using YKanBan.Storage.AppData;
using YKanBan.Tests.TestUtilities;

namespace YKanBan.Tests.Storage.AppData;

/// <summary>
/// Tests for app.json round-tripping, kebab-case naming and graceful
/// degradation on a missing or corrupt file.
/// </summary>
[TestClass]
public class AppConfigStoreTests {
    [TestMethod]
    public void LoadMissingFileReturnsDefaults() {
        using var directory = new TempDirectory();
        var store = new AppConfigStore(Path.Combine(directory.FullPath, "app.json"));

        AppConfig config = store.Load();

        Assert.AreEqual(AppConfig.CurrentFormatVersion, config.Version);
        Assert.AreEqual(AppConfig.DefaultLanguage, config.Language);
        Assert.AreEqual(ThemeOption.FollowSystem, config.Theme);
        Assert.AreEqual(SortOption.IdAscending, config.Display.CardSort);
        Assert.AreEqual(SortOption.IdAscending, config.Display.ColumnSort);
        Assert.AreEqual(ColumnWidthPreset.Standard, config.Display.ColumnWidth.Preset);
        Assert.AreEqual(320, config.Display.ColumnWidth.CustomPixels);
        Assert.IsTrue(config.Confirmations.DeleteCard);
        Assert.IsTrue(config.Confirmations.DeleteColumn);
        Assert.IsTrue(config.Confirmations.DeleteTag);
        Assert.IsTrue(config.Confirmations.DiscardEdit);
    }

    [TestMethod]
    public void LoadCorruptFileBacksUpAndReturnsDefaults() {
        using var directory = new TempDirectory();
        string path = Path.Combine(directory.FullPath, "app.json");
        File.WriteAllText(path, "{ this is not valid json");
        var store = new AppConfigStore(path);

        AppConfig config = store.Load();

        Assert.AreEqual(AppConfig.CurrentFormatVersion, config.Version);
        Assert.IsTrue(File.Exists(path + ".bak"));
        Assert.AreEqual("{ this is not valid json", File.ReadAllText(path + ".bak"));
    }

    [TestMethod]
    public void LoadJsonNullReturnsDefaults() {
        using var directory = new TempDirectory();
        string path = Path.Combine(directory.FullPath, "app.json");
        File.WriteAllText(path, "null");
        var store = new AppConfigStore(path);

        Assert.AreEqual(AppConfig.CurrentFormatVersion, store.Load().Version);
    }

    [TestMethod]
    public void LoadNumericEnumValueIsRejectedAndBackedUp() {
        using var directory = new TempDirectory();
        string path = Path.Combine(directory.FullPath, "app.json");

        // Integer enum values are not accepted; the file is treated like corrupt.
        File.WriteAllText(path, """{ "theme": 1 }""");
        var store = new AppConfigStore(path);

        AppConfig config = store.Load();

        Assert.AreEqual(ThemeOption.FollowSystem, config.Theme);
        Assert.IsTrue(File.Exists(path + ".bak"));
    }

    [TestMethod]
    public void LoadUnreadableFileReturnsDefaults() {
        // File sharing is only reliably enforced on Windows, so this branch is exercised there.
        if (!OperatingSystem.IsWindows()) {
            return;
        }

        using var directory = new TempDirectory();
        string path = Path.Combine(directory.FullPath, "app.json");
        File.WriteAllText(path, """{ "version": 1 }""");

        // Hold the file exclusively so the store's read fails with an I/O error.
        using FileStream hold = File.Open(path, FileMode.Open, FileAccess.Read, FileShare.None);
        var store = new AppConfigStore(path);

        Assert.AreEqual(AppConfig.CurrentFormatVersion, store.Load().Version);
    }

    [TestMethod]
    public void LoadReadsKebabCaseKeysAndEnumValues() {
        using var directory = new TempDirectory();
        string path = Path.Combine(directory.FullPath, "app.json");
        File.WriteAllText(path, $$"""
            {
              "version": {{AppConfig.CurrentFormatVersion}},
              "language": "zh-Hans",
              "theme": "dark",
              "display": {
                "column-width": { "preset": "custom", "custom-pixels": 400 },
                "card-sort": "title-asc",
                "column-sort": "id-desc"
              },
              "confirmations": {
                "delete-card": false,
                "delete-column": false,
                "delete-tag": false,
                "discard-edit": false
              }
            }
            """);
        var store = new AppConfigStore(path);

        AppConfig config = store.Load();

        Assert.AreEqual("zh-Hans", config.Language);
        Assert.AreEqual(ThemeOption.Dark, config.Theme);
        Assert.AreEqual(SortOption.TitleAscending, config.Display.CardSort);
        Assert.AreEqual(SortOption.IdDescending, config.Display.ColumnSort);
        Assert.AreEqual(ColumnWidthPreset.Custom, config.Display.ColumnWidth.Preset);
        Assert.AreEqual(400, config.Display.ColumnWidth.CustomPixels);
        Assert.IsFalse(config.Confirmations.DeleteCard);
        Assert.IsFalse(config.Confirmations.DeleteColumn);
        Assert.IsFalse(config.Confirmations.DeleteTag);
        Assert.IsFalse(config.Confirmations.DiscardEdit);
    }

    [TestMethod]
    public void LoadMissingSectionsFillsDefaults() {
        using var directory = new TempDirectory();
        string path = Path.Combine(directory.FullPath, "app.json");
        File.WriteAllText(path, $$"""{ "version": {{AppConfig.CurrentFormatVersion}} }""");
        var store = new AppConfigStore(path);

        AppConfig config = store.Load();

        Assert.IsNotNull(config.Display);
        Assert.IsNotNull(config.Display.ColumnWidth);
        Assert.IsNotNull(config.Confirmations);
        Assert.AreEqual(ColumnWidthPreset.Standard, config.Display.ColumnWidth.Preset);
    }

    [TestMethod]
    public void SaveWritesKebabCaseKeysAndEnumValues() {
        using var directory = new TempDirectory();
        string path = Path.Combine(directory.FullPath, "app.json");
        var store = new AppConfigStore(path);

        var config = new AppConfig {
            Theme = ThemeOption.FollowSystem,
            Display = new DisplaySettings {
                CardSort = SortOption.UpdatedDescending,
                ColumnSort = SortOption.CreatedAscending,
                ColumnWidth = new ColumnWidthSettings { Preset = ColumnWidthPreset.Custom, CustomPixels = 500 },
            },
            Confirmations = new ConfirmationSettings { DeleteColumn = false },
        };
        store.Save(config);

        string json = File.ReadAllText(path);
        StringAssert.Contains(json, "\"delete-column\"");
        StringAssert.Contains(json, "\"discard-edit\"");
        StringAssert.Contains(json, "\"card-sort\"");
        StringAssert.Contains(json, "\"column-sort\"");
        StringAssert.Contains(json, "\"custom-pixels\"");
        StringAssert.Contains(json, "\"follow-system\"");
        StringAssert.Contains(json, "\"updated-desc\"");
        StringAssert.Contains(json, "\"created-asc\"");
        // No member-name CamelCase must leak into the file.
        Assert.IsFalse(json.Contains("deleteColumn", StringComparison.Ordinal));
        Assert.IsFalse(json.Contains("CustomPixels", StringComparison.Ordinal));
    }

    [TestMethod]
    public void SaveThenLoadRoundTrips() {
        using var directory = new TempDirectory();
        string path = Path.Combine(directory.FullPath, "app.json");
        var store = new AppConfigStore(path);

        var config = new AppConfig {
            Language = "zh-Hans",
            Theme = ThemeOption.Light,
            Display = new DisplaySettings {
                CardSort = SortOption.CreatedDescending,
                ColumnSort = SortOption.TitleAscending,
                ColumnWidth = new ColumnWidthSettings { Preset = ColumnWidthPreset.Wide },
            },
            Confirmations = new ConfirmationSettings { DiscardEdit = false },
        };
        store.Save(config);

        AppConfig reloaded = store.Load();
        Assert.AreEqual(config.Language, reloaded.Language);
        Assert.AreEqual(config.Theme, reloaded.Theme);
        Assert.AreEqual(config.Display.CardSort, reloaded.Display.CardSort);
        Assert.AreEqual(config.Display.ColumnSort, reloaded.Display.ColumnSort);
        Assert.AreEqual(config.Display.ColumnWidth.Preset, reloaded.Display.ColumnWidth.Preset);
        Assert.AreEqual(config.Confirmations.DiscardEdit, reloaded.Confirmations.DiscardEdit);
    }
}