com.alicizax.unity.packagemanager/Editor/PackageManager/PackageOperationRunner.cs

namespace AlicizaX.PackageManager.Editor
{
    using System;
    using UnityEditor;
    using UnityEditor.PackageManager;
    using UnityEditor.PackageManager.Requests;

    internal static class PackageOperationRunner
    {
        private static AddRequest s_addRequest;
        private static RemoveRequest s_removeRequest;
        private static Action<bool, string> s_callback;
        private static string s_operationName;

        public static bool IsBusy => s_addRequest != null || s_removeRequest != null;

        public static void RunAdd(string packageIdentifier, Action<bool, string> callback)
        {
            if (IsBusy)
            {
                callback?.Invoke(false, "Another package operation is in progress.");
                return;
            }

            s_operationName = $"Add {packageIdentifier}";
            s_callback = callback;
            s_addRequest = Client.Add(packageIdentifier);
            EditorApplication.update -= Poll;
            EditorApplication.update += Poll;
        }

        public static void RunRemove(string packageName, Action<bool, string> callback)
        {
            if (IsBusy)
            {
                callback?.Invoke(false, "Another package operation is in progress.");
                return;
            }

            s_operationName = $"Remove {packageName}";
            s_callback = callback;
            s_removeRequest = Client.Remove(packageName);
            EditorApplication.update -= Poll;
            EditorApplication.update += Poll;
        }

        private static void Poll()
        {
            if (s_addRequest != null)
            {
                if (!s_addRequest.IsCompleted)
                {
                    return;
                }

                var success = s_addRequest.Status == StatusCode.Success;
                var message = success ? s_addRequest.Result?.name : s_addRequest.Error?.message;
                s_addRequest = null;
                Complete(success, message);
                return;
            }

            if (s_removeRequest != null)
            {
                if (!s_removeRequest.IsCompleted)
                {
                    return;
                }

                var success = s_removeRequest.Status == StatusCode.Success;
                var message = success ? s_removeRequest.PackageIdOrName : s_removeRequest.Error?.message;
                s_removeRequest = null;
                Complete(success, message);
                return;
            }

            EditorApplication.update -= Poll;
        }

        private static void Complete(bool success, string message)
        {
            EditorApplication.update -= Poll;

            var callback = s_callback;
            var operationName = s_operationName;
            s_callback = null;
            s_operationName = null;

            if (!success)
            {
                UnityEngine.Debug.LogError($"{operationName} failed: {message}");
            }

            callback?.Invoke(success, message);
        }
    }
}