using Xunit;

namespace MrGameEng.Mods.Tests;

public sealed class LanguageManagerTests : IDisposable
{
    private readonly string _root = Directory.CreateTempSubdirectory("mrge-lang-tests-").FullName;
    private int _modCounter;

    public void Dispose() => Directory.Delete(_root, recursive: true);

    private Mod WriteLanguageMod(string code, string fileName, string json)
    {
        var id = $"mod{_modCounter++:D2}";
        var modDir = Path.Combine(_root, id);
        var languageDir = Path.Combine(modDir, "Languages", code);
        Directory.CreateDirectory(languageDir);
        File.WriteAllText(Path.Combine(languageDir, fileName), json);
        return new Mod(new ModInfo { Id = id }, modDir);
    }

    [Fact]
    public void Get_UsesCurrentLanguage_FallsBackToDefault_ThenKey()
    {
        var mod = WriteLanguageMod(
            "en",
            "ui.json",
            """{ "hud.title": "Title", "hud.only-en": "English only" }"""
        );
        var ruDir = Path.Combine(mod.RootPath, "Languages", "ru");
        Directory.CreateDirectory(ruDir);
        File.WriteAllText(Path.Combine(ruDir, "ui.json"), """{ "hud.title": "Заголовок" }""");

        var languages = new LanguageManager(defaultLanguage: "en");
        languages.Load([mod]);

        Assert.True(languages.SetLanguage("ru"));
        Assert.Equal("Заголовок", languages.Get("hud.title"));
        Assert.Equal("English only", languages.Get("hud.only-en")); // fallback на en
        Assert.Equal("hud.missing", languages.Get("hud.missing")); // ключ виден, не краш
    }

    [Fact]
    public void Load_LaterMod_OverridesKey()
    {
        var core = WriteLanguageMod(
            "en",
            "ui.json",
            """{ "hud.title": "Core", "hud.other": "Other" }"""
        );
        var patch = WriteLanguageMod("en", "ui.json", """{ "hud.title": "Patched" }""");

        var languages = new LanguageManager();
        languages.Load([core, patch]);

        Assert.Equal("Patched", languages.Get("hud.title"));
        Assert.Equal("Other", languages.Get("hud.other"));
    }

    [Fact]
    public void SetLanguage_UnknownCode_ReturnsFalse_AndKeepsCurrent()
    {
        var languages = new LanguageManager();
        languages.Load([WriteLanguageMod("en", "ui.json", """{ "k": "v" }""")]);

        Assert.False(languages.SetLanguage("fr"));
        Assert.Equal("en", languages.CurrentLanguage);
        Assert.Equal(["en"], languages.AvailableLanguages);
    }

    [Fact]
    public void Format_SubstitutesArguments()
    {
        var languages = new LanguageManager();
        languages.Load([WriteLanguageMod("en", "ui.json", """{ "hud.pop": "population {0}" }""")]);

        Assert.Equal("population 80", languages.Format("hud.pop", 80));
    }

    [Fact]
    public void Load_NonStringValue_Throws()
    {
        var mod = WriteLanguageMod("en", "ui.json", """{ "bad": { "nested": true } }""");

        var languages = new LanguageManager();
        Assert.Throws<InvalidDataException>(() => languages.Load([mod]));
    }

    [Fact]
    public void Revision_Bumps_OnLoadAndLanguageSwitch()
    {
        var languages = new LanguageManager();
        var before = languages.Revision;
        languages.Load([WriteLanguageMod("ru", "ui.json", """{ "k": "v" }""")]);
        Assert.NotEqual(before, languages.Revision);

        before = languages.Revision;
        languages.SetLanguage("ru");
        Assert.NotEqual(before, languages.Revision);
    }
}