// Copyright 2022 Huawei Cloud Computing Technology Co., Ltd.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "src/buildtool/file_system/file_system_manager.hpp"

#include <chrono>
#include <cstddef>
#include <cstdlib>
#include <filesystem>
#include <fstream>
#include <functional>
#include <memory>
#include <optional>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

#include "catch2/catch_test_macros.hpp"
#include "catch2/generators/catch_generators_all.hpp"
#include "fmt/core.h"
#include "src/buildtool/file_system/object_type.hpp"
#include "src/buildtool/logging/log_level.hpp"
#include "src/buildtool/logging/logger.hpp"
#include "src/buildtool/storage/config.hpp"
#include "src/buildtool/system/system.hpp"
#include "src/utils/cpp/tmp_dir.hpp"
#include "test/utils/hermeticity/test_storage_config.hpp"

class CopyFileFixture {
  public:
    CopyFileFixture() noexcept {
        REQUIRE(FileSystemManager::CreateDirectory(to_.parent_path()));
    }
    CopyFileFixture(CopyFileFixture const&) = delete;
    CopyFileFixture(CopyFileFixture&&) = delete;
    ~CopyFileFixture() noexcept { CHECK(std::filesystem::remove(to_)); }
    auto operator=(CopyFileFixture const&) -> CopyFileFixture& = delete;
    auto operator=(CopyFileFixture&&) -> CopyFileFixture& = delete;

    std::filesystem::path const from_{
        "test/buildtool/file_system/data/example_file"};
    std::filesystem::path const to_{"./tmp-CopyFile/copied_file"};
};

class WriteFileFixture {
  public:
    WriteFileFixture() noexcept {
        REQUIRE(FileSystemManager::CreateDirectory(root_dir_));
    }
    WriteFileFixture(WriteFileFixture const&) = delete;
    WriteFileFixture(WriteFileFixture&&) = delete;
    ~WriteFileFixture() noexcept { CHECK(std::filesystem::remove(file_path_)); }
    auto operator=(WriteFileFixture const&) -> WriteFileFixture& = delete;
    auto operator=(WriteFileFixture&&) -> WriteFileFixture& = delete;

    std::filesystem::path const relative_path_parent_{
        GENERATE(as<std::filesystem::path>{},
                 ".",
                 "level0",
                 "level0/level1",
                 "a/b/c/d",
                 "./a/../e")};
    std::filesystem::path const root_dir_{"./tmp-RemoveFile"};
    std::filesystem::path const file_path_{root_dir_ / relative_path_parent_ /
                                           "file"};
};

class SymlinkTestsFixture {
  public:
    SymlinkTestsFixture() noexcept {
        REQUIRE(FileSystemManager::CreateDirectory(root_dir_));
        create_files();
        create_symlinks();
    }
    SymlinkTestsFixture(SymlinkTestsFixture const&) = delete;
    SymlinkTestsFixture(SymlinkTestsFixture&&) = delete;
    ~SymlinkTestsFixture() noexcept {
        CHECK(std::filesystem::remove_all(root_dir_));
    }
    auto operator=(SymlinkTestsFixture const&) -> SymlinkTestsFixture& = delete;
    auto operator=(SymlinkTestsFixture&&) -> SymlinkTestsFixture& = delete;

    std::filesystem::path const root_dir_{"./tmp-Symlinks"};

    using filetree_t = std::unordered_map<std::string, ObjectType>;
    filetree_t const kExpected = {{"foo", ObjectType::File},
                                  {"baz", ObjectType::Tree},
                                  {"baz/foo", ObjectType::File},
                                  {"bazz", ObjectType::Tree},
                                  {"bazz/baz", ObjectType::Tree},
                                  {"bazz/baz/foo", ObjectType::File}};

    struct LinkInfo {
        std::string to;
        std::string link;
        bool resolvesToExisting;
        bool isNonUpwards;
    };
    std::vector<LinkInfo> const kSymExpected = {
        {.to = "baz",
         .link = "baz_l",
         .resolvesToExisting = true,
         .isNonUpwards = true},
        {.to = "../foo",
         .link = "baz/foo_l",
         .resolvesToExisting = true,
         .isNonUpwards = false},
        {.to = "baz/foo_l",
         .link = "bar_l",
         .resolvesToExisting = true,
         .isNonUpwards = true},
        {.to = "does_not_exist",
         .link = "baz/non_existing_l",
         .resolvesToExisting = false,
         .isNonUpwards = true},
        {.to = "non_existing_l",
         .link = "baz/non_existing_indirect_l",
         .resolvesToExisting = false,
         .isNonUpwards = true},
        {.to = "baz/../../does_not_exist",
         .link = "non_existing_sneaky_l",
         .resolvesToExisting = false,
         .isNonUpwards = false}};

    // distinct dir entries
    size_t const num_entries_{12U};
    // distinct dir entries after removing all subdirs named "baz"
    size_t const num_root_file_entries_{5U};

    void create_files() {
        for (auto const& [path, type] : kExpected) {
            switch (type) {
                case ObjectType::File: {
                    if (not FileSystemManager::WriteFile("",
                                                         root_dir_ / path)) {
                        Logger::Log(LogLevel::Error,
                                    "Could not create test file at path {}",
                                    (root_dir_ / path).string());
                        std::exit(1);
                    };
                } break;
                case ObjectType::Tree: {
                    if (not FileSystemManager::CreateDirectory(root_dir_ /
                                                               path)) {
                        Logger::Log(LogLevel::Error,
                                    "Could not create test dir at path {}",
                                    (root_dir_ / path).string());
                        std::exit(1);
                    };
                } break;
                default: {
                    Logger::Log(LogLevel::Error,
                                "File system failure in creating test dir");
                    std::exit(1);
                }
            }
        }
    }

    void create_symlinks() {
        for (auto const& link_info : kSymExpected) {
            if (not FileSystemManager::CreateSymlink(
                    link_info.to, root_dir_ / link_info.link)) {
                Logger::Log(
                    LogLevel::Error,
                    "File system failure in creating symlink at path {}",
                    (root_dir_ / link_info.link).string());
                std::exit(1);
            }
        }
    }
};

namespace {

namespace fs = std::filesystem;

constexpr auto kFilePerms =
    fs::perms::owner_read | fs::perms::group_read | fs::perms::others_read;

constexpr auto kInstalledPerms = fs::perms::owner_write;

constexpr auto kExecPerms =
    fs::perms::owner_exec | fs::perms::group_exec | fs::perms::others_exec;

auto HasFilePermissions(fs::path const& path) noexcept -> bool {
    try {
        return fs::status(path).permissions() == kFilePerms;
    } catch (...) {
        return false;
    }
}

auto HasInstalledFilePermissions(fs::path const& path) noexcept -> bool {
    try {
        return fs::status(path).permissions() == (kFilePerms | kInstalledPerms);
    } catch (...) {
        return false;
    }
}

auto HasExecutablePermissions(fs::path const& path) noexcept -> bool {
    try {
        return fs::status(path).permissions() == (kFilePerms | kExecPerms);
    } catch (...) {
        return false;
    }
}

auto HasInstalledExecutablePermissions(fs::path const& path) noexcept -> bool {
    try {
        return fs::status(path).permissions() ==
               (kFilePerms | kExecPerms | kInstalledPerms);
    } catch (...) {
        return false;
    }
}

auto HasEpochTime(fs::path const& path) noexcept -> bool {
    try {
        return fs::last_write_time(path) ==
               System::GetPosixEpoch<std::chrono::file_clock>();
    } catch (...) {
        return false;
    }
}

}  // namespace

TEST_CASE("Exists", "[file_system]") {
    CHECK(FileSystemManager::Exists("test/buildtool/file_system/data/"));
    CHECK(FileSystemManager::Exists(
        "test/buildtool/file_system/data/example_file"));
    CHECK(FileSystemManager::Exists(
        "test/buildtool/file_system/data/empty_executable"));
}

TEST_CASE("IsFile", "[file_system]") {
    CHECK(FileSystemManager::IsFile(
        "test/buildtool/file_system/data/example_file"));
    CHECK(FileSystemManager::IsFile(
        "test/buildtool/file_system/data/empty_executable"));
    CHECK_FALSE(FileSystemManager::IsFile("test/buildtool/file_system/data/"));
}

TEST_CASE("IsExecutable", "[file_system]") {
    CHECK(FileSystemManager::IsExecutable(
        "test/buildtool/file_system/data/empty_executable"));
    CHECK_FALSE(FileSystemManager::IsExecutable(
        "test/buildtool/file_system/data/example_file"));
    CHECK_FALSE(
        FileSystemManager::IsExecutable("test/buildtool/file_system/data/"));
}

TEST_CASE("IsDirectory", "[file_system]") {
    CHECK(FileSystemManager::IsDirectory("test/buildtool/file_system/data"));
    CHECK_FALSE(FileSystemManager::IsDirectory(
        "test/buildtool/file_system/data/example_file"));
    CHECK_FALSE(FileSystemManager::IsDirectory(
        "test/buildtool/file_system/data/empty_executable"));
}

TEST_CASE("Type", "[file_system]") {
    auto const type_file =
        FileSystemManager::Type("test/buildtool/file_system/data/example_file");
    REQUIRE(type_file);
    CHECK(*type_file == ObjectType::File);

    auto const type_exec = FileSystemManager::Type(
        "test/buildtool/file_system/data/empty_executable");
    REQUIRE(type_exec);
    CHECK(*type_exec == ObjectType::Executable);

    auto const type_dir =
        FileSystemManager::Type("test/buildtool/file_system/data/");
    REQUIRE(type_dir);
    CHECK(*type_dir == ObjectType::Tree);
}

TEST_CASE("CreateDirectory", "[file_system]") {
    auto const dir = GENERATE(as<std::filesystem::path>{},
                              "level0",
                              "level0/level1",
                              "a/b/c/d",
                              "./a/../e");
    CHECK(FileSystemManager::CreateDirectory(dir));
    CHECK(FileSystemManager::IsDirectory(dir));

    // If we have created the directory already, CreateDirectory() returns true
    // and the state of things doesn't change
    CHECK(FileSystemManager::CreateDirectory(dir));
    CHECK(FileSystemManager::IsDirectory(dir));
}

TEST_CASE("ChangeDirectory", "[file_system]") {
    auto const starting_dir = FileSystemManager::GetCurrentDirectory();

    auto const new_dir = GENERATE(as<std::filesystem::path>{},
                                  "level0",
                                  "level0/level1",
                                  "a/b/c/d",
                                  "./a/../e");

    REQUIRE(FileSystemManager::CreateDirectory(new_dir));
    {
        auto anchor = FileSystemManager::ChangeDirectory(new_dir);
        CHECK(std::filesystem::equivalent(
            starting_dir / new_dir, FileSystemManager::GetCurrentDirectory()));
    }
    CHECK(starting_dir == FileSystemManager::GetCurrentDirectory());
}

TEST_CASE("ReadFile", "[file_system]") {
    SECTION("Existing file") {
        std::string const expected_content{"test\n"};
        std::filesystem::path file{"./tmp-ReadFile/file"};

        REQUIRE(FileSystemManager::CreateDirectory(file.parent_path()));
        std::ofstream writer{file};
        writer << expected_content;
        writer.close();

        auto const content = FileSystemManager::ReadFile(file);
        CHECK(content.has_value());
        CHECK(content == expected_content);
    }
    SECTION("Non-existing file") {
        std::filesystem::path file{
            "test/buildtool/file_system/data/this_file_does_not_exist"};
        REQUIRE(not FileSystemManager::Exists(file));

        auto const content = FileSystemManager::ReadFile(file);
        CHECK_FALSE(content.has_value());
    }
}

TEST_CASE_METHOD(CopyFileFixture, "CopyFile", "[file_system]") {
    auto run_test = [&](bool fd_less) {
        // Copy file was successful
        CHECK(FileSystemManager::CopyFile(from_, to_, fd_less));

        // file exists
        CHECK(FileSystemManager::IsFile(to_));

        // Contents are equal
        auto const content_from = FileSystemManager::ReadFile(from_);
        CHECK(content_from.has_value());
        auto const content_to = FileSystemManager::ReadFile(to_);
        CHECK(content_to.has_value());
        CHECK(content_from == content_to);
    };

    SECTION("direct") {
        run_test(false);
    }
    SECTION("fd_less") {
        run_test(true);
    }
}

TEST_CASE("CopyFile equivalent", "[file_system]") {
    auto storage_config = TestStorageConfig::Create();

    auto temp_dir = storage_config.Get().CreateTypedTmpDir("test");
    REQUIRE(temp_dir);

    auto const nested = temp_dir->GetPath() / "dir";
    auto const source = nested / "copy-self";
    auto const target = nested / "../dir/copy-self";

    REQUIRE(FileSystemManager::CreateDirectory(nested));
    REQUIRE(FileSystemManager::CreateFile(source));
    REQUIRE(FileSystemManager::IsFile(source));
    REQUIRE(FileSystemManager::IsFile(target));

    // Paths are different, but equivalent:
    REQUIRE(source != target);
    REQUIRE(std::filesystem::equivalent(source, target));

    CHECK(FileSystemManager::CopyFile(source, target));
    CHECK(FileSystemManager::IsFile(source));
    CHECK(FileSystemManager::IsFile(target));
}

TEST_CASE_METHOD(CopyFileFixture, "CopyFileAs", "[file_system]") {
    SECTION("as file") {
        auto run_test = [&]<bool kSetEpochTime = false>(bool fd_less) {
            // Copy as file was successful
            CHECK(FileSystemManager::CopyFileAs<kSetEpochTime>(
                from_, to_, ObjectType::File, fd_less));

            // file exists
            CHECK(FileSystemManager::IsFile(to_));
            CHECK(not FileSystemManager::IsExecutable(to_));

            // Contents are equal
            auto const content_from = FileSystemManager::ReadFile(from_);
            CHECK(content_from.has_value());
            auto const content_to = FileSystemManager::ReadFile(to_);
            CHECK(content_to.has_value());
            CHECK(content_from == content_to);

            // permissions should be 0444
            CHECK(HasFilePermissions(to_));
            if constexpr (kSetEpochTime) {
                CHECK(HasEpochTime(to_));
            }
        };

        SECTION("direct") {
            run_test(false);
        }
        SECTION("fd_less") {
            run_test(true);
        }
        SECTION("direct with epoch") {
            run_test.template operator()<true>(false);
        }
        SECTION("fd_less with epoch") {
            run_test.template operator()<true>(true);
        }
    }
    SECTION("as installed file") {
        auto run_test = [&]<bool kSetEpochTime = false>(bool fd_less) {
            // Copy as file was successful
            CHECK(FileSystemManager::CopyFileAs<kSetEpochTime,
                                                /*kSetWritable=*/true>(
                from_, to_, ObjectType::File, fd_less));

            // file exists
            CHECK(FileSystemManager::IsFile(to_));
            CHECK(not FileSystemManager::IsExecutable(to_));

            // Contents are equal
            auto const content_from = FileSystemManager::ReadFile(from_);
            CHECK(content_from.has_value());
            auto const content_to = FileSystemManager::ReadFile(to_);
            CHECK(content_to.has_value());
            CHECK(content_from == content_to);

            // permissions should be 0644
            CHECK(HasInstalledFilePermissions(to_));
            if constexpr (kSetEpochTime) {
                CHECK(HasEpochTime(to_));
            }
        };

        SECTION("direct") {
            run_test(false);
        }
        SECTION("fd_less") {
            run_test(true);
        }
        SECTION("direct with epoch") {
            run_test.template operator()<true>(false);
        }
        SECTION("fd_less with epoch") {
            run_test.template operator()<true>(true);
        }
    }
    SECTION("as executable") {
        auto run_test = [&]<bool kSetEpochTime = false>(bool fd_less) {
            // Copy as file was successful
            CHECK(FileSystemManager::CopyFileAs<kSetEpochTime>(
                from_, to_, ObjectType::Executable, fd_less));

            // file exists
            CHECK(FileSystemManager::IsExecutable(to_));

            // Contents are equal
            auto const content_from = FileSystemManager::ReadFile(from_);
            CHECK(content_from.has_value());
            auto const content_to = FileSystemManager::ReadFile(to_);
            CHECK(content_to.has_value());
            CHECK(content_from == content_to);

            // permissions should be 0555
            CHECK(HasExecutablePermissions(to_));
            if constexpr (kSetEpochTime) {
                CHECK(HasEpochTime(to_));
            }
        };

        SECTION("direct") {
            run_test(false);
        }
        SECTION("fd_less") {
            run_test(true);
        }
        SECTION("direct with epoch") {
            run_test.template operator()<true>(false);
        }
        SECTION("fd_less with epoch") {
            run_test.template operator()<true>(true);
        }
    }
    SECTION("as installed executable") {
        auto run_test = [&]<bool kSetEpochTime = false>(bool fd_less) {
            // Copy as file was successful
            CHECK(FileSystemManager::CopyFileAs<kSetEpochTime,
                                                /*kSetWritable=*/true>(
                from_, to_, ObjectType::Executable, fd_less));

            // file exists
            CHECK(FileSystemManager::IsExecutable(to_));

            // Contents are equal
            auto const content_from = FileSystemManager::ReadFile(from_);
            CHECK(content_from.has_value());
            auto const content_to = FileSystemManager::ReadFile(to_);
            CHECK(content_to.has_value());
            CHECK(content_from == content_to);

            // permissions should be 0755
            CHECK(HasInstalledExecutablePermissions(to_));
            if constexpr (kSetEpochTime) {
                CHECK(HasEpochTime(to_));
            }
        };

        SECTION("direct") {
            run_test(false);
        }
        SECTION("fd_less") {
            run_test(true);
        }
        SECTION("direct with epoch") {
            run_test.template operator()<true>(false);
        }
        SECTION("fd_less with epoch") {
            run_test.template operator()<true>(true);
        }
    }
}

TEST_CASE("RemoveFile", "[file_system]") {
    SECTION("Existing file") {
        std::filesystem::path from{
            "test/buildtool/file_system/data/example_file"};

        std::filesystem::path to{"./tmp-RemoveFile/copied_file"};
        REQUIRE(FileSystemManager::CreateDirectory(to.parent_path()));

        CHECK(FileSystemManager::CopyFile(from, to));

        CHECK(FileSystemManager::Exists(to));

        CHECK(FileSystemManager::RemoveFile(to));

        CHECK(not FileSystemManager::Exists(to));
    }
    SECTION("Non-existing file") {
        std::filesystem::path file{
            "test/buildtool/file_system/data/"
            "this_file_does_not_exist_neither"};
        CHECK(not FileSystemManager::Exists(file));
        CHECK(FileSystemManager::RemoveFile(file));  // nothing to delete
    }
    SECTION("Existing but not file") {
        std::filesystem::path dir{"./tmp-RemoveFile/dir"};
        CHECK(FileSystemManager::CreateDirectory(dir));
        CHECK(not FileSystemManager::RemoveFile(dir));
        CHECK(FileSystemManager::Exists(dir));
    }
}

TEST_CASE_METHOD(WriteFileFixture, "WriteFile", "[file_system]") {
    std::string const content{"This are the contents\nof the file.\n"};

    auto run_test = [&](bool fd_less) {
        CHECK(FileSystemManager::WriteFile(content, file_path_, fd_less));
        CHECK(FileSystemManager::IsDirectory(file_path_.parent_path()));
        CHECK(FileSystemManager::IsFile(file_path_));

        auto const written_content = FileSystemManager::ReadFile(file_path_);
        CHECK(written_content.has_value());
        CHECK(written_content == content);
    };

    SECTION("direct") {
        run_test(false);
    }
    SECTION("fd-less") {
        run_test(true);
    }
}

TEST_CASE_METHOD(WriteFileFixture, "WriteFileAs", "[file_system]") {
    SECTION("as a file") {
        std::string const content{"This are the contents\nof the file.\n"};

        auto run_test = [&]<bool kSetEpochTime = false>(bool fd_less) {
            CHECK(FileSystemManager::WriteFileAs<kSetEpochTime>(
                content, file_path_, ObjectType::File, fd_less));
            CHECK(FileSystemManager::IsDirectory(file_path_.parent_path()));
            CHECK(FileSystemManager::IsFile(file_path_));
            CHECK(not FileSystemManager::IsExecutable(file_path_));

            auto const written_content =
                FileSystemManager::ReadFile(file_path_);
            CHECK(written_content.has_value());
            CHECK(written_content == content);

            // permissions should be 0444
            CHECK(HasFilePermissions(file_path_));
            if constexpr (kSetEpochTime) {
                CHECK(HasEpochTime(file_path_));
            }
        };

        SECTION("direct") {
            run_test(false);
        }
        SECTION("fd-less") {
            run_test(true);
        }
        SECTION("direct with epoch") {
            run_test.template operator()<true>(false);
        }
        SECTION("fd-less with epoch") {
            run_test.template operator()<true>(true);
        }
    }
    SECTION("as an executable") {
        std::string const content{"\n"};

        auto run_test = [&]<bool kSetEpochTime = false>(bool fd_less) {
            CHECK(FileSystemManager::WriteFileAs<kSetEpochTime>(
                content, file_path_, ObjectType::Executable, fd_less));
            CHECK(FileSystemManager::IsDirectory(file_path_.parent_path()));
            CHECK(FileSystemManager::IsExecutable(file_path_));

            auto const written_content =
                FileSystemManager::ReadFile(file_path_);
            CHECK(written_content.has_value());
            CHECK(written_content == content);

            // permissions should be 0555
            CHECK(HasExecutablePermissions(file_path_));
            if constexpr (kSetEpochTime) {
                CHECK(HasEpochTime(file_path_));
            }
        };

        SECTION("direct") {
            run_test(false);
        }
        SECTION("fd-less") {
            run_test(true);
        }
        SECTION("direct with epoch") {
            run_test.template operator()<true>(false);
        }
        SECTION("fd-less with epoch") {
            run_test.template operator()<true>(true);
        }
    }
}

TEST_CASE("FileSystemManager", "[file_system]") {
    // test file and test file content with newline and null characters
    std::filesystem::path test_file{"test/file"};
    std::filesystem::path copy_file{"test/copy"};
    std::string test_content;
    test_content += "test1";
    test_content += '\n';
    test_content += '\0';
    test_content += "test2";

    CHECK(FileSystemManager::IsRelativePath(test_file));
    CHECK(not FileSystemManager::IsAbsolutePath(test_file));

    // create parent directory
    REQUIRE(FileSystemManager::CreateDirectory(test_file.parent_path()));

    // scope to test RAII "DirectoryAnchor" (should restore CWD on destruction)
    {
        // change directory and obtain DirectoryAnchor
        auto anchor =
            FileSystemManager::ChangeDirectory(test_file.parent_path());

        std::ofstream file{test_file.filename()};
        REQUIRE(file);
        file << test_content;
        file.close();

        // check if file exists
        REQUIRE(FileSystemManager::IsFile(test_file.filename()));
    }  // restore CWD to parent path

    // check if file exists with full path
    REQUIRE(FileSystemManager::IsFile(test_file));

    // read file content and compare with input above
    auto const file_content = FileSystemManager::ReadFile(test_file);
    REQUIRE(file_content.has_value());
    CHECK(file_content == test_content);

    // copy file without 'overwrite'
    CHECK(FileSystemManager::CopyFile(test_file,
                                      copy_file,
                                      /*fd_less=*/false,
                                      std::filesystem::copy_options::none));

    // copy file with 'overwrite'
    CHECK(FileSystemManager::CopyFile(copy_file, test_file));

    // remove files and verify removal
    CHECK(FileSystemManager::RemoveFile(test_file));
    CHECK(not FileSystemManager::IsFile(test_file));
    CHECK(FileSystemManager::RemoveFile(copy_file));
    CHECK(not FileSystemManager::IsFile(copy_file));
}

TEST_CASE("CreateFileHardlink", "[file_system]") {
    std::filesystem::path to{"./tmp-CreateFileHardlink/linked_file"};
    REQUIRE(FileSystemManager::CreateDirectory(to.parent_path()));

    SECTION("Existing file") {
        std::filesystem::path from{"example_file"};
        {
            std::ofstream f{from};
            f << "foo";
        }

        CHECK(FileSystemManager::CreateFileHardlink(from, to));
        CHECK(FileSystemManager::Exists(to));

        CHECK_FALSE(FileSystemManager::CreateFileHardlink(from, to));
        CHECK(FileSystemManager::Exists(to));

        CHECK(FileSystemManager::RemoveFile(to));
        CHECK(not FileSystemManager::Exists(to));
    }
    SECTION("Non-existing file") {
        std::filesystem::path from{
            "test/buildtool/file_system/data/this_file_does_not_exist"};

        CHECK_FALSE(FileSystemManager::CreateFileHardlink(from, to));
        CHECK_FALSE(FileSystemManager::Exists(to));
    }
    SECTION("Existing but not file") {
        std::filesystem::path from{"./tmp-CreateFileHardlink/dir"};
        CHECK(FileSystemManager::CreateDirectory(from));

        CHECK_FALSE(FileSystemManager::CreateFileHardlink(from, to));
        CHECK_FALSE(FileSystemManager::Exists(to));
    }
}

TEST_CASE("CopyDirectoryImpl", "[file_system]") {
    std::filesystem::path to{"./tmp-CreateDirCopy/tmp-dir"};
    REQUIRE(FileSystemManager::CreateDirectory(to.parent_path()));

    CHECK(FileSystemManager::CreateDirectory("a/b/c/d"));
    CHECK(FileSystemManager::IsDirectory("a/b/c/d"));

    CHECK(FileSystemManager::WriteFile("boo", "a/bb.txt"));

    // Test copy
    CHECK(FileSystemManager::CopyDirectoryImpl("a", to));

    // Result should be in tmp-dir now
    CHECK(FileSystemManager::IsDirectory(to));

    CHECK(FileSystemManager::IsDirectory(to / "b"));

    CHECK(FileSystemManager::IsDirectory(to / "b/c"));

    CHECK(FileSystemManager::IsFile(to / "bb.txt"));
}

TEST_CASE_METHOD(CopyFileFixture, "CreateFileHardlinkAs", "[file_system]") {
    auto set_perm = [&](bool is_executable) {
        auto const content = FileSystemManager::ReadFile(from_);
        REQUIRE(content);
        REQUIRE(FileSystemManager::RemoveFile(from_));
        REQUIRE(FileSystemManager::WriteFileAs(
            *content,
            from_,
            is_executable ? ObjectType::Executable : ObjectType::File));
    };
    auto run_test = [&]<bool kSetEpochTime = false>(bool is_executable) {
        // Hard link creation was successful
        CHECK(FileSystemManager::CreateFileHardlinkAs<kSetEpochTime>(
            from_,
            to_,
            is_executable ? ObjectType::Executable : ObjectType::File));

        // file exists
        CHECK(is_executable == FileSystemManager::IsExecutable(to_));

        // executables are special permission files
        CHECK(FileSystemManager::IsFile(to_));

        // permissions should be 0555 or 0444
        CHECK((is_executable ? HasExecutablePermissions(to_)
                             : HasFilePermissions(to_)));
        if constexpr (kSetEpochTime) {
            CHECK(HasEpochTime(to_));
        }
    };
    SECTION("as file") {
        SECTION("from file") {
            set_perm(false);
            run_test(false);
        }
        SECTION("from executable") {
            set_perm(true);
            run_test(false);
        }
    }
    SECTION("as executable") {
        SECTION("from file") {
            set_perm(false);
            run_test(true);
        }
        SECTION("from executable") {
            set_perm(true);
            run_test(true);
        }
    }
    SECTION("as file with epoch") {
        SECTION("from file") {
            set_perm(false);
            run_test.template operator()<true>(false);
        }
        SECTION("from executable") {
            set_perm(true);
            run_test.template operator()<true>(false);
        }
    }
    SECTION("as executable with epoch") {
        SECTION("from file") {
            set_perm(false);
            run_test.template operator()<true>(true);
        }
        SECTION("from executable") {
            set_perm(true);
            run_test.template operator()<true>(true);
        }
    }
}

TEST_CASE_METHOD(SymlinkTestsFixture, "Symlinks", "[file_system]") {
    CHECK(std::filesystem::is_directory(root_dir_ / "baz"));
    CHECK(std::filesystem::is_symlink(root_dir_ / "baz_l"));
    CHECK_FALSE(std::filesystem::is_directory(
        std::filesystem::symlink_status(root_dir_ / "baz_l")));

    auto i = GENERATE(range(0U, 6U /* kSymExpected.size() */));

    SECTION(fmt::format("Non-upwards symlinks - entry {}", i)) {
        CHECK(FileSystemManager::IsNonUpwardsSymlink(root_dir_ /
                                                     kSymExpected[i].link) ==
              kSymExpected[i].isNonUpwards);
    }

    SECTION(fmt::format("Resolve symlinks - entry {}", i)) {
        auto path = root_dir_ / kSymExpected[i].link;
        REQUIRE(FileSystemManager::ResolveSymlinks(&path));
        CHECK(FileSystemManager::Exists(path) ==
              kSymExpected[i].resolvesToExisting);
    }
}

TEST_CASE_METHOD(SymlinkTestsFixture,
                 "ReadDirectoryEntriesRecursive",
                 "[file_system]") {
    size_t count{};
    auto use_entry = [&count](std::filesystem::path const& /*name*/,
                              bool /*is_tree*/) {
        ++count;
        return true;
    };

    SECTION("Check directory is complete") {
        REQUIRE(FileSystemManager::ReadDirectoryEntriesRecursive(root_dir_,
                                                                 use_entry));
        CHECK(count == num_entries_);
    }

    SECTION("Check directory with missing paths") {
        REQUIRE(FileSystemManager::ReadDirectoryEntriesRecursive(
            root_dir_,
            use_entry,
            /*ignored_subdirs=*/
            {"baz"}));
        CHECK(count == num_root_file_entries_);
    }
}