using System.Numerics;
using Dalamud.Bindings.ImGui;
using Dalamud.Interface;
using HellionChat.Integrations;
using HellionChat.Themes;
using HellionChat.Ui.StyleEngine;
using HellionChat.Util;

namespace HellionChat.Ui.Components;

// 30px header row pinned to the top of the main chat window. Crown stays
// rendered as a brand anchor even when the Honorific IPC drops out; the
// bracketed title only appears when there is actually a title to show.
internal sealed class HonorificHeader
{
    // Scaled: MainWindow reserves body height against this, so it follows.
    public static float Height => StyleEngine.Metrics.HonorificHeight;

    // SelfTest observables — set on the real Draw path so a headless step can
    // assert the gate/colour/truncation outcome instead of re-implementing it.
    internal bool LastTitleRendered { get; private set; }
    internal uint LastTitleColorAbgr { get; private set; }
    internal string? LastRenderedTitle { get; private set; }

    private readonly HonorificService _honorific;
    private readonly FontManager _fonts;
    private readonly ThemeRegistry _themes;
    private readonly TokenResolver _resolver;

    public HonorificHeader(
        HonorificService honorific,
        FontManager fonts,
        ThemeRegistry themes,
        TokenResolver resolver
    )
    {
        _honorific = honorific;
        _fonts = fonts;
        _themes = themes;
        _resolver = resolver;
    }

    // Same singleton the AboutTab integrations section uses; lets a SelfTest
    // drive the gate branches via HonorificService.TestOnly_SetState.
    internal HonorificService GetServiceForSelfTest() => _honorific;

    public void Draw(float maxWidth)
    {
        LastTitleRendered = false;
        LastRenderedTitle = null;

        // First-frame guard: components must not lay out before the atlas
        // is finished or text metrics collapse into placeholder widths.
        if (!_fonts.FontsReady)
        {
            ImGui.TextUnformatted("Loading fonts…");
            return;
        }

        var theme = _themes.Active;
        var origin = ImGui.GetCursorScreenPos();
        var dl = ImGui.GetWindowDrawList();

        var crownColor = ColourUtil.RgbaToAbgr(
            _resolver.Resolve(Token.HonorificCrown, theme.Colors)
        );
        var crownGlyph = FontAwesomeIcon.Crown.ToIconString();
        float crownWidth;
        using (_fonts.FontAwesome.Push())
        {
            crownWidth = ImGui.CalcTextSize(crownGlyph).X;
            dl.AddText(
                origin + new Vector2(0f, StyleEngine.Metrics.CenterY(Height)),
                crownColor,
                crownGlyph
            );
        }

        // Gate the bracketed title through the 1.5.6 contract (toggle, IPC
        // availability, IsOriginal, empty-title) — the crown above stays
        // unconditional as the permanent brand anchor. NOTE divergence from
        // 1.5.6: there a failed gate hid the whole slot incl. crown; here the
        // crown persists by design.
        if (
            HonorificService.ShouldRenderSlot(
                Plugin.Config.ShowHonorificTitleInHeader,
                _honorific.IsAvailable,
                _honorific.CurrentTitle
            )
        )
        {
            var current = _honorific.CurrentTitle!;
            var titleColor = HonorificTitleColor.ResolveTitleAbgr(current.Color, theme);
            LastTitleColorAbgr = titleColor;

            // Budget the title against the row width. CalcTextSize inside
            // TruncateToFitWidth measures the *Regular* font, so this must run
            // OUTSIDE the FontAwesome.Push block above (crownWidth was measured
            // inside it, which is correct).
            var gap = StyleEngine.Metrics.HonorificBracketGap;
            var maxTitleWidth = maxWidth - crownWidth - gap - StyleEngine.Metrics.HonorificInset;
            if (maxTitleWidth > 0f)
            {
                var rendered = StringUtil.TruncateToFitWidth($"«{current.Title}»", maxTitleWidth);
                LastRenderedTitle = rendered;
                dl.AddText(
                    origin + new Vector2(crownWidth + gap, StyleEngine.Metrics.CenterY(Height)),
                    titleColor,
                    rendered
                );
                LastTitleRendered = true;
            }
        }

        // Reserve the row height even when no title rendered so the layout
        // below stays stable across IPC reconnect cycles.
        ImGui.Dummy(new Vector2(maxWidth, Height));
    }
}