// 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

#include "executable_semantics/ast/declaration.h"

#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/Casting.h"

namespace Carbon {

using llvm::cast;

Declaration::~Declaration() = default;

void Declaration::Print(llvm::raw_ostream& out) const {
  switch (kind()) {
    case DeclarationKind::InterfaceDeclaration: {
      const auto& iface_decl = cast<InterfaceDeclaration>(*this);
      PrintID(out);
      out << " {\n";
      for (Nonnull<Declaration*> m : iface_decl.members()) {
        out << *m;
      }
      out << "}\n";
      break;
    }
    case DeclarationKind::ImplDeclaration: {
      const auto& impl_decl = cast<ImplDeclaration>(*this);
      PrintID(out);
      out << " {\n";
      for (Nonnull<Declaration*> m : impl_decl.members()) {
        out << *m;
      }
      out << "}\n";
      break;
    }
    case DeclarationKind::FunctionDeclaration:
      cast<FunctionDeclaration>(*this).PrintDepth(-1, out);
      break;

    case DeclarationKind::ClassDeclaration: {
      const auto& class_decl = cast<ClassDeclaration>(*this);
      PrintID(out);
      if (class_decl.type_params().has_value()) {
        out << **class_decl.type_params();
      }
      out << " {\n";
      for (Nonnull<Declaration*> m : class_decl.members()) {
        out << *m;
      }
      out << "}\n";
      break;
    }

    case DeclarationKind::ChoiceDeclaration: {
      const auto& choice = cast<ChoiceDeclaration>(*this);
      PrintID(out);
      out << " {\n";
      for (Nonnull<const AlternativeSignature*> alt : choice.alternatives()) {
        out << *alt << ";\n";
      }
      out << "}\n";
      break;
    }

    case DeclarationKind::VariableDeclaration: {
      const auto& var = cast<VariableDeclaration>(*this);
      PrintID(out);
      if (var.has_initializer()) {
        out << " = " << var.initializer();
      }
      out << ";\n";
      break;
    }
  }
}

void Declaration::PrintID(llvm::raw_ostream& out) const {
  switch (kind()) {
    case DeclarationKind::InterfaceDeclaration: {
      const auto& iface_decl = cast<InterfaceDeclaration>(*this);
      out << "interface" << iface_decl.name();
      break;
    }
    case DeclarationKind::ImplDeclaration: {
      const auto& impl_decl = cast<ImplDeclaration>(*this);
      switch (impl_decl.kind()) {
        case ImplKind::InternalImpl:
          break;
        case ImplKind::ExternalImpl:
          out << "external ";
          break;
      }
      out << "impl " << *impl_decl.impl_type() << " as "
          << impl_decl.interface();
      break;
    }
    case DeclarationKind::FunctionDeclaration:
      out << "fn " << cast<FunctionDeclaration>(*this).name();
      break;

    case DeclarationKind::ClassDeclaration: {
      const auto& class_decl = cast<ClassDeclaration>(*this);
      out << "class " << class_decl.name();
      break;
    }

    case DeclarationKind::ChoiceDeclaration: {
      const auto& choice = cast<ChoiceDeclaration>(*this);
      out << "choice " << choice.name();
      break;
    }

    case DeclarationKind::VariableDeclaration: {
      const auto& var = cast<VariableDeclaration>(*this);
      out << "var " << var.binding();
      break;
    }
  }
}

auto GetName(const Declaration& declaration) -> std::optional<std::string> {
  switch (declaration.kind()) {
    case DeclarationKind::FunctionDeclaration:
      return cast<FunctionDeclaration>(declaration).name();
    case DeclarationKind::ClassDeclaration:
      return cast<ClassDeclaration>(declaration).name();
    case DeclarationKind::ChoiceDeclaration:
      return cast<ChoiceDeclaration>(declaration).name();
    case DeclarationKind::InterfaceDeclaration:
      return cast<InterfaceDeclaration>(declaration).name();
    case DeclarationKind::VariableDeclaration:
      return cast<VariableDeclaration>(declaration).binding().name();
    case DeclarationKind::ImplDeclaration:
      return std::nullopt;
  }
}

void GenericBinding::Print(llvm::raw_ostream& out) const {
  out << name() << ":! " << type();
}

void GenericBinding::PrintID(llvm::raw_ostream& out) const { out << name(); }

void ReturnTerm::Print(llvm::raw_ostream& out) const {
  switch (kind_) {
    case ReturnKind::Omitted:
      return;
    case ReturnKind::Auto:
      out << "-> auto";
      return;
    case ReturnKind::Expression:
      CHECK(type_expression_.has_value());
      out << "-> " << **type_expression_;
      return;
  }
}

auto FunctionDeclaration::Create(
    Nonnull<Arena*> arena, SourceLocation source_loc, std::string name,
    std::vector<Nonnull<AstNode*>> deduced_params,
    std::optional<Nonnull<BindingPattern*>> me_pattern,
    Nonnull<TuplePattern*> param_pattern, ReturnTerm return_term,
    std::optional<Nonnull<Block*>> body)
    -> ErrorOr<Nonnull<FunctionDeclaration*>> {
  std::vector<Nonnull<GenericBinding*>> resolved_params;
  // Look for the `me` parameter in the `deduced_parameters`
  // and put it in the `me_pattern`.
  for (Nonnull<AstNode*> param : deduced_params) {
    switch (param->kind()) {
      case AstNodeKind::GenericBinding:
        resolved_params.push_back(&cast<GenericBinding>(*param));
        break;
      case AstNodeKind::BindingPattern: {
        Nonnull<BindingPattern*> bp = &cast<BindingPattern>(*param);
        if (me_pattern.has_value() || bp->name() != "me") {
          return CompilationError(source_loc)
                 << "illegal binding pattern in implicit parameter list";
        }
        me_pattern = bp;
        break;
      }
      default:
        return CompilationError(source_loc)
               << "illegal AST node in implicit parameter list";
    }
  }
  return arena->New<FunctionDeclaration>(source_loc, name, resolved_params,
                                         me_pattern, param_pattern, return_term,
                                         body);
}

void FunctionDeclaration::PrintDepth(int depth, llvm::raw_ostream& out) const {
  out << "fn " << name_ << " ";
  if (!deduced_parameters_.empty()) {
    out << "[";
    llvm::ListSeparator sep;
    for (Nonnull<const GenericBinding*> deduced : deduced_parameters_) {
      out << sep << *deduced;
    }
    out << "]";
  }
  out << *param_pattern_ << return_term_;
  if (body_) {
    out << " {\n";
    (*body_)->PrintDepth(depth, out);
    out << "\n}\n";
  } else {
    out << ";\n";
  }
}

auto ImplDeclaration::Create(Nonnull<Arena*> arena, SourceLocation source_loc,
                             ImplKind kind, Nonnull<Expression*> impl_type,
                             Nonnull<Expression*> interface,
                             std::vector<Nonnull<AstNode*>> deduced_params,
                             std::vector<Nonnull<Declaration*>> members)
    -> ErrorOr<Nonnull<ImplDeclaration*>> {
  std::vector<Nonnull<GenericBinding*>> resolved_params;
  for (Nonnull<AstNode*> param : deduced_params) {
    switch (param->kind()) {
      case AstNodeKind::GenericBinding:
        resolved_params.push_back(&cast<GenericBinding>(*param));
        break;
      default:
        return CompilationError(source_loc)
               << "illegal AST node in implicit parameter list of impl";
    }
  }
  return arena->New<ImplDeclaration>(source_loc, kind, impl_type, interface,
                                     resolved_params, members);
}

void AlternativeSignature::Print(llvm::raw_ostream& out) const {
  out << "alt " << name() << " " << signature();
}

void AlternativeSignature::PrintID(llvm::raw_ostream& out) const {
  out << name();
}

}  // namespace Carbon