path_location_intf.hpp

// Copyright Take Vos 2022.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt)
 
#pragma once
 
#include "../utility/utility.hpp"
#include "../metadata/metadata.hpp"
#include "../macros.hpp"
#include <filesystem>
#include <ranges>
#include <fstream>
#include <string>
#include <ranges>
 
hi_export_module(hikogui.path.path_location : intf);
 
hi_export namespace hi { inline namespace v1 {
 
 
template<typename Context>
concept path_range =
    std::ranges::input_range<Context> and
    std::convertible_to<std::ranges::range_value_t<std::remove_cvref_t<Context>>, std::filesystem::path> and
    not std::convertible_to<Context, std::filesystem::path>;
 
template<path_range Locations>
[[nodiscard]] hi_inline std::optional<std::filesystem::path>
find_path(Locations &&locations, std::filesystem::path const& ref) noexcept
{
    if (ref.is_absolute()) {
        if (std::filesystem::exists(ref)) {
            return ref;
        } else {
            return {};
        }
    } else {
        for (auto const& base : locations) {
            auto path = base / ref;
            if (std::filesystem::exists(path)) {
                return path;
            }
        }
        return {};
    }
}
 
[[nodiscard]] std::filesystem::path executable_file() noexcept;
 
[[nodiscard]] hi_inline std::filesystem::path executable_dir() noexcept
{
    auto tmp = executable_file();
    tmp.remove_filename();
    return tmp;
}
 
[[nodiscard]] std::filesystem::path data_dir() noexcept;
 
[[nodiscard]] std::filesystem::path log_dir() noexcept;
 
[[nodiscard]] std::filesystem::path preferences_file() noexcept;
 
[[nodiscard]] hi_inline generator<std::filesystem::path> resource_dirs() noexcept;
 
[[nodiscard]] hi_inline generator<std::filesystem::path> system_font_dirs() noexcept;
 
[[nodiscard]] hi_inline generator<std::filesystem::path> font_files() noexcept;
 
[[nodiscard]] hi_inline generator<std::filesystem::path> theme_files() noexcept;
 
[[nodiscard]] hi_inline std::optional<std::filesystem::path> source_dir_parse_cmake_install(std::filesystem::path path) noexcept
{
    if (not std::filesystem::exists(path)) {
        return std::nullopt;
    }
 
    auto line = std::string{};
    try {
        auto fd = std::ifstream{path.string()};
        line = getline(fd, 512);
        fd.close();
 
    } catch (...) {
        return std::nullopt;
    }
 
    auto const cmake_install_start = std::string{"# Install script for directory: "};
    if (not line.starts_with(cmake_install_start)) {
        return std::nullopt;
    }
 
    auto source_dir = std::filesystem::path{line.substr(cmake_install_start.size())};
    if (not std::filesystem::exists(source_dir)) {
        return std::nullopt;
    }
 
    return source_dir;
}
 
[[nodiscard]] hi_inline std::optional<std::filesystem::path> source_dir() noexcept
{
    // If the cmake_install.cmake file exists then the executable is located in a build directory.
    if (auto path = source_dir_parse_cmake_install(executable_dir() / "cmake_install.cmake")) {
        return *path;
    }
 
    // When using a cmake multi-config generator, the cmake_install.cmake file is located one directory up.
    if (auto path = source_dir_parse_cmake_install(executable_dir() / ".." / "cmake_install.cmake")) {
        return *path;
    }
 
    return std::nullopt;
}
 
[[nodiscard]] hi_inline std::optional<std::filesystem::path> library_install_dir() noexcept
{
    // path is:
    //  - /install_dir/include/hikogui/path/path_location_impl.hpp
    //  - /build_dir/src/hikogui/path/path_location_impl.hpp
    // becomes:
    //  - /install_dir/
    //  - /build_dir/
    auto path = std::filesystem::path{__FILE__};
    path.replace_filename("../../..");
    auto install_path = std::filesystem::canonical(path);
    
    if (install_path != library_source_dir()) {
        return install_path;
    } else {
        return std::nullopt;
    }
}
 
}} // namespace hi::v1