using System.Text;
using MrGameEng.Core;
using Xunit;

namespace MrGameEng.DevConsole.Tests;

public class DevConsoleTests
{
    private static string Visible(DevConsole console, int lines = 50)
    {
        var sb = new StringBuilder();
        console.BuildVisibleText(sb, lines);
        return sb.ToString();
    }

    [Fact]
    public void Execute_RunsRegisteredCommand_WithArguments()
    {
        using var console = new DevConsole();
        string[]? received = null;
        console.Register("test", "test command", (_, args) => received = args);

        console.Execute("test one two");

        Assert.NotNull(received);
        Assert.Equal(["one", "two"], received!);
        Assert.Contains("> test one two", Visible(console));
    }

    [Fact]
    public void Execute_UnknownCommand_ReportsWithoutThrowing()
    {
        using var console = new DevConsole();

        console.Execute("nosuchcommand");

        Assert.Contains("unknown command 'nosuchcommand'", Visible(console));
    }

    [Fact]
    public void Execute_HandlerException_IsCaughtAndLogged()
    {
        using var console = new DevConsole();
        console.Register("boom", "throws", (_, _) => throw new InvalidOperationException("kaboom"));

        console.Execute("boom");

        Assert.Contains("[err] kaboom", Visible(console));
    }

    [Fact]
    public void RingBuffer_OverflowDropsOldestLines()
    {
        using var console = new DevConsole(capacity: 4);

        for (var i = 0; i < 10; i++)
        {
            console.WriteLine($"line{i}");
        }

        var visible = Visible(console);
        Assert.DoesNotContain("line5", visible);
        Assert.Contains("line6", visible);
        Assert.Contains("line9", visible);
    }

    [Fact]
    public void BuildVisibleText_RespectsWindowAndScroll()
    {
        using var console = new DevConsole();
        for (var i = 0; i < 10; i++)
        {
            console.WriteLine($"line{i}");
        }

        var sb = new StringBuilder();
        console.BuildVisibleText(sb, 3);
        Assert.Equal("line7\nline8\nline9", sb.ToString());

        console.Scroll(+2);
        console.BuildVisibleText(sb, 3);
        Assert.StartsWith("line5\nline6\nline7", sb.ToString());
    }

    [Fact]
    public void History_NavigatesUpAndDown()
    {
        using var console = new DevConsole();
        console.Register("a", "", (_, _) => { });
        console.Execute("a 1");
        console.Execute("a 2");

        Assert.Equal("a 2", console.HistoryPrevious());
        Assert.Equal("a 1", console.HistoryPrevious());
        Assert.Equal("a 1", console.HistoryPrevious()); // упёрлись в начало
        Assert.Equal("a 2", console.HistoryNext());
        Assert.Equal("", console.HistoryNext());        // за последним — пустая строка
    }

    [Fact]
    public void Complete_SingleMatch_CompletesWithTrailingSpace()
    {
        using var console = new DevConsole();

        Assert.Equal("echo ", console.Complete("ec"));
    }

    [Fact]
    public void Complete_MultipleMatches_ReturnsCommonPrefix_AndListsOptions()
    {
        using var console = new DevConsole();
        console.Register("spawn", "", (_, _) => { });
        console.Register("spawnall", "", (_, _) => { });

        var completed = console.Complete("sp");

        Assert.Equal("spawn", completed);
        Assert.Contains("spawn  spawnall", Visible(console));
    }

    [Fact]
    public void LogMessages_AreCaptured_WithLevelTags()
    {
        using var console = new DevConsole();

        Log.Info("plain info");
        Log.Warning("careful");

        var visible = Visible(console);
        Assert.Contains("plain info", visible);
        Assert.Contains("[warn] careful", visible);
    }

    [Fact]
    public void Revision_ChangesOnlyOnVisibleChanges()
    {
        using var console = new DevConsole();
        var before = console.Revision;

        console.WriteLine("x");
        Assert.NotEqual(before, console.Revision);

        before = console.Revision;
        _ = Visible(console); // чтение не меняет ревизию
        Assert.Equal(before, console.Revision);
    }
}