using SpaceRTS2.Assets.Utils;
using System;
using System.Collections.Generic;
using UnityEngine;
using Vectrosity;

namespace SpaceRTS2.Assets.Game.Ships
{
    public sealed class SelectionHud : ShipComponent
    {
        private static readonly Vector3[] corners = new Vector3[8];
        private VectorLine selectionLines;
        private List<Vector2> selectionPoints;

        public BoxCollider boxCollider;

        public MeshRenderer mesh;

        public void Stop()
        {
            if (selectionLines != null)
            {
                VectorLine.Destroy(ref selectionLines);
            }
        }

        public void LateUpdate()
        {
            var camera = Camera.main;

            if (!ship || !ship.isSelected || boxCollider == null || camera == null || mesh == null || !mesh.isVisible)
            {
                return;
            }

            var minX = int.MaxValue;
            var minY = int.MaxValue;

            var maxX = int.MinValue;
            var maxY = int.MinValue;

            boxCollider.GetPoints(corners);

            Vector3 screenPosition;

            for (var i = 0; i < 8; i++)
            {
                screenPosition = camera.WorldToScreenPoint(boxCollider.transform.TransformPoint(corners[i]));

                minX = Math.Min(minX, (int)screenPosition.x);
                minY = Math.Min(minY, (int)screenPosition.y);

                maxX = Math.Max(maxX, (int)screenPosition.x);
                maxY = Math.Max(maxY, (int)screenPosition.y);
            }

            if (selectionLines == null)
            {
                selectionPoints = new List<Vector2>(16);

                for (var i = 0; i < 16; i++)
                {
                    selectionPoints.Add(Vector2.zero);
                }

                selectionLines = new VectorLine("ShipSelection", selectionPoints, 1f, LineType.Discrete)
                {
                    color = HudConstants.SelectionColor
                };
            }

            var w = HudConstants.SelectionRectLines;

            // Top Left
            selectionPoints[0] = new Vector2(minX, maxY);
            selectionPoints[1] = new Vector2(minX + w, maxY);

            selectionPoints[2] = new Vector2(minX, maxY);
            selectionPoints[3] = new Vector2(minX, maxY - w);

            // Bottom Left
            selectionPoints[4] = new Vector2(minX, minY);
            selectionPoints[5] = new Vector2(minX + w, minY);

            selectionPoints[6] = new Vector2(minX, minY);
            selectionPoints[7] = new Vector2(minX, minY + w);

            // Top Right
            selectionPoints[8] = new Vector2(maxX, maxY);
            selectionPoints[9] = new Vector2(maxX - w, maxY);

            selectionPoints[10] = new Vector2(maxX, maxY);
            selectionPoints[11] = new Vector2(maxX, maxY - w);

            // Bottom Left
            selectionPoints[12] = new Vector2(maxX, minY);
            selectionPoints[13] = new Vector2(maxX - w, minY);

            selectionPoints[14] = new Vector2(maxX, minY);
            selectionPoints[15] = new Vector2(maxX, minY + w);

            selectionLines.Draw();
        }
    }
}