#include <kapi/filesystem.hpp>

#include <kernel/test_support/filesystem/storage_boot_module_vfs_fixture.hpp>

#include <kstd/system_error.hpp>

#include <catch2/catch_test_macros.hpp>

#include <algorithm>
#include <cstddef>
#include <filesystem>
#include <string_view>
#include <vector>

SCENARIO_METHOD(kernel::tests::filesystem::storage_boot_module_vfs_fixture, "Kapi filesystem with real images",
                "[kapi][filesystem]")
{
  auto const image_path_1 = std::filesystem::path{KERNEL_TEST_ASSETS_DIR} / "ext2_1KB_fs.img";
  auto const image_path_2 = std::filesystem::path{KERNEL_TEST_ASSETS_DIR} / "ext2_2KB_fs.img";

  GIVEN("Two real image files")
  {
    REQUIRE(std::filesystem::exists(image_path_1));
    REQUIRE(std::filesystem::exists(image_path_2));
    REQUIRE_NOTHROW(
        setup_modules_from_img_and_init_vfs({"test_img_module_1", "test_img_module_2"}, {image_path_1, image_path_2}));

    THEN("files can be opened, read and closed again")
    {
      auto fd = kapi::filesystem::open("/information/info_1.txt").value();

      auto buffer = std::vector<std::byte>(6);
      auto bytes_read = kapi::filesystem::read(fd, buffer.data(), buffer.size());
      REQUIRE(bytes_read);

      std::string_view buffer_as_str{reinterpret_cast<char *>(buffer.data()), static_cast<size_t>(*bytes_read)};
      REQUIRE(buffer_as_str == "info_1");

      REQUIRE(kapi::filesystem::close(fd));
    }

    THEN("files can be opened, written to, read from and closed again")
    {
      auto write_fd = kapi::filesystem::open("/information/info_1.txt");
      REQUIRE(write_fd);

      auto write_buffer = std::vector<std::byte>{std::byte{'H'}, std::byte{'e'}};

      auto const bytes_written = kapi::filesystem::write(*write_fd, write_buffer.data(), write_buffer.size());
      REQUIRE(bytes_written == 2);

      auto read_fd = kapi::filesystem::open("/information/info_1.txt");
      REQUIRE(read_fd);

      auto read_buffer = std::vector<std::byte>(6);
      auto const bytes_read = kapi::filesystem::read(*read_fd, read_buffer.data(), read_buffer.size());
      REQUIRE(bytes_read);

      std::string_view buffer_as_str{reinterpret_cast<char *>(read_buffer.data()), static_cast<size_t>(*bytes_read)};
      REQUIRE(buffer_as_str == "Hefo_1");

      REQUIRE(kapi::filesystem::close(*write_fd));
      REQUIRE(kapi::filesystem::close(*read_fd));
    }

    THEN("files can be opened through absolute symbolic link, read and closed again")
    {
      auto fd = kapi::filesystem::open("/symlinks/information_directory_absolute/info_1.txt").value();

      auto buffer = std::vector<std::byte>(6);
      auto bytes_read = kapi::filesystem::read(fd, buffer.data(), buffer.size());
      REQUIRE(bytes_read);

      std::string_view buffer_as_str{reinterpret_cast<char *>(buffer.data()), static_cast<size_t>(*bytes_read)};
      REQUIRE(buffer_as_str == "info_1");

      REQUIRE(kapi::filesystem::close(fd));
    }

    THEN("files can be opened through relative symbolic link, read and closed again")
    {
      auto fd = kapi::filesystem::open("/symlinks/information_directory_relative/info_1.txt").value();

      auto buffer = std::vector<std::byte>(6);
      auto bytes_read = kapi::filesystem::read(fd, buffer.data(), buffer.size());
      REQUIRE(bytes_read);

      std::string_view buffer_as_str{reinterpret_cast<char *>(buffer.data()), static_cast<size_t>(*bytes_read)};
      REQUIRE(buffer_as_str == "info_1");

      REQUIRE(kapi::filesystem::close(fd));
    }

    THEN("files can be opened through relative symbolic link over multiple mount points, read and closed again")
    {
      CHECK(kapi::filesystem::mount("/archiv/2024.img", "/information"));

      auto fd = kapi::filesystem::open("/information/symlinks/traverse_back_twice/information/sheep_1.txt").value();

      auto buffer = std::vector<std::byte>(7);
      auto bytes_read = kapi::filesystem::read(fd, buffer.data(), buffer.size());
      REQUIRE(bytes_read);

      std::string_view buffer_as_str{reinterpret_cast<char *>(buffer.data()), static_cast<size_t>(*bytes_read)};
      REQUIRE(buffer_as_str == "sheep_1");

      REQUIRE(kapi::filesystem::close(fd));
    }

    THEN("a filesystem can be mounted, files can be opened, read and closed again and unmounted")
    {
      REQUIRE(kapi::filesystem::mount("/dev/ram16", "/information"));

      auto fd = kapi::filesystem::open("/information/monkey_house/monkey_1.txt").value();

      auto buffer = std::vector<std::byte>(8);
      auto bytes_read = kapi::filesystem::read(fd, buffer.data(), buffer.size());
      REQUIRE(bytes_read);

      std::string_view buffer_as_str{reinterpret_cast<char *>(buffer.data()), static_cast<size_t>(*bytes_read)};
      REQUIRE(buffer_as_str == "monkey_1");

      REQUIRE(kapi::filesystem::close(fd));
      REQUIRE(kapi::filesystem::umount("/information"));
    }

    THEN("a filesystem cannot be unmounted if files are still open and can be unmounted after files are closed")
    {
      REQUIRE(kapi::filesystem::mount("/dev/ram16", "/information"));

      auto fd = kapi::filesystem::open("/information/monkey_house/monkey_1.txt").value();

      REQUIRE(!kapi::filesystem::umount("/information"));

      REQUIRE(kapi::filesystem::close(fd));
      REQUIRE(kapi::filesystem::umount("/information"));
    }

    THEN("device can be opened as file and read from")
    {
      auto fd = kapi::filesystem::open("/dev/ram0").value();

      auto buffer = std::vector<std::byte>(512);
      auto bytes_read = kapi::filesystem::read(fd, buffer.data(), buffer.size());
      REQUIRE(bytes_read);

      REQUIRE(kapi::filesystem::close(fd));
    }

    THEN("device can be opened as file and written to and read from again")
    {
      auto read_fd = kapi::filesystem::open("/dev/ram16").value();

      auto buffer = std::vector<std::byte>(512, std::byte{0xAB});
      auto bytes_written = kapi::filesystem::write(read_fd, buffer.data(), buffer.size());
      REQUIRE(bytes_written);

      auto write_fd = kapi::filesystem::open("/dev/ram16").value();

      auto read_buffer = std::vector<std::byte>(512);
      auto bytes_read = kapi::filesystem::read(write_fd, read_buffer.data(), read_buffer.size());
      REQUIRE(bytes_read);

      REQUIRE(std::equal(buffer.begin(), buffer.end(), read_buffer.begin()));

      REQUIRE(kapi::filesystem::close(write_fd));
      REQUIRE(kapi::filesystem::close(read_fd));
    }

    THEN("invalid paths cannot be mounted or unmounted")
    {
      REQUIRE(!kapi::filesystem::mount("/dev/ram16", "invalid_path"));
    }

    THEN("invalid paths cannot be unmounted")
    {
      REQUIRE(!kapi::filesystem::umount("invalid_path"));
    }

    THEN("non existent files cannot be opened")
    {
      auto fd = kapi::filesystem::open("/information/non_existent.txt");
      REQUIRE(!fd);
    }

    THEN("not opened files cannot closed")
    {
      REQUIRE(!kapi::filesystem::close(999));
    }

    THEN("same file cannot be closed twice")
    {
      auto fd = kapi::filesystem::open("/information/info_1.txt").value();

      REQUIRE(kapi::filesystem::close(fd));
      REQUIRE(!kapi::filesystem::close(fd));
    }

    THEN("not opened files cannot be read from")
    {
      std::vector<std::byte> buffer(10);
      auto const invalid_fd = 999uz;
      auto bytes_read = kapi::filesystem::read(invalid_fd, buffer.data(), buffer.size());
      REQUIRE(!bytes_read);
    }

    THEN("not opened files cannot be written to")
    {
      std::vector<std::byte> buffer(10);
      auto const invalid_fd = 999uz;
      auto bytes_written = kapi::filesystem::write(invalid_fd, buffer.data(), buffer.size());
      REQUIRE(!bytes_written);
    }

    THEN("a new file can be created, written to, read from, and closed again")
    {
      auto new_file_path = "/information/new_information.txt";

      REQUIRE(kapi::filesystem::open(new_file_path) < 0);

      REQUIRE(kapi::filesystem::create(new_file_path) == 0);

      auto fd = kapi::filesystem::open(new_file_path);
      REQUIRE(fd >= 0);

      auto write_buffer = std::vector<std::byte>{std::byte{'T'}, std::byte{'e'}, std::byte{'s'}, std::byte{'t'}};
      kapi::filesystem::write(fd, write_buffer.data(), write_buffer.size());

      REQUIRE(kapi::filesystem::close(fd) == 0);

      fd = kapi::filesystem::open(new_file_path);
      REQUIRE(fd >= 0);

      auto read_buffer = std::vector<std::byte>(4);
      auto bytes_read = kapi::filesystem::read(fd, read_buffer.data(), read_buffer.size());

      std::string_view buffer_as_str{reinterpret_cast<char *>(read_buffer.data()), static_cast<size_t>(bytes_read)};
      REQUIRE(buffer_as_str == "Test");

      REQUIRE(kapi::filesystem::close(fd) == 0);
    }

    THEN("a new directory can be created and a file within can be created, opened, and closed again")
    {
      auto new_directory_path = "/information/new_directory";
      auto new_file_path = "/information/new_directory/new_information.txt";

      REQUIRE(kapi::filesystem::open(new_file_path) < 0);

      REQUIRE(kapi::filesystem::mkdir(new_directory_path) == 0);
      REQUIRE(kapi::filesystem::create(new_file_path) == 0);

      auto fd = kapi::filesystem::open(new_file_path);
      REQUIRE(fd >= 0);
      REQUIRE(kapi::filesystem::close(fd) == 0);
    }

    THEN("a file can be created in a mounted filesystem, opened, and closed again")
    {
      kapi::filesystem::mount("/dev/ram16", "/information");

      auto new_file_path = "/information/monkey_house/monkey_4.txt";
      REQUIRE(kapi::filesystem::open(new_file_path) < 0);
      REQUIRE(kapi::filesystem::create(new_file_path) == 0);

      auto fd = kapi::filesystem::open(new_file_path);
      REQUIRE(fd >= 0);
      REQUIRE(kapi::filesystem::close(fd) == 0);

      REQUIRE(kapi::filesystem::umount("/information") == 0);
    }
  }
}