--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/org/prevayler/implementation/CommandInputStream.java	Sat Mar 21 11:00:06 2009 +0000
@@ -0,0 +1,109 @@
+/*
+  The copyright of all source code included in this Prevayler distribution is
+  held by Klaus Wuestefeld, except the files that specifically state otherwise.
+  All rights are reserved. "PREVAYLER" is a trademark of Klaus Wuestefeld.
+
+
+  BSD License:
+
+  Redistribution and use in source and binary forms, with or without
+  modification, are permitted provided that the following conditions are met:
+
+  - Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimer.
+
+  - Redistributions in binary form must reproduce the above copyright notice,
+  this list of conditions and the following disclaimer in the documentation
+  and/or other materials provided with the distribution.
+ 
+  - Neither the name of Prevayler nor the names of its contributors may be used
+  to endorse or promote products derived from this software without specific
+  prior written permission.
+
+
+  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
+  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
+  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
+  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
+  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
+  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+  POSSIBILITY OF SUCH DAMAGE.
+*/
+
+package org.prevayler.implementation;
+
+import java.io.*;
+import org.prevayler.*;
+
+/** Provides an easy API for reading commands and snapshots.
+*/
+class CommandInputStream {
+
+    public CommandInputStream(String directory) throws IOException {
+	fileFinder = new NumberFileFinder(directory);
+    }
+
+    public PrevalentSystem readLastSnapshot() throws IOException, ClassNotFoundException {
+	File snapshotFile = fileFinder.lastSnapshot();
+	if (snapshotFile == null) return null;
+	out(snapshotFile);
+
+	ObjectInputStream ois = new ObjectInputStream(new FileInputStream(snapshotFile));
+	try {
+	    return (PrevalentSystem)ois.readObject();
+	} finally {
+	    ois.close();
+	}
+    }
+
+    public Command readCommand() throws IOException, ClassNotFoundException {
+	if (currentLogStream == null) currentLogStream = newLogStream();  //Throws EOFException if there are no more log streams.
+
+	try {
+	    return (Command)currentLogStream.readObject();
+	} catch (EOFException eof) {
+	    //No more commands in this file.
+	} catch (ObjectStreamException osx) {
+	    logStreamExceptionMessage(osx);
+	} catch (RuntimeException rx) {
+	    logStreamExceptionMessage(rx);    //Some stream corruptions cause runtime exceptions!
+	}
+
+	currentLogStream.close();
+	currentLogStream = null;
+	return readCommand();
+    }
+
+    public CommandOutputStream commandOutputStream(boolean shouldReset,
+                                                   boolean shouldClean,
+                                                   int aBufferSize) {
+	return new CommandOutputStream(fileFinder.fileCreator(), shouldReset,
+                                   shouldClean, aBufferSize);
+    }
+
+    private ObjectInputStream newLogStream() throws IOException {
+	File logFile = fileFinder.nextPendingLog();  //Throws EOFException if there are no more pending log files.
+	out(logFile);
+	return new ObjectInputStream(new BufferedInputStream(new FileInputStream(logFile)));
+    }
+
+    private void logStreamExceptionMessage(Exception exception) {
+	out("   " + exception);
+	out("   Some commands might have been lost. Looking for the next file..." );
+    }
+
+    private static void out(File file) {
+	out("Reading: " + file + "...");
+    }
+
+    private static void out(Object obj) {
+	System.out.println(obj);
+    }
+
+    private NumberFileFinder fileFinder;
+    private ObjectInputStream currentLogStream;
+}