HellionChat/HellionChat/Ui/StyleEngine/Widgets/ChannelHeader.cs

using System.Numerics;
using Dalamud.Bindings.ImGui;
using Dalamud.Interface;
using Dalamud.Interface.ManagedFontAtlas;
using HellionChat.Util;

namespace HellionChat.Ui.StyleEngine.Widgets;

// The band above the conversation: which channel you are in on the left, where
// you are and what time it is on the right.
//
// Set apart by small caps with wide tracking rather than by size. That is a
// deliberate departure from the mockup, which asks for one pixel smaller than
// body text: one pixel would cost a whole additional font handle at full glyph
// range, because tab names are free user input and can be CJK. Tracking carries
// the same weight in every palette and costs nothing.
//
// Which face draws what is not a style choice here, it is a constraint. The meta
// face has a glyph range of ASCII plus a middle dot, so only the world name and
// the clock can use it. The tab name and the translated "no world" stand-in go
// through the body face, or they come out as rows of question marks.
internal static class ChannelHeader
{
    private const float InsetRaw = 14f;
    private const float PadYRaw = 7f;
    private const float TrackRaw = 1.8f;
    private const float DetailTrackRaw = 0.9f;
    private const float IconGapRaw = 8f;

    // Measured, never a fixed 32px: the band has to hold a line of text, and the
    // font comes from Config, which display scaling does not feed into.
    internal static float Height =>
        ImGui.GetTextLineHeight() + MathF.Round(PadYRaw * 2f * Metrics.Scale);

    // The body face follows the same switch every other push site follows. Two
    // settings decide it, and reading only one of them is how a window ends up
    // half in the game font and half in the bundled one.
    private static IFontHandle BodyFace(FontManager fonts) =>
        Plugin.Config.FontsEnabled || Plugin.Config.UseHellionFont
            ? fonts.RegularFont!
            : fonts.Axis;

    // Same switch for the meta face. With the game font selected there is no
    // stepped-down variant to fall back to, so the size distinction is simply
    // dropped -- the same honest limitation the sender weight has.
    private static IFontHandle MetaFace(FontManager fonts) =>
        Plugin.Config.FontsEnabled || Plugin.Config.UseHellionFont ? fonts.MetaFont! : fonts.Axis;

    internal static void Draw(
        Tab tab,
        ChannelHeaderMode mode,
        FontManager fonts,
        ChannelHeaderDetailParts detail,
        float reservedBelow
    )
    {
        var scale = Metrics.Scale;
        var width = ImGui.GetContentRegionAvail().X;
        var height = Height;
        var origin = ImGui.GetCursorScreenPos();

        var theme = Plugin.Instance.ThemeRegistry.Active;
        var surface = theme.Colors.Surface;

        var body = BodyFace(fonts);
        var meta = MetaFace(fonts);

        var icon = Components.Sidebar.ResolveTabIcon(tab);
        var track = TrackRaw * scale;
        var detailTrack = DetailTrackRaw * scale;
        // Screenshot mode hides the name of a tell tab, because that name IS the
        // conversation partner: AutoTellTabsService builds it as "Player@World".
        // Drawing it in tracked caps above a log whose messages are anonymised
        // would give away in the header exactly what the log is hiding.
        var namesAPartner = tab.TellTarget?.IsSet() == true;
        var showName =
            mode is ChannelHeaderMode.Full && !(Plugin.Config.ScreenshotMode && namesAPartner);

        // ToUpperInvariant allocates, so only where the name is actually drawn.
        var name = showName ? tab.Name.ToUpperInvariant() : string.Empty;

        Vector2 iconSize;
        using (fonts.FontAwesome.Push())
            iconSize = ImGui.CalcTextSize(icon.ToIconString());

        var nameRun = 0f;
        if (showName)
        {
            using (body.Push())
                nameRun = DrawListExtensions.MeasureTrackedText(name, track);
            nameRun += iconSize.X + IconGapRaw * scale;
        }

        // Measured under the face that will draw it, which is the whole point of
        // splitting the detail in two: the stand-in is translated and the meta
        // face cannot render most of those translations.
        float whereRun;
        using ((detail.WhereIsTranslated ? body : meta).Push())
            whereRun = DrawListExtensions.MeasureTrackedText(detail.Where, detailTrack);

        // No separator with nothing in front of it -- screenshot mode leaves the
        // clock standing alone.
        var rest =
            detail.Where.Length == 0
                ? detail.Clock
                : ChannelHeaderDetailParts.Separator + detail.Clock;

        float restRun;
        using (meta.Push())
            restRun = DrawListExtensions.MeasureTrackedText(rest, detailTrack);

        var detailRun = whereRun + restRun;
        var inset = InsetRaw * scale;

        var plan = ChannelHeaderLayout.Plan(
            showName ? ChannelHeaderMode.Full : ChannelHeaderMode.DetailOnly,
            width - inset * 2f,
            ImGui.GetContentRegionAvail().Y - height - reservedBelow,
            nameRun,
            detailRun,
            scale
        );

        if (!plan.ShowHeader)
            return;

        var dl = ImGui.GetWindowDrawList();
        var bottomRight = origin + new Vector2(width, height);
        dl.AddRectFilled(origin, bottomRight, ColourUtil.RgbaToAbgr(surface));
        dl.AddLine(
            new Vector2(origin.X, bottomRight.Y - 1f),
            new Vector2(bottomRight.X, bottomRight.Y - 1f),
            ColourUtil.RgbaToAbgr(theme.Colors.Border),
            MathF.Max(1f, scale)
        );

        var textY = origin.Y + MathF.Round(PadYRaw * scale);

        if (plan.ShowName)
        {
            var accent = ColourUtil.RgbaToAbgr(
                ColourUtil.EnsureContrast(theme.Colors.Accent, surface, 4.5f)
            );
            var x = origin.X + inset;

            // Centred against the band, not aligned to the text baseline:
            // FontAwesome is a fixed-width handle built at Dalamud's own size and
            // does not follow Config.FontSizeV2, so the text line height would
            // misplace it at any other body size. Same reasoning as the sidebar.
            using (fonts.FontAwesome.Push())
                dl.AddText(
                    new Vector2(x, origin.Y + MetricsMath.CenterY(height, iconSize.Y)),
                    accent,
                    icon.ToIconString()
                );

            x += iconSize.X + IconGapRaw * scale;

            using (body.Push())
                dl.DrawTrackedText(new Vector2(x, textY), name, accent, track);
        }

        if (plan.ShowDetail)
        {
            var muted = ColourUtil.RgbaToAbgr(
                ColourUtil.EnsureContrast(theme.Colors.TextMuted, surface, 4.5f)
            );

            var whereFace = detail.WhereIsTranslated ? body : meta;
            var x = bottomRight.X - inset - detailRun;

            using (whereFace.Push())
                dl.DrawTrackedText(
                    new Vector2(x, textY + DropFor(body, whereFace, scale)),
                    detail.Where,
                    muted,
                    detailTrack
                );

            x += whereRun;

            using (meta.Push())
                dl.DrawTrackedText(
                    new Vector2(x, textY + DropFor(body, meta, scale)),
                    rest,
                    muted,
                    detailTrack
                );
        }

        // ItemSize rather than a cursor move: it advances the cursor AND extends
        // CursorMaxPos, which is what the enclosing layout measures.
        ImGui.SetCursorScreenPos(origin);
        ImGuiP.ItemSize(new Vector2(width, height - ImGui.GetStyle().ItemSpacing.Y));
    }

    internal static ChannelHeaderDetailParts CurrentDetail()
    {
        // IsValid guards the row reference, but the case that actually happens is
        // subtler: logged out resolves to row zero, which exists and carries an
        // empty name. Format treats blank as missing, which covers both.
        var world = Plugin.PlayerState.HomeWorld.IsValid
            ? Plugin.PlayerState.HomeWorld.Value.Name.ExtractText()
            : null;

        return ChannelHeaderDetail.Format(
            world,
            DateTimeOffset.Now,
            Plugin.Config.Use24HourClock,
            Resources.HellionStrings.ChannelHeader_NotLoggedIn,
            Plugin.Config.ScreenshotMode
        );
    }

    // Zero whenever both runs use the same handle, which is the common case.
    private static float DropFor(IFontHandle body, IFontHandle other, float scale)
    {
        if (ReferenceEquals(body, other))
            return 0f;

        float bodyAscent;
        using (body.Push())
            bodyAscent = ImGui.GetFont().Ascent;

        float otherAscent;
        using (other.Push())
            otherAscent = ImGui.GetFont().Ascent;

        return BaselineMath.OffsetFor(bodyAscent, otherAscent, scale);
    }
}