HellionChat/HellionChat/Ui/Components/MessageList.cs

using System.Globalization;
using System.Numerics;
using Dalamud.Bindings.ImGui;
using Dalamud.Interface.Utility.Raii;
using HellionChat.Util;

namespace HellionChat.Ui.Components;

// Virtualised message list. Compact mode reuses ImGuiListClipper because
// rows have a constant line height; card mode falls back to a linear
// render with a per-message height cache and an IsItemVisible skip path
// so off-screen rows place a Dummy of the cached height rather than
// running the full render again.
internal sealed class MessageList
{
    private const float CompactRowHeight = 18f;

    private readonly FontManager _fonts;
    private readonly ChunkRenderer _chunkRenderer;

    private PayloadHandler? _handler;

    // §6.2: setter-injection breaks the PayloadHandler → MainWindow → MessageList → PayloadHandler 3-cycle.
    // Wired by PayloadHandlerInitHostedService.StartAsync after both singletons exist.
    internal void AttachPayloadHandler(PayloadHandler handler)
    {
        _handler = handler;
    }

    public MessageList(FontManager fonts, ChunkRenderer chunkRenderer)
    {
        _fonts = fonts;
        _chunkRenderer = chunkRenderer;
    }

    public void Draw(Tab tab)
    {
        if (!_fonts.FontsReady)
        {
            ImGui.TextUnformatted("Loading fonts…");
            return;
        }

        // No own ImRaii.Child here — MainWindow already wraps the message
        // area in one. Nesting would give the window two stacked scrolls
        // and a runaway content-height computation.
        using var messages = tab.Messages.GetReadOnly(3);
        var compact = Plugin.Config.UseCompactDensity;

        // Track whether the user was pinned to the bottom before this frame
        // so newly arriving rows do not yank them up. The check runs against
        // the parent child's scroll state, which is the one MainWindow owns.
        var pinnedToBottom = ImGui.GetScrollY() >= ImGui.GetScrollMaxY() - 1f;

        if (compact)
            DrawCompact(messages);
        else
            DrawCard(tab, messages);

        if (pinnedToBottom)
            ImGui.SetScrollHereY(1f);

        // OpenPopup in Click() and BeginPopup here share the ##hellion-main-area scope -> Popup-ID matches.
        _handler?.Draw();
    }

    private void DrawCompact(IReadOnlyList<Message> messages)
    {
        unsafe
        {
            var clipper = new ImGuiListClipperPtr(ImGuiNative.ImGuiListClipper());
            try
            {
                clipper.Begin(messages.Count, CompactRowHeight);
                while (clipper.Step())
                {
                    for (var i = clipper.DisplayStart; i < clipper.DisplayEnd; i++)
                        DrawCompactRow(messages[i]);
                }
                clipper.End();
            }
            finally
            {
                clipper.Destroy();
            }
        }
    }

    private void DrawCompactRow(Message message)
    {
        // B2-1/B2-2: render the sender through DrawChunks (the name-aware path
        // that applies WorldSuffixMode/NameFormMode via ForDisplay), not as a
        // flat SenderSource.TextValue string. message.Sender already carries the
        // channel brackets/colon as ChunkSource.None wrappers (MessageManager
        // .cs:300-314), so the separator is rendered by the chunks. 1.5.6 parity
        // (ChatLogWindow.cs:1965: DrawChunks(message.Sender) + SameLine).
        var timestamp = FormatTimestamp(message.Date);
        if (message.Sender.Count > 0)
        {
            ImGui.TextUnformatted($"{timestamp}  ");
            ImGui.SameLine(0f, 0f);
            _chunkRenderer.DrawChunks(message.Sender, wrap: true, handler: _handler, lineWidth: 0f);
            ImGui.SameLine(0f, 0f);
        }
        else
        {
            ImGui.TextUnformatted(timestamp);
            ImGui.SameLine(0f, 0f);
        }
        _chunkRenderer.DrawChunks(message.Content, wrap: true, handler: _handler, lineWidth: 0f);
    }

    private void DrawCard(Tab tab, IReadOnlyList<Message> messages)
    {
        var tabId = tab.Identifier;
        for (var i = 0; i < messages.Count; i++)
        {
            var msg = messages[i];

            // Cached row: place a Dummy of the known height and skip the
            // full render path if the row is off-screen. Mirrors the
            // v1.5.6 Card-Mode pattern in ChatLogWindow.DrawMessages.
            msg.Height.TryGetValue(tabId, out var cachedHeight);
            if (cachedHeight is float h)
            {
                var beforeDummy = ImGui.GetCursorPos();
                ImGui.Dummy(new Vector2(10f, h));
                var visible = ImGui.IsItemVisible();
                msg.IsVisible[tabId] = visible;
                if (!visible)
                    continue;
                ImGui.SetCursorPos(beforeDummy);
            }

            var before = ImGui.GetCursorPosY();
            DrawCardRow(msg);
            var after = ImGui.GetCursorPosY();
            msg.Height[tabId] = after - before;
        }
    }

    private void DrawCardRow(Message message)
    {
        // B2-1/B2-2: sender via DrawChunks (name-aware path), on its own line
        // with content below — 1.5.6 card parity (ChatLogWindow.cs:1913, no
        // SameLine after the sender). The 1.5.6 channel-colour push on the
        // sender is deferred styling polish (masterplan §6 -> v1.9.0); plain
        // text here.
        var timestamp = FormatTimestamp(message.Date);
        if (message.Sender.Count > 0)
        {
            ImGui.TextUnformatted($"{timestamp}  ");
            ImGui.SameLine(0f, 0f);
            _chunkRenderer.DrawChunks(message.Sender, wrap: true, handler: _handler, lineWidth: 0f);
        }
        else
        {
            ImGui.TextUnformatted(timestamp);
        }
        _chunkRenderer.DrawChunks(message.Content, wrap: true, handler: _handler, lineWidth: 0f);
    }

    private static string FormatTimestamp(DateTimeOffset date)
    {
        var local = date.ToLocalTime();
        return Plugin.Config.Use24HourClock
            ? local.ToString("HH:mm", CultureInfo.InvariantCulture)
            : local.ToString("h:mm tt", CultureInfo.InvariantCulture);
    }
}