#include <torch/csrc/jit/ir/ir.h>

#include <algorithm>
#include <unordered_map>

#include <ATen/core/functional.h>
#include <ATen/core/interned_strings.h>
#include <c10/util/Exception.h>
#include <c10/util/hash.h>
#include <torch/csrc/jit/ir/node_hashing.h>
#include <torch/csrc/jit/passes/common_subexpression_elimination.h>

namespace torch {
namespace jit {

namespace {

bool tensorEqual(const at::Tensor& lhs, const at::Tensor& rhs) {
  return lhs.options().type_equal(rhs.options()) && lhs.equal(rhs);
}

bool typeListEqual(
    const std::vector<TypePtr>& lhs,
    const std::vector<TypePtr>& rhs) {
  if (lhs.size() != rhs.size())
    return false;
  for (size_t i = 0; i < lhs.size(); ++i) {
    if (*lhs[i] != *rhs[i]) {
      return false;
    }
  }
  return true;
}

template <typename attribute_type> // int64_t, bool, double
bool attributesEqual(attribute_type a1, attribute_type a2) {
  return a1 == a2;
}

bool attributesEqual(const at::Tensor& a1, const at::Tensor& a2) {
  return tensorEqual(a1, a2);
}

bool ivaluesEqual(const IValue& a1, const IValue& a2);

bool attributesEqual(
    const std::vector<at::Tensor>& lhs,
    const std::vector<at::Tensor>& rhs) {
  if (lhs.size() != rhs.size())
    return false;
  return std::equal(lhs.begin(), lhs.end(), rhs.begin(), tensorEqual);
}

bool attributesEqual(at::ArrayRef<IValue> a1, at::ArrayRef<IValue> a2) {
  if (a1.size() != a2.size()) {
    return false;
  }
  for (size_t i = 0; i < a1.size(); ++i) {
    if (!ivaluesEqual(a1[i], a2[i])) {
      return false;
    }
  }
  return true;
}

bool attributesEqual(const IValue& a1, const IValue& a2) {
  return ivaluesEqual(a1, a2);
}

// this is not a general-purpose comparison of IValues, it only covers the
// ivalues that are allowed as attributes, and it does not check type
// equivalence of containers.
bool ivaluesEqual(const IValue& a1, const IValue& a2) {
  if (a1.tagKind() != a2.tagKind()) {
    return false;
  }
  if (a1.isInt()) {
    return a1.toInt() == a2.toInt();
  }
  if (a1.isBool()) {
    return a1.toBool() == a2.toBool();
  }
  if (a1.isDouble()) {
    return a1.toDouble() == a2.toDouble();
  }
  if (a1.isTensor()) {
    return attributesEqual(a1.toTensor(), a2.toTensor());
  }
  if (a1.isNone()) {
    return true;
  }
  if (a1.isString()) {
    return a1.toStringRef() == a2.toStringRef();
  }
  if (a1.isList()) {
    return attributesEqual(a1.toListRef(), a2.toListRef());
  }
  if (a1.isTuple()) {
    at::ArrayRef<IValue> a1_elem = a1.toTuple()->elements();
    at::ArrayRef<IValue> a2_elem = a2.toTuple()->elements();
    return attributesEqual(a1_elem, a2_elem);
  }
  if (a1.isGenericDict()) {
    auto a1_dict = a1.toGenericDict();
    auto a2_dict = a2.toGenericDict();
    if (a1_dict.size() != a2_dict.size()) {
      return false;
    }

    auto it_a1 = a1_dict.begin();
    auto it_a2 = a2_dict.begin();

    while (it_a1 != a1_dict.end()) {
      const auto& e_a1 = *it_a1;
      const auto& e_a2 = *it_a2;

      if (!ivaluesEqual(e_a1.key(), e_a2.key()) ||
          !ivaluesEqual(e_a1.value(), e_a2.value())) {
        return false;
      }
      it_a1++;
      it_a2++;
    }
    return true;
  }
  if (a1.isEnum()) {
    return a1.toEnumHolder() == a2.toEnumHolder();
  }
  if (a1.isObject()) {
    return &a1.toObjectRef() == &a2.toObjectRef();
  }
  TORCH_INTERNAL_ASSERT(false);
}

// Check whether two nodes have the same attributes in CSE.
// This function may be too conservative for general use.
// Do NOT support g/gs attributes.
bool attributesEqualCSE(const Node* lhs, const Node* rhs) {
  AT_ASSERT(lhs != nullptr);
  AT_ASSERT(rhs != nullptr);
  // One has attributes, the other does not.
  if (lhs->hasAttributes() != rhs->hasAttributes())
    return false;
  // Neither has attributes.
  if (!lhs->hasAttributes() && !rhs->hasAttributes())
    return true;

  auto lnames = lhs->attributeNames();
  auto rnames = rhs->attributeNames();
  std::sort(lnames.begin(), lnames.end());
  std::sort(rnames.begin(), rnames.end());
  if (lnames != rnames)
    return false;

  for (auto name : lnames) {
    if (lhs->kindOf(name) != rhs->kindOf(name))
      return false;

#define COMPARE_ATTRIBUTEVALUE(selector)                            \
  case AttributeKind::selector: {                                   \
    if (!attributesEqual(lhs->selector(name), rhs->selector(name))) \
      return false;                                                 \
  } break;

    switch (lhs->kindOf(name)) {
      COMPARE_ATTRIBUTEVALUE(f)
      COMPARE_ATTRIBUTEVALUE(fs)
      COMPARE_ATTRIBUTEVALUE(i)
      COMPARE_ATTRIBUTEVALUE(is)
      COMPARE_ATTRIBUTEVALUE(s)
      COMPARE_ATTRIBUTEVALUE(ss)
      COMPARE_ATTRIBUTEVALUE(t)
      COMPARE_ATTRIBUTEVALUE(ts)
      COMPARE_ATTRIBUTEVALUE(ival)
      case AttributeKind::ty:
        if (*lhs->ty(name) != *rhs->ty(name)) {
          return false;
        }
        break;
      case AttributeKind::tys:
        if (!typeListEqual(lhs->tys(name), rhs->tys(name))) {
          return false;
        }
        break;
      case AttributeKind::g:
      case AttributeKind::gs:
        return false;
    }

#undef COMPARE_ATTRIBUTEVALUE
  }

  return true;
}

} // anonymous namespace

size_t HashNode::operator()(const Node* k) const {
  AT_ASSERT(k != nullptr);
  size_t constant_hash = 0;
  if (k->kind() == prim::Constant) {
    TypePtr type = k->output()->type();
    if (type->isSubtypeOf(NumberType::get()) &&
        k->kindOf(attr::value) == AttributeKind::i) {
      constant_hash = std::hash<int64_t>{}(k->i(attr::value));
    } else if (
        type->isSubtypeOf(NumberType::get()) &&
        k->kindOf(attr::value) == AttributeKind::f) {
      constant_hash = std::hash<double>{}(k->f(attr::value));
    } else if (type->isSubtypeOf(BoolType::get())) {
      constant_hash = std::hash<bool>{}(k->i(attr::value));
    }
  }
  return get_hash(
      k->kind(),
      fmap(k->outputs(), [](const Value* v) { return v->type()->kind(); }),
      fmap(k->inputs(), [](const Value* v) { return v->unique(); }),
      constant_hash);
};

bool EqualNode::operator()(const Node* lhs, const Node* rhs) const {
  if (lhs == nullptr && rhs == nullptr)
    return true;
  if (lhs == nullptr || rhs == nullptr)
    return false;

  if (lhs->kind() != rhs->kind())
    return false;

  // Check whether the output types are the same.
  auto lhs_outputs = lhs->outputs();
  auto rhs_outputs = rhs->outputs();
  if (lhs_outputs.size() != rhs_outputs.size())
    return false;
  for (size_t i = 0; i < lhs_outputs.size(); ++i) {
    if (*lhs_outputs[i]->type() != *rhs_outputs[i]->type())
      return false;
  }

  // Check whether the inputs are the same.
  auto lhs_inputs = lhs->inputs();
  auto rhs_inputs = rhs->inputs();
  if (lhs_inputs.size() != rhs_inputs.size())
    return false;
  if (!std::equal(lhs_inputs.begin(), lhs_inputs.end(), rhs_inputs.begin()))
    return false;

  if (!attributesEqualCSE(lhs, rhs))
    return false;

  return true;
};

} // namespace jit
} // namespace torch
