// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

#ifndef CARBON_TOOLCHAIN_SEM_IR_TYPE_H_
#define CARBON_TOOLCHAIN_SEM_IR_TYPE_H_

#include "llvm/ADT/STLExtras.h"
#include "toolchain/base/shared_value_stores.h"
#include "toolchain/sem_ir/constant.h"
#include "toolchain/sem_ir/ids.h"
#include "toolchain/sem_ir/inst.h"
#include "toolchain/sem_ir/type_info.h"

namespace Carbon::SemIR {

#define CARBON_TYPE_QUALIFIERS(X) \
  X(Const)                        \
  X(MaybeUnformed)                \
  X(Partial)

CARBON_DEFINE_RAW_ENUM_MASK(TypeQualifiers, uint8_t) {
  CARBON_TYPE_QUALIFIERS(CARBON_RAW_ENUM_MASK_ENUMERATOR)
};

// Represents a set of keyword modifiers, using a separate bit per modifier.
class TypeQualifiers : public CARBON_ENUM_MASK_BASE(TypeQualifiers) {
 public:
  CARBON_TYPE_QUALIFIERS(CARBON_ENUM_MASK_CONSTANT_DECL)
};

#define CARBON_TYPE_QUALIFIERS_WITH_TYPE(X) \
  CARBON_ENUM_MASK_CONSTANT_DEFINITION(TypeQualifiers, X)
CARBON_TYPE_QUALIFIERS(CARBON_TYPE_QUALIFIERS_WITH_TYPE)
#undef CARBON_TYPE_QUALIFIERS_WITH_TYPE

// Provides a ValueStore wrapper with an API specific to types.
class TypeStore : public Yaml::Printable<TypeStore> {
 public:
  // Used to return information about an integer type in `GetIntTypeInfo`.
  struct IntTypeInfo {
    bool is_signed;
    IntId bit_width;
  };

  explicit TypeStore(File* file) : file_(file) {}

  // Returns the ID of the constant used to define the specified type.
  auto GetConstantId(TypeId type_id) const -> ConstantId {
    if (!type_id.has_value()) {
      // TODO: Investigate replacing this with a CHECK or returning `None`.
      return ConstantId::NotConstant;
    }
    return type_id.AsConstantId();
  }

  // Returns the type ID for a constant that is a type value, i.e. it is a value
  // of type `TypeType`.
  //
  // Facet values are of the same typishness as types, but are not themselves
  // types, so they can not be passed here. They should be converted to a type
  // through an `as type` conversion, that is, to a value of type `TypeType`.
  auto GetTypeIdForTypeConstantId(ConstantId constant_id) const -> TypeId;

  // Returns the type ID for an instruction whose constant value is a type
  // value, i.e. it is a value of type `TypeType`.
  //
  // Instructions whose values are facet values (see `FacetValue`) produce a
  // value of the same typishness as types, but which are themselves not types,
  // so they can not be passed here. They should be converted to a type through
  // an `as type` conversion, such as to a `FacetAccessType` instruction whose
  // value is of type `TypeType`.
  auto GetTypeIdForTypeInstId(InstId inst_id) const -> TypeId;
  auto GetTypeIdForTypeInstId(TypeInstId inst_id) const -> TypeId;

  // Converts an `InstId` to a `TypeInstId` of the same id value. This process
  // involves checking that the type of the instruction's value is `TypeType`,
  // and then this check is encoded in the type system via `TypeInstId`.
  auto GetAsTypeInstId(InstId inst_id) const -> TypeInstId;

  // Returns the ID of the instruction used to define the specified type.
  auto GetInstId(TypeId type_id) const -> TypeInstId;

  // Returns the instruction used to define the specified type.
  auto GetAsInst(TypeId type_id) const -> Inst;

  // Returns the unattached form of the given type.
  auto GetUnattachedType(TypeId type_id) const -> TypeId;

  // Converts an ArrayRef of `InstId`s to a range of `TypeInstId`s via
  // GetAsTypeInstId().
  auto GetBlockAsTypeInstIds(llvm::ArrayRef<InstId> array
                             [[clang::lifetimebound]]) const -> auto {
    return llvm::map_range(array, [&](InstId type_inst_id) {
      return GetAsTypeInstId(type_inst_id);
    });
  }

  // Converts an ArrayRef of `InstId`s to a range of `TypeId`s via
  // GetTypeIdForTypeInstId().
  auto GetBlockAsTypeIds(llvm::ArrayRef<InstId> array
                         [[clang::lifetimebound]]) const -> auto {
    return llvm::map_range(array, [&](InstId type_inst_id) {
      return GetTypeIdForTypeInstId(type_inst_id);
    });
  }

  // Returns whether the specified kind of instruction was used to define the
  // type.
  template <typename InstT>
  auto Is(TypeId type_id) const -> bool {
    return GetAsInst(type_id).Is<InstT>();
  }

  // Returns the instruction used to define the specified type, which is known
  // to be a particular kind of instruction.
  template <typename InstT>
  auto GetAs(TypeId type_id) const -> InstT {
    return GetAsInst(type_id).As<InstT>();
  }

  // Returns the instruction used to define the specified type, if it is of a
  // particular kind.
  template <typename InstT>
  auto TryGetAs(TypeId type_id) const -> std::optional<InstT> {
    return GetAsInst(type_id).TryAs<InstT>();
  }

  // Returns whether two type IDs represent the same type. This includes the
  // case where they might be in different generics and thus might have
  // different ConstantIds, but are still symbolically equal.
  auto AreEqualAcrossDeclarations(TypeId a, TypeId b) const -> bool {
    return GetInstId(a) == GetInstId(b);
  }

  // Gets the value representation to use for a type. This returns an
  // `None` type if the given type is not complete.
  auto GetValueRepr(TypeId type_id) const -> ValueRepr {
    if (auto type_info = complete_type_info_.Lookup(type_id)) {
      return type_info.value().value_repr;
    }
    return {.kind = ValueRepr::Unknown};
  }

  // Gets the `CompleteTypeInfo` for a type, with an empty value if the type is
  // not complete.
  auto GetCompleteTypeInfo(TypeId type_id) const -> CompleteTypeInfo {
    if (auto type_info = complete_type_info_.Lookup(type_id)) {
      return type_info.value();
    }
    return {.value_repr = {.kind = ValueRepr::Unknown}};
  }

  // Sets the `CompleteTypeInfo` associated with a type, marking it as complete.
  // This can be used with abstract types.
  auto SetComplete(TypeId type_id, const CompleteTypeInfo& info) -> void {
    CARBON_CHECK(info.value_repr.kind != ValueRepr::Unknown);
    auto insert_info = complete_type_info_.Insert(type_id, info);
    CARBON_CHECK(insert_info.is_inserted(), "Type {0} completed more than once",
                 type_id);
    complete_types_.push_back(type_id);
    CARBON_CHECK(IsComplete(type_id));
  }

  // Get the object representation associated with a type. For a non-class type,
  // this is the type itself. `None` is returned if the object representation
  // cannot be determined because the type is not complete.
  auto GetObjectRepr(TypeId type_id) const -> TypeId;

  // Get the type that the given type adapts, or `None` if the type is not known
  // to be an adapter, including the case where the type is an incomplete class.
  auto GetAdaptedType(TypeId type_id) const -> TypeId;

  // Returns the non-adapter type that is compatible with the specified type.
  auto GetTransitiveAdaptedType(TypeId type_id) const -> TypeId;

  // Determines whether the given type is known to be complete. This does not
  // determine whether the type could be completed, only whether it has been.
  auto IsComplete(TypeId type_id) const -> bool {
    return complete_type_info_.Contains(type_id);
  }

  // Removes any top-level qualifiers from a type.
  auto GetUnqualifiedType(TypeId type_id) const -> TypeId {
    return GetUnqualifiedTypeAndQualifiers(type_id).first;
  }

  // Removes any top-level qualifiers from a type and returns the unqualified
  // type and qualifiers.
  auto GetUnqualifiedTypeAndQualifiers(TypeId type_id) const
      -> std::pair<TypeId, TypeQualifiers>;

  // Returns the non-adapter unqualified type that is compatible with the
  // specified type.
  auto GetTransitiveUnqualifiedAdaptedType(TypeId type_id) const
      -> std::pair<TypeId, TypeQualifiers>;

  // Determines whether the given type is a signed integer type. This includes
  // the case where the type is `Core.IntLiteral` or a class type whose object
  // representation is a signed integer type.
  auto IsSignedInt(TypeId int_type_id) const -> bool;

  // Returns integer type information from a type ID that is known to represent
  // an integer type. Abstracts away the difference between an `IntType`
  // instruction defined type, a singleton instruction defined type, and a class
  // adapting such a type. Uses IntId::None for types that have a
  // non-constant width and for IntLiteral.
  auto GetIntTypeInfo(TypeId int_type_id) const -> IntTypeInfo;

  // Similar to `GetIntTypeInfo`, except allows non-`IntType` types to be
  // handled.
  auto TryGetIntTypeInfo(TypeId int_type_id) const
      -> std::optional<IntTypeInfo>;

  // Returns whether `type_id` represents a facet type.
  auto IsFacetType(TypeId type_id) const -> bool {
    return type_id == TypeType::TypeId || Is<FacetType>(type_id);
  }

  // Returns a list of types that were completed in this file, in the order in
  // which they were completed. Earlier types in this list cannot contain
  // instances of later types.
  auto complete_types() const -> llvm::ArrayRef<TypeId> {
    return complete_types_;
  }

  auto OutputYaml() const -> Yaml::OutputMapping {
    return Yaml::OutputMapping([&](Yaml::OutputMapping::Map map) {
      for (auto type_id : complete_types_) {
        auto info = GetCompleteTypeInfo(type_id);
        map.Add(PrintToString(type_id),
                Yaml::OutputMapping([&](Yaml::OutputMapping::Map map2) {
                  map2.Add("value_repr", Yaml::OutputScalar(info.value_repr));
                  if (info.abstract_class_id.has_value()) {
                    map2.Add("abstract_class_id",
                             Yaml::OutputScalar(info.abstract_class_id));
                  }
                }));
      }
    });
  }

  auto CollectMemUsage(MemUsage& mem_usage, llvm::StringRef label) const
      -> void {
    mem_usage.Collect(MemUsage::ConcatLabel(label, "complete_type_info_"),
                      complete_type_info_);
    mem_usage.Collect(MemUsage::ConcatLabel(label, "complete_types_"),
                      complete_types_);
  }

 private:
  File* file_;
  Map<TypeId, CompleteTypeInfo> complete_type_info_;
  llvm::SmallVector<TypeId> complete_types_;
};

// Returns the scrutinee type of `type_id`, which must be a `PatternType`.
auto ExtractScrutineeType(const File& sem_ir, TypeId type_id) -> TypeId;

}  // namespace Carbon::SemIR

#endif  // CARBON_TOOLCHAIN_SEM_IR_TYPE_H_