add preferred language (#109)

* add explicit warning for zero/invalid duration media items

* set dateadded on plex media versions

* add media stream table

* save local media streams to db

* save plex media streams to db

* add preferred language settings (no validation)

* use preferred language if possible

* code cleanup

* proper language code validation

* force scan of all libraries to pull in media streams

ErsatzTV/Pages/FFmpeg.razor

@@ -3,6 +3,7 @@
 @using ErsatzTV.Application.FFmpegProfiles.Commands
 @using ErsatzTV.Application.FFmpegProfiles.Queries
 @using Unit = LanguageExt.Unit
+@using System.Globalization
 @inject IDialogService Dialog
 @inject IMediator Mediator
 @inject ILogger<FFmpeg> Logger
@@ -29,6 +30,9 @@
                         }
                     </MudSelect>
                 </MudElement>
+                <MudElement HtmlTag="div" Class="mt-3">
+                    <MudTextField T="string" Label="Preferred Language Code" @bind-Value="_ffmpegSettings.PreferredLanguageCode" Validation="@(new Func<string, string>(ValidateLanguageCode))" Required="true" RequiredError="Preferred Language Code is required!"/>
+                </MudElement>
                 <MudElement HtmlTag="div" Class="mt-3">
                     <MudSwitch T="bool"
                                Label="Save troubleshooting reports to disk"
@@ -133,6 +137,19 @@
 
     private static string ValidatePathExists(string path) => !File.Exists(path) ? "Path does not exist" : null;
 
+    private static string ValidateLanguageCode(string languageCode)
+    {
+        if (string.IsNullOrWhiteSpace(languageCode))
+        {
+            return null;
+        }
+
+        Option<CultureInfo> culture = CultureInfo.GetCultures(CultureTypes.NeutralCultures)
+            .FirstOrDefault(ci => string.Equals(ci.ThreeLetterISOLanguageName, languageCode, StringComparison.OrdinalIgnoreCase));
+
+        return culture.IsNone ? "Preferred language code is invalid" : null;
+    }
+
     private async Task LoadFFmpegProfilesAsync() =>
         _ffmpegProfiles = await Mediator.Send(new GetAllFFmpegProfiles());