/* 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 <boost/variant.hpp>
#include <functional>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>

#include "paddle/framework/attribute.pb.h"
#include "paddle/framework/op_desc.pb.h"
#include "paddle/platform/enforce.h"

namespace paddle {
namespace framework {

typedef boost::variant<boost::blank, int, float, std::string, std::vector<int>,
                       std::vector<float>, std::vector<std::string>>
    Attribute;

typedef std::unordered_map<std::string, Attribute> AttributeMap;

template <typename T>
AttrType AttrTypeID();

Attribute GetAttrValue(const AttrDesc& attr_desc);

// check whether a value(attribute) fit a certain limit
template <typename T>
class LargerThanChecker {
 public:
  explicit LargerThanChecker(T lower_bound) : lower_bound_(lower_bound) {}
  void operator()(T& value) const {
    PADDLE_ENFORCE(value > lower_bound_, "larger_than check fail");
  }

 private:
  T lower_bound_;
};

// we can provide users more common Checker, like 'LessThanChecker',
// 'BetweenChecker'...

template <typename T>
class DefaultValueSetter {
 public:
  explicit DefaultValueSetter(T default_value)
      : default_value_(default_value) {}
  void operator()(T& value) const { value = default_value_; }

 private:
  T default_value_;
};

template <typename T>
class EnumInContainer {
 public:
  explicit EnumInContainer(const std::unordered_set<T>& c) : container_(c) {}
  void operator()(T& val) const {
    PADDLE_ENFORCE(container_.find(val) != container_.end(),
                   "Value %s is not in enum container %s", val,
                   ContainerDebugString());
  }

 private:
  std::string ContainerDebugString() const {
    std::ostringstream sout;
    sout << "[";
    size_t cnt = 0;
    for (auto& v : container_) {
      sout << v;
      ++cnt;
      if (cnt != container_.size()) {
        sout << " ,";
      }
    }
    sout << "]";
    return sout.str();
  }

  std::unordered_set<T> container_;
};

// check whether a certain attribute fit its limits
// an attribute can have more than one limits
template <typename T>
class TypedAttrChecker {
  typedef std::function<void(T&)> ValueChecker;

 public:
  explicit TypedAttrChecker(const std::string& attr_name)
      : attr_name_(attr_name) {}

  TypedAttrChecker& InEnum(const std::unordered_set<T>& range) {
    value_checkers_.push_back(EnumInContainer<T>(range));
    return *this;
  }

  TypedAttrChecker& LargerThan(const T& lower_bound) {
    value_checkers_.push_back(LargerThanChecker<T>(lower_bound));
    return *this;
  }

  // we can add more common limits, like LessThan(), Between()...

  TypedAttrChecker& SetDefault(const T& default_value) {
    PADDLE_ENFORCE(default_value_setter_.empty(),
                   "%s can't have more than one default value!", attr_name_);
    default_value_setter_.push_back(DefaultValueSetter<T>(default_value));
    return *this;
  }

  // allow users provide their own checker
  TypedAttrChecker& AddCustomChecker(const ValueChecker& checker) {
    value_checkers_.push_back(checker);
    return *this;
  }

  void operator()(AttributeMap& attr_map) const {
    if (!attr_map.count(attr_name_)) {
      // user do not set this attr
      PADDLE_ENFORCE(!default_value_setter_.empty(),
                     "Attribute '%s' is required!", attr_name_);
      // default_value_setter_ has no more than one element
      T val;
      (default_value_setter_[0])(val);
      attr_map[attr_name_] = val;
    }
    Attribute& attr = attr_map.at(attr_name_);
    T& attr_value = boost::get<T>(attr);
    for (const auto& checker : value_checkers_) {
      checker(attr_value);
    }
  }

 private:
  std::string attr_name_;
  std::vector<ValueChecker> value_checkers_;
  std::vector<ValueChecker> default_value_setter_;
};

// check whether op's all attributes fit their own limits
class OpAttrChecker {
  typedef std::function<void(AttributeMap&)> AttrChecker;

 public:
  template <typename T>
  TypedAttrChecker<T>& AddAttrChecker(const std::string& attr_name) {
    attr_checkers_.push_back(TypedAttrChecker<T>(attr_name));
    AttrChecker& checker = attr_checkers_.back();
    return *(checker.target<TypedAttrChecker<T>>());
  }

  void Check(AttributeMap& attr_map) const {
    for (const auto& checker : attr_checkers_) {
      checker(attr_map);
    }
  }

 private:
  std::vector<AttrChecker> attr_checkers_;
};

}  // namespace framework
}  // namespace paddle