// Copyright (C) 2020-2025 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-bir-builder-expr-stmt.h"
#include "rust-bir-builder-lazyboolexpr.h"
#include "rust-bir-builder-pattern.h"
#include "rust-bir-builder-struct.h"
#include "rust-hir-expr.h"

namespace Rust {
namespace BIR {

using LoopAndLabelCtx = BuilderContext::LoopAndLabelCtx;

BuilderContext::LoopAndLabelCtx &
ExprStmtBuilder::setup_loop (HIR::BaseLoopExpr &expr)
{
  NodeId label
    = (expr.has_loop_label ())
	? expr.get_loop_label ().get_lifetime ().get_mappings ().get_nodeid ()
	: UNKNOWN_NODEID;
  PlaceId label_var = take_or_create_return_place (lookup_type (expr));

  BasicBlockId continue_bb = new_bb ();
  push_goto (continue_bb);
  ctx.current_bb = continue_bb;
  // falseUnwind
  start_new_consecutive_bb ();

  BasicBlockId break_bb = new_bb ();
  // We are still outside the loop block;
  ScopeId continue_scope
    = ctx.place_db.get_current_scope_id ().next_scope_id ();
  ctx.loop_and_label_stack.emplace_back (true, label, label_var, break_bb,
					 continue_bb, continue_scope);

  return ctx.loop_and_label_stack.back ();
}

BuilderContext::LoopAndLabelCtx &
ExprStmtBuilder::get_label_ctx (HIR::Lifetime &label)
{
  NodeId label_id = resolve_label (label);
  auto lookup = std::find_if (ctx.loop_and_label_stack.rbegin (),
			      ctx.loop_and_label_stack.rend (),
			      [label_id] (LoopAndLabelCtx &info) {
				return info.label == label_id;
			      });
  rust_assert (lookup != ctx.loop_and_label_stack.rend ());
  return *lookup;
}

LoopAndLabelCtx &
ExprStmtBuilder::get_unnamed_loop_ctx ()
{
  auto lookup
    = std::find_if (ctx.loop_and_label_stack.rbegin (),
		    ctx.loop_and_label_stack.rend (),
		    [] (LoopAndLabelCtx &info) { return info.is_loop; });
  rust_assert (lookup != ctx.loop_and_label_stack.rend ());
  return *lookup;
}

void
ExprStmtBuilder::visit (HIR::ClosureExpr &expr)
{
  auto closure_ty = lookup_type (expr)->as<TyTy::ClosureType> ();
  std::vector<PlaceId> captures;
  std::vector<location_t> capture_locations;
  for (auto &capture : closure_ty->get_captures ())
    {
      captures.push_back (ctx.place_db.lookup_variable (capture));
      auto location = Analysis::Mappings::get ()
			.lookup_ast_item (capture)
			.value ()
			->get_locus ();
      capture_locations.push_back (location);
    }
  move_all (captures, capture_locations);

  // Note: Not a coercion site for captures.
  return_expr (new InitializerExpr (std::move (captures)), lookup_type (expr),
	       expr.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::StructExprStructFields &fields)
{
  auto *p_adt_type = lookup_type (fields)->as<TyTy::ADTType> ();
  auto struct_ty = p_adt_type->get_variants ().at (0);
  auto init_values = StructBuilder (ctx, struct_ty).build (fields);
  // collect fields locations
  std::vector<location_t> field_locations;
  for (auto &field : fields.get_fields ())
    {
      field_locations.push_back (field->get_locus ());
    }
  move_all (init_values, field_locations);
  return_expr (new InitializerExpr (std::move (init_values)),
	       lookup_type (fields), fields.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::StructExprStruct &expr)
{
  // There is no way to modify empty struct, which makes them constant.
  return_place (ctx.place_db.get_constant (lookup_type (expr)),
		expr.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::LiteralExpr &expr)
{
  // Different literal values of the same type are not distinguished in BIR.
  return_place (ctx.place_db.get_constant (lookup_type (expr)),
		expr.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::BorrowExpr &expr)
{
  auto operand = visit_expr (expr.get_expr ());
  if (ctx.place_db[operand].is_constant ())
    {
      // Cannot borrow a constant, must create a temporary copy.
      push_tmp_assignment (operand, expr.get_locus ());
      operand = translated;
    }

  // BorrowExpr cannot be annotated with lifetime.
  return_borrowed (operand, lookup_type (expr), expr.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::DereferenceExpr &expr)
{
  auto operand = visit_expr (expr.get_expr ());
  return_place (ctx.place_db.lookup_or_add_path (Place::DEREF,
						 lookup_type (expr), operand),
		expr.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::ErrorPropagationExpr &expr)
{
  // TODO: desugar in AST->HIR
  rust_sorry_at (expr.get_locus (), "error propagation is not supported");
}

void
ExprStmtBuilder::visit (HIR::NegationExpr &expr)
{
  PlaceId operand = visit_expr (expr.get_expr ());
  return_expr (new Operator<1> (
		 {move_place (operand, expr.get_expr ().get_locus ())}),
	       lookup_type (expr), expr.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::ArithmeticOrLogicalExpr &expr)
{
  PlaceId lhs = visit_expr (expr.get_lhs ());
  PlaceId rhs = visit_expr (expr.get_rhs ());
  return_expr (new Operator<2> (
		 {move_place (lhs, expr.get_lhs ().get_locus ()),
		  move_place (rhs, expr.get_rhs ().get_locus ())}),
	       lookup_type (expr), expr.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::ComparisonExpr &expr)
{
  PlaceId lhs = visit_expr (expr.get_lhs ());
  PlaceId rhs = visit_expr (expr.get_rhs ());
  return_expr (new Operator<2> (
		 {move_place (lhs, expr.get_lhs ().get_locus ()),
		  move_place (rhs, expr.get_rhs ().get_locus ())}),
	       lookup_type (expr), expr.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::LazyBooleanExpr &expr)
{
  return_place (LazyBooleanExprBuilder (ctx, take_or_create_return_place (
					       lookup_type (expr)))
		  .build (expr),
		expr.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::TypeCastExpr &expr)
{
  auto operand = visit_expr (expr.get_expr ());
  return_expr (new Operator<1> ({operand}), lookup_type (expr),
	       expr.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::AssignmentExpr &expr)
{
  auto lhs = visit_expr (expr.get_lhs ());
  auto rhs = visit_expr (expr.get_rhs ());
  push_assignment (lhs, rhs, expr.get_locus ());
  translated = INVALID_PLACE;
}

void
ExprStmtBuilder::visit (HIR::CompoundAssignmentExpr &expr)
{
  auto lhs = visit_expr (expr.get_lhs ());
  auto rhs = visit_expr (expr.get_rhs ());
  push_assignment (lhs, new Operator<2> ({lhs, rhs}), expr.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::GroupedExpr &expr)
{
  return_place (visit_expr (expr.get_expr_in_parens ()), expr.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::ArrayExpr &expr)
{
  auto &elems = expr.get_internal_elements ();
  switch (elems.get_array_expr_type ())
    {
      case HIR::ArrayElems::VALUES: {
	auto &elem_vals = (static_cast<HIR::ArrayElemsValues &> (elems));
	auto init_values = visit_list (elem_vals.get_values ());
	// collect locations
	std::vector<location_t> value_locations;
	for (auto &value : elem_vals.get_values ())
	  {
	    value_locations.push_back (value->get_locus ());
	  }
	move_all (init_values, value_locations);
	return_expr (new InitializerExpr (std::move (init_values)),
		     lookup_type (expr), expr.get_locus ());
	break;
      }
      case HIR::ArrayElems::COPIED: {
	auto &elem_copied = (static_cast<HIR::ArrayElemsCopied &> (elems));
	auto init = visit_expr (elem_copied.get_elem_to_copy ());
	return_expr (new InitializerExpr ({init}), lookup_type (expr),
		     expr.get_locus ());
	break;
      }
    }
}

void
ExprStmtBuilder::visit (HIR::ArrayIndexExpr &expr)
{
  auto lhs = visit_expr (expr.get_array_expr ());
  auto rhs = visit_expr (expr.get_index_expr ());
  // The index is not tracked in BIR.
  std::ignore = rhs;
  return_place (ctx.place_db.lookup_or_add_path (Place::INDEX,
						 lookup_type (expr), lhs),
		expr.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::TupleExpr &expr)
{
  std::vector<PlaceId> init_values = visit_list (expr.get_tuple_elems ());
  return_expr (new InitializerExpr (std::move (init_values)),
	       lookup_type (expr), expr.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::TupleIndexExpr &expr)
{
  auto tuple = visit_expr (expr.get_tuple_expr ());
  return_place (ctx.place_db.lookup_or_add_path (Place::FIELD,
						 lookup_type (expr), tuple,
						 expr.get_tuple_index ()),
		expr.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::CallExpr &expr)
{
  PlaceId fn = visit_expr (expr.get_fnexpr ());
  std::vector<PlaceId> arguments = visit_list (expr.get_arguments ());

  const auto fn_type
    = ctx.place_db[fn].tyty->as<const TyTy::CallableTypeInterface> ();

  for (size_t i = 0; i < fn_type->get_num_params (); ++i)
    {
      coercion_site (arguments[i], fn_type->get_param_type_at (i));
    }

  // collect parameter locations
  std::vector<location_t> parameter_locations;
  for (auto &parameter : expr.get_arguments ())
    {
      parameter_locations.push_back (parameter->get_locus ());
    }
  move_all (arguments, parameter_locations);

  return_expr (new CallExpr (fn, std::move (arguments)), lookup_type (expr),
	       expr.get_locus (), true);
}

void
ExprStmtBuilder::visit (HIR::InlineAsm &expr)
{}

void
ExprStmtBuilder::visit (HIR::MethodCallExpr &expr)
{}

void
ExprStmtBuilder::visit (HIR::FieldAccessExpr &expr)
{
  auto receiver = visit_expr (expr.get_receiver_expr ());
  auto type = autoderef (receiver);
  rust_assert (type->get_kind () == TyTy::ADT);
  auto adt = type->as<TyTy::ADTType> ();
  rust_assert (!adt->is_enum ());
  rust_assert (adt->number_of_variants () == 1);
  auto struct_ty = adt->get_variants ().at (0);

  TyTy::StructFieldType *field_ty = nullptr;
  size_t field_index = 0;
  bool ok = struct_ty->lookup_field (expr.get_field_name ().as_string (),
				     &field_ty, &field_index);
  rust_assert (ok);

  return_place (ctx.place_db.lookup_or_add_path (Place::FIELD,
						 field_ty->get_field_type (),
						 receiver, field_index),
		expr.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::BlockExpr &block)
{
  push_new_scope ();

  if (block.has_label ())
    {
      NodeId label
	= block.get_label ().get_lifetime ().get_mappings ().get_nodeid ();
      PlaceId label_var = take_or_create_return_place (lookup_type (block));
      ctx.loop_and_label_stack.emplace_back (
	false, label, label_var, new_bb (), INVALID_BB,
	ctx.place_db.get_current_scope_id ());
    }

  // Eliminates dead code after break, continue, return.
  bool unreachable = false;
  for (auto &stmt : block.get_statements ())
    {
      stmt->accept_vis (*this);
      if (ctx.get_current_bb ().is_terminated ())
	{
	  unreachable = true;
	  break;
	}
    }

  if (block.has_label ())
    {
      auto block_ctx = ctx.loop_and_label_stack.back ();
      if (block.has_expr () && !unreachable)
	{
	  push_assignment (block_ctx.label_var,
			   visit_expr (block.get_final_expr ()),
			   block.get_start_locus ());
	}
      if (!ctx.get_current_bb ().is_terminated ())
	{
	  push_goto (block_ctx.break_bb);
	}
      ctx.current_bb = block_ctx.break_bb;
      ctx.loop_and_label_stack.pop_back ();

      return_place (block_ctx.label_var, block.get_start_locus ());
    }
  else if (block.has_expr () && !unreachable)
    {
      return_place (visit_expr (block.get_final_expr (),
				take_or_create_return_place (
				  lookup_type (block.get_final_expr ()))),
		    block.get_start_locus ());
    }

  if (!unreachable)
    pop_scope ();
  else
    ctx.place_db.pop_scope ();
}

void
ExprStmtBuilder::visit (HIR::ContinueExpr &cont)
{
  LoopAndLabelCtx info = cont.has_label () ? get_label_ctx (cont.get_label ())
					   : get_unnamed_loop_ctx ();
  start_new_consecutive_bb ();
  unwind_until (info.continue_scope);
  push_goto (info.continue_bb);
  // No code allowed after continue. Handled in BlockExpr.
}

void
ExprStmtBuilder::visit (HIR::BreakExpr &brk)
{
  LoopAndLabelCtx info = brk.has_label () ? get_label_ctx (brk.get_label ())
					  : get_unnamed_loop_ctx ();
  if (brk.has_break_expr ())
    push_assignment (info.label_var, visit_expr (brk.get_expr ()),
		     brk.get_locus ());

  start_new_consecutive_bb ();
  unwind_until (ctx.place_db.get_scope (info.continue_scope).parent);
  push_goto (info.break_bb);
  // No code allowed after continue. Handled in BlockExpr.
}

void
ExprStmtBuilder::visit (HIR::RangeFromToExpr &range)
{
  auto from = visit_expr (range.get_from_expr ());
  auto to = visit_expr (range.get_to_expr ());
  return_expr (new InitializerExpr ({from, to}), lookup_type (range),
	       range.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::RangeFromExpr &expr)
{
  auto from = visit_expr (expr.get_from_expr ());
  return_expr (new InitializerExpr ({from}), lookup_type (expr),
	       expr.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::RangeToExpr &expr)
{
  auto to = visit_expr (expr.get_to_expr ());
  return_expr (new InitializerExpr ({to}), lookup_type (expr),
	       expr.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::RangeFullExpr &expr)
{
  return_expr (new InitializerExpr ({}), lookup_type (expr), expr.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::RangeFromToInclExpr &expr)
{
  auto from = visit_expr (expr.get_from_expr ());
  auto to = visit_expr (expr.get_to_expr ());
  return_expr (new InitializerExpr ({from, to}), lookup_type (expr),
	       expr.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::RangeToInclExpr &expr)
{
  auto to = visit_expr (expr.get_to_expr ());
  return_expr (new InitializerExpr ({to}), lookup_type (expr),
	       expr.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::ReturnExpr &ret)
{
  if (ret.has_return_expr ())
    {
      push_assignment (RETURN_VALUE_PLACE,
		       move_place (visit_expr (ret.get_expr ()),
				   ret.get_expr ().get_locus ()),
		       ret.get_expr ().get_locus ());
    }
  unwind_until (ROOT_SCOPE);
  push_return (ret.get_locus ());
  translated = INVALID_PLACE;
}

void
ExprStmtBuilder::visit (HIR::UnsafeBlockExpr &expr)
{
  rust_sorry_at (expr.get_locus (), "unsafe blocks are not supported");
}

void
ExprStmtBuilder::visit (HIR::LoopExpr &expr)
{
  auto loop = setup_loop (expr);

  std::ignore = visit_expr (expr.get_loop_block ());
  if (!ctx.get_current_bb ().is_terminated ())
    push_goto (loop.continue_bb);

  ctx.current_bb = loop.break_bb;
}

void
ExprStmtBuilder::visit (HIR::WhileLoopExpr &expr)
{
  auto loop = setup_loop (expr);

  auto cond_val = visit_expr (expr.get_predicate_expr ());
  auto body_bb = new_bb ();
  push_switch (cond_val, expr.get_locus (), {body_bb, loop.break_bb});

  ctx.current_bb = body_bb;
  std::ignore = visit_expr (expr.get_loop_block ());
  push_goto (loop.continue_bb);

  ctx.current_bb = loop.break_bb;
}

void
ExprStmtBuilder::visit (HIR::WhileLetLoopExpr &expr)
{
  // TODO: Desugar in AST->HIR
  rust_sorry_at (expr.get_locus (), "while let loops are not yet supported");
}

void
ExprStmtBuilder::visit (HIR::IfExpr &expr)
{
  // If without else cannot return a non-unit value (see [E0317]).

  if (expr.get_if_block ().statements.empty ())
    return;

  push_switch (visit_expr (expr.get_if_condition ()), expr.get_locus ());
  BasicBlockId if_block = ctx.current_bb;

  ctx.current_bb = new_bb ();
  BasicBlockId then_start_block = ctx.current_bb;
  std::ignore = visit_expr (expr.get_if_block ());
  if (!ctx.get_current_bb ().is_terminated ())
    push_goto (INVALID_BB); // Resolved later.
  BasicBlockId then_end_block = ctx.current_bb;

  ctx.current_bb = new_bb ();
  BasicBlockId final_block = ctx.current_bb;
  return_unit (expr);

  // Jumps are added at the end to match rustc MIR order for easier comparison.
  add_jump (if_block, then_start_block);
  add_jump (if_block, final_block);

  auto &then_end_bb = ctx.basic_blocks[then_end_block];
  if (then_end_bb.is_goto_terminated () && then_end_bb.successors.empty ())
    add_jump (then_end_block, final_block);
}

void
ExprStmtBuilder::visit (HIR::IfExprConseqElse &expr)
{
  push_switch (move_place (visit_expr (expr.get_if_condition ()),
			   expr.get_if_condition ().get_locus ()),
	       expr.get_locus ());
  BasicBlockId if_end_bb = ctx.current_bb;

  PlaceId result = take_or_create_return_place (lookup_type (expr));

  ctx.current_bb = new_bb ();
  BasicBlockId then_start_bb = ctx.current_bb;
  std::ignore = visit_expr (expr.get_if_block (), result);
  if (!ctx.get_current_bb ().is_terminated ())
    push_goto (INVALID_BB); // Resolved later.
  BasicBlockId then_end_bb = ctx.current_bb;

  ctx.current_bb = new_bb ();
  BasicBlockId else_start_bb = ctx.current_bb;
  std::ignore = visit_expr (expr.get_else_block (), result);
  if (!ctx.get_current_bb ().is_terminated ())
    push_goto (INVALID_BB); // Resolved later.
  BasicBlockId else_end_bb = ctx.current_bb;

  ctx.current_bb = new_bb ();
  BasicBlockId final_start_bb = ctx.current_bb;
  return_place (result, expr.get_locus ());

  // Jumps are added at the end to match rustc MIR order for easier comparison.
  add_jump (if_end_bb, then_start_bb);
  add_jump (if_end_bb, else_start_bb);

  auto &then_bb = ctx.basic_blocks[then_end_bb];
  if (then_bb.is_goto_terminated () && then_bb.successors.empty ())
    add_jump (then_end_bb, final_start_bb);

  auto &else_bb = ctx.basic_blocks[else_end_bb];
  if (else_bb.is_goto_terminated () && else_bb.successors.empty ())
    add_jump (else_end_bb, final_start_bb);
}

void
ExprStmtBuilder::visit (HIR::MatchExpr &expr)
{
  rust_sorry_at (expr.get_locus (), "match expressions are not supported");
  //  // TODO
  //  expr.get_scrutinee_expr ()->accept_vis (*this);
  //  PlaceId scrutinee = translated;
  //
  //  BasicBlockId final_bb = new_bb ();
  //
  //  BasicBlockId next_case_bb = new_bb ();
  //  for (auto &match_case : expr.get_match_cases ())
  //    {
  //      BasicBlockId body_bb = new_bb ();
  //
  //      BasicBlockId next_pattern_bb = new_bb ();
  //      for (auto &pat : match_case.get_arm ().get_patterns ())
  //	{
  //	  compile_pattern_validation (*pat, scrutinee);
  //	  push_switch (translated);
  //	  add_jump_to (next_pattern_bb);
  //	  start_new_subsequent_bb ();
  //	  compile_pattern_bindings (*pat, scrutinee);
  //	  add_jump_to (body_bb);
  //
  //	  ctx.current_bb = next_pattern_bb;
  //	  next_pattern_bb = new_bb ();
  //	}
  //      ctx.current_bb = next_pattern_bb;
  //      // No pattern matched, go to the next case.
  //      add_jump_to (next_case_bb);
  //
  //      ctx.current_bb = body_bb;
  //      match_case.get_expr ()->accept_vis (*this);
  //      add_jump_to (final_bb);
  //
  //      ctx.current_bb = next_case_bb;
  //      next_case_bb = new_bb ();
  //    }
  //  add_jump_to (final_bb);
  //
  //  ctx.current_bb = final_bb;
}

void
ExprStmtBuilder::visit (HIR::AwaitExpr &expr)
{
  rust_sorry_at (expr.get_locus (), "await expressions are not supported");
}

void
ExprStmtBuilder::visit (HIR::AsyncBlockExpr &expr)
{
  rust_sorry_at (expr.get_locus (), "async blocks are not supported");
}

void
ExprStmtBuilder::visit (HIR::QualifiedPathInExpression &expr)
{
  // Note: Type is only stored for the expr, not the segment.
  PlaceId result = resolve_variable_or_fn (expr, lookup_type (expr));
  return_place (result, expr.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::PathInExpression &expr)
{
  // Note: Type is only stored for the expr, not the segment.
  PlaceId result = resolve_variable_or_fn (expr, lookup_type (expr));
  return_place (result, expr.get_locus ());
}

void
ExprStmtBuilder::visit (HIR::LetStmt &stmt)
{
  tl::optional<PlaceId> init;
  tl::optional<TyTy::BaseType *> type_annotation;

  if (stmt.has_type ())
    type_annotation = lookup_type (stmt.get_type ());

  if (stmt.get_pattern ().get_pattern_type () == HIR::Pattern::IDENTIFIER)
    {
      // Only if a pattern is just an identifier, no destructuring is needed.
      // Hoverer PatternBindingBuilder cannot change existing temporary
      // (init expr is evaluated before pattern binding) into a
      // variable, so it would emit extra assignment.
      auto var = declare_variable (stmt.get_pattern ().get_mappings ());
      if (stmt.has_type ())
	push_user_type_ascription (var, lookup_type (stmt.get_type ()));

      if (stmt.has_init_expr ())
	std::ignore = visit_expr (stmt.get_init_expr (), var);
    }
  else
    {
      if (stmt.has_init_expr ())
	init = visit_expr (stmt.get_init_expr ());

      PatternBindingBuilder (ctx, init, type_annotation)
	.go (stmt.get_pattern ());
    }
}

void
ExprStmtBuilder::visit (HIR::ExprStmt &stmt)
{
  PlaceId result = visit_expr (stmt.get_expr ());
  // We must read the value for current liveness and we must not store it into
  // the same place.
  if (result != INVALID_PLACE)
    push_tmp_assignment (result, stmt.get_locus ());
}
} // namespace BIR
} // namespace Rust