using System.Globalization;
using CursorLang.Core.Models;

namespace CursorLang.Core.Tests.Models;

public sealed class KeyboardLayoutTests
{
    [Theory]
    [InlineData(0x0409, "EN")]
    [InlineData(0x0419, "RU")]
    [InlineData(0x040C, "FR")]
    [InlineData(0x0407, "DE")]
    public void The_short_name_comes_from_the_language_code(int localeId, string expected)
    {
        KeyboardLayout layout = KeyboardLayout.FromLocaleId(localeId);

        Assert.Equal(expected, layout.ShortName);
        Assert.Equal(localeId, layout.LocaleId);
    }

    [Fact]
    public void The_full_name_joins_the_short_name_and_the_native_language_name()
    {
        KeyboardLayout layout = KeyboardLayout.FromLocaleId(0x0419);

        Assert.Equal($"RU — {new CultureInfo(0x0419).NativeName}", layout.DisplayName);
    }

    // A layout may belong to a language the system does not know — that is not an error
    [Fact]
    public void An_unknown_locale_is_shown_by_its_own_code()
    {
        int unknown = FindUnknownLocaleId();

        KeyboardLayout layout = KeyboardLayout.FromLocaleId(unknown);

        string expected = $"0x{unknown:X4}";
        Assert.Equal(expected, layout.ShortName);
        Assert.Equal(expected, layout.DisplayName);
    }

    [Fact]
    public void Layouts_of_the_same_locale_are_equal()
    {
        Assert.Equal(KeyboardLayout.FromLocaleId(0x0409), KeyboardLayout.FromLocaleId(0x0409));
        Assert.NotEqual(KeyboardLayout.FromLocaleId(0x0409), KeyboardLayout.FromLocaleId(0x0419));
    }

    [Fact]
    public void A_layout_can_also_be_built_directly()
    {
        var layout = new KeyboardLayout(1, "XX", "XX — language");

        Assert.Equal(1, layout.LocaleId);
        Assert.Equal("XX", layout.ShortName);
        Assert.Equal("XX — language", layout.DisplayName);
    }

    // An identifier with no culture behind it in Windows
    private static int FindUnknownLocaleId()
    {
        for (int candidate = 0x1000; candidate <= 0xFFFF; candidate++)
        {
            try
            {
                _ = new CultureInfo(candidate);
            }
            catch (CultureNotFoundException)
            {
                return candidate;
            }
        }

        throw new InvalidOperationException("The system knows every locale identifier");
    }
}