using System.Collections.Generic;
using System.Linq;

namespace ytLive.Models;

/// <summary>Keeps exactly one Scoreboard layer in EVERY scene.
///
/// <para>Creator ruling (2026-10-30): "YT_ACTIVITY_TICKER … is available to all scenes." The
/// scoreboard is not something to add five times — it exists once per scene like the Background and
/// the Brand logo, and a creator turns it off per scene with the ordinary eye toggle. Removing it is
/// therefore not a delete: it heals on the next load.</para>
///
/// <para>Pure over a scene collection, so the rule is testable without a view-model.</para></summary>
public static class ScoreboardHealer
{
    public const string LayerName = "Scoreboard";

    /// <summary>The strip's default box: full width, a strip's height, and its Y for the bottom
    /// edge. Geometry only — the EDGE itself is resolved against the social bar at render time.</summary>
    public const double StripHeight = 56;
    public const double BottomY = 1080 - StripHeight;

    /// <summary>Ensures one scoreboard per scene, appended as the TOPMOST layer: it is a full-width
    /// strip drawn over the scene, and inserting it above the background would break the Brand
    /// logo's documented invariant ("directly above the background"). Returns true when anything
    /// changed, so the caller can save.</summary>
    public static bool Ensure(IEnumerable<Scene> scenes)
    {
        var changed = false;
        foreach (var scene in scenes)
        {
            var existing = scene.Elements.OfType<Source>().Where(s => s.IsScoreboard).ToList();

            // More than one: keep the first, drop the rest.
            foreach (var extra in existing.Skip(1))
            {
                scene.Elements.Remove(extra);
                changed = true;
            }
            if (existing.Count > 0) continue;

            scene.Elements.Add(new Source
            {
                Name = LayerName,
                Type = SourceType.Scoreboard,
                IsEnabled = true,
                X = 0,
                Y = BottomY,
                Width = 1920,
                Height = StripHeight,
            });
            changed = true;
        }
        return changed;
    }
}