// Copyright (C) 2020-2023 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/>.

#ifndef RUST_AST_STATEMENT_H
#define RUST_AST_STATEMENT_H

#include "rust-ast.h"
#include "rust-path.h"
#include "rust-expr.h"

namespace Rust {
namespace AST {
// Just a semi-colon, which apparently is a statement.
class EmptyStmt : public Stmt
{
  Location locus;

  // TODO: find another way to store this to save memory?
  bool marked_for_strip = false;

public:
  std::string as_string () const override { return std::string (1, ';'); }

  EmptyStmt (Location locus) : locus (locus) {}

  Location get_locus () const override final { return locus; }

  void accept_vis (ASTVisitor &vis) override;

  // Can't think of any invalid invariants, so store boolean.
  void mark_for_strip () override { marked_for_strip = true; }
  bool is_marked_for_strip () const override { return marked_for_strip; }

  bool is_item () const override final { return false; }

protected:
  /* Use covariance to implement clone function as returning this object rather
   * than base */
  EmptyStmt *clone_stmt_impl () const override { return new EmptyStmt (*this); }
};

/* Variable assignment let statement - type of "declaration statement" as it
 * introduces new name into scope */
class LetStmt : public Stmt
{
  // bool has_outer_attrs;
  std::vector<Attribute> outer_attrs;

  std::unique_ptr<Pattern> variables_pattern;

  // bool has_type;
  std::unique_ptr<Type> type;

  // bool has_init_expr;
  std::unique_ptr<Expr> init_expr;

  Location locus;

public:
  Type *inferedType;

  // Returns whether let statement has outer attributes.
  bool has_outer_attrs () const { return !outer_attrs.empty (); }

  // Returns whether let statement has a given return type.
  bool has_type () const { return type != nullptr; }

  // Returns whether let statement has an initialisation expression.
  bool has_init_expr () const { return init_expr != nullptr; }

  std::string as_string () const override;

  LetStmt (std::unique_ptr<Pattern> variables_pattern,
	   std::unique_ptr<Expr> init_expr, std::unique_ptr<Type> type,
	   std::vector<Attribute> outer_attrs, Location locus)
    : outer_attrs (std::move (outer_attrs)),
      variables_pattern (std::move (variables_pattern)),
      type (std::move (type)), init_expr (std::move (init_expr)), locus (locus)
  {}

  // Copy constructor with clone
  LetStmt (LetStmt const &other)
    : outer_attrs (other.outer_attrs), locus (other.locus)
  {
    // guard to prevent null dereference (only required if error state)
    if (other.variables_pattern != nullptr)
      variables_pattern = other.variables_pattern->clone_pattern ();

    // guard to prevent null dereference (always required)
    if (other.init_expr != nullptr)
      init_expr = other.init_expr->clone_expr ();
    if (other.type != nullptr)
      type = other.type->clone_type ();
  }

  // Overloaded assignment operator to clone
  LetStmt &operator= (LetStmt const &other)
  {
    outer_attrs = other.outer_attrs;
    locus = other.locus;

    // guard to prevent null dereference (only required if error state)
    if (other.variables_pattern != nullptr)
      variables_pattern = other.variables_pattern->clone_pattern ();
    else
      variables_pattern = nullptr;

    // guard to prevent null dereference (always required)
    if (other.init_expr != nullptr)
      init_expr = other.init_expr->clone_expr ();
    else
      init_expr = nullptr;
    if (other.type != nullptr)
      type = other.type->clone_type ();
    else
      type = nullptr;

    return *this;
  }

  // move constructors
  LetStmt (LetStmt &&other) = default;
  LetStmt &operator= (LetStmt &&other) = default;

  Location get_locus () const override final { return locus; }

  void accept_vis (ASTVisitor &vis) override;

  // Invalid if pattern is null, so base stripping on that.
  void mark_for_strip () override { variables_pattern = nullptr; }
  bool is_marked_for_strip () const override
  {
    return variables_pattern == nullptr;
  }

  // TODO: this mutable getter seems really dodgy. Think up better way.
  std::vector<Attribute> &get_outer_attrs () { return outer_attrs; }
  const std::vector<Attribute> &get_outer_attrs () const { return outer_attrs; }

  // TODO: is this better? Or is a "vis_block" better?
  std::unique_ptr<Expr> &get_init_expr ()
  {
    rust_assert (has_init_expr ());
    return init_expr;
  }

  std::unique_ptr<Pattern> &get_pattern ()
  {
    rust_assert (variables_pattern != nullptr);
    return variables_pattern;
  }

  std::unique_ptr<Type> &get_type ()
  {
    rust_assert (has_type ());
    return type;
  }

  bool is_item () const override final { return false; }

protected:
  /* Use covariance to implement clone function as returning this object rather
   * than base */
  LetStmt *clone_stmt_impl () const override { return new LetStmt (*this); }
};

/* Abstract base class for expression statements (statements containing an
 * expression) */
class ExprStmt : public Stmt
{
public:
  enum ExprStmtType
  {
    WITH_BLOCK,
    WITHOUT_BLOCK
  };

protected:
  Location locus;

public:
  Location get_locus () const override final { return locus; }

  bool is_item () const override final { return false; }

  virtual ExprStmtType get_type () const = 0;

protected:
  ExprStmt (Location locus) : locus (locus) {}
};

/* Statement containing an expression without a block (or, due to technical
 * difficulties, can only be guaranteed to hold an expression). */
class ExprStmtWithoutBlock : public ExprStmt
{
  // TODO: ensure that this works
  std::unique_ptr<ExprWithoutBlock> expr;
  /* HACK: cannot ensure type safety of ExprWithoutBlock due to Pratt parsing,
   * so have to store more general type of Expr. FIXME: fix this issue somehow
   * or redesign AST. */
  // std::unique_ptr<Expr> expr;

public:
  std::string as_string () const override;

  ExprStmtWithoutBlock (std::unique_ptr<ExprWithoutBlock> expr, Location locus)
    : ExprStmt (locus), expr (std::move (expr->to_stmt ()))
  {}

  /*ExprStmtWithoutBlock (std::unique_ptr<Expr> expr, Location locus)
    : ExprStmt (locus), expr (std::move (expr))
  {}*/

  // Copy constructor with clone
  ExprStmtWithoutBlock (ExprStmtWithoutBlock const &other) : ExprStmt (other)
  {
    // guard to prevent null dereference (only required if error state)
    if (other.expr != nullptr)
      expr = other.expr->clone_expr_without_block ();
  }
  /*ExprStmtWithoutBlock (ExprStmtWithoutBlock const &other)
    : ExprStmt (other), expr (other.expr->clone_expr ())
  {}*/

  // Overloaded assignment operator to clone
  ExprStmtWithoutBlock &operator= (ExprStmtWithoutBlock const &other)
  {
    ExprStmt::operator= (other);
    // expr = other.expr->clone_expr ();

    // guard to prevent null dereference (only required if error state)
    if (other.expr != nullptr)
      expr = other.expr->clone_expr_without_block ();
    else
      expr = nullptr;

    return *this;
  }

  // move constructors
  ExprStmtWithoutBlock (ExprStmtWithoutBlock &&other) = default;
  ExprStmtWithoutBlock &operator= (ExprStmtWithoutBlock &&other) = default;

  void accept_vis (ASTVisitor &vis) override;

  // Invalid if expr is null, so base stripping on that.
  void mark_for_strip () override { expr = nullptr; }
  bool is_marked_for_strip () const override { return expr == nullptr; }

  // TODO: is this better? Or is a "vis_block" better?
  std::unique_ptr<ExprWithoutBlock> &get_expr ()
  {
    rust_assert (expr != nullptr);
    return expr;
  }

  ExprStmtType get_type () const override
  {
    return ExprStmtType::WITHOUT_BLOCK;
  };

protected:
  /* Use covariance to implement clone function as returning this object rather
   * than base */
  ExprStmtWithoutBlock *clone_stmt_impl () const override
  {
    return new ExprStmtWithoutBlock (*this);
  }
};

// Statement containing an expression with a block
class ExprStmtWithBlock : public ExprStmt
{
  std::unique_ptr<ExprWithBlock> expr;
  bool semicolon_followed;

public:
  std::string as_string () const override;

  std::vector<LetStmt *> locals;

  ExprStmtWithBlock (std::unique_ptr<ExprWithBlock> expr, Location locus,
		     bool semicolon_followed)
    : ExprStmt (locus), expr (std::move (expr)),
      semicolon_followed (semicolon_followed)
  {}

  // Copy constructor with clone
  ExprStmtWithBlock (ExprStmtWithBlock const &other) : ExprStmt (other)
  {
    // guard to prevent null dereference (only required if error state)
    if (other.expr != nullptr)
      expr = other.expr->clone_expr_with_block ();
  }

  // Overloaded assignment operator to clone
  ExprStmtWithBlock &operator= (ExprStmtWithBlock const &other)
  {
    ExprStmt::operator= (other);

    // guard to prevent null dereference (only required if error state)
    if (other.expr != nullptr)
      expr = other.expr->clone_expr_with_block ();
    else
      expr = nullptr;

    return *this;
  }

  // move constructors
  ExprStmtWithBlock (ExprStmtWithBlock &&other) = default;
  ExprStmtWithBlock &operator= (ExprStmtWithBlock &&other) = default;

  void accept_vis (ASTVisitor &vis) override;

  // Invalid if expr is null, so base stripping on that.
  void mark_for_strip () override { expr = nullptr; }
  bool is_marked_for_strip () const override { return expr == nullptr; }

  // TODO: is this better? Or is a "vis_block" better?
  std::unique_ptr<ExprWithBlock> &get_expr ()
  {
    rust_assert (expr != nullptr);
    return expr;
  }

  bool is_semicolon_followed () const { return semicolon_followed; }

  ExprStmtType get_type () const override { return ExprStmtType::WITH_BLOCK; };

protected:
  /* Use covariance to implement clone function as returning this object rather
   * than base */
  ExprStmtWithBlock *clone_stmt_impl () const override
  {
    return new ExprStmtWithBlock (*this);
  }
};

} // namespace AST
} // namespace Rust

#endif