using AcDream.Core.Chat;
using AcDream.UI.Abstractions.Panels.Chat;

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

/// <summary>
/// Phase K.2 — Tab fires <see cref="AcDream.UI.Abstractions.Input.InputAction.ToggleChatEntry"/>,
/// which calls <see cref="ChatPanel.FocusInput"/>. The chat panel honors
/// the request on the very next <see cref="ChatPanel.Render"/> by emitting
/// a <c>SetKeyboardFocusHere</c> immediately before the input field. After
/// it fires once, subsequent renders without another <c>FocusInput</c>
/// call must not re-fire (one-shot semantics) — otherwise the chat field
/// would steal focus on every frame and the user could never click out.
/// </summary>
public sealed class ChatPanelFocusTests
{
    private sealed class NullBus : AcDream.UI.Abstractions.ICommandBus
    {
        public void Publish<T>(T command) where T : notnull { }
    }

    [Fact]
    public void FocusInput_NextRender_EmitsSetKeyboardFocusHereBeforeInput()
    {
        var panel = new ChatPanel(new ChatVM(new ChatLog()));
        var renderer = new FakePanelRenderer();

        panel.FocusInput();
        panel.Render(new PanelContext(0.016f, new NullBus()), renderer);

        // Find the SetKeyboardFocusHere call; it must come before the
        // InputTextSubmit call so ImGui applies the focus to that widget.
        int focusIdx = -1, inputIdx = -1;
        for (int i = 0; i < renderer.Calls.Count; i++)
        {
            if (renderer.Calls[i].Method == "SetKeyboardFocusHere") focusIdx = i;
            else if (renderer.Calls[i].Method == "InputTextSubmit")  inputIdx = i;
        }
        Assert.True(focusIdx >= 0, "ChatPanel must call SetKeyboardFocusHere when FocusInput requested.");
        Assert.True(inputIdx >= 0, "ChatPanel must still render the InputTextSubmit field.");
        Assert.True(focusIdx < inputIdx, "SetKeyboardFocusHere must precede the InputTextSubmit it targets.");
    }

    [Fact]
    public void Render_WithoutFocusInputCall_DoesNotEmitSetKeyboardFocusHere()
    {
        var panel = new ChatPanel(new ChatVM(new ChatLog()));
        var renderer = new FakePanelRenderer();

        panel.Render(new PanelContext(0.016f, new NullBus()), renderer);

        Assert.DoesNotContain(renderer.Calls, c => c.Method == "SetKeyboardFocusHere");
    }

    [Fact]
    public void FocusInput_OnlyAffectsTheNextRender_OneShot()
    {
        var panel = new ChatPanel(new ChatVM(new ChatLog()));

        // Frame 1 — FocusInput requested → expect a SetKeyboardFocusHere.
        var r1 = new FakePanelRenderer();
        panel.FocusInput();
        panel.Render(new PanelContext(0.016f, new NullBus()), r1);
        Assert.Contains(r1.Calls, c => c.Method == "SetKeyboardFocusHere");

        // Frame 2 — no further FocusInput call → must NOT re-fire.
        var r2 = new FakePanelRenderer();
        panel.Render(new PanelContext(0.016f, new NullBus()), r2);
        Assert.DoesNotContain(r2.Calls, c => c.Method == "SetKeyboardFocusHere");
    }
}