#include "kernel/filesystem/ext2/filesystem.hpp"

#include "kernel/devices/storage/management.hpp"
#include "kernel/filesystem/ext2/inode.hpp"
#include "kernel/filesystem/filesystem.hpp"
#include "kernel/test_support/devices/block_device.hpp"
#include "kernel/test_support/filesystem/ext2.hpp"
#include "kernel/test_support/filesystem/storage_boot_module_fixture.hpp"

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

#include <catch2/catch_test_macros.hpp>

#include <array>
#include <cstdint>
#include <filesystem>

SCENARIO_METHOD(kernel::tests::filesystem::storage_boot_module_fixture,
                "Ext2 filesystem mount and lookup with real image", "[filesystem][ext2][filesystem][img]")
{
  auto const image_path = std::filesystem::path{KERNEL_TEST_ASSETS_DIR} / "ext2_1KB_fs.img";

  GIVEN("a mounted ext2 filesystem from a real image")
  {
    REQUIRE(std::filesystem::exists(image_path));
    REQUIRE_NOTHROW(setup_modules_from_img({"test_img_module"}, {image_path}));

    auto boot_device = kernel::devices::storage::management::get().determine_boot_device();
    REQUIRE(boot_device != nullptr);

    auto fs = kernel::filesystem::ext2::filesystem{};
    REQUIRE(fs.mount(boot_device) == kernel::filesystem::filesystem::operation_result::success);

    THEN("the root inode is available and is a directory")
    {
      REQUIRE(fs.root_inode() != nullptr);
      REQUIRE(fs.root_inode()->is_directory());
    }

    THEN("lookup resolves known entries from the image")
    {
      auto information = fs.lookup(fs.root_inode(), "information");
      REQUIRE(information != nullptr);
      REQUIRE(information->is_directory());

      auto info_1 = fs.lookup(information, "info_1.txt");
      REQUIRE(info_1 != nullptr);
      REQUIRE(info_1->is_regular());
    }

    THEN("lookup returns null for invalid inputs")
    {
      REQUIRE(fs.lookup(nullptr, "information") == nullptr);

      auto information = fs.lookup(fs.root_inode(), "information");
      REQUIRE(information != nullptr);
      auto info_1 = fs.lookup(information, "info_1.txt");
      REQUIRE(info_1 != nullptr);

      REQUIRE(fs.lookup(info_1, "anything") == nullptr);
      REQUIRE(fs.lookup(fs.root_inode(), "does_not_exist") == nullptr);
    }
  }
}

SCENARIO("Ext2 filesystem rejects invalid magic", "[filesystem][ext2][filesystem]")
{
  auto const block_size = 1024;
  GIVEN("a block device that does not contain an ext2 superblock")
  {
    auto device = kstd::make_shared<kernel::tests::devices::block_device>(0, 0, "mock", block_size, 2 * block_size);
    REQUIRE(device != nullptr);

    auto fs = kernel::filesystem::ext2::filesystem{};

    THEN("mount fails with invalid_magic_number")
    {
      REQUIRE(fs.mount(device) == kernel::filesystem::filesystem::operation_result::invalid_magic_number);
    }
  }
}

SCENARIO("Ext2 block mapping includes direct and all indirect levels", "[filesystem][ext2][filesystem]")
{
  auto const block_size = 1024;

  GIVEN("a minimally valid ext2 layout with configured indirect block tables")
  {
    auto device = kstd::make_shared<kernel::tests::devices::block_device>(0, 0, "mock", block_size, 128 * block_size);
    REQUIRE(device != nullptr);

    kernel::tests::filesystem::ext2::setup_mock_ext2_layout(*device);

    auto fs = kernel::filesystem::ext2::filesystem{};
    REQUIRE(fs.mount(device) == kernel::filesystem::filesystem::operation_result::success);

    auto inode_data = kernel::filesystem::ext2::inode_data{};
    inode_data.block[0] = 7;

    inode_data.block[12] = 30;
    kernel::tests::filesystem::ext2::write_u32(*device, 30 * block_size, 31);

    inode_data.block[13] = 40;
    kernel::tests::filesystem::ext2::write_u32(*device, 40 * block_size, 41);
    kernel::tests::filesystem::ext2::write_u32(*device, 41 * block_size, 42);

    inode_data.block[14] = 50;
    kernel::tests::filesystem::ext2::write_u32(*device, 50 * block_size, 51);
    kernel::tests::filesystem::ext2::write_u32(*device, 51 * block_size, 52);
    kernel::tests::filesystem::ext2::write_u32(*device, 52 * block_size, 53);

    auto const numbers_per_block = static_cast<uint32_t>(block_size / sizeof(uint32_t));
    auto const singly_start = static_cast<uint32_t>(kernel::filesystem::ext2::constants::direct_block_count);
    auto const doubly_start = singly_start + numbers_per_block;
    auto const triply_start = doubly_start + numbers_per_block * numbers_per_block;

    THEN("mapping resolves direct, singly, doubly and triply indirect indexes")
    {
      REQUIRE(fs.map_inode_block_index_to_global_block_number(0, inode_data) == 7);
      REQUIRE(fs.map_inode_block_index_to_global_block_number(singly_start, inode_data) == 31);
      REQUIRE(fs.map_inode_block_index_to_global_block_number(doubly_start, inode_data) == 42);
      REQUIRE(fs.map_inode_block_index_to_global_block_number(triply_start, inode_data) == 53);
    }

    THEN("mapping returns zero for out-of-range indexes")
    {
      auto const beyond_triply = triply_start + numbers_per_block * numbers_per_block * numbers_per_block;
      REQUIRE(fs.map_inode_block_index_to_global_block_number(beyond_triply, inode_data) == 0);
    }
  }
}