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

#include "kernel/devices/storage/management.hpp"
#include "kernel/filesystem/ext2/filesystem.hpp"
#include "kernel/filesystem/filesystem.hpp"
#include "kernel/test_support/cpu.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 <cstddef>
#include <filesystem>
#include <string_view>

SCENARIO("Ext2 inode initialization and properties", "[filesystem][ext2][inode]")
{
  GIVEN("an ext2 filesystem")
  {
    auto fs = kernel::filesystem::ext2::filesystem{};

    THEN("the inode is initialized and has the kind regular")
    {
      auto inode = kernel::filesystem::ext2::inode{&fs};
      REQUIRE(inode.is_regular());
      REQUIRE(!inode.is_directory());
      REQUIRE(!inode.is_device());
    }
  }

  GIVEN("no filesystem (null pointer)")
  {
    THEN("constructing an inode with a null filesystem pointer panics")
    {
      REQUIRE_THROWS_AS(kernel::filesystem::ext2::inode{nullptr}, kernel::tests::cpu::halt);
    }
  }
}

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

  GIVEN("a mounted ext2 filesystem and a regular file inode")
  {
    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);

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

    THEN("reading from offset zero returns expected file prefix")
    {
      auto buffer = kstd::vector<std::byte>(6);
      auto const bytes_read = file->read(buffer.data(), 0, buffer.size());

      REQUIRE(bytes_read == 6);

      auto const text = std::string_view{reinterpret_cast<char const *>(buffer.data()), bytes_read};
      REQUIRE(text == "info_1");
    }

    THEN("reading with an offset returns the expected byte")
    {
      auto buffer = kstd::vector<std::byte>(1);
      auto const bytes_read = file->read(buffer.data(), 5, buffer.size());

      REQUIRE(bytes_read == 1);
      REQUIRE(static_cast<char>(buffer[0]) == '1');
    }
  }
}

SCENARIO("Ext2 inode read stops when block mapping resolves to zero", "[filesystem][ext2][inode]")
{
  auto const block_size = 1024;
  GIVEN("an ext2 inode without mapped data blocks")
  {
    auto device = kstd::make_shared<kernel::tests::devices::block_device>(0, 0, "mock", block_size, 64 * 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 = kernel::filesystem::ext2::inode{&fs};
    inode.m_data.blocks = 2;
    inode.m_data.block[0] = 0;

    auto buffer = kstd::vector<std::byte>(32, std::byte{0xAB});

    THEN("no bytes are read")
    {
      auto const bytes_read = inode.read(buffer.data(), 0, buffer.size());
      REQUIRE(bytes_read == 0);
    }
  }
}

SCENARIO("Ext2 inode read across block boundaries", "[filesystem][ext2][inode]")
{
  auto const block_size = 1024;
  GIVEN("an ext2 inode with two direct blocks and a block size of 1024 bytes")
  {
    auto device = kstd::make_shared<kernel::tests::devices::block_device>(0, 0, "mock", block_size, 64 * 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 = kernel::filesystem::ext2::inode{&fs};
    inode.m_data.blocks = 2;
    inode.m_data.block[0] = 20;
    kernel::tests::filesystem::ext2::write_bytes(*device, 21 * block_size - 6, "Hello ", 6);
    inode.m_data.block[1] = 21;
    kernel::tests::filesystem::ext2::write_bytes(*device, 21 * block_size, "World!", 6);

    auto buffer = kstd::vector<std::byte>(12, std::byte{0x00});

    THEN("reading across the block boundary returns the combined content")
    {
      auto const bytes_read = inode.read(buffer.data(), block_size - 6, buffer.size());
      REQUIRE(bytes_read == 12);

      auto const text = std::string_view{reinterpret_cast<char const *>(buffer.data()), bytes_read};
      REQUIRE(text == "Hello World!");
    }
  }
}

SCENARIO("Ext2 inode write is not implemented", "[filesystem][ext2][inode]")
{
  GIVEN("an ext2 inode")
  {
    auto fs = kernel::filesystem::ext2::filesystem{};
    auto inode = kernel::filesystem::ext2::inode{&fs};

    THEN("writing to the inode panics")
    {
      auto buffer = kstd::vector<std::byte>(32, std::byte{0x00});
      REQUIRE_THROWS_AS(inode.write(buffer.data(), 0, buffer.size()), kernel::tests::cpu::halt);
    }
  }
}