Orchard/src/Orchard.Web/Modules/Orchard.PackageManager/Events/ExtensionDisplayEventHandler.cs

using System.Collections.Generic;
using System.Linq;
using Orchard.Environment.Extensions.Models;
using Orchard.Localization;
using Orchard.PackageManager.Services;
using Orchard.Packaging.Services;

namespace Orchard.PackageManager.Events {
    public class ExtensionDisplayEventHandler : IExtensionDisplayEventHandler {
        private readonly IBackgroundPackageUpdateStatus _backgroundPackageUpdateStatus;
        private readonly IPackagingSourceManager _packagingSourceManager;
        private readonly IPackageUpdateService _packageUpdateService;

        public ExtensionDisplayEventHandler(IBackgroundPackageUpdateStatus backgroundPackageUpdateStatus,
            IPackagingSourceManager packagingSourceManager,
            IPackageUpdateService packageUpdateService) {

            _backgroundPackageUpdateStatus = backgroundPackageUpdateStatus;
            _packagingSourceManager = packagingSourceManager;
            _packageUpdateService = packageUpdateService;

            T = NullLocalizer.Instance;
        }

        public Localizer T { get; set; }

        public IEnumerable<string> Displaying(ExtensionDescriptor extensionDescriptor) {
            // Get status from background task state or directly
            _backgroundPackageUpdateStatus.Value =
                _backgroundPackageUpdateStatus.Value ??
                _packageUpdateService.GetPackagesStatus(_packagingSourceManager.GetSources());

            UpdatePackageEntry updatePackageEntry = _backgroundPackageUpdateStatus.Value.Entries
                .Where(package => package.ExtensionsDescriptor.Id.Equals(extensionDescriptor.Id)).FirstOrDefault();

            if (updatePackageEntry != null) {
                if (updatePackageEntry.NewVersionToInstall != null) {
                    yield return T("New version available: {0}", updatePackageEntry.NewVersionToInstall.Version).ToString();
                }
            }
        }
    }
}