#pragma once
#include <vector>
#include <cstdint>
#include <string>
#include <memory>
#include <vector>
#include <ATen/ATen.h>
#include "ATen/Utils.h"

#include <torch/csrc/jit/assertions.h>
#include <torch/csrc/jit/interned_strings.h>

namespace torch { namespace jit {

enum class AttributeKind {
  f,fs,i,is,s,ss,t,ts,g,gs
};
static inline const char * toString(AttributeKind kind) {
  static const char* names[] = {"f","fs","i","is","s","ss","t","ts","g","gs"};
  JIT_ASSERT(size_t(kind) < sizeof(names)/sizeof(AttributeKind));
  return names[int(kind)];
}

struct AttributeValue {
  AttributeValue(Symbol name)
  : name(name) {}
  using Ptr = std::unique_ptr<AttributeValue>;
  Symbol name;
  virtual AttributeKind kind() const = 0;
  virtual Ptr clone() const = 0;
  virtual ~AttributeValue() = default;
};

template<typename T, AttributeKind Kind>
struct ScalarAttributeValue : public AttributeValue {
  using ConstructorType = T;
  using ValueType = T;
  ScalarAttributeValue(Symbol name, ConstructorType value_)
  : AttributeValue(name), value_(std::move(value_)) {}
  ValueType & value() {
    return value_;
  }
  Ptr clone() const override {
    return Ptr(new ScalarAttributeValue(name, value_));
  }
  AttributeKind kind() const override { return Kind; }
private:
  ValueType value_;
};

template<typename T, AttributeKind Kind>
struct VectorAttributeValue : public AttributeValue {
  using ConstructorType = std::vector<T>;
  using ValueType = std::vector<T>;
  VectorAttributeValue(Symbol name, ConstructorType value_)
  : AttributeValue(name), value_(std::move(value_)) {}
  ValueType & value() {
    return value_;
  }
  AttributeKind kind() const override { return Kind; }
  std::unique_ptr<AttributeValue> clone() const override {
    auto copy = value_;
    return Ptr(new VectorAttributeValue(name, std::move(copy)));
  }
private:
  ValueType value_;
};

using FloatAttr = ScalarAttributeValue<double,AttributeKind::f>;
using FloatsAttr = VectorAttributeValue<double,AttributeKind::fs>;
using IntAttr = ScalarAttributeValue<int64_t,AttributeKind::i>;
using IntsAttr = VectorAttributeValue<int64_t,AttributeKind::is>;
using StringAttr = ScalarAttributeValue<std::string,AttributeKind::s>;
using StringsAttr = VectorAttributeValue<std::string,AttributeKind::ss>;
using TensorAttr = ScalarAttributeValue<at::Tensor,AttributeKind::t>;
using TensorsAttr = VectorAttributeValue<at::Tensor,AttributeKind::ts>;
struct Graph;
using GraphAttr = ScalarAttributeValue<std::shared_ptr<Graph>,AttributeKind::g>;
using GraphsAttr = VectorAttributeValue<std::shared_ptr<Graph>,AttributeKind::gs>;

struct AttributeError : public std::exception {
  AttributeError(Symbol name, bool defined) {
    std::stringstream ss;
    if(!defined) {
      ss << "required keyword attribute '" << name.toUnqualString() << "' is undefined.";
    } else {
      ss << "required keyword attribute '" << name.toUnqualString() << "' has the wrong type";
    }
    msg = ss.str();
  }
  const char* what() const noexcept override  {
    return msg.c_str();
  }
private:
  std::string msg;
};

// CRTP so that Node which inherits Attributes can be return for
// method chaining e.g:
// Node * n = g->create(kSelect)->i_(kOffset,3)->f_(kValue,3.5);
// we return Derived* pointers because Nodes are normally held as pointers.
template<typename Derived>
struct Attributes {
  Attributes() = default;
  void copyAttributes(const Attributes & rhs) {
    values_.clear();
    for(auto & i : rhs.values_) {
      values_.push_back(i->clone());
    }
  }
  bool hasAttribute(Symbol name) const {
    JIT_ASSERT(name.is_attr());
    return find(name,false) != values_.end();
  }
  // We want direct string accessors, as it is nicer to use than
  // hasAttribute(Symbol::attr("blah"))
  //
  // For some reason, &Attributes<Node>::hasAttribute in pybind11 is able to
  // give the pybind11 metaprogramming machinery "the right type", but
  // the equivalent looking lambda [](Attributes<Node>& a, const std::string&)
  // doesn't work!  So instead we define the methods on the class so we can
  // continue using the old idiom.
  bool hasAttributeS(const std::string& name) const {
    return hasAttribute(Symbol::attr(name));
  }
  AttributeKind kindOf(Symbol name) const {
    JIT_ASSERT(name.is_attr());
    return (*find(name,true))->kind();
  }
  AttributeKind kindOfS(const std::string& name) const {
    return kindOf(Symbol::attr(name));
  }
  Derived* removeAttribute(Symbol name) {
    JIT_ASSERT(name.is_attr());
    values_.erase(find(name,true));
    return This();
  }
  Derived* removeAttributeS(const std::string& name) {
    return removeAttribute(Symbol::attr(name));
  }
  bool hasAttributes() const {
    return values_.size() > 0;
  }
  size_t numAttributes() const {
    return values_.size();
  }
  // The names are returned in order, since name actually is the index.
  std::vector<Symbol> attributeNames() const {
    std::vector<Symbol> names;
    for(auto & a : values_)
      names.push_back(a->name);
    return names;
  }
  std::vector<const char*> attributeNamesS() const {
    std::vector<const char*> names;
    for(auto & a : values_)
      names.push_back(a->name.toUnqualString());
    return names;
  }

  #define CREATE_ACCESSOR(Kind, method) \
  Derived* method##_(Symbol name, Kind##Attr::ConstructorType v) { \
    return set<Kind##Attr>(name,std::forward<Kind##Attr::ConstructorType>(v)); \
  } \
  const Kind##Attr::ValueType& method(Symbol name) const { \
    return get<Kind##Attr>(name); \
  }
  CREATE_ACCESSOR(Float,f)
  CREATE_ACCESSOR(Floats,fs)
  CREATE_ACCESSOR(String,s)
  CREATE_ACCESSOR(Strings,ss)
  CREATE_ACCESSOR(Int,i)
  CREATE_ACCESSOR(Ints,is)
  CREATE_ACCESSOR(Graph,g)
  CREATE_ACCESSOR(Graphs,gs)

  #undef CREATE_ACCESSOR

  // Our Graphs are not very const-correct, so we need to allow returning
  // non-const references too
  GraphAttr::ValueType& g(Symbol name) {
    return get<GraphAttr>(name);
  }

  // does not use CREATE_ACCESSOR because we need additional asserts
  Derived* t_(Symbol name, TensorAttr::ConstructorType v) {
    JIT_ASSERT(!v.defined() || !v.is_variable());
    return set<TensorAttr>(name,std::forward<TensorAttr::ConstructorType>(v));
  }
  const TensorAttr::ValueType& t(Symbol name) const {
    return get<TensorAttr>(name);
  }

  Derived* ts_(Symbol name, TensorsAttr::ConstructorType v) {
    for(auto & t : v) {
      JIT_ASSERT(!t.defined() || !t.is_variable());
    }
    return set<TensorsAttr>(name,std::forward<TensorsAttr::ConstructorType>(v));
  }
  const TensorsAttr::ValueType& ts(Symbol name) const {
    return get<TensorsAttr>(name);
  }

private:
  // UBSAN error: https://github.com/pytorch/pytorch/issues/9055
  Derived* This() __ubsan_ignore_vptr__ {
    return static_cast<Derived*>(this);
  }
  template<typename T>
  Derived* set(Symbol name, typename T::ConstructorType v) {
    JIT_ASSERT(name.is_attr());
    auto it = find(name, false);
    auto nv = AVPtr(new T(name, std::forward<typename T::ConstructorType>(v)));
    if(it == values_.end()) {
      values_.push_back(std::move(nv));
    } else {
      *it = std::move(nv);
    }
    return This();
  }
  template<typename T>
  typename T::ValueType & get(Symbol name) const {
    JIT_ASSERT(name.is_attr());
    auto it = find(name, true);
    auto* child = dynamic_cast<T*>(it->get());
    if(child == nullptr) {
      throw AttributeError(name, true);
    }
    return child->value();
  }
  using AVPtr = AttributeValue::Ptr;
  // NB: For determinism, we use a vector rather than a hash map.  This does
  // mean that lookups are O(n), so you shouldn't use Attributes to store
  // a big pile of messages.
  std::vector<AVPtr> values_;
  using iterator = std::vector<AVPtr>::iterator;
  iterator find(Symbol name, bool required) {
    JIT_ASSERT(name.is_attr());
    auto it = std::find_if(values_.begin(), values_.end(),[&](const AVPtr & v) {
      return v->name == name;
    });
    if(required && it == values_.end()) {
      throw AttributeError(name, false);
    }
    JIT_ASSERT(!required || it != values_.end());
    return it;
  }
  using const_iterator = std::vector<AVPtr>::const_iterator;
  const_iterator find(Symbol name, bool required) const {
    JIT_ASSERT(name.is_attr());
    auto it = std::find_if(values_.begin(), values_.end(),[&](const AVPtr & v) {
      return v->name == name;
    });
    if(required && it == values_.end()) {
      throw AttributeError(name, false);
    }
    JIT_ASSERT(!required || it != values_.end());
    return it;
  }
};

}}
