/* Dependency graph analysis.
   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/boot/dependency.h"

#include "elna/boot/driver.h"
#include "elna/boot/materialization.h"
#include "elna/boot/name_analysis.h"
#include "elna/boot/type_check.h"
#include "elna/boot/validation.h"
#include "parser.hh"

namespace elna::boot
{
    circular_import_error::circular_import_error(const source_position position,
            const std::string& module_name)
        : diagnostic(position), module_name(module_name)
    {
    }

    std::string circular_import_error::what() const
    {
        return "Circular import of module '" + this->module_name + "'";
    }

    read_result read_source(std::istream& entry_point, const target_info& target)
    {
        driver parse_driver;
        lexer tokenizer(entry_point);
        yy::parser parser(tokenizer, parse_driver);

        if (parser() != 0)
        {
            diagnostic_list errors;
            std::swap(errors, parse_driver.errors());
            return read_result{ std::in_place_type<diagnostic_list>, std::move(errors) };
        }
        std::unique_ptr<unit> tree;
        std::swap(tree, parse_driver.tree);
        materialization_visitor materialization_visitor(target);
        tree->accept(&materialization_visitor);

        if (materialization_visitor.has_errors())
        {
            diagnostic_list errors;
            std::swap(errors, materialization_visitor.errors());
            return read_result{ std::in_place_type<diagnostic_list>, std::move(errors) };
        }
        return read_result{ std::in_place_type<std::unique_ptr<unit>>, std::move(tree) };
    }

    analysis_result analyze_semantics(std::unique_ptr<unit>& tree,
            const std::vector<std::shared_ptr<symbol_table>>& imports,
            const std::shared_ptr<symbol_table>& globals, const target_info& target,
            const std::filesystem::path& module_path)
    {
        forward_declaration_visitor forward_declarer;

        tree->accept(&forward_declarer);

        analysis_result result{
            .value = symbol_bag(std::move(forward_declarer.unresolved), globals),
            .errors = std::move(forward_declarer.errors())
        };
        if (!result.errors.empty())
        {
            return result;
        }
        for (const auto& import : imports)
        {
            result.value.add_import(import);
        }
        declaration_visitor declarations(result.value, target, module_path);
        tree->accept(&declarations);

        if (declarations.has_errors())
        {
            std::swap(result.errors, declarations.errors());
            return result;
        }
        name_analysis_visitor name_analyser(result.value, target, module_path);
        tree->accept(&name_analyser);

        if (name_analyser.has_errors())
        {
            std::swap(result.errors, name_analyser.errors());
            return result;
        }
        type_analysis_visitor type_analyzer(result.value, target);
        tree->accept(&type_analyzer);

        if (type_analyzer.has_errors())
        {
            std::swap(result.errors, type_analyzer.errors());
            return result;
        }
        validation_visitor validator(result.value, target);
        tree->accept(&validator);

        if (validator.has_errors())
        {
            std::swap(result.errors, validator.errors());
            return result;
        }
        return result;
    }

    std::filesystem::path build_path(const std::vector<std::string>& segments)
    {
        std::filesystem::path result;
        std::vector<std::string>::const_iterator segment_iterator = std::cbegin(segments);

        if (segment_iterator == std::cend(segments))
        {
            return result;
        }
        result = *segment_iterator;

        ++segment_iterator;
        for (; segment_iterator != std::cend(segments); ++segment_iterator)
        {
            result /= *segment_iterator;
        }
        result.replace_extension(".elna");

        return result;
    }
}