#include "kernel/filesystem/vfs.hpp"

#include "kernel/filesystem/open_file_description.hpp"
#include "kernel/test_support/filesystem/storage_boot_module_vfs_fixture.hpp"

#include <kstd/memory>
#include <kstd/vector>

#include <catch2/catch_test_macros.hpp>

#include <cstddef>
#include <filesystem>
#include <string_view>

SCENARIO_METHOD(kernel::tests::filesystem::storage_boot_module_vfs_fixture, "VFS with dummy modules",
                "[filesystem][vfs]")
{
  GIVEN("an initialized boot module registry with multiple modules")
  {
    REQUIRE_NOTHROW(setup_modules_and_init_vfs(5));

    THEN("vfs initializes and provides /dev mount")
    {
      auto & vfs = kernel::filesystem::vfs::get();
      auto dev = vfs.open("/dev");

      REQUIRE(dev != nullptr);
    }

    THEN("vfs initializes root filesystem with boot device if boot module is present")
    {
      auto & vfs = kernel::filesystem::vfs::get();
      auto root_file = vfs.open("/");

      REQUIRE(root_file != nullptr);
    }
  }
}

SCENARIO_METHOD(kernel::tests::filesystem::storage_boot_module_vfs_fixture, "VFS with file backed image",
                "[filesystem][vfs][img]")
{
  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";
  auto const image_path_3 = std::filesystem::path{KERNEL_TEST_ASSETS_DIR} / "ext2_4KB_fs.img";

  GIVEN("a real image file")
  {
    REQUIRE(std::filesystem::exists(image_path_1));
    REQUIRE_NOTHROW(setup_modules_from_img_and_init_vfs({"test_img_module"}, {image_path_1}));

    THEN("vfs initializes and provides expected mount points")
    {
      auto & vfs = kernel::filesystem::vfs::get();
      auto root = vfs.open("/");
      auto dev = vfs.open("/dev");
      auto information = vfs.open("/information/info_1.txt");

      REQUIRE(root != nullptr);
      REQUIRE(dev != nullptr);
      REQUIRE(information != nullptr);
    }
  }

  GIVEN("three real image files")
  {
    REQUIRE(std::filesystem::exists(image_path_1));
    REQUIRE(std::filesystem::exists(image_path_2));
    REQUIRE(std::filesystem::exists(image_path_3));
    REQUIRE_NOTHROW(setup_modules_from_img_and_init_vfs({"test_img_module_1", "test_img_module_2", "test_img_module_3"},
                                                        {image_path_1, image_path_2, image_path_3}));

    auto & vfs = kernel::filesystem::vfs::get();

    THEN("vfs initializes first module as root")
    {
      auto & vfs = kernel::filesystem::vfs::get();
      auto info1 = vfs.open("/information/info_1.txt");
      auto info2 = vfs.open("/information/info_2.txt");

      REQUIRE(info1 != nullptr);
      REQUIRE(info2 != nullptr);
    }

    THEN("second image can be mounted, data retrieved and unmounted again")
    {
      REQUIRE(vfs.do_mount("/dev/ram16", "/information") == kernel::filesystem::vfs::operation_result::success);

      auto mounted_monkey_1 = vfs.open("/information/monkey_house/monkey_1.txt");
      REQUIRE(mounted_monkey_1 != nullptr);

      REQUIRE(vfs.unmount("/information") == kernel::filesystem::vfs::operation_result::success);
      auto unmounted_monkey_1 = vfs.open("/information/monkey_house/monkey_1.txt");
      REQUIRE(unmounted_monkey_1 == nullptr);

      auto info_1 = vfs.open("/information/info_1.txt");
      REQUIRE(info_1 != nullptr);
    }

    THEN("third image can be mounted in a mounted file system, unmount only if no child mount exists")
    {
      REQUIRE(vfs.do_mount("/dev/ram16", "/information") == kernel::filesystem::vfs::operation_result::success);
      REQUIRE(vfs.do_mount("/dev/ram32", "/information/monkey_house/infrastructure") ==
              kernel::filesystem::vfs::operation_result::success);

      auto mounted_monkey_1 = vfs.open("/information/monkey_house/monkey_1.txt");
      auto mounted_fish1 = vfs.open("/information/monkey_house/infrastructure/enclosures/aquarium/tank_1/fish_1.txt");

      REQUIRE(mounted_monkey_1 != nullptr);
      REQUIRE(mounted_fish1 != nullptr);

      REQUIRE(vfs.unmount("/information") == kernel::filesystem::vfs::operation_result::unmount_failed);
      REQUIRE(vfs.unmount("/information/monkey_house/infrastructure") ==
              kernel::filesystem::vfs::operation_result::success);
      REQUIRE(vfs.unmount("/information") == kernel::filesystem::vfs::operation_result::success);
    }

    THEN("images can be stacked mounted and correct file system is unmounted again")
    {
      REQUIRE(vfs.do_mount("/dev/ram16", "/information") == kernel::filesystem::vfs::operation_result::success);
      REQUIRE(vfs.do_mount("/dev/ram32", "/information") == kernel::filesystem::vfs::operation_result::success);

      auto mounted_tickets = vfs.open("/information/entrance/tickets.txt");
      REQUIRE(mounted_tickets != nullptr);

      REQUIRE(vfs.unmount("/information") == kernel::filesystem::vfs::operation_result::success);
      mounted_tickets = vfs.open("/information/entrance/tickets.txt");
      REQUIRE(mounted_tickets == nullptr);

      auto mounted_monkey = vfs.open("/information/monkey_house/monkey_1.txt");
      REQUIRE(mounted_monkey != nullptr);
    }

    THEN("mount with null file system fails")
    {
      REQUIRE(vfs.do_mount("/closed.txt", "/information") ==
              kernel::filesystem::vfs::operation_result::invalid_filesystem);
    }

    THEN("mount with invalid path fails")
    {
      REQUIRE(vfs.do_mount("/dev/ram16", "") == kernel::filesystem::vfs::operation_result::invalid_path);
      REQUIRE(vfs.do_mount("/dev/ram16", "information") == kernel::filesystem::vfs::operation_result::invalid_path);
      REQUIRE(vfs.do_mount("/dev/ram16", "/information/") == kernel::filesystem::vfs::operation_result::invalid_path);
    }

    THEN("mount with non-existent source path fails")
    {
      REQUIRE(vfs.do_mount("/dev/nonexistent", "/information") ==
              kernel::filesystem::vfs::operation_result::non_existent_path);
    }

    THEN("mount with non-existent mount point fails")
    {
      REQUIRE(vfs.do_mount("/dev/ram16", "/information/nonexistent") ==
              kernel::filesystem::vfs::operation_result::mount_point_not_found);
    }

    THEN("unmount with invalid path fails")
    {
      REQUIRE(vfs.unmount("") == kernel::filesystem::vfs::operation_result::invalid_path);
      REQUIRE(vfs.unmount("information") == kernel::filesystem::vfs::operation_result::invalid_path);
      REQUIRE(vfs.unmount("/information/") == kernel::filesystem::vfs::operation_result::invalid_path);
    }

    THEN("unmounting non-existent mount point returns expected error code")
    {
      REQUIRE(vfs.unmount("/information/nonexistent") ==
              kernel::filesystem::vfs::operation_result::mount_point_not_found);
    }
  }

  GIVEN("A real image file containing as filesystem formatted files")
  {
    REQUIRE(std::filesystem::exists(image_path_1));
    REQUIRE_NOTHROW(setup_modules_from_img_and_init_vfs({"test_img_module_1"}, {image_path_1}));

    THEN("the file-filesystem in the image can be mounted, files can be read and unmounted again")
    {
      auto & vfs = kernel::filesystem::vfs::get();
      REQUIRE(vfs.do_mount("/archiv/2024.img", "/information") == kernel::filesystem::vfs::operation_result::success);

      auto info_1 = vfs.open("/information/info_1.txt");
      REQUIRE(info_1 == nullptr);

      auto dentry = vfs.open("/information/sheep_1.txt");
      REQUIRE(dentry != nullptr);
      auto sheep_1_ofd = kstd::make_shared<kernel::filesystem::open_file_description>(dentry->get_inode());

      kstd::vector<std::byte> buffer(7);
      auto bytes_read = sheep_1_ofd->read(buffer.data(), buffer.size());
      std::string_view buffer_as_str{reinterpret_cast<char *>(buffer.data()), bytes_read};
      REQUIRE(buffer_as_str == "sheep_1");

      REQUIRE(vfs.unmount("/information") == kernel::filesystem::vfs::operation_result::success);
      auto unmounted_sheep_1 = vfs.open("/information/sheep_1.txt");
      REQUIRE(unmounted_sheep_1 == nullptr);
    }

    THEN("the file-filesystem in the image can be mounted and in this filesystem can another file-filesystem be "
         "mounted, files can be read and unmounted again")
    {
      auto & vfs = kernel::filesystem::vfs::get();
      REQUIRE(vfs.do_mount("/archiv/2024.img", "/information") == kernel::filesystem::vfs::operation_result::success);
      REQUIRE(vfs.do_mount("/archiv/2025.img", "/information/stable") ==
              kernel::filesystem::vfs::operation_result::success);

      auto sheep_1 = vfs.open("/information/sheep_1.txt");
      auto goat_1 = vfs.open("/information/stable/petting_zoo/goat_1.txt");
      REQUIRE(sheep_1 != nullptr);
      REQUIRE(goat_1 != nullptr);

      auto sheep_1_ofd = kstd::make_shared<kernel::filesystem::open_file_description>(sheep_1->get_inode());
      auto goat_1_ofd = kstd::make_shared<kernel::filesystem::open_file_description>(goat_1->get_inode());

      kstd::vector<std::byte> sheep_buffer(7);
      auto bytes_read = sheep_1_ofd->read(sheep_buffer.data(), sheep_buffer.size());
      std::string_view buffer_as_str{reinterpret_cast<char *>(sheep_buffer.data()), bytes_read};
      REQUIRE(buffer_as_str == "sheep_1");

      kstd::vector<std::byte> goat_buffer(6);
      bytes_read = goat_1_ofd->read(goat_buffer.data(), goat_buffer.size());
      buffer_as_str = std::string_view{reinterpret_cast<char *>(goat_buffer.data()), bytes_read};
      REQUIRE(buffer_as_str == "goat_1");

      REQUIRE(vfs.unmount("/information") == kernel::filesystem::vfs::operation_result::unmount_failed);

      REQUIRE(vfs.unmount("/information/stable") == kernel::filesystem::vfs::operation_result::success);
      auto unmounted_goat_1 = vfs.open("/information/stable/petting_zoo/goat_1.txt");
      REQUIRE(unmounted_goat_1 == nullptr);

      auto still_mounted_sheep_1 = vfs.open("/information/sheep_1.txt");
      REQUIRE(still_mounted_sheep_1 != nullptr);

      REQUIRE(vfs.unmount("/information") == kernel::filesystem::vfs::operation_result::success);
      auto unmounted_sheep_1 = vfs.open("/information/sheep_1.txt");
      REQUIRE(unmounted_sheep_1 == nullptr);
    }
  }
}