using System.IO;
using AcDream.UI.Abstractions.Panels.Settings;

namespace AcDream.UI.Abstractions.Tests.Panels.Settings;

/// <summary>
/// L.0: <see cref="SettingsStore"/> reads / writes <c>settings.json</c>.
/// Tests use a temp-file path so they don't touch the user's
/// %LOCALAPPDATA% file.
/// </summary>
public sealed class SettingsStoreTests : System.IDisposable
{
    private readonly string _tempPath;

    public SettingsStoreTests()
    {
        // Unique per-test file under the system temp dir so parallel test
        // runners don't clobber each other.
        _tempPath = Path.Combine(
            Path.GetTempPath(),
            $"acdream-settings-test-{System.Guid.NewGuid():N}.json");
    }

    public void Dispose()
    {
        if (File.Exists(_tempPath)) File.Delete(_tempPath);
    }

    [Fact]
    public void LoadDisplay_returns_defaults_when_file_is_missing()
    {
        var store = new SettingsStore(_tempPath);
        var loaded = store.LoadDisplay();
        Assert.Equal(DisplaySettings.Default, loaded);
    }

    [Fact]
    public void SaveDisplay_then_LoadDisplay_round_trips_all_fields()
    {
        var store = new SettingsStore(_tempPath);
        var original = new DisplaySettings(
            Resolution: "2560x1440",
            Fullscreen: true,
            VSync: false,
            FieldOfView: 100f,
            Gamma: 1.4f,
            ShowFps: true);

        store.SaveDisplay(original);
        var loaded = store.LoadDisplay();

        Assert.Equal(original, loaded);
    }

    [Fact]
    public void LoadDisplay_falls_back_to_defaults_when_file_is_corrupt()
    {
        File.WriteAllText(_tempPath, "{ this is not valid json");
        var store = new SettingsStore(_tempPath);

        var loaded = store.LoadDisplay();

        Assert.Equal(DisplaySettings.Default, loaded);
    }

    [Fact]
    public void LoadDisplay_falls_back_per_field_when_keys_missing()
    {
        // Partial file — only resolution set; everything else should
        // pick up DisplaySettings.Default values.
        File.WriteAllText(_tempPath, """
            {
              "version": 1,
              "display": { "resolution": "1366x768" }
            }
            """);
        var store = new SettingsStore(_tempPath);

        var loaded = store.LoadDisplay();

        Assert.Equal("1366x768", loaded.Resolution);
        Assert.Equal(DisplaySettings.Default.Fullscreen, loaded.Fullscreen);
        Assert.Equal(DisplaySettings.Default.VSync, loaded.VSync);
        Assert.Equal(DisplaySettings.Default.FieldOfView, loaded.FieldOfView);
    }

    [Fact]
    public void SaveDisplay_preserves_unknown_top_level_keys()
    {
        // Forward-compat: a newer client may have written sections we
        // don't know about (audio, gameplay). Saving display must not
        // delete those, otherwise running an older client would silently
        // drop the user's other-tab preferences.
        File.WriteAllText(_tempPath, """
            {
              "version": 1,
              "display": { "resolution": "1280x720" },
              "audio": { "master": 0.5, "music": 0.7 }
            }
            """);
        var store = new SettingsStore(_tempPath);

        store.SaveDisplay(DisplaySettings.Default with { Resolution = "1920x1080" });

        var raw = File.ReadAllText(_tempPath);
        Assert.Contains("\"audio\"", raw);
        Assert.Contains("\"master\"", raw);
        Assert.Contains("0.5", raw);
        // And the new display value did get written.
        Assert.Contains("1920x1080", raw);
    }

    [Fact]
    public void DefaultPath_is_under_LocalAppData_acdream()
    {
        var path = SettingsStore.DefaultPath();
        Assert.EndsWith("acdream" + Path.DirectorySeparatorChar + "settings.json", path);
    }

    // -- Audio section round-trip ----------------------------------------

    [Fact]
    public void LoadAudio_returns_defaults_when_file_is_missing()
    {
        var store = new SettingsStore(_tempPath);
        Assert.Equal(AudioSettings.Default, store.LoadAudio());
    }

    [Fact]
    public void SaveAudio_then_LoadAudio_round_trips_all_fields()
    {
        var store = new SettingsStore(_tempPath);
        var original = new AudioSettings(Master: 0.3f, Music: 0.45f, Sfx: 0.9f, Ambient: 0.6f);

        store.SaveAudio(original);
        var loaded = store.LoadAudio();

        Assert.Equal(original, loaded);
    }

    [Fact]
    public void LoadAudio_falls_back_per_field_when_keys_missing()
    {
        File.WriteAllText(_tempPath, """
            {
              "version": 1,
              "audio": { "master": 0.25 }
            }
            """);
        var store = new SettingsStore(_tempPath);

        var loaded = store.LoadAudio();

        Assert.Equal(0.25f, loaded.Master);
        Assert.Equal(AudioSettings.Default.Music, loaded.Music);
        Assert.Equal(AudioSettings.Default.Sfx, loaded.Sfx);
        Assert.Equal(AudioSettings.Default.Ambient, loaded.Ambient);
    }

    [Fact]
    public void SaveAudio_preserves_display_section()
    {
        // Save display first, then audio — display values must survive.
        var store = new SettingsStore(_tempPath);
        store.SaveDisplay(DisplaySettings.Default with { Resolution = "2560x1440" });
        store.SaveAudio(AudioSettings.Default with { Master = 0.4f });

        Assert.Equal("2560x1440", store.LoadDisplay().Resolution);
        Assert.Equal(0.4f, store.LoadAudio().Master);
    }

    [Fact]
    public void SaveDisplay_after_SaveAudio_preserves_audio_section()
    {
        // Reverse order — audio must survive a subsequent display save.
        var store = new SettingsStore(_tempPath);
        store.SaveAudio(AudioSettings.Default with { Music = 0.1f });
        store.SaveDisplay(DisplaySettings.Default with { ShowFps = true });

        Assert.Equal(0.1f, store.LoadAudio().Music);
        Assert.True(store.LoadDisplay().ShowFps);
    }

    // -- Gameplay section round-trip --------------------------------------

    [Fact]
    public void LoadGameplay_returns_defaults_when_file_is_missing()
    {
        var store = new SettingsStore(_tempPath);
        Assert.Equal(GameplaySettings.Default, store.LoadGameplay());
    }

    [Fact]
    public void SaveGameplay_then_LoadGameplay_round_trips_all_fields()
    {
        var store = new SettingsStore(_tempPath);
        var original = GameplaySettings.Default with
        {
            AutoTarget = false,
            AdvancedCombatUI = true,
            ShowHelm = false,
            LockUI = true,
            UseMouseTurning = true,
        };

        store.SaveGameplay(original);
        var loaded = store.LoadGameplay();

        Assert.Equal(original, loaded);
    }

    [Fact]
    public void LoadGameplay_falls_back_per_field_when_keys_missing()
    {
        File.WriteAllText(_tempPath, """
            {
              "version": 1,
              "gameplay": { "lockUI": true }
            }
            """);
        var store = new SettingsStore(_tempPath);

        var loaded = store.LoadGameplay();

        Assert.True(loaded.LockUI);
        Assert.Equal(GameplaySettings.Default.AutoTarget, loaded.AutoTarget);
        Assert.Equal(GameplaySettings.Default.ShowHelm, loaded.ShowHelm);
    }

    [Fact]
    public void All_three_sections_coexist_in_one_settings_json()
    {
        var store = new SettingsStore(_tempPath);
        store.SaveDisplay(DisplaySettings.Default with { Resolution = "2560x1440" });
        store.SaveAudio(AudioSettings.Default with { Master = 0.5f });
        store.SaveGameplay(GameplaySettings.Default with { LockUI = true });

        // All three load correctly from the same file.
        Assert.Equal("2560x1440", store.LoadDisplay().Resolution);
        Assert.Equal(0.5f, store.LoadAudio().Master);
        Assert.True(store.LoadGameplay().LockUI);
    }
}