_broadcast(const LoDTensor& vec_a,
                                         const LoDTensor& vec_b,
                                         BinaryOperation f) {
  PADDLE_ENFORCE_EQ(vec_a.dims().size(), 2);
  PADDLE_ENFORCE_EQ(vec_b.dims().size(), 2);
  PADDLE_ENFORCE_EQ(vec_a.dims()[0], vec_b.dims()[0]);
  PADDLE_ENFORCE_EQ(vec_b.dims()[1], 1);
  LoDTensor vec_y;
  vec_y.Resize(vec_a.dims());
  const float* a = vec_a.data<float>();
  const float* b = vec_b.data<float>();
  float* y = vec_y.mutable_data<float>(platform::CPUPlace());
  size_t a_height = vec_a.dims()[0];
  size_t a_width = vec_a.dims()[1];
  for (size_t h = 0; h < a_height; h++) {
    for (size_t w = 0; w < a_width; ++w) {
      *(y++) = f(*(a++), b[h]);
    }
  }
  return vec_y;
}

// reshape to two dimensions {A, B * C * ...}
void make_tensor_2d(LoDTensor* tensor_to_reshape) {
  auto dims_count = tensor_to_reshape->dims().size();
  PADDLE_ENFORCE_GT(dims_count, 0);

  int size2 = 1;
  for (int i = 1; i < dims_count; i++) {
    size2 *= tensor_to_reshape->dims()[i];
  }
  tensor_to_reshape->Resize(make_ddim({tensor_to_reshape->dims()[0], size2}));
}

void recompute_conv_weights(LoDTensor* weights, LoDTensor* tmp) {
  // remember the weights tensor shape {A, B, C, ...}
  auto weights_shape = weights->dims();
  // reduce the weights to 2d {A, B * C * ...}
  make_tensor_2d(weights);
  // make tmp tensor 2d by adding 1 as second dim {A, 1}
  make_tensor_2d(tmp);

  *weights =
      tensor_apply_eltwise_broadcast(*weights, *tmp, std::multiplies<float>());
  // reshape weights to the original dims {A, B, C, ...}
  weights->Resize(weights_shape);
}

void recompute_bias_and_weights(const Scope* scope,
                                ir::Node* conv_weight,            //
                                const ir::Node& bn_scale,         //
                                const LoDTensor& bn_bias_tensor,  //
                                const ir::Node& bn_mean,          //
                                const ir::Node& bn_variance,      //
                                LoDTensor* eltwise_y_in_tensor,   //
                                float epsilon) {
  // Re-compute bias of conv2d from BN
  PADDLE_ENFORCE_EQ(eltwise_y_in_tensor->dims(), bn_bias_tensor.dims());

  auto* scale_tensor = scope->FindVar(bn_scale.Name())->GetMutable<LoDTensor>();
  auto* variance_tensor =
      scope->FindVar(bn_variance.Name())->GetMutable<LoDTensor>();
  auto* mean_tensor = scope->FindVar(bn_mean.Name())->GetMutable<LoDTensor>();

  auto std_tensor = LoDTensor();
  std_tensor.Resize(bn_bias_tensor.dims());
  std_tensor =
      tensor_apply(*variance_tensor, [&](float x) { return x + epsilon; });

  using EigenVectorArrayMap =
      Eigen::Map<Eigen::Array<float, Eigen::Dynamic, 1>>;

  EigenVectorArrayMap std_vec(
      std_tensor.mutable_data<float>(platform::CPUPlace()), std_tensor.numel(),
      1);
  std_vec = std_vec.sqrt();
  auto tmp_tensor =
      tensor_apply_eltwise(*scale_tensor, std_tensor, std::divides<float>());
  auto tensor_minus = tensor_apply_eltwise(*eltwise_y_in_tensor, *mean_tensor,
                                           std::minus<float>());
  auto tensor_mul =
      tensor_apply_eltwise(tensor_minus, tmp_tensor, std::multiplies<float>());
  *eltwise_y_in_tensor =
      tensor_apply_eltwise(tensor_mul, bn_bias_tensor, std::plus<float>());

  // Re-compute weight of conv2d from BN
  auto* current_param =
      scope->FindVar(conv_weight->Name())->GetMutable<LoDTensor>();
  recompute_conv_weights(current_param, &tmp_tensor);
}

std::unique_ptr<ir::Graph> ConvBNFusePass::ApplyImpl(
    std::unique_ptr<ir::Graph> graph) const {
  PADDLE_ENFORCE(graph.get());
  FusePassBase::Init(name_scope_, graph.get());

  auto* scope = param_scope();
  PADDLE_ENFORCE(scope);

  GraphPatternDetector gpd;
  auto* conv_input =
      gpd.mutable_pattern()
          ->NewNode(patterns::PDNodeName(name_scope_, "conv_input"))
          ->AsInput()
          ->assert_is_op_input("conv2d", "Input");
  patterns::ConvBN conv_bn_pattern(gpd.mutable_pattern(), name_scope_);
  conv_bn_pattern(conv_input, false /*with_eltwise_add*/);

  int found_conv_bn_count = 0;
  auto handler = [&](const GraphPatternDetector::subgraph_t& subgraph,
                     Graph* g) {
    VLOG(4) << "handle ConvBN fuse";

    // conv, batch_norm,
    // conv_weight, conv_out,
    // bn_scale, bn_bias, bn_mean, bn_variance,
    // bn_out, bn_mean_out, bn_variance_out, bn_saved_mean, bn_saved_variance
    GET_CONV_BN_NODES(conv_bn_pattern);

    // Create eltwise_y (conv bias) variable
    VarDesc eltwise_y_in_desc(
        patterns::PDNodeName(name_scope_, "eltwise_y_in"));
    auto* eltwise_y_in_node = g->CreateVarNode(&eltwise_y_in_desc);
    auto* eltwise_y_in_tensor =
        scope->Var(eltwise_y_in_node->Name())->GetMutable<LoDTensor>();

    // Get batch norm bias
    auto* bn_bias_tensor =
        scope->FindVar(bn_bias->Name())->GetMutable<LoDTensor>();

    // Initialize eltwise_y
    eltwise_y_in_tensor->Resize(bn_bias_tensor->dims());
    std::fill_n(eltwise_y_in_tensor->mutable_data<float>(platform::CPUPlace()),
                eltwise_y_in_tensor->numel(), 0.0f);

    // update weights and biases
    float epsilon = boost::get<float>(batch_norm->Op()->GetAttr("epsilon"));
    recompute_bias_and_weights(scope, conv_weight, *bn_scale, *bn_bias_tensor,
                               *bn_mean, *bn_variance, eltwise_y_in_tensor,
                               epsilon);

    // Create an elementwise add node
    OpDesc desc;
    desc.SetInput("X", std::vector<std::string>({conv_out->Name()}));
    desc.SetInput("Y", std::vector<std::string>({eltwise_y_in_node->Name()}));
    desc.SetOutput("Out", std::vector<std::string>({bn_out->Name()}));
    desc.SetType("elementwise_add");
    desc.SetAttr("axis", 1);
    bool a = boost::get<bool>(conv->Op()->GetAttr("use_mkldnn"));
    desc.SetAttr("use_mkldnn", a);
    auto eltwise_op = g->CreateOpNode(&desc);  // OpDesc will be copied.

    GraphSafeRemoveNodes(graph.get(), {bn_scale, bn_bias, bn_mean, bn_variance,
                                       batch_norm, bn_mean_out, bn_variance_out,
                                       bn_saved_mean, bn_saved_variance});

    PADDLE_ENFORCE(subgraph.count(conv_input));
    IR_NODE_LINK_TO(conv_out, eltwise_op);
    IR_NODE_LINK_TO(eltwise_y_in_node, eltwise_op);
    IR_NODE_LINK_TO(eltwise_op, bn_out);

    found_conv_bn_count++;
  };

  gpd(graph.get(), handler);

  AddStatis(found_conv_bn_count);
  return graph;
}

std::unique_ptr<ir::Graph> ConvEltwiseAddBNFusePass::ApplyImpl(
    std::unique_ptr<ir::Graph> graph) const {
  PADDLE_ENFORCE(graph.get());
  FusePassBase::Init(name_scope_, graph.get());

  auto* scope = param_scope();
  PADDLE_ENFORCE(scope);

  GraphPatternDetector gpd;
  auto* conv_input =
      gpd.mutable_pattern()
          ->NewNode(patterns::PDNodeName(name_scope_, "conv_input"))
          ->AsInput()
          ->assert_is_op_input("conv2d", "Input");
  patterns::ConvBN conv_bn_pattern(gpd.mutable_pattern(), name_scope_);
  conv_bn_pattern(conv_input, true /*with_eltwise_add*/);

  int found_conv_bn_count = 0;
  auto handler = [&](const GraphPatternDetector::subgraph_t& subgraph,
                     Graph* g) {
    VLOG(4) << "handle ConvBN fuse";

    // conv, batch_norm,
    // conv_weight, conv_out,
    // bn_scale, bn_bias, bn_mean, bn_variance,
    // bn_out, bn_mean_out, bn_variance_out, bn_saved_mean,bn_saved_variance
    GET_CONV_BN_NODES(conv_bn_pattern);
    // OPERATORS
    GET_IR_NODE_FROM_SUBGRAPH(eltwise, eltwise, conv_bn_pattern);
    // BIAS inputs
    GET_IR_NODE_FROM_SUBGRAPH(eltwise_y_in, eltwise_y_in, conv_bn_pattern);
    // BIAS outputs
    GET_IR_NODE_FROM_SUBGRAPH(eltwise_out, eltwise_out, conv_bn_pattern);

    // Get eltwise_y (conv bias) variable
    auto* eltwise_y_in_tensor =
        scope->FindVar(eltwise_y_in->Name())->GetMutable<LoDTensor>();

    // Get batch norm bias
    auto* bn_bias_tensor =
        scope->FindVar(bn_bias->Name())->GetMutable<LoDTensor>();

    // update weights and biases
    float epsilon = boost::get<float>(batch_norm->Op()->GetAttr("epsilon"));
    recompute_bias_and_weights(scope, conv_weight, *bn_scale, *bn_bias_tensor,
                               *bn_mean, *bn_variance, eltwise_y_in_tensor,
                               epsilon);

    // Update the elementwise_add node
    eltwise->Op()->SetAttr("axis", 1);
    eltwise->Op()->SetOutput("Out", std::vector<std::string>({bn_out->Name()}));

    GraphSafeRemoveNodes(
        graph.get(),
        {bn_scale, bn_bias, bn_mean, bn_variance, batch_norm, bn_mean_out,
         bn_variance_out, bn_saved_mean, bn_saved_variance, eltwise_out});

    PADDLE_ENFORCE(subgraph.count(conv_input));
    IR_NODE_LINK_TO(eltwise, bn_out);

    found_conv_bn_count++;
  };

  gpd(graph.get(), handler);

  AddStatis(found_conv_bn_count);
  return graph;
}

}  // namespace ir
}  // namespace framework
}  // namespace paddle

REGISTER_PASS(conv_bn_fuse_pass, paddle::framework::ir::ConvBNFusePass);
REGISTER_PASS(conv_eltwiseadd_bn_fuse_pass,
              paddle::framework::ir::ConvEltwiseAddBNFusePass);