// Copyright (C) 2020 Free Software Foundation, Inc.

// This file is part of GCC.

// GCC is free software; you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the Free
// Software Foundation; either version 3, or (at your option) any later
// version.

// GCC is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
// for more details.

// You should have received a copy of the GNU General Public License
// along with GCC; see the file COPYING3.  If not see
// <http://www.gnu.org/licenses/>.

#include "rust-ast-lower.h"
#include "rust-ast-lower-item.h"
#include "rust-ast-lower-expr.h"
#include "rust-ast-lower-block.h"

namespace Rust {
namespace HIR {

ASTLowering::ASTLowering (AST::Crate &astCrate) : astCrate (astCrate) {}

ASTLowering::~ASTLowering () {}

HIR::Crate
ASTLowering::Resolve (AST::Crate &astCrate)
{
  ASTLowering resolver (astCrate);
  return resolver.go ();
}

HIR::Crate
ASTLowering::go ()
{
  std::vector<std::unique_ptr<HIR::Item> > items;
  std::vector<HIR::Attribute> inner_attrs;
  bool has_utf8bom = false;
  bool has_shebang = false;

  for (auto it = astCrate.items.begin (); it != astCrate.items.end (); it++)
    {
      auto translated = ASTLoweringItem::translate (it->get ());
      if (translated != nullptr)
	items.push_back (std::unique_ptr<HIR::Item> (translated));
    }

  auto mappings = Analysis::Mappings::get ();
  auto crate_num = mappings->get_current_crate ();
  Analysis::NodeMapping mapping (crate_num, UNKNOWN_NODEID,
				 mappings->get_next_hir_id (crate_num),
				 UNKNOWN_LOCAL_DEFID);

  return HIR::Crate (std::move (items), std::move (inner_attrs), mapping,
		     has_utf8bom, has_shebang);
}

// rust-ast-lower-block.h
void
ASTLoweringBlock::visit (AST::BlockExpr &expr)
{
  std::vector<HIR::Attribute> inner_attribs;
  std::vector<HIR::Attribute> outer_attribs;

  std::vector<std::unique_ptr<HIR::Stmt> > block_stmts;
  bool block_did_terminate = false;
  expr.iterate_stmts ([&] (AST::Stmt *s) mutable -> bool {
    bool terminated = false;
    auto translated_stmt = ASTLoweringStmt::translate (s, &terminated);
    block_stmts.push_back (std::unique_ptr<HIR::Stmt> (translated_stmt));
    block_did_terminate = terminated;
    return !block_did_terminate;
  });

  // if there was a return expression everything after that becomes
  // unreachable code. This can be detected for any AST NodeIDs that have no
  // associated HIR Mappings
  expr.iterate_stmts ([&] (AST::Stmt *s) -> bool {
    HirId ref;
    if (!mappings->lookup_node_to_hir (mappings->get_current_crate (),
				       s->get_node_id (), &ref))
      rust_warning_at (s->get_locus_slow (), 0, "unreachable statement");

    return true;
  });

  bool tail_reachable = expr.has_tail_expr () && !block_did_terminate;
  if (expr.has_tail_expr () && block_did_terminate)
    {
      // warning unreachable tail expressions
      rust_warning_at (expr.get_tail_expr ()->get_locus_slow (), 0,
		       "unreachable expression");
    }

  HIR::ExprWithoutBlock *tail_expr = nullptr;
  if (expr.has_tail_expr ())
    {
      tail_expr = (HIR::ExprWithoutBlock *) ASTLoweringExpr::translate (
	expr.get_tail_expr ().get ());
    }

  auto crate_num = mappings->get_current_crate ();
  Analysis::NodeMapping mapping (crate_num, expr.get_node_id (),
				 mappings->get_next_hir_id (crate_num),
				 UNKNOWN_LOCAL_DEFID);
  translated
    = new HIR::BlockExpr (mapping, std::move (block_stmts),
			  std::unique_ptr<HIR::ExprWithoutBlock> (tail_expr),
			  tail_reachable, std::move (inner_attribs),
			  std::move (outer_attribs), expr.get_locus ());

  terminated = block_did_terminate || expr.has_tail_expr ();
}

void
ASTLoweringIfBlock::visit (AST::IfExpr &expr)
{
  bool ignored_terminated = false;
  HIR::Expr *condition
    = ASTLoweringExpr::translate (expr.get_condition_expr ().get (),
				  &ignored_terminated);
  HIR::BlockExpr *block
    = ASTLoweringBlock::translate (expr.get_if_block ().get (),
				   &ignored_terminated);

  auto crate_num = mappings->get_current_crate ();
  Analysis::NodeMapping mapping (crate_num, expr.get_node_id (),
				 mappings->get_next_hir_id (crate_num),
				 UNKNOWN_LOCAL_DEFID);

  translated = new HIR::IfExpr (mapping, std::unique_ptr<HIR::Expr> (condition),
				std::unique_ptr<HIR::BlockExpr> (block),
				expr.get_locus ());
}

void
ASTLoweringIfBlock::visit (AST::IfExprConseqElse &expr)
{
  HIR::Expr *condition
    = ASTLoweringExpr::translate (expr.get_condition_expr ().get ());

  bool if_block_terminated = false;
  bool else_block_termianted = false;

  HIR::BlockExpr *if_block
    = ASTLoweringBlock::translate (expr.get_if_block ().get (),
				   &if_block_terminated);
  HIR::BlockExpr *else_block
    = ASTLoweringBlock::translate (expr.get_else_block ().get (),
				   &else_block_termianted);

  terminated = if_block_terminated && else_block_termianted;

  auto crate_num = mappings->get_current_crate ();
  Analysis::NodeMapping mapping (crate_num, expr.get_node_id (),
				 mappings->get_next_hir_id (crate_num),
				 UNKNOWN_LOCAL_DEFID);

  translated
    = new HIR::IfExprConseqElse (mapping,
				 std::unique_ptr<HIR::Expr> (condition),
				 std::unique_ptr<HIR::BlockExpr> (if_block),
				 std::unique_ptr<HIR::BlockExpr> (else_block),
				 expr.get_locus ());
}

void
ASTLoweringIfBlock::visit (AST::IfExprConseqIf &expr)
{
  HIR::Expr *condition
    = ASTLoweringExpr::translate (expr.get_condition_expr ().get ());

  bool ignored_terminated = false;
  HIR::BlockExpr *block
    = ASTLoweringBlock::translate (expr.get_if_block ().get (),
				   &ignored_terminated);
  HIR::IfExpr *conseq_if_expr
    = ASTLoweringIfBlock::translate (expr.get_conseq_if_expr ().get (),
				     &ignored_terminated);

  auto crate_num = mappings->get_current_crate ();
  Analysis::NodeMapping mapping (crate_num, expr.get_node_id (),
				 mappings->get_next_hir_id (crate_num),
				 UNKNOWN_LOCAL_DEFID);

  translated
    = new HIR::IfExprConseqIf (mapping, std::unique_ptr<HIR::Expr> (condition),
			       std::unique_ptr<HIR::BlockExpr> (block),
			       std::unique_ptr<HIR::IfExpr> (conseq_if_expr),
			       expr.get_locus ());
}

// rust-ast-lower-struct-field-expr.h

void
ASTLowerStructExprField::visit (AST::StructExprFieldIdentifierValue &field)
{
  HIR::Expr *value = ASTLoweringExpr::translate (field.get_value ().get ());

  auto crate_num = mappings->get_current_crate ();
  Analysis::NodeMapping mapping (crate_num, field.get_node_id (),
				 mappings->get_next_hir_id (crate_num),
				 UNKNOWN_LOCAL_DEFID);

  translated = new HIR::StructExprFieldIdentifierValue (
    mapping, field.get_field_name (), std::unique_ptr<HIR::Expr> (value),
    field.get_locus ());
}

} // namespace HIR
} // namespace Rust