using System;
using UnityEngine;

namespace CSharpESP
{
    public static class MathUtils
    {
        /// <summary>
        /// Converts a world coordinate into Unity GUI screen coordinates.
        /// Returns false if the point is behind the camera frustum.
        /// </summary>
        public static bool WorldToScreen(Camera camera, Vector3 worldPos, out Vector2 screenPos)
        {
            screenPos = Vector2.zero;
            if (camera == null) return false;

            Vector3 viewPos = camera.WorldToScreenPoint(worldPos);
            if (viewPos.z <= 0.01f)
            {
                return false;
            }

            // Invert Y coordinate for GUI coordinate space
            screenPos = new Vector2(viewPos.x, Screen.height - viewPos.y);
            return true;
        }

        /// <summary>
        /// Calculates the 8 world-space corner vertices of an axis-aligned bounding box.
        /// </summary>
        public static Vector3[] GetBoundsVertices(Bounds bounds)
        {
            Vector3 center = bounds.center;
            Vector3 ext = bounds.extents;

            return new Vector3[8]
            {
                new Vector3(center.x - ext.x, center.y - ext.y, center.z - ext.z), // 0: Bottom-Left-Back
                new Vector3(center.x + ext.x, center.y - ext.y, center.z - ext.z), // 1: Bottom-Right-Back
                new Vector3(center.x + ext.x, center.y - ext.y, center.z + ext.z), // 2: Bottom-Right-Front
                new Vector3(center.x - ext.x, center.y - ext.y, center.z + ext.z), // 3: Bottom-Left-Front
                new Vector3(center.x - ext.x, center.y + ext.y, center.z - ext.z), // 4: Top-Left-Back
                new Vector3(center.x + ext.x, center.y + ext.y, center.z - ext.z), // 5: Top-Right-Back
                new Vector3(center.x + ext.x, center.y + ext.y, center.z + ext.z), // 6: Top-Right-Front
                new Vector3(center.x - ext.x, center.y + ext.y, center.z + ext.z)  // 7: Top-Left-Front
            };
        }

        /// <summary>
        /// Computes a screen-aligned 2D rectangle encapsulating the 3D bounds vertices.
        /// </summary>
        public static bool GetScreenRectFromBounds(Camera camera, Bounds bounds, out Rect screenRect)
        {
            screenRect = Rect.zero;
            Vector3[] vertices = GetBoundsVertices(bounds);

            float minX = float.MaxValue;
            float maxX = float.MinValue;
            float minY = float.MaxValue;
            float maxY = float.MinValue;
            bool anyVisible = false;

            for (int i = 0; i < 8; i++)
            {
                if (WorldToScreen(camera, vertices[i], out Vector2 screenPoint))
                {
                    minX = Mathf.Min(minX, screenPoint.x);
                    maxX = Mathf.Max(maxX, screenPoint.x);
                    minY = Mathf.Min(minY, screenPoint.y);
                    maxY = Mathf.Max(maxY, screenPoint.y);
                    anyVisible = true;
                }
            }

            if (!anyVisible || maxX <= minX || maxY <= minY)
            {
                return false;
            }

            screenRect = new Rect(minX, minY, maxX - minX, maxY - minY);
            return true;
        }

        /// <summary>
        /// Calculates distance in meters between camera and target position.
        /// </summary>
        public static float GetDistance(Camera camera, Vector3 targetPos)
        {
            if (camera == null) return 0f;
            return Vector3.Distance(camera.transform.position, targetPos);
        }
    }
}