added UI for opening a database with OTPs. Some TODOs and things not yet working!

src/Kp2aBusinessLogic/Io/BuiltInFileStorage.cs

@@ -107,16 +107,6 @@ namespace keepass2android.Io
 			}
 		}
 
-		public bool CompleteIoId()
-		{
-			throw new NotImplementedException();
-		}
-
-		public bool? FileExists()
-		{
-			throw new NotImplementedException();
-		}
-
 		public string GetFilenameWithoutPathAndExt(IOConnectionInfo ioc)
 		{
 			return UrlUtil.StripExtension(
@@ -207,5 +197,19 @@ namespace keepass2android.Io
 				parent += "/";
 			return parent + newFilename;
 		}
+
+		public IOConnectionInfo GetParentPath(IOConnectionInfo ioc)
+		{
+			return IoUtil.GetParentPath(ioc);
+		}
+
+		public IOConnectionInfo GetFilePath(IOConnectionInfo folderPath, string filename)
+		{
+			IOConnectionInfo res = folderPath.CloneDeep();
+			if (!res.Path.EndsWith("/"))
+				res.Path += "/";
+			res.Path += filename;
+			return res;
+		}
 	}
 }

src/Kp2aBusinessLogic/Io/CachingFileStorage.cs

@@ -400,16 +400,6 @@ namespace keepass2android.Io
 			return new CachedWriteTransaction(ioc, useFileTransaction, this);
 		}
 
-		public bool CompleteIoId()
-		{
-			throw new NotImplementedException();
-		}
-
-		public bool? FileExists()
-		{
-			throw new NotImplementedException();
-		}
-
 		public string GetFilenameWithoutPathAndExt(IOConnectionInfo ioc)
 		{
 			return UrlUtil.StripExtension(
@@ -487,6 +477,54 @@ namespace keepass2android.Io
 			return _cachedStorage.CreateFilePath(parent, newFilename);
 		}
 
+		public IOConnectionInfo GetParentPath(IOConnectionInfo ioc)
+		{
+			return _cachedStorage.GetParentPath(ioc);
+		}
+
+		public IOConnectionInfo GetFilePath(IOConnectionInfo folderPath, string filename)
+		{
+			try
+			{
+				IOConnectionInfo res = _cachedStorage.GetFilePath(folderPath, filename);
+				//some file storage implementations require accessing the network to determine the file path (e.g. because
+				//they might contain file ids). In this case, we need to cache the result to enable cached access to such files
+				StoreFilePath(folderPath, filename, res);
+				return res;
+			}
+			catch (Exception)
+			{
+				IOConnectionInfo res;
+				if (!TryGetCachedFilePath(folderPath, filename, out res)) throw;
+				return res;
+			}
+			
+		}
+
+		private void StoreFilePath(IOConnectionInfo folderPath, string filename, IOConnectionInfo res)
+		{
+			File.WriteAllText(CachedFilePath(GetPseudoIoc(folderPath, filename)) + ".filepath", res.Path);
+		}
+
+		private IOConnectionInfo GetPseudoIoc(IOConnectionInfo folderPath, string filename)
+		{
+			IOConnectionInfo res = folderPath.CloneDeep();
+			if (!res.Path.EndsWith("/"))
+				res.Path += "/";
+			res.Path += filename;
+			return res;
+		}
+
+		private bool TryGetCachedFilePath(IOConnectionInfo folderPath, string filename, out IOConnectionInfo res)
+		{
+			res = folderPath.CloneDeep();
+			string filePathCache = CachedFilePath(GetPseudoIoc(folderPath, filename)) + ".filepath";
+			if (!File.Exists(filePathCache))
+				return false;
+			res.Path = File.ReadAllText(filePathCache);
+			return true;
+		}
+
 
 		public string GetBaseVersionHash(IOConnectionInfo ioc)
 		{

src/Kp2aBusinessLogic/Io/IFileStorage.cs

@@ -82,19 +82,6 @@ namespace keepass2android.Io
 		/// <param name="useFileTransaction">if true, force to use file system level transaction. This might be ignored if the file storage has built in transaction support</param>
 		IWriteTransaction OpenWriteTransaction(IOConnectionInfo ioc, bool useFileTransaction);
 
-		/// <summary>
-		/// brings up a dialog to query credentials or something like this.
-		/// </summary>
-		/// <returns>true if success, false if error or cancelled by user</returns>
-		bool CompleteIoId( /*in/out ioId*/);
-
-
-		/// <summary>
-		/// Checks whether the given file exists.
-		/// </summary>
-		/// <returns>true if it exists, false if not. Null if the check couldn't be performed (e.g. because no credentials available or no connection established.)</returns>
-		bool? FileExists( /*ioId*/);
-
 		string GetFilenameWithoutPathAndExt(IOConnectionInfo ioc);
 		
 		/// <summary>
@@ -135,10 +122,10 @@ namespace keepass2android.Io
 		void StartSelectFile(IFileStorageSetupInitiatorActivity activity, bool isForSave, int requestCode, string protocolId);
 
 		/// <summary>
-		/// Initiates the process for choosing a file in the given file storage.
+		/// Initiates the process for using a file in the given file storage.
 		/// The file storage should either call OnImmediateResult or StartFileUsageProcess
 		/// If alwaysReturnSuccess is true, the activity should be finished with ResultCode Ok.
-		/// This can make sense if a higher-level file storage has the file cached by still wants to 
+		/// This can make sense if a higher-level file storage has the file cached but still wants to 
 		/// give the cached storage the chance to initialize file access.
 		/// </summary>
 		void PrepareFileUsage(IFileStorageSetupInitiatorActivity activity, IOConnectionInfo ioc, int requestCode, bool alwaysReturnSuccess);
@@ -157,6 +144,17 @@ namespace keepass2android.Io
 		//returns the path of a file "newFilename" in the folder "parent"
 		//this may create the file if this is required to get a path (if a UUID is part of the file path)
 		string CreateFilePath(string parent, string newFilename);
+
+		/// <summary>
+		/// returns the parent folder of ioc
+		/// </summary>
+		IOConnectionInfo GetParentPath(IOConnectionInfo ioc);
+
+		/// <summary>
+		/// returns the file path of the file "filename" in the folderPath.
+		/// </summary>
+		/// The method may throw FileNotFoundException or not in case the file doesn't exist.
+		IOConnectionInfo GetFilePath(IOConnectionInfo folderPath, string filename);
 	}
 
 	public interface IWriteTransaction: IDisposable

src/Kp2aBusinessLogic/Io/IoUtil.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Text;
 using Java.IO;
+using KeePassLib.Serialization;
 
 namespace keepass2android.Io
 {
@@ -30,5 +31,20 @@ namespace keepass2android.Io
 		}
 
 
+		public static IOConnectionInfo GetParentPath(IOConnectionInfo ioc)
+		{
+			var iocParent = ioc.CloneDeep();
+			if (iocParent.Path.EndsWith("/"))
+				iocParent.Path = iocParent.Path.Substring(0, iocParent.Path.Length - 1);
+
+			int slashPos = iocParent.Path.LastIndexOf("/", StringComparison.Ordinal);
+			if (slashPos == -1)
+				iocParent.Path = "";
+			else
+			{
+				iocParent.Path = iocParent.Path.Substring(0, slashPos);
+			}
+			return iocParent;
+		}
 	}
 }

src/Kp2aBusinessLogic/Io/JavaFileStorage.cs

@@ -151,16 +151,6 @@ namespace keepass2android.Io
 			}
 		}
 
-		public bool CompleteIoId()
-		{
-			throw new NotImplementedException();
-		}
-
-		public bool? FileExists()
-		{
-			throw new NotImplementedException();
-		}
-
 		public string GetFilenameWithoutPathAndExt(IOConnectionInfo ioc)
 		{
 			return UrlUtil.StripExtension(