chameleon/Assets/Scripts/Editor/WebAssets/EditorWebRequest.cs

using System;
using UnityEditor;
using UnityEngine;
using UnityEngine.Networking;

namespace Chameleon.Editor.WebAssets
{
    /// <summary>
    /// Non-blocking UnityWebRequest transport for editor tools. All requests poll on
    /// EditorApplication.update — never blocks the editor. Shared by the Poly Haven
    /// and ambientCG importers.
    /// </summary>
    public static class EditorWebRequest
    {
        public const string UserAgent = "Chameleon-Unity-AssetImporter/1.0";

        /// <summary>GET a URL and return the response body as text.</summary>
        public static void GetText(string url, Action<string> onDone, Action<string> onError)
        {
            var req = UnityWebRequest.Get(url);
            req.SetRequestHeader("User-Agent", UserAgent);
            Send(req, () => onDone?.Invoke(req.downloadHandler.text), onError);
        }

        /// <summary>Fetches an image as a Texture2D (browser thumbnails, previews).</summary>
        public static void GetTexture(string url, Action<Texture2D> onDone, Action<string> onError)
        {
            var req = UnityWebRequestTexture.GetTexture(url);
            req.SetRequestHeader("User-Agent", UserAgent);
            Send(req, () =>
            {
                var tex = DownloadHandlerTexture.GetContent(req);
                // Survive play-mode enter/exit cleanup — otherwise Unity destroys these
                // loose runtime textures and browser previews go blank.
                if (tex)
                    tex.hideFlags = HideFlags.HideAndDontSave;
                onDone?.Invoke(tex);
            }, onError);
        }

        /// <summary>Streams a file straight to disk (no RAM peak on big downloads).</summary>
        public static void DownloadFile(string url, string destPath, Action onDone,
            Action<string> onError, Action<float> onProgress = null)
        {
            var req = new UnityWebRequest(url, UnityWebRequest.kHttpVerbGET);
            req.downloadHandler = new DownloadHandlerFile(destPath) { removeFileOnAbort = true };
            req.SetRequestHeader("User-Agent", UserAgent);
            Send(req, () => onDone?.Invoke(), onError, onProgress);
        }

        public static void Send(UnityWebRequest req, Action onSuccess, Action<string> onError,
            Action<float> onProgress = null)
        {
            var op = req.SendWebRequest();
            void Tick()
            {
                if (onProgress != null && !op.isDone)
                    onProgress(req.downloadProgress);

                if (!op.isDone)
                    return;

                EditorApplication.update -= Tick;
                try
                {
                    if (req.result != UnityWebRequest.Result.Success)
                    {
                        onError?.Invoke($"{req.error} ({req.url})");
                    }
                    else
                    {
                        onProgress?.Invoke(1f);
                        onSuccess?.Invoke();
                    }
                }
                finally
                {
                    req.Dispose();
                }
            }
            EditorApplication.update += Tick;
        }
    }
}