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

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

/// <summary>
/// Phase J Tier 3: <see cref="ChatPanel.Render"/> must reserve footer
/// space for the separator + input field so the input stays anchored
/// at the bottom across window resizes (the user reported the input
/// disappearing when the window shrank). The pattern is the standard
/// ImGui chat-window layout: a scrollable child filling
/// <c>(0, -footerHeight)</c>, then the separator + input below it.
/// </summary>
public sealed class ChatPanelLayoutTests
{
    private sealed class NoBus : ICommandBus
    {
        public void Publish<T>(T command) where T : notnull { /* no-op */ }
    }

    [Fact]
    public void Render_OrderIs_Begin_BeginChild_EndChild_Separator_InputTextSubmit_End()
    {
        var log = new ChatLog();
        log.OnSystemMessage("seed", chatType: 0);
        var vm  = new ChatVM(log);
        var panel = new ChatPanel(vm);
        var renderer = new FakePanelRenderer();

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

        var methods = renderer.Calls.Select(c => c.Method).ToList();
        int beginIdx        = methods.IndexOf("Begin");
        int beginChildIdx   = methods.IndexOf("BeginChild");
        int endChildIdx     = methods.IndexOf("EndChild");
        // L.0 follow-up: Copy-mode toggle adds a Separator above the
        // chat tail, so multiple Separators now exist. The footer
        // separator (the one we care about for input layout) is the
        // LAST one — between EndChild and the input field.
        int separatorIdx    = methods.LastIndexOf("Separator");
        int inputSubmitIdx  = methods.IndexOf("InputTextSubmit");
        int endIdx          = methods.IndexOf("End");

        // All present
        Assert.True(beginIdx       >= 0, "Begin missing");
        Assert.True(beginChildIdx  >= 0, "BeginChild missing");
        Assert.True(endChildIdx    >= 0, "EndChild missing");
        Assert.True(separatorIdx   >= 0, "Separator missing");
        Assert.True(inputSubmitIdx >= 0, "InputTextSubmit missing");
        Assert.True(endIdx         >= 0, "End missing");

        // Order: Begin < BeginChild < EndChild < Separator < InputTextSubmit < End
        Assert.True(beginIdx       < beginChildIdx);
        Assert.True(beginChildIdx  < endChildIdx);
        Assert.True(endChildIdx    < separatorIdx);
        Assert.True(separatorIdx   < inputSubmitIdx);
        Assert.True(inputSubmitIdx < endIdx);
    }

    [Fact]
    public void Render_BeginChild_ReservesNegativeFooterFromFrameHeight()
    {
        var log = new ChatLog();
        var vm  = new ChatVM(log);
        var panel = new ChatPanel(vm);
        var renderer = new FakePanelRenderer { FrameHeightWithSpacingValue = 24f };

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

        var beginChildCall = renderer.Calls.Single(c => c.Method == "BeginChild");
        var size = (System.Numerics.Vector2)beginChildCall.Args[1]!;
        // Width 0 = fill available; height < 0 = "fill minus this".
        // Reserved height should equal FrameHeightWithSpacing + a small
        // separator pad (~6f) so the input never visually clips the
        // last chat line.
        Assert.Equal(0f, size.X);
        Assert.True(size.Y < 0, $"expected negative reserve, got {size.Y}");
        Assert.True(size.Y <= -24f, $"expected at least -24f reserve, got {size.Y}");
    }

    [Fact]
    public void Render_NewEntries_ScrollsToBottom()
    {
        // First render establishes the baseline (no auto-scroll because
        // _lastRenderedCount == lines.Count == 0). Then a second render
        // after a new entry should fire SetScrollHereY(1.0f).
        var log = new ChatLog();
        var vm  = new ChatVM(log);
        var panel = new ChatPanel(vm);
        var renderer = new FakePanelRenderer();
        var ctx = new PanelContext(0.016f, new NoBus());

        panel.Render(ctx, renderer);
        Assert.DoesNotContain(renderer.Calls, c => c.Method == "SetScrollHereY");

        // Append a new entry, render again — auto-scroll should fire.
        log.OnLocalSpeech("Caith", "hello", senderGuid: 0xAA, isRanged: false);
        renderer.Calls.Clear();
        panel.Render(ctx, renderer);

        var scrollCall = renderer.Calls.Single(c => c.Method == "SetScrollHereY");
        Assert.Equal(1.0f, (float)scrollCall.Args[0]!);
    }

    [Fact]
    public void Render_NoNewEntries_DoesNotForceScroll()
    {
        var log = new ChatLog();
        log.OnSystemMessage("seed", chatType: 0);
        var vm  = new ChatVM(log);
        var panel = new ChatPanel(vm);
        var renderer = new FakePanelRenderer();
        var ctx = new PanelContext(0.016f, new NoBus());

        // First render establishes count baseline (1 entry). The first
        // render auto-scrolls because lines.Count (1) > _lastRenderedCount
        // (0). Subsequent renders without new entries should NOT scroll.
        panel.Render(ctx, renderer);
        renderer.Calls.Clear();
        panel.Render(ctx, renderer);

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