// Copyright 2021 The Tint Authors.
//
// 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.

#ifndef SRC_PROGRAM_H_
#define SRC_PROGRAM_H_

#include <string>
#include <unordered_set>

#include "src/ast/function.h"
#include "src/program_id.h"
#include "src/sem/info.h"
#include "src/sem/type_manager.h"
#include "src/symbol_table.h"

namespace tint {

// Forward declarations
class CloneContext;

namespace ast {

class Module;

}  // namespace ast

/// Program holds the AST, Type information and SymbolTable for a tint program.
class Program {
 public:
  /// ASTNodeAllocator is an alias to BlockAllocator<ast::Node>
  using ASTNodeAllocator = BlockAllocator<ast::Node>;

  /// SemNodeAllocator is an alias to BlockAllocator<sem::Node>
  using SemNodeAllocator = BlockAllocator<sem::Node>;

  /// Constructor
  Program();

  /// Move constructor
  /// @param rhs the Program to move
  Program(Program&& rhs);

  /// Move constructor from builder
  /// @param builder the builder used to construct the program
  explicit Program(ProgramBuilder&& builder);

  /// Destructor
  ~Program();

  /// Move assignment operator
  /// @param rhs the Program to move
  /// @return this Program
  Program& operator=(Program&& rhs);

  /// @returns the unique identifier for this program
  ProgramID ID() const { return id_; }

  /// @returns a reference to the program's types
  const sem::Manager& Types() const {
    AssertNotMoved();
    return types_;
  }

  /// @returns a reference to the program's AST nodes storage
  const ASTNodeAllocator& ASTNodes() const {
    AssertNotMoved();
    return ast_nodes_;
  }

  /// @returns a reference to the program's semantic nodes storage
  const SemNodeAllocator& SemNodes() const {
    AssertNotMoved();
    return sem_nodes_;
  }

  /// @returns a reference to the program's AST root Module
  const ast::Module& AST() const {
    AssertNotMoved();
    return *ast_;
  }

  /// @returns a reference to the program's semantic info
  const sem::Info& Sem() const {
    AssertNotMoved();
    return sem_;
  }

  /// @returns a reference to the program's SymbolTable
  const SymbolTable& Symbols() const {
    AssertNotMoved();
    return symbols_;
  }

  /// @returns a reference to the program's diagnostics
  const diag::List& Diagnostics() const {
    AssertNotMoved();
    return diagnostics_;
  }

  /// Performs a deep clone of this program.
  /// The returned Program will contain no pointers to objects owned by this
  /// Program, and so after calling, this Program can be safely destructed.
  /// @return a new Program copied from this Program
  Program Clone() const;

  /// Performs a deep clone of this Program's AST nodes, types and symbols into
  /// a new ProgramBuilder. Semantic nodes are not cloned, as these will be
  /// rebuilt when the ProgramBuilder builds its Program.
  /// The returned ProgramBuilder will contain no pointers to objects owned by
  /// this Program, and so after calling, this Program can be safely destructed.
  /// @return a new ProgramBuilder copied from this Program
  ProgramBuilder CloneAsBuilder() const;

  /// @returns true if the program has no error diagnostics and is not missing
  /// information
  bool IsValid() const;

  /// @return the TypeInfo pointers of all transforms that have been applied to
  /// this program.
  std::unordered_set<const TypeInfo*> TransformsApplied() const {
    return transforms_applied_;
  }

  /// @param transform the TypeInfo of the transform
  /// @returns true if the transform with the given TypeInfo was applied to the
  /// Program
  bool HasTransformApplied(const TypeInfo* transform) const {
    return transforms_applied_.count(transform);
  }

  /// @returns true if the transform of type `T` was applied.
  template <typename T>
  bool HasTransformApplied() const {
    return HasTransformApplied(&TypeInfo::Of<T>());
  }

  /// Helper for returning the resolved semantic type of the expression `expr`.
  /// @param expr the AST expression
  /// @return the resolved semantic type for the expression, or nullptr if the
  /// expression has no resolved type.
  sem::Type* TypeOf(const ast::Expression* expr) const;

  /// Helper for returning the resolved semantic type of the AST type `type`.
  /// @param type the AST type
  /// @return the resolved semantic type for the type, or nullptr if the type
  /// has no resolved type.
  const sem::Type* TypeOf(const ast::Type* type) const;

  /// Helper for returning the resolved semantic type of the AST type
  /// declaration `type_decl`.
  /// @param type_decl the AST type declaration
  /// @return the resolved semantic type for the type declaration, or nullptr if
  /// the type declaration has no resolved type.
  const sem::Type* TypeOf(const ast::TypeDecl* type_decl) const;

  /// A function that can be used to print a program
  using Printer = std::string (*)(const Program*);

  /// The Program printer used for testing and debugging.
  static Printer printer;

 private:
  Program(const Program&) = delete;

  /// Asserts that the program has not been moved.
  void AssertNotMoved() const;

  ProgramID id_;
  sem::Manager types_;
  ASTNodeAllocator ast_nodes_;
  SemNodeAllocator sem_nodes_;
  ast::Module* ast_ = nullptr;
  sem::Info sem_;
  SymbolTable symbols_{id_};
  diag::List diagnostics_;
  std::unordered_set<const TypeInfo*> transforms_applied_;
  bool is_valid_ = false;  // Not valid until it is built
  bool moved_ = false;
};

/// @param program the Program
/// @returns the ProgramID of the Program
inline ProgramID ProgramIDOf(const Program* program) {
  return program->ID();
}

}  // namespace tint

#endif  // SRC_PROGRAM_H_