display reason why file is read only when first opening a database

src/Kp2aBusinessLogic/Io/AndroidContentStorage.cs

@@ -206,12 +206,15 @@ namespace keepass2android.Io
 			return _ctx.ContentResolver.PersistedUriPermissions.Any(p => p.Uri.ToString().Equals(ioc.Path));
 		}
 
-		public bool IsReadOnly(IOConnectionInfo ioc)
+
+		public bool IsReadOnly(IOConnectionInfo ioc, OptionalOut<UiStringKey> reason = null)
 		{
 			//on pre-Kitkat devices, we can't write content:// files
 			if (!IsKitKatOrLater)
 			{
 				Kp2aLog.Log("File is read-only because we're not on KitKat or later.");
+				if (reason != null)
+					reason.Result = UiStringKey.ReadOnlyReason_PreKitKat;
 				return true;
 			}
 				
@@ -226,7 +229,12 @@ namespace keepass2android.Io
 				{
 					int flags = cursor.GetInt(cursor.GetColumnIndex(DocumentsContract.Document.ColumnFlags));
 					Kp2aLog.Log("File flags: " + flags);
-					return (flags & (long) DocumentContractFlags.SupportsWrite) == 0;
+					if ((flags & (long) DocumentContractFlags.SupportsWrite) == 0)
+					{
+						if (reason != null)
+							reason.Result = UiStringKey.ReadOnlyReason_ReadOnlyFlag;
+						return true;
+					}
 				}
 			}
 			finally

src/Kp2aBusinessLogic/Io/BuiltInFileStorage.cs

@@ -370,14 +370,24 @@ namespace keepass2android.Io
 			
 		}
 
-		public bool IsReadOnly(IOConnectionInfo ioc)
+		public bool IsReadOnly(IOConnectionInfo ioc, OptionalOut<UiStringKey> reason = null)
 		{
 			if (ioc.IsLocalFile())
 			{
 				if (IsLocalFileFlaggedReadOnly(ioc))
+				{
+					if (reason != null)
+						reason.Result = UiStringKey.ReadOnlyReason_ReadOnlyFlag;
 					return true;
+				}
+
 				if (IsReadOnlyBecauseKitkatRestrictions(ioc))
+				{
+					if (reason != null)
+						reason.Result = UiStringKey.ReadOnlyReason_ReadOnlyKitKat;
 					return true;
+				}
+					
 
 				return false;
 			}

src/Kp2aBusinessLogic/Io/CachingFileStorage.cs

@@ -556,11 +556,11 @@ namespace keepass2android.Io
 			return _cachedStorage.IsPermanentLocation(ioc);
 		}
 
-		public bool IsReadOnly(IOConnectionInfo ioc)
+		public bool IsReadOnly(IOConnectionInfo ioc, OptionalOut<UiStringKey> reason = null)
 		{
 			//even though the cache can always be written, the changes made in the cache could not be transferred to the cached file
 			//so we better treat the cache as read-only as well.
-			return _cachedStorage.IsReadOnly(ioc);
+			return _cachedStorage.IsReadOnly(ioc, reason);
 		}
 
 		private void StoreFilePath(IOConnectionInfo folderPath, string filename, IOConnectionInfo res)

src/Kp2aBusinessLogic/Io/IFileStorage.cs

@@ -15,6 +15,11 @@ namespace keepass2android.Io
 		FileChooserPrepared = FullFilenameSelected + 1,
 		FileUsagePrepared = FileChooserPrepared + 1
 	}
+	
+		public class OptionalOut<T>
+		{
+			public T Result { get; set; }
+		}
 
 	public static class FileStorageSetupDefs
 	{
@@ -165,10 +170,14 @@ namespace keepass2android.Io
 		/// Does not require to exist forever!
 		bool IsPermanentLocation(IOConnectionInfo ioc);
 
+		
+
 		/// <summary>
 		/// Should return true if the file cannot be written.
 		/// </summary>
-		bool IsReadOnly(IOConnectionInfo ioc);
+		bool IsReadOnly(IOConnectionInfo ioc, OptionalOut<UiStringKey> reason = null );
+
+		
 	}
 
 	public interface IPermissionRequestingFileStorage

src/Kp2aBusinessLogic/Io/JavaFileStorage.cs

@@ -289,7 +289,7 @@ namespace keepass2android.Io
 			return true;
 		}
 
-		public bool IsReadOnly(IOConnectionInfo ioc)
+		public bool IsReadOnly(IOConnectionInfo ioc, OptionalOut<UiStringKey> reason = null)
 		{
 			return false; //TODO implement. note, however, that we MAY return false even if it's read-only
 		}

src/Kp2aBusinessLogic/Io/OfflineSwitchableFileStorage.cs

@@ -176,9 +176,9 @@ namespace keepass2android.Io
 			return _baseStorage.IsPermanentLocation(ioc);
 		}
 
-		public bool IsReadOnly(IOConnectionInfo ioc)
+		public bool IsReadOnly(IOConnectionInfo ioc, OptionalOut<UiStringKey> reason = null)
 		{
-			return _baseStorage.IsReadOnly(ioc);
+			return _baseStorage.IsReadOnly(ioc, reason);
 		}
 
 	public void OnRequestPermissionsResult(IFileStorageSetupActivity fileStorageSetupActivity, int requestCode,