#include <kernel/filesystem/mount_table.hpp>

#include <kernel/filesystem/dentry.hpp>
#include <kernel/filesystem/mount.hpp>
#include <kernel/test_support/filesystem/filesystem.hpp>
#include <kernel/test_support/filesystem/inode.hpp>

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

#include <catch2/catch_test_macros.hpp>

#include <string_view>

SCENARIO("Mount table construction", "[filesystem][mount_table]")
{
  GIVEN("an empty mount table")
  {
    kernel::filesystem::mount_table table;

    THEN("removing any mount returns mount_not_found")
    {
      REQUIRE(table.remove_mount("/") == kernel::filesystem::mount_table::operation_result::mount_not_found);
      REQUIRE(table.remove_mount("/any/path") == kernel::filesystem::mount_table::operation_result::mount_not_found);
    }
  }
}

SCENARIO("Adding, finding and removing mounts in the mount table", "[filesystem][mount_table]")
{
  GIVEN("a mount table and some mounts")
  {
    kernel::filesystem::mount_table table;

    auto fs1 = kstd::make_shared<kernel::tests::filesystem::filesystem>();
    auto root_dentry1 = kstd::make_shared<kernel::filesystem::dentry>(
        nullptr, kstd::make_shared<kernel::tests::filesystem::inode>(), "/");
    auto mount_dentry1 = kstd::make_shared<kernel::filesystem::dentry>(
        nullptr, kstd::make_shared<kernel::tests::filesystem::inode>(), "/");
    auto mount1 = kstd::make_shared<kernel::filesystem::mount>(mount_dentry1, root_dentry1, fs1, nullptr);

    auto fs2 = kstd::make_shared<kernel::tests::filesystem::filesystem>();
    auto root_dentry2 = kstd::make_shared<kernel::filesystem::dentry>(
        nullptr, kstd::make_shared<kernel::tests::filesystem::inode>(), "/");
    auto mount_dentry2 = kstd::make_shared<kernel::filesystem::dentry>(
        nullptr, kstd::make_shared<kernel::tests::filesystem::inode>(), "/mnt");
    auto mount2 = kstd::make_shared<kernel::filesystem::mount>(mount_dentry2, root_dentry2, fs2, nullptr);

    table.add_mount(mount1);
    table.add_mount(mount2);

    THEN("dentry flags are set correctly for mounted dentries")
    {
      REQUIRE(mount_dentry1->has_flag(kernel::filesystem::dentry::dentry_flags::is_mount_point));
      REQUIRE(mount_dentry2->has_flag(kernel::filesystem::dentry::dentry_flags::is_mount_point));
    }

    THEN("finding mounts by exact valid path returns the correct mount")
    {
      REQUIRE(table.find_mount("/") == mount1);
      REQUIRE(table.find_mount("/mnt") == mount2);
    }

    THEN("finding mounts by exact invalid path returns null")
    {
      REQUIRE(table.find_mount("/nonexistent") == nullptr);
      REQUIRE(table.find_mount("/mnt/file") == nullptr);
    }

    THEN("removing a mount that has no child mounts succeeds")
    {
      REQUIRE(table.remove_mount("/mnt") == kernel::filesystem::mount_table::operation_result::removed);
      REQUIRE_FALSE(root_dentry2->has_flag(kernel::filesystem::dentry::dentry_flags::is_mount_point));
    }

    THEN("removing a mount that does not exist returns mount_not_found")
    {
      REQUIRE(table.remove_mount("/nonexistent") == kernel::filesystem::mount_table::operation_result::mount_not_found);
    }
  }

  GIVEN("multiple mounts with the same path")
  {
    kernel::filesystem::mount_table table;

    auto fs1 = kstd::make_shared<kernel::tests::filesystem::filesystem>();
    auto root_dentry1 = kstd::make_shared<kernel::filesystem::dentry>(
        nullptr, kstd::make_shared<kernel::tests::filesystem::inode>(), "/");
    auto mount_dentry1 = kstd::make_shared<kernel::filesystem::dentry>(
        nullptr, kstd::make_shared<kernel::tests::filesystem::inode>(), "/");
    auto mount1 = kstd::make_shared<kernel::filesystem::mount>(mount_dentry1, root_dentry1, fs1, nullptr);

    auto fs2 = kstd::make_shared<kernel::tests::filesystem::filesystem>();
    auto root_dentry2 = kstd::make_shared<kernel::filesystem::dentry>(
        nullptr, kstd::make_shared<kernel::tests::filesystem::inode>(), "/");
    auto mount_dentry2 = kstd::make_shared<kernel::filesystem::dentry>(
        nullptr, kstd::make_shared<kernel::tests::filesystem::inode>(), "/");
    auto mount2 = kstd::make_shared<kernel::filesystem::mount>(mount_dentry2, root_dentry2, fs2, nullptr);

    table.add_mount(mount1);
    table.add_mount(mount2);

    THEN("finding mounts by exact valid path returns the correct mount")
    {
      REQUIRE(table.find_mount("/") == mount2);
    }

    THEN("removing the topmost mount with the same path succeeds")
    {
      REQUIRE(table.remove_mount("/") == kernel::filesystem::mount_table::operation_result::removed);
      REQUIRE_FALSE(root_dentry2->has_flag(kernel::filesystem::dentry::dentry_flags::is_mount_point));
    }
  }

  GIVEN("a mount with child mounts")
  {
    kernel::filesystem::mount_table table;

    auto fs1 = kstd::make_shared<kernel::tests::filesystem::filesystem>();
    auto root_dentry1 = kstd::make_shared<kernel::filesystem::dentry>(
        nullptr, kstd::make_shared<kernel::tests::filesystem::inode>(), "/");
    auto mount_dentry1 = kstd::make_shared<kernel::filesystem::dentry>(
        nullptr, kstd::make_shared<kernel::tests::filesystem::inode>(), "/");
    auto mount1 = kstd::make_shared<kernel::filesystem::mount>(mount_dentry1, root_dentry1, fs1, nullptr);

    auto fs2 = kstd::make_shared<kernel::tests::filesystem::filesystem>();
    auto root_dentry2 = kstd::make_shared<kernel::filesystem::dentry>(
        nullptr, kstd::make_shared<kernel::tests::filesystem::inode>(), "/");
    auto mount_dentry2 = kstd::make_shared<kernel::filesystem::dentry>(
        mount_dentry1, kstd::make_shared<kernel::tests::filesystem::inode>(), "mnt");
    auto mount2 = kstd::make_shared<kernel::filesystem::mount>(mount_dentry2, root_dentry2, fs2, mount1);

    auto fs3 = kstd::make_shared<kernel::tests::filesystem::filesystem>();
    auto root_dentry3 = kstd::make_shared<kernel::filesystem::dentry>(
        nullptr, kstd::make_shared<kernel::tests::filesystem::inode>(), "/");
    auto mount_dentry3 = kstd::make_shared<kernel::filesystem::dentry>(
        mount_dentry2, kstd::make_shared<kernel::tests::filesystem::inode>(), "submnt");
    auto mount3 = kstd::make_shared<kernel::filesystem::mount>(mount_dentry3, root_dentry3, fs3, mount2);

    table.add_mount(mount1);
    table.add_mount(mount2);
    table.add_mount(mount3);

    THEN("removing a mount with child mounts returns has_child_mounts")
    {
      REQUIRE(table.remove_mount("/") == kernel::filesystem::mount_table::operation_result::has_child_mounts);
      REQUIRE(table.remove_mount("/mnt") == kernel::filesystem::mount_table::operation_result::has_child_mounts);
    }

    THEN("removing a leaf mount succeeds")
    {
      REQUIRE(table.remove_mount("/mnt/submnt") == kernel::filesystem::mount_table::operation_result::removed);
      REQUIRE_FALSE(root_dentry3->has_flag(kernel::filesystem::dentry::dentry_flags::is_mount_point));
    }
  }
}