/* Utilities to manipulate GCC trees.
   Copyright (C) 2025 Free Software Foundation, Inc.

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 "elna/gcc/elna-tree.h"
#include "elna/gcc/elna-diagnostic.h"

#include "stor-layout.h"
#include "fold-const.h"
#include "diagnostic-core.h"
#include "stringpool.h"

namespace elna
{
namespace gcc
{
    bool is_pointer_type(tree type)
    {
        gcc_assert(TYPE_P(type));
        return TREE_CODE(type) == POINTER_TYPE;
    }

    bool is_integral_type(tree type)
    {
        gcc_assert(TYPE_P(type));
        return TREE_CODE(type) == INTEGER_TYPE;
    }

    bool are_compatible_pointers(tree lhs, tree rhs)
    {
        tree lhs_type = TREE_TYPE(lhs);
        tree rhs_type = TREE_TYPE(rhs);

        return (is_pointer_type(lhs_type) && rhs == null_pointer_node)
            || (is_pointer_type(lhs_type) && lhs_type == rhs_type);
    }

    tree tree_chain_base::head()
    {
        return first;
    }

    void tree_chain_base::append(tree t)
    {
        gcc_assert(t != NULL_TREE);

        if (this->first == NULL_TREE)
        {
            this->first = this->last = t;
        }
        else
        {
            chain(t);
            this->last = t;
        }
    }

    void tree_chain::chain(tree t)
    {
        TREE_CHAIN(this->last) = t;
    }

    void block_chain::chain(tree t)
    {
        BLOCK_CHAIN(this->last) = t;
    }

    tree_symbol_mapping::tree_symbol_mapping(tree bind_expression, tree block)
        : m_bind_expression(bind_expression), m_block(block)
    {
    }

    tree tree_symbol_mapping::bind_expression()
    {
        return m_bind_expression;
    }

    tree tree_symbol_mapping::block()
    {
        return m_block;
    }

    block_scope::block_scope()
        : m_statement_list(alloc_stmt_list())
    {
    }

    void block_scope::append_statement(tree statement_tree)
    {
        if (!defers.empty())
        {
            append_to_statement_list(statement_tree, &this->defers.front().second);
        }
        else
        {
            append_to_statement_list(statement_tree, &this->m_statement_list);
        }
    }

    void block_scope::defer(tree statement_tree)
    {
        defers.push_front({ statement_tree, alloc_stmt_list() });
    }

    tree block_scope::chain_defer()
    {
        if (this->defers.empty())
        {
            return m_statement_list;
        }
        std::forward_list<std::pair<tree, tree>>::iterator defer_iterator =
            this->defers.begin();
        tree defer_tree = build2(TRY_FINALLY_EXPR, void_type_node, defer_iterator->second, defer_iterator->first);

        ++defer_iterator;
        for (; defer_iterator != this->defers.end(); ++defer_iterator)
        {
            append_to_statement_list(defer_tree, &defer_iterator->second);
            defer_tree = build2(TRY_FINALLY_EXPR, void_type_node, defer_iterator->second, defer_iterator->first);
        }
        return build2(COMPOUND_EXPR, TREE_TYPE(defer_tree), m_statement_list, defer_tree);
    }

    tree build_field(location_t location, tree record_type, const std::string name, tree type)
    {
        tree field_declaration = build_decl(location,
                FIELD_DECL, get_identifier(name.c_str()), type);
        TREE_ADDRESSABLE(field_declaration) = 1;
        DECL_CONTEXT(field_declaration) = record_type;

        return field_declaration;
    }

    std::shared_ptr<boot::symbol_table<tree>> builtin_symbol_table()
    {
        std::shared_ptr<boot::symbol_table<tree>> initial_table =
            std::make_shared<boot::symbol_table<tree>>();

        initial_table->enter("Int", long_integer_type_node);
        initial_table->enter("Word", size_type_node);
        initial_table->enter("Bool", boolean_type_node);
        initial_table->enter("Float", double_type_node);
        initial_table->enter("Char", unsigned_char_type_node);
        initial_table->enter("Byte", make_unsigned_type(8));

        tree string_record = make_node(RECORD_TYPE);
        tree_chain record_chain;

        record_chain.append(build_field(UNKNOWN_LOCATION, string_record, "length", initial_table->lookup("Word")));
        record_chain.append(build_field(UNKNOWN_LOCATION, string_record, "ptr",
                    build_pointer_type_for_mode(initial_table->lookup("Char"), VOIDmode, true)));

        TYPE_FIELDS(string_record) = record_chain.head();
        layout_type(string_record);

        initial_table->enter("String", string_record);

        return initial_table;
    }

    tree do_pointer_arithmetic(boot::binary_operator binary_operator, tree left, tree right)
    {
        if (binary_operator == boot::binary_operator::sum)
        {
            tree pointer{ NULL_TREE };
            tree offset{ NULL_TREE };

            if (is_pointer_type(TREE_TYPE(left)) && is_integral_type(TREE_TYPE(right)))
            {
                pointer = left;
                offset = right;
            }
            else if (is_integral_type(TREE_TYPE(left)) && is_pointer_type(TREE_TYPE(right)))
            {
                pointer = right;
                offset = left;
            }
            else
            {
                return error_mark_node;
            }
            tree size_exp = fold_convert(TREE_TYPE(offset), size_in_bytes(TREE_TYPE(TREE_TYPE(pointer))));

            offset = fold_build2(MULT_EXPR, TREE_TYPE(offset), offset, size_exp);
            offset = fold_convert(sizetype, offset);

            return fold_build2(POINTER_PLUS_EXPR, TREE_TYPE(pointer), pointer, offset);
        }
        else if (binary_operator == boot::binary_operator::subtraction)
        {
            if (is_pointer_type(TREE_TYPE(left)) && is_integral_type(TREE_TYPE(right)))
            {
                tree pointer_type = TREE_TYPE(left);
                tree offset_type = TREE_TYPE(right);
                tree size_exp = fold_convert(offset_type, size_in_bytes(TREE_TYPE(pointer_type)));

                tree convert_expression = fold_build2(MULT_EXPR, offset_type, right, size_exp);
                convert_expression = fold_convert(sizetype, convert_expression);

                convert_expression = fold_build1(NEGATE_EXPR, sizetype, convert_expression);
                return fold_build2(POINTER_PLUS_EXPR, pointer_type, left, convert_expression);
            } else if (is_pointer_type(TREE_TYPE(left)) && is_pointer_type(TREE_TYPE(right))
                    && TREE_TYPE(left) == TREE_TYPE(right))
            {
                return fold_build2(POINTER_DIFF_EXPR, ssizetype, left, right);
            }
        }
        return error_mark_node;
    }

    tree build_binary_operation(bool condition, boot::binary_expression *expression,
            tree_code operator_code, tree left, tree right, tree target_type)
    {
        location_t expression_location = get_location(&expression->position());
        tree left_type = TREE_TYPE(left);
        tree right_type = TREE_TYPE(right);

        if (condition)
        {
            return build2_loc(expression_location, operator_code, target_type, left, right);
        }
        else
        {
            error_at(expression_location,
                    "invalid operands of type %s and %s for operator %s",
                    print_type(left_type).c_str(), print_type(right_type).c_str(),
                    elna::boot::print_binary_operator(expression->operation()));
            return error_mark_node;
        }
    }
}
}