using System;
using System.Linq;
using System.Numerics;
using Dalamud.Bindings.ImGui;
using Dalamud.Interface;
using FFXIVClientStructs.FFXIV.Client.UI.Agent;
using Mappy.Classes;
using Mappy.Data;

namespace Mappy.MapRenderer;

public partial class MapRenderer
{
    private unsafe void DrawMovementTrail()
    {
        if (!System.SystemConfig.ShowMovementTrail) return;

        var agent = AgentMap.Instance();
        var territoryId = agent->SelectedTerritoryId;
        var mapId = agent->SelectedMapId;

        var now = DateTime.UtcNow.Subtract(DateTime.UnixEpoch).TotalSeconds;
        var fadeTime = System.SystemConfig.MovementTrailFadeTimeSeconds;

        foreach (var pt in System.MovementTrailConfig.GetVisiblePoints(territoryId, mapId).ToList()) {
            var age = now - pt.TimeStamp;
            var alpha = (float)((fadeTime - age) / fadeTime * 0.9);
            if (alpha <= 0f) continue;

            // Same coordinate space as map notes: world X,Z
            var pos = new Vector2(pt.X, pt.Y) * Scale * DrawHelpers.GetMapScaleFactor() + DrawHelpers.GetCombinedOffsetVector() * Scale;

            var size = Math.Clamp(4 * Scale, 3f, 25f);
            var screenPos = ImGui.GetWindowPos() + DrawPosition + pos;

            var color = System.MovementTrailConfig.TrailColor with { W = alpha };
            var drawList = ImGui.GetWindowDrawList();
            drawList.AddCircleFilled(screenPos, size, ImGui.GetColorU32(color));
        }
    }
}