using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using UnityEngine;
using static UnityEditor.Toast;

namespace UnityEditor
{
    public static class ToastHelpers
    {
        private static readonly Vector4 WINDOW_PADDING = new Vector4(10f, 30f, 80f, 10f);

        [DllImport("user32.dll")]
        private static extern bool GetWindowRect(IntPtr hwnd, ref Rect rectangle);

        [StructLayout(LayoutKind.Sequential)]
        private struct Rect
        {
            public int Left { get; set; }
            public int Top { get; set; }
            public int Right { get; set; }
            public int Bottom { get; set; }

            public UnityEngine.Rect ToUnityRect()
            {
                return new UnityEngine.Rect(Left, Top, Right - Left, Bottom - Top);
            }
        }

        internal static UnityEngine.Rect GetEditorWindowPosition(this EditorWindow window, ToastPosition corner)
        {
            Vector2 windowSize = window.position.size;

            Rect editorRect = new Rect();
            GetWindowRect(Process.GetCurrentProcess().MainWindowHandle, ref editorRect);
            UnityEngine.Rect unityEditorRect = editorRect.ToUnityRect();

            Vector2 position = CalculatePosition(corner, unityEditorRect, windowSize);
            return new UnityEngine.Rect(position.x, position.y, windowSize.x, windowSize.y);
        }

        private static Vector2 CalculatePosition(ToastPosition corner, UnityEngine.Rect editorRect, Vector2 windowSize)
        {
            return corner switch
            {
                ToastPosition.TopLeft => new Vector2(
                    editorRect.x + WINDOW_PADDING.w,
                    editorRect.y + WINDOW_PADDING.z),
                ToastPosition.TopRight => new Vector2(
                    editorRect.xMax - windowSize.x - WINDOW_PADDING.x,
                    editorRect.y + WINDOW_PADDING.z),
                ToastPosition.TopCenter => new Vector2(
                    editorRect.center.x - windowSize.x / 2 - WINDOW_PADDING.x,
                    editorRect.y + WINDOW_PADDING.z),
                ToastPosition.BottomLeft => new Vector2(
                    editorRect.x + WINDOW_PADDING.w,
                    editorRect.yMax - windowSize.y - WINDOW_PADDING.y),
                ToastPosition.BottomRight => new Vector2(
                    editorRect.xMax - windowSize.x - WINDOW_PADDING.x,
                    editorRect.yMax - windowSize.y - WINDOW_PADDING.y),
                ToastPosition.BottomCenter => new Vector2(
                    editorRect.center.x - windowSize.x / 2 - WINDOW_PADDING.x,
                    editorRect.yMax - windowSize.y - WINDOW_PADDING.y),
                _ => throw new ArgumentOutOfRangeException(nameof(corner), corner, null)
            };
        }
    }
}