using System.Numerics;

namespace Aeshnidae.Invasions;

/// <summary>
/// The show (Tom, 2026-09-27: "fireworks or any kind of visual effect"). Client effects are
/// ACE's PlayScripts - effects already in every retail client - broadcast on an object everyone
/// near can see. The fireworks are a retail object (Settings.CelebrationWcid, "Anniversary
/// Effect"), set down round the town and taken away again after CelebrationSeconds. No dat is
/// touched. World thread only.
/// </summary>
public static class Effects
{
    private sealed record Display(WorldObject Object, DateTime Until);

    private static readonly List<Display> _displays = new();
    private static readonly HashSet<string> _warned = new(StringComparer.OrdinalIgnoreCase);

    private static Settings S => Mod.Settings;

    public static int Showing => _displays.Count;

    /// <summary>A PlayScript by name ("PortalExit"), or null for empty/unknown (unknown is logged once).</summary>
    public static PlayScript? Parse(string? name)
    {
        if (string.IsNullOrWhiteSpace(name))
            return null;

        if (Enum.TryParse<PlayScript>(name.Trim(), ignoreCase: true, out var script) && script != PlayScript.Invalid)
            return script;

        if (_warned.Add(name))
            ModManager.Log($"[{Mod.Name}] '{name}' is not a PlayScript name; that effect is off", ModManager.LogLevel.Warn);
        return null;
    }

    /// <summary>Play the named effect on the object, for everyone who can see it.</summary>
    public static bool Play(WorldObject? wo, string? effect)
    {
        var script = Parse(effect);
        if (wo is null || script is null || wo.IsDestroyed)
            return false;

        try
        {
            wo.EnqueueBroadcast(new GameMessageScript(wo.Guid, script.Value));
            return true;
        }
        catch (Exception ex)
        {
            ModManager.Log($"[{Mod.Name}] effect {script} on {wo.Name} failed: {ex.Message}", ModManager.LogLevel.Warn);
            return false;
        }
    }

    /// <summary>Set the fireworks off round a point (global metres). Returns how many displays went up.</summary>
    public static int Celebrate(Vector2 center)
    {
        if (S.CelebrationWcid == 0 || S.CelebrationCount <= 0)
            return 0;

        var until = DateTime.UtcNow.AddSeconds(Math.Max(5, S.CelebrationSeconds));
        var radius = Math.Max(6, S.CelebrationRadius);
        var up = 0;

        for (var i = 0; i < S.CelebrationCount; i++)
        {
            // Spread evenly round the centre, each at a random distance.
            var angle = Math.PI * 2 * i / S.CelebrationCount + Random.Shared.NextDouble() * 0.5;
            var spot = Placement.RingSpot(center, 5, radius, tries: 10, angle: angle, spread: 0.4)
                    ?? Placement.RingSpot(center, 0, radius, tries: 10);
            if (spot is null)
                continue;

            WorldObject? wo = null;
            try
            {
                wo = WorldObjectFactory.CreateNewWorldObject(S.CelebrationWcid);
                if (wo is null)
                {
                    ModManager.Log($"[{Mod.Name}] celebration wcid {S.CelebrationWcid} does not exist", ModManager.LogLevel.Warn);
                    return up;
                }

                wo.Location = spot;
                // The backstop if this mod is gone before it takes them away.
                wo.Lifespan = (int)Math.Max(5, S.CelebrationSeconds) + 30;

                if (!wo.EnterWorld())
                {
                    wo.Destroy();
                    continue;
                }

                _displays.Add(new Display(wo, until));
                up++;
            }
            catch (Exception ex)
            {
                ModManager.Log($"[{Mod.Name}] a firework display failed: {ex.Message}", ModManager.LogLevel.Warn);
                try { wo?.Destroy(); } catch { /* already gone */ }
            }
        }

        return up;
    }

    /// <summary>Take away displays whose time is up.</summary>
    public static void Tick(DateTime now)
    {
        for (var i = _displays.Count - 1; i >= 0; i--)
        {
            var d = _displays[i];
            if (now < d.Until && !d.Object.IsDestroyed)
                continue;

            try
            {
                if (!d.Object.IsDestroyed)
                    d.Object.Destroy();
            }
            catch { /* its lifespan will */ }

            _displays.RemoveAt(i);
        }
    }

    /// <summary>Mod.Dispose: take the displays away on the world thread (their Lifespan is the backstop).</summary>
    public static void Shutdown()
    {
        if (_displays.Count == 0)
            return;

        var left = _displays.ToList();
        _displays.Clear();

        try
        {
            WorldManager.EnqueueAction(new ActionEventDelegate(() =>
            {
                foreach (var d in left)
                    try { if (!d.Object.IsDestroyed) d.Object.Destroy(); } catch { /* lifespan */ }
            }));
        }
        catch { /* their Lifespan takes them */ }
    }
}