/* 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. */

#pragma once

#include <algorithm>
#include <atomic>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
#include "paddle/framework/attribute.h"
#include "paddle/framework/grad_op_builder.h"
#include "paddle/framework/op_desc.pb.h"
#include "paddle/framework/scope.h"

namespace paddle {
namespace framework {

// this class not only make proto but also init attribute checkers.
class OpProtoAndCheckerMaker {
 public:
  OpProtoAndCheckerMaker(OpProto* proto, OpAttrChecker* op_checker)
      : proto_(proto), op_checker_(op_checker) {}

  ~OpProtoAndCheckerMaker() {
    PADDLE_ENFORCE(validated_, "should call Validate after build");
  }

  void Validate() {
    validated_ = true;
    CheckNoDuplicatedInOutAttrs();
  }

 protected:
  struct VariableBuilder {
    VarProto* var_;
    std::function<void()> on_multiple_;
    std::function<void()> on_temporary_;

    VariableBuilder& SetMultiple() {
      var_->set_multiple(true);
      on_multiple_();
      return *this;
    }

    VariableBuilder& SetTemporary() {
      PADDLE_ENFORCE(bool(on_temporary_), "Cannot set temporary");
      var_->set_temporary(true);
      on_temporary_();
      return *this;
    }

    VariableBuilder& IgnoreGradient() {
      var_->set_ignore_gradient(true);
      return *this;
    }
  };

  VariableBuilder AddInput(const std::string& name,
                           const std::string& comment) {
    auto input = proto_->mutable_inputs()->Add();
    *input->mutable_name() = name;
    *input->mutable_comment() = comment;
    return VariableBuilder{input, [=] { this->SetHasMultipleInput(); },
                           nullptr};
  }

  VariableBuilder AddOutput(const std::string& name,
                            const std::string& comment) {
    auto output = proto_->mutable_outputs()->Add();
    *output->mutable_name() = name;
    *output->mutable_comment() = comment;
    return VariableBuilder{output, [=] { this->SetHasMultipleOutput(); },
                           [=] { this->SetHasTemporaryOutput(); }};
  }

  template <typename T>
  TypedAttrChecker<T>& AddAttr(const std::string& name,
                               const std::string& comment,
                               bool generated = false) {
    auto attr = proto_->mutable_attrs()->Add();
    *attr->mutable_name() = name;
    *attr->mutable_comment() = comment;
    attr->set_generated(generated);
    attr->set_type(AttrTypeID<T>());
    return op_checker_->AddAttrChecker<T>(name);
  }

  void AddComment(const std::string& comment) {
    *(proto_->mutable_comment()) = comment;
  }

 private:
  void SetHasMultiple(const std::string& in_out, bool* flag) {
    if (!*flag) {
      AddAttr<std::vector<int>>(in_out + "_format",
                                "The multiple index of " + in_out +
                                    "\n"
                                    R"DOC(
This attribute is used by Paddle core framework. Paddle's Op support each input
or output could be a list of variable. This attribute is used to show how that
list organized.

e.g.
  input = ["a", "b", "c", "d", "e", "f"]
  input_format = [0, 4, 5, 6]

means
  The number of all input variables this op is six, and they are segmented into
  three inputs.

  The first input is input[0:4], second is input[4:5], third is input[5:6].
)DOC",
                                /*generated*/ true);
      *flag = true;
    }
  }

  void SetHasMultipleInput() { SetHasMultiple("input", &has_multiple_input_); }
  void SetHasMultipleOutput() {
    SetHasMultiple("output", &has_multiple_output_);
  }

  void SetHasTemporaryOutput() {
    if (!has_temporary_output_) {
      AddAttr<std::vector<int>>("temporary_index",
                                R"DOC(The temporary index of output.

Not all output of Paddle Op is used by user. For faster computation, each op
could output some its internal state to other op, other op could take that
output to make compute faster.

Add a mark to which output is temporary is helpful for future optimization.
)DOC",
                                /*generated*/ true)
          .SetDefault(std::vector<int>());
      has_temporary_output_ = true;
    }
  }

  void CheckNoDuplicatedInOutAttrs() {
    std::unordered_set<std::string> names;
    auto checker = [&](const std::string& name) {
      PADDLE_ENFORCE(!names.count(name), "[%s] is duplicated", name);
      names.insert(name);
    };
    for (auto& attr : proto_->attrs()) {
      checker(attr.name());
    }
    for (auto& input : proto_->inputs()) {
      checker(input.name());
    }
    for (auto& output : proto_->outputs()) {
      checker(output.name());
    }
  }

  OpProto* proto_;
  OpAttrChecker* op_checker_;
  bool validated_{false};
  bool has_multiple_input_{false};
  bool has_multiple_output_{false};
  bool has_temporary_output_{false};
};

class OpRegistry {
  using OpCreator = std::function<OperatorBase*()>;
  using VarIndexMap = std::unordered_map<std::string, int>;
  using VarNameList = std::vector<std::string>;

 public:
  template <typename OpType, typename ProtoMakerType>
  static void RegisterOp(const std::string& op_type) {
    op_creators()[op_type] = [] { return new OpType; };
    OpAttrChecker& op_checker = op_checkers()[op_type];
    OpProto& op_proto = protos()[op_type];
    auto maker = ProtoMakerType(&op_proto, &op_checker);
    maker.Validate();
    *op_proto.mutable_type() = op_type;
    PADDLE_ENFORCE(
        op_proto.IsInitialized(),
        "Fail to initialize %s's OpProto, because %s is not initialized",
        op_type, op_proto.InitializationErrorString());

    VarIndexMaps()[op_type].reset(new VarIndexMap());
    auto& varmap = *VarIndexMaps()[op_type];
    int idx = 0;
    for (auto& var : op_proto.inputs()) {
      varmap[var.name()] = idx++;
    }
    idx = 0;
    for (auto& var : op_proto.outputs()) {
      varmap[var.name()] = idx++;
    }
  }

  template <typename GradOpType>
  static void RegisterGradOp(const std::string& op_type,
                             const std::string& grad_op_type) {
    op_creators()[grad_op_type] = [] { return new GradOpType; };
    grad_ops()[op_type] = grad_op_type;
  }

  static std::shared_ptr<OperatorBase> CreateOp(const std::string& type,
                                                const VarNameList& inputs,
                                                const VarNameList& outputs,
                                                const AttributeMap& attrs) {
    auto op_create_it = op_creators().find(type);
    PADDLE_ENFORCE(op_create_it != op_creators().end(),
                   "Operator %s cannot be found.", type);

    auto op = op_create_it->second();
    op->type_ = type;
    op->inputs_ = inputs;
    op->outputs_ = outputs;

    op->attrs_ = attrs;
    op_checkers().at(type).Check(op->attrs_);

    GenerateTempVariableName(op);

    {
      auto var_index_it = VarIndexMaps().find(type);
      if (var_index_it != VarIndexMaps().end()) {
        op->in_out_idxs_ = var_index_it->second;
      }
    }

    op->Init();
    return std::shared_ptr<OperatorBase>(op);
  }

  static std::shared_ptr<OperatorBase> CreateOp(const OpDesc& op_desc) {
    std::vector<std::string> inputs;
    inputs.reserve((size_t)op_desc.inputs_size());
    std::copy(op_desc.inputs().begin(), op_desc.inputs().end(),
              std::back_inserter(inputs));

    std::vector<std::string> outputs;
    outputs.reserve((size_t)op_desc.outputs_size());
    std::copy(op_desc.outputs().begin(), op_desc.outputs().end(),
              std::back_inserter(outputs));

    AttributeMap attrs;
    for (auto& attr : op_desc.attrs()) {
      attrs[attr.name()] = GetAttrValue(attr);
    }

    return CreateOp(op_desc.type(), inputs, outputs, attrs);
  }

  static std::shared_ptr<OperatorBase> CreateGradOp(const OperatorBase& op) {
    PADDLE_ENFORCE(!op.IsNetOp(),
                   "Use framework::Backward to get backward ops");
    std::shared_ptr<OperatorBase> grad_op(BuildGradOp(&op));
    grad_op->Init();
    return grad_op;
  }

  static std::unordered_map<std::string, OpProto>& protos() {
    static std::unordered_map<std::string, OpProto> protos_;
    return protos_;
  }

  static std::unordered_map<std::string, std::string>& grad_ops() {
    static std::unordered_map<std::string, std::string> grad_ops_;
    return grad_ops_;
  }

  static std::unordered_map<std::string, std::shared_ptr<VarIndexMap>>&
  VarIndexMaps() {
    static std::unordered_map<std::string, std::shared_ptr<VarIndexMap>> maps_;
    return maps_;
  }

  static std::unordered_map<std::string, OpCreator>& op_creators() {
    static std::unordered_map<std::string, OpCreator> op_creators_;
    return op_creators_;
  }

 private:
  static std::unordered_map<std::string, OpAttrChecker>& op_checkers() {
    static std::unordered_map<std::string, OpAttrChecker> op_checkers_;
    return op_checkers_;
  }

  static void GenerateTempVariableName(OperatorBase* op) {
    static std::atomic<size_t> gUniqId(0UL);
    for (auto& outname : op->outputs_) {
      if (outname == kTempVarName) {
        outname += op->type_;
        outname += "@";
        outname += std::to_string(gUniqId.fetch_add(1));
      }
    }
  }
};

class Registrar {
 public:
  void Touch() {}
};

template <typename OpType, typename ProtoMakerType>
class OpRegistrar : public Registrar {
 public:
  explicit OpRegistrar(const char* op_type) {
    OpRegistry::RegisterOp<OpType, ProtoMakerType>(op_type);
  }
};

template <typename GradOpType>
class GradOpRegistrar : public Registrar {
 public:
  GradOpRegistrar(const char* op_type, const char* grad_op_type) {
    OpRegistry::RegisterGradOp<GradOpType>(op_type, grad_op_type);
  }
};

template <typename PlaceType, typename KernelType>
class OpKernelRegistrar : public Registrar {
 public:
  explicit OpKernelRegistrar(const char* op_type) {
    ::paddle::framework::OperatorWithKernel::OpKernelKey key;
    key.place_ = PlaceType();
    ::paddle::framework::OperatorWithKernel::AllOpKernels()[op_type][key].reset(
        new KernelType);
  }
};

/**
 * check if MACRO is used in GLOBAL NAMESPACE.
 */
#define STATIC_ASSERT_GLOBAL_NAMESPACE(uniq_name, msg)                        \
  struct __test_global_namespace_##uniq_name##__ {};                          \
  static_assert(std::is_same<::__test_global_namespace_##uniq_name##__,       \
                             __test_global_namespace_##uniq_name##__>::value, \
                msg)

/**
 * Macro to Register Operator.
 */
#define REGISTER_OP(op_type, op_class, op_maker_class)                        \
  STATIC_ASSERT_GLOBAL_NAMESPACE(                                             \
      __reg_op__##op_type, "REGISTER_OP must be called in global namespace"); \
  static ::paddle::framework::OpRegistrar<op_class, op_maker_class>           \
      __op_registrar_##op_type##__(#op_type);                                 \
  int TouchOpRegistrar_##op_type() {                                          \
    __op_registrar_##op_type##__.Touch();                                     \
    return 0;                                                                 \
  }

/**
 * Macro to Register Gradient Operator.
 */
#define REGISTER_GRADIENT_OP(op_type, grad_op_type, grad_op_class)           \
  STATIC_ASSERT_GLOBAL_NAMESPACE(                                            \
      __reg_gradient_op__##op_type##_##grad_op_type,                         \
      "REGISTER_GRADIENT_OP must be called in global namespace");            \
  static ::paddle::framework::GradOpRegistrar<grad_op_class>                 \
      __op_gradient_registrar_##op_type##_##grad_op_type##__(#op_type,       \
                                                             #grad_op_type); \
  int TouchOpGradientRegister_##op_type() {                                  \
    __op_gradient_registrar_##op_type##_##grad_op_type##__.Touch();          \
    return 0;                                                                \
  }

/**
 * Macro to Register OperatorKernel.
 */
#define REGISTER_OP_KERNEL(op_type, DEVICE_TYPE, place_class, ...)        \
  STATIC_ASSERT_GLOBAL_NAMESPACE(                                         \
      __reg_op_kernel_##op_type##_##DEVICE_TYPE##__,                      \
      "REGISTER_OP_KERNEL must be called in global namespace");           \
  static ::paddle::framework::OpKernelRegistrar<place_class, __VA_ARGS__> \
      __op_kernel_registrar_##op_type##_##DEVICE_TYPE##__(#op_type);      \
  int TouchOpKernelRegistrar_##op_type##_##DEVICE_TYPE() {                \
    __op_kernel_registrar_##op_type##_##DEVICE_TYPE##__.Touch();          \
    return 0;                                                             \
  }

/**
 * Macro to Forbid user register Gradient Operator.
 */
#define NO_GRADIENT(op_type)                           \
  STATIC_ASSERT_GLOBAL_NAMESPACE(                      \
      __reg_gradient_op__##op_type##_##op_type##_grad, \
      "NO_GRADIENT must be called in global namespace")

#define REGISTER_OP_GPU_KERNEL(op_type, ...) \
  REGISTER_OP_KERNEL(op_type, GPU, ::paddle::platform::GPUPlace, __VA_ARGS__)

#define REGISTER_OP_CPU_KERNEL(op_type, ...) \
  REGISTER_OP_KERNEL(op_type, CPU, ::paddle::platform::CPUPlace, __VA_ARGS__)

/**
 * Macro to mark what Operator and Kernel we will use and tell the compiler to
 * link them into target.
 */
#define USE_OP_ITSELF(op_type)                                    \
  STATIC_ASSERT_GLOBAL_NAMESPACE(                                 \
      __use_op_itself_##op_type,                                  \
      "USE_OP_ITSELF must be called in global namespace");        \
  extern int TouchOpRegistrar_##op_type();                        \
  static int use_op_itself_##op_type##_ __attribute__((unused)) = \
      TouchOpRegistrar_##op_type()

#define USE_OP_KERNEL(op_type, DEVICE_TYPE)                      \
  STATIC_ASSERT_GLOBAL_NAMESPACE(                                \
      __use_op_kernel_##op_type##_##DEVICE_TYPE##__,             \
      "USE_OP_KERNEL must be in global namespace");              \
  extern int TouchOpKernelRegistrar_##op_type##_##DEVICE_TYPE(); \
  static int use_op_kernel_##op_type##_##DEVICE_TYPE##_          \
      __attribute__((unused)) =                                  \
          TouchOpKernelRegistrar_##op_type##_##DEVICE_TYPE()

#ifdef PADDLE_ONLY_CPU
#define USE_OP(op_type)   \
  USE_OP_ITSELF(op_type); \
  USE_OP_KERNEL(op_type, CPU)
#else
#define USE_OP(op_type)        \
  USE_OP_ITSELF(op_type);      \
  USE_OP_KERNEL(op_type, CPU); \
  USE_OP_KERNEL(op_type, GPU)
#endif

}  // namespace framework
}  // namespace paddle