Adds last message correction functionality. Implementation provided by Ivan Vergiliev.

21 files changed, 959 insertions, 69 deletions

diff --git a/src/net/java/sip/communicator/impl/gui/main/chat/ChatConversationPanel.java b/src/net/java/sip/communicator/impl/gui/main/chat/ChatConversationPanel.java
index 678a71f..4e98ef8 100755
--- a/src/net/java/sip/communicator/impl/gui/main/chat/ChatConversationPanel.java
+++ b/src/net/java/sip/communicator/impl/gui/main/chat/ChatConversationPanel.java
@@ -20,6 +20,7 @@ import javax.swing.*;
 import javax.swing.event.*;
 import javax.swing.text.*;
 import javax.swing.text.html.*;
+import javax.swing.text.html.HTML.*;
 
 import net.java.sip.communicator.impl.gui.*;
 import net.java.sip.communicator.impl.gui.customcontrols.*;
@@ -364,6 +365,68 @@ public class ChatConversationPanel
 //    }
 
     /**
+     * Retrieves the contents of the sent message with the given ID.
+     * 
+     * @param messageUID The ID of the message to retrieve.
+     * @return The contents of the message, or null if the message is not found.
+     */
+    public String getMessageContents(String messageUID)
+    {
+        Element root = document.getDefaultRootElement();
+        Element e = document.getElement(root, Attribute.ID, messageUID);
+        if (e == null)
+        {
+            logger.warn("Could not find message with ID" + messageUID);
+            return null;
+        }
+
+        int elemLen = e.getEndOffset() - e.getStartOffset();
+        String res = null;
+        try
+        {
+            res = document.getText(e.getStartOffset(), elemLen);
+        }
+        catch (BadLocationException exc)
+        {
+            logger.warn("Could not get message contents for message "
+                    + "with ID" + messageUID, exc);
+        }
+        return res;
+    }
+
+    /**
+     * Creates a tag that shows the last edit time of a message, in the format
+     *  (Edited at ...).
+     * If <tt>date < 0</tt>, returns an empty tag that serves as a placeholder
+     * for future corrections of this message.
+     * 
+     * @param messageUID The ID of the edited message.
+     * @param date The date when the message was last edited, or -1 to generate
+     * an empty tag.
+     * @return The string representation of the tag.
+     */
+    private String generateEditedAtTag(String messageUID, long date)
+    {
+        StringBuilder res = new StringBuilder();
+        // Use a <cite /> tag here as most of the other inline tags (e.g. h1-7,
+        // b, i) cause different problems when used in setOuterHTML.
+        res.append("<cite id='");
+        res.append(messageUID);
+        res.append("-editedAt'> ");
+        if (date > 0)
+        {
+            res.append("&nbsp;");
+            String contents = GuiActivator.getResources().getI18NString(
+                    "service.gui.EDITED_AT",
+                    new String[] { GuiUtils.formatTime(date) }
+            );
+            res.append(contents);
+        }
+        res.append("</cite>");
+        return res.toString();
+    }
+
+    /**
      * Processes the message given by the parameters.
      *
      * @param chatMessage the message
@@ -384,14 +447,18 @@ public class ChatConversationPanel
         String messageType = chatMessage.getMessageType();
         String messageTitle = chatMessage.getMessageTitle();
         String message = chatMessage.getMessage();
+        String messageUID = chatMessage.getMessageUID();
 
         String msgID = "message";
         String msgHeaderID = "messageHeader";
         String chatString = "";
         String endHeaderTag = "";
         String dateString = getDateString(date);
+        String idAttr = messageUID == null ? "" : " id='" + messageUID + "'";
+        String dateAttr = " date='" + date + "'";
+        String editedAtTag = generateEditedAtTag(messageUID, -1);
 
-        String startDivTag = "<DIV identifier=\"" + msgID + "\">";
+        String startDivTag = "<DIV identifier=\"" + msgID + "\"" + idAttr + ">";
         String startHistoryDivTag
             = "<DIV identifier=\"" + msgID + "\" style=\"color:#707070;\">";
         String startSystemDivTag
@@ -417,7 +484,7 @@ public class ChatConversationPanel
             this.lastIncomingMsgTimestamp = System.currentTimeMillis();
 
             chatString      = "<h2 identifier=\"" + msgHeaderID + "\""
-                                    + " date=\"" + date + "\">"
+                                    + dateAttr + ">"
                                     + "<a style=\"color:#ef7b1e;"
                                     + "font-weight:bold;"
                                     + "text-decoration:none;\" "
@@ -427,8 +494,8 @@ public class ChatConversationPanel
 
             chatString
                 += dateString + contactDisplayName + " at "
-                    + GuiUtils.formatTime(date)
-                    + endHeaderTag + startDivTag + startPlainTextTag
+                    + GuiUtils.formatTime(date) + editedAtTag + endHeaderTag
+                    + startDivTag + startPlainTextTag
                     + formatMessage(message, contentType, keyword)
                     + endPlainTextTag + endDivTag;
         }
@@ -451,7 +518,7 @@ public class ChatConversationPanel
         else if (messageType.equals(Chat.OUTGOING_MESSAGE))
         {
             chatString      = "<h3 identifier=\"" + msgHeaderID + "\""
-                                    + " date=\"" + date + "\">"
+                                    + dateAttr + ">"
                                     + "<a style=\"color:#2e538b;"
                                     + "font-weight:bold;"
                                     + "text-decoration:none;\" "
@@ -461,7 +528,7 @@ public class ChatConversationPanel
 
             chatString
                 += dateString + contactDisplayName + " at "
-                    + GuiUtils.formatTime(date) + endHeaderTag
+                    + GuiUtils.formatTime(date) + editedAtTag + endHeaderTag
                     + startDivTag + startPlainTextTag
                     + formatMessage(message, contentType, keyword)
                     + endPlainTextTag + endDivTag;
@@ -514,7 +581,7 @@ public class ChatConversationPanel
         else if (messageType.equals(Chat.HISTORY_INCOMING_MESSAGE))
         {
             chatString      = "<h2 identifier=\"" + msgHeaderID + "\""
-                                    + " date=\"" + date + "\">"
+                                + dateAttr + ">"
                                 + "<a style=\"color:#ef7b1e;"
                                 + "font-weight:bold;"
                                 + "text-decoration:none;\" "
@@ -524,15 +591,15 @@ public class ChatConversationPanel
 
             chatString
                 += dateString + contactDisplayName
-                    + " at " + GuiUtils.formatTime(date)
-                    + endHeaderTag + startHistoryDivTag + startPlainTextTag
+                    + " at " + GuiUtils.formatTime(date) + endHeaderTag
+                    + editedAtTag + startHistoryDivTag + startPlainTextTag
                     + formatMessage(message, contentType, keyword)
                     + endPlainTextTag + endDivTag;
         }
         else if (messageType.equals(Chat.HISTORY_OUTGOING_MESSAGE))
         {
             chatString      = "<h3 identifier=\"" + msgHeaderID + "\""
-                                    + " date=\"" + date + "\">"
+                                + dateAttr + ">"
                                 + "<a style=\"color:#2e538b;"
                                 + "font-weight:bold;"
                                 + "text-decoration:none;\" "
@@ -542,8 +609,8 @@ public class ChatConversationPanel
 
             chatString
                 += dateString
-                    + contactDisplayName
-                    + " at " + GuiUtils.formatTime(date) + endHeaderTag
+                    + contactDisplayName + " at " + GuiUtils.formatTime(date)
+                    + editedAtTag + endHeaderTag
                     + startHistoryDivTag + startPlainTextTag
                     + formatMessage(message, contentType, keyword)
                     + endPlainTextTag + endDivTag;
@@ -564,6 +631,68 @@ public class ChatConversationPanel
     }
 
     /**
+     * Replaces the contents of the message with ID of the corrected message
+     * specified in chatMessage, with this message.
+     * 
+     * @param chatMessage A <tt>ChatMessage</tt> that contains all the required
+     * information to correct the old message.
+     */
+    public void correctMessage(ChatMessage chatMessage)
+    {
+        String correctedUID = chatMessage.getCorrectedMessageUID();
+        Element root = document.getDefaultRootElement();
+        Element e = document.getElement(root, Attribute.ID, correctedUID);
+        if (e == null)
+        {
+            logger.warn("Could not find message with ID " + correctedUID);
+            return;
+        }
+        int len = e.getEndOffset() - e.getStartOffset();
+        
+        StringBuilder newContents = new StringBuilder();
+        String bgColor = GuiActivator.getResources().getColorString(
+                "service.gui.CHAT_EDIT_MESSAGE_BACKGROUND");
+        newContents.append("<div identifier='message' id='");
+        newContents.append(chatMessage.getMessageUID());
+        newContents.append("' bgcolor='");
+        newContents.append(bgColor);
+        newContents.append("'>");
+        if (chatMessage.getContentType().equals(TEXT_CONTENT_TYPE))
+        {
+            newContents.append(START_PLAINTEXT_TAG);
+            newContents.append(chatMessage.getMessage());
+            newContents.append(END_PLAINTEXT_TAG);
+        }
+        else
+        {
+            newContents.append(chatMessage.getMessage());
+        }
+        newContents.append("</div>");
+        
+        Element header = document.getElement(root, Attribute.ID,
+                correctedUID + "-editedAt");
+        
+        try
+        {
+            if (header != null)
+            {
+                String newHeaderContents = generateEditedAtTag(
+                        chatMessage.getMessageUID(), chatMessage.getDate());
+                document.setOuterHTML(header, newHeaderContents);
+            }
+            document.setOuterHTML(e, newContents.toString());
+        }
+        catch (BadLocationException ex)
+        {
+            logger.error("Could not replace chat message", ex);
+        }
+        catch (IOException ex)
+        {
+            logger.error("Could not replace chat message", ex);
+        }
+    }
+
+    /**
      * Appends the given string at the end of the contained in this panel
      * document.
      *
diff --git a/src/net/java/sip/communicator/impl/gui/main/chat/ChatMessage.java b/src/net/java/sip/communicator/impl/gui/main/chat/ChatMessage.java
index ca48a06..98e006a 100644
--- a/src/net/java/sip/communicator/impl/gui/main/chat/ChatMessage.java
+++ b/src/net/java/sip/communicator/impl/gui/main/chat/ChatMessage.java
@@ -49,6 +49,17 @@ public class ChatMessage
      * The content type of the message.
      */
     private final String contentType;
+    
+    /**
+     * A unique identifier for this message.
+     */
+    private String messageUID;
+    
+    /**
+     * The unique identifier of the message that this message should replace,
+     * or <tt>null</tt> if this is a new message.
+     */
+    private String correctedMessageUID;
 
     /**
      * Creates a <tt>ChatMessage</tt> by specifying all parameters of the
@@ -65,7 +76,8 @@ public class ChatMessage
                         String message,
                         String contentType)
     {
-        this(contactName, null, date, messageType, null, message, contentType);
+        this(contactName, null, date, messageType,
+                null, message, contentType, null, null);
     }
 
     /**
@@ -86,7 +98,7 @@ public class ChatMessage
                         String contentType)
     {
         this(contactName, null, date, messageType,
-            messageTitle, message, contentType);
+                messageTitle, message, contentType, null, null);
     }
 
     /**
@@ -107,7 +119,7 @@ public class ChatMessage
                         String contentType)
     {
         this(contactName, contactDisplayName, date, messageType,
-            null, message, contentType);
+                null, message, contentType, null, null);
     }
 
     /**
@@ -119,6 +131,8 @@ public class ChatMessage
      * @param messageType the type (INCOMING or OUTGOING)
      * @param message the content
      * @param contentType the content type (e.g. "text", "text/html", etc.)
+     * @param messageUID The ID of the message.
+     * @param correctedMessageUID The ID of the message being replaced.
      */
     public ChatMessage( String contactName,
                         String contactDisplayName,
@@ -126,7 +140,9 @@ public class ChatMessage
                         String messageType,
                         String messageTitle,
                         String message,
-                        String contentType)
+                        String contentType,
+                        String messageUID,
+                        String correctedMessageUID)
     {
         this.contactName = contactName;
         this.contactDisplayName = contactDisplayName;
@@ -135,6 +151,8 @@ public class ChatMessage
         this.messageTitle = messageTitle;
         this.message = message;
         this.contentType = contentType;
+        this.messageUID = messageUID;
+        this.correctedMessageUID = correctedMessageUID;
     }
 
     /**
@@ -216,4 +234,26 @@ public class ChatMessage
     {
         return contentType;
     }
+    
+    /**
+     * Returns the UID of this message.
+     * 
+     * @return the UID of this message.
+     */
+    public String getMessageUID()
+    {
+        return messageUID;
+    }
+
+    /**
+     * Returns the UID of the message that this message replaces, or
+     * <tt>null</tt> if this is a new message.
+     * 
+     * @return the UID of the message that this message replaces, or
+     * <tt>null</tt> if this is a new message.
+     */
+    public String getCorrectedMessageUID()
+    {
+        return correctedMessageUID;
+    }
 }
diff --git a/src/net/java/sip/communicator/impl/gui/main/chat/ChatPanel.java b/src/net/java/sip/communicator/impl/gui/main/chat/ChatPanel.java
index 70a8ab9..9cf6f62 100644
--- a/src/net/java/sip/communicator/impl/gui/main/chat/ChatPanel.java
+++ b/src/net/java/sip/communicator/impl/gui/main/chat/ChatPanel.java
@@ -138,6 +138,17 @@ public class ChatPanel
      */
     private final Hashtable<String, Object> activeFileTransfers
         = new Hashtable<String, Object>();
+    
+    /**
+     * The ID of the message being corrected, or <tt>null</tt> if
+     * not correcting any message.
+     */
+    private String correctedMessageUID = null;
+    
+    /**
+     * The ID of the last sent message in this chat.
+     */
+    private String lastSentMessageUID = null;
 
     /**
      * Creates a <tt>ChatPanel</tt> which is added to the given chat window.
@@ -490,6 +501,17 @@ public class ChatPanel
     }
 
     /**
+     * Returns the ID of the last message sent in this chat, or <tt>null</tt>
+     * if no messages have been sent yet.
+     * 
+     * @return the ID of the last message sent in this chat, or <tt>null</tt>
+     * if no messages have been sent yet.
+     */
+    public String getLastSentMessageUID() {
+        return lastSentMessageUID;
+    }
+
+    /**
      * Every time the chat panel is shown we set it as a current chat panel.
      * This is done here and not in the Tab selection listener, because the tab
      * change event is not fired when the user clicks on the close tab button
@@ -589,7 +611,8 @@ public class ChatPanel
                             evt.getTimestamp(),
                             messageType,
                             evt.getSourceMessage().getContent(),
-                            evt.getSourceMessage().getContentType());
+                            evt.getSourceMessage().getContentType(),
+                            evt.getSourceMessage().getMessageUID());
             }
             else if(o instanceof MessageReceivedEvent)
             {
@@ -612,7 +635,8 @@ public class ChatPanel
                                 evt.getTimestamp(),
                                 messageType,
                                 evt.getSourceMessage().getContent(),
-                                evt.getSourceMessage().getContentType());
+                                evt.getSourceMessage().getContentType(),
+                                evt.getSourceMessage().getMessageUID());
                 }
             }
             else if(o instanceof ChatRoomMessageDeliveredEvent)
@@ -684,7 +708,8 @@ public class ChatPanel
     public void addMessage(String contactName, long date,
             String messageType, String message, String contentType)
     {
-        addMessage(contactName, null, date, messageType, message, contentType);
+        addMessage(contactName, null, date, messageType, message, contentType,
+                null, null);
     }
 
     /**
@@ -701,11 +726,12 @@ public class ChatPanel
      * @param contentType the content type
      */
     public void addMessage(String contactName, String displayName, long date,
-            String messageType, String message, String contentType)
+            String messageType, String message, String contentType,
+            String messageUID, String correctedMessageUID)
     {
-        ChatMessage chatMessage
-            = new ChatMessage(contactName, displayName, date,
-                messageType, message, contentType);
+        ChatMessage chatMessage = new ChatMessage(contactName, displayName,
+                date, messageType, null, message, contentType,
+                messageUID, correctedMessageUID);
 
         this.addChatMessage(chatMessage);
 
@@ -769,11 +795,15 @@ public class ChatPanel
         }
         else
         {
-            appendChatMessage(chatMessage);
+            displayChatMessage(chatMessage);
         }
 
         // change the last history message timestamp after we add one.
         this.lastHistoryMsgTimestamp = chatMessage.getDate();
+        if (chatMessage.getMessageType().equals(Chat.OUTGOING_MESSAGE))
+        {
+            this.lastSentMessageUID = chatMessage.getMessageUID();
+        }
     }
 
     /**
@@ -809,6 +839,20 @@ public class ChatPanel
                 message, "text");
     }
 
+    private void displayChatMessage(ChatMessage chatMessage)
+    {
+        if (chatMessage.getCorrectedMessageUID() != null
+                && conversationPanel.getMessageContents(
+                chatMessage.getCorrectedMessageUID()) != null)
+        {
+            applyMessageCorrection(chatMessage);
+        }
+        else
+        {
+            appendChatMessage(chatMessage);
+        }
+    }
+
     /**
      * Passes the message to the contained <code>ChatConversationPanel</code>
      * for processing and appends it at the end of the conversationPanel
@@ -855,6 +899,17 @@ public class ChatPanel
 
     /**
      * Passes the message to the contained <code>ChatConversationPanel</code>
+     * for processing and replaces the specified message with this one.
+     *
+     * @param chatMessage The message used as a correction.
+     */
+    private void applyMessageCorrection(ChatMessage message)
+    {
+        conversationPanel.correctMessage(message);
+    }
+
+    /**
+     * Passes the message to the contained <code>ChatConversationPanel</code>
      * for processing.
      *
      * @param contactName The name of the contact sending the message.
@@ -875,9 +930,37 @@ public class ChatPanel
                                          String message,
                                          String contentType)
     {
+      return processHistoryMessage(contactName, contactDisplayName,
+              date, messageType, message, contentType, null);
+    }
+
+    /**
+     * Passes the message to the contained <code>ChatConversationPanel</code>
+     * for processing.
+     *
+     * @param contactName The name of the contact sending the message.
+     * @param contactDisplayName the display name of the contact sending the
+     * message
+     * @param date The time at which the message is sent or received.
+     * @param messageType The type of the message. One of OUTGOING_MESSAGE
+     * or INCOMING_MESSAGE.
+     * @param message The message text.
+     * @param contentType the content type of the message (html or plain text)
+     * @param messageId The ID of the message.
+     *
+     * @return a string containing the processed message.
+     */
+    private String processHistoryMessage(String contactName,
+                                         String contactDisplayName,
+                                         long date,
+                                         String messageType,
+                                         String message,
+                                         String contentType,
+                                         String messageId)
+    {
         ChatMessage chatMessage = new ChatMessage(
             contactName, contactDisplayName, date,
-                messageType, null, message, contentType);
+                messageType, null, message, contentType, messageId, null);
 
         String processedMessage =
             this.conversationPanel.processMessage(chatMessage);
@@ -1372,7 +1455,7 @@ public class ChatPanel
                 OperationSetBasicInstantMessaging.HTML_MIME_TYPE).trim();
 
             plainText = getTextFromWriteArea(
-                OperationSetBasicInstantMessaging.DEFAULT_MIME_TYPE);
+                OperationSetBasicInstantMessaging.DEFAULT_MIME_TYPE).trim();
 
             // clear the message earlier
             // to avoid as much as possible to not sending it twice (double enter)
@@ -1399,8 +1482,19 @@ public class ChatPanel
 
         try
         {
-            chatSession.getCurrentChatTransport()
-                .sendInstantMessage(messageText, mimeType);
+            if (isMessageCorrectionActive()
+                    && chatSession.getCurrentChatTransport()
+                        .allowsMessageCorrections())
+            {
+                chatSession.getCurrentChatTransport().correctInstantMessage(
+                        messageText, mimeType, correctedMessageUID);
+            }
+            else
+            {
+                chatSession.getCurrentChatTransport().sendInstantMessage(
+                        messageText, mimeType);
+            }
+            stopMessageCorrection();
         }
         catch (IllegalStateException ex)
         {
@@ -1459,6 +1553,58 @@ public class ChatPanel
     }
 
     /**
+     * Enters editing mode for the last sent message in this chat.
+     */
+    public void startLastMessageCorrection()
+    {
+        startMessageCorrection(lastSentMessageUID);
+    }
+
+    /**
+     * Enters editing mode for the message with the specified id - puts the
+     * message contents in the write panel and changes the background.
+     * 
+     * @param correctedMessageUID The ID of the message being corrected.
+     */
+    public void startMessageCorrection(String correctedMessageUID)
+    {
+        this.correctedMessageUID = correctedMessageUID;
+        this.refreshWriteArea();
+        String messageContents
+            = conversationPanel.getMessageContents(correctedMessageUID);
+        if (messageContents == null)
+        {
+            this.stopMessageCorrection();
+            return;
+        }
+        Color bgColor = new Color(GuiActivator.getResources()
+                .getColor("service.gui.CHAT_EDIT_MESSAGE_BACKGROUND"));
+        this.writeMessagePanel.setEditorPaneBackground(bgColor);
+        this.setMessage(messageContents);
+    }
+
+    /**
+     * Exits editing mode, clears the write panel and the background.
+     */
+    public void stopMessageCorrection()
+    {
+        this.correctedMessageUID = null;
+        this.writeMessagePanel.setEditorPaneBackground(Color.WHITE);
+        this.refreshWriteArea();
+    }
+
+    /**
+     * Returns whether a message is currently being edited.
+     * 
+     * @return <tt>true</tt> if a message is currently being edited,
+     * <tt>false</tt> otherwise.
+     */
+    public boolean isMessageCorrectionActive()
+    {
+        return correctedMessageUID != null;
+    }
+
+    /**
      * Listens for SMS messages and shows them in the chat.
      */
     private class SmsMessageListener implements MessageListener
@@ -2358,7 +2504,7 @@ public class ChatPanel
 
                 if (incomingEvent instanceof ChatMessage)
                 {
-                    this.appendChatMessage((ChatMessage) incomingEvent);
+                    this.displayChatMessage((ChatMessage) incomingEvent);
                 }
                 else if (incomingEvent instanceof ChatConversationComponent)
                 {
diff --git a/src/net/java/sip/communicator/impl/gui/main/chat/ChatTransport.java b/src/net/java/sip/communicator/impl/gui/main/chat/ChatTransport.java
index ba13dbc..12aeedd 100644
--- a/src/net/java/sip/communicator/impl/gui/main/chat/ChatTransport.java
+++ b/src/net/java/sip/communicator/impl/gui/main/chat/ChatTransport.java
@@ -35,6 +35,15 @@ public interface ChatTransport
      * messaging, otherwise returns <code>false</code>
      */
     public boolean allowsInstantMessage();
+    
+    /**
+     * Returns <tt>true</tt> if this chat transport supports message
+     * corrections and false otherwise.
+     * 
+     * @return <code>true</code> if this chat transport supports message
+     * corrections and false otherwise.
+     */
+    public boolean allowsMessageCorrections();
 
     /**
      * Returns <code>true</code> if this chat transport supports sms
@@ -100,6 +109,20 @@ public interface ChatTransport
     public void sendInstantMessage( String message,
                                     String mimeType)
         throws Exception;
+	
+    /**
+     * Sends <tt>message</tt> as a message correction through this transport,
+     * specifying the mime type (html or plain text) and the id of the
+     * message to replace.
+     * 
+     * @param message The message to send.
+     * @param mimeType The mime type of the message to send: text/html or
+     * text/plain.
+     * @param correctedMessageUID The ID of the message being corrected by
+     * this message.
+     */
+    public void correctInstantMessage(String message, String mimeType,
+            String correctedMessageUID);
 
     /**
      * Determines whether this chat transport supports the supplied content type
diff --git a/src/net/java/sip/communicator/impl/gui/main/chat/ChatWritePanel.java b/src/net/java/sip/communicator/impl/gui/main/chat/ChatWritePanel.java
index a93cedb..855dd77 100755
--- a/src/net/java/sip/communicator/impl/gui/main/chat/ChatWritePanel.java
+++ b/src/net/java/sip/communicator/impl/gui/main/chat/ChatWritePanel.java
@@ -674,6 +674,27 @@ public class ChatWritePanel
                 ex.printStackTrace();
             }
         }
+        else if (e.getKeyCode() == KeyEvent.VK_UP)
+        {
+            // Only enters editing mode if the write panel is empty in
+            // order not to lose the current message contents, if any.
+            if (this.chatPanel.getLastSentMessageUID() != null
+                    && this.chatPanel.isWriteAreaEmpty())
+            {
+                this.chatPanel.startLastMessageCorrection();
+            }
+        }
+        else if (e.getKeyCode() == KeyEvent.VK_DOWN)
+        {
+            if (chatPanel.isMessageCorrectionActive())
+            {
+                Document doc = editorPane.getDocument();
+                if (editorPane.getCaretPosition() == doc.getLength())
+                {
+                    chatPanel.stopMessageCorrection();
+                }
+            }
+        }
     }
 
     public void keyReleased(KeyEvent e) {}
@@ -1297,4 +1318,15 @@ public class ChatWritePanel
             smsNumberLabel.setText(String.valueOf(smsNumberCount));
         }
     }
+
+    /**
+     * Sets the background of the write area to the specified color.
+     * 
+     * @param color The color to set the background to.
+     */
+    public void setEditorPaneBackground(Color color)
+    {
+        this.centerPanel.setBackground(color);
+        this.editorPane.setBackground(color);
+    }
 }
diff --git a/src/net/java/sip/communicator/impl/gui/main/chat/MetaContactChatTransport.java b/src/net/java/sip/communicator/impl/gui/main/chat/MetaContactChatTransport.java
index e3e0b83..73a8ae9 100644
--- a/src/net/java/sip/communicator/impl/gui/main/chat/MetaContactChatTransport.java
+++ b/src/net/java/sip/communicator/impl/gui/main/chat/MetaContactChatTransport.java
@@ -110,9 +110,6 @@ public class MetaContactChatTransport
         }
     }
 
-
-
-
     /**
      * Returns the contact associated with this transport.
      * @return the contact associated with this transport
@@ -194,6 +191,30 @@ public class MetaContactChatTransport
     }
 
     /**
+     * Returns <code>true</code> if this chat transport supports message
+     * corrections and false otherwise.
+     * 
+     * @return <code>true</code> if this chat transport supports message
+     * corrections and false otherwise.
+     */
+    public boolean allowsMessageCorrections()
+    {
+        OperationSetContactCapabilities capOpSet = getProtocolProvider()
+                .getOperationSet(OperationSetContactCapabilities.class);
+
+        if (capOpSet != null)
+        {
+            return capOpSet.getOperationSet(
+                    contact, OperationSetMessageCorrection.class) != null;
+        }
+        else
+        {
+            return contact.getProtocolProvider().getOperationSet(
+                    OperationSetMessageCorrection.class) != null;
+        }
+    }
+
+    /**
      * Returns <code>true</code> if this chat transport supports sms
      * messaging, otherwise returns <code>false</code>.
      * 
@@ -260,8 +281,8 @@ public class MetaContactChatTransport
     }
 
     /**
-     * Sends the given instant message trough this chat transport, by specifying
-     * the mime type (html or plain text).
+     * Sends the given instant message through this chat transport,
+     * by specifying the mime type (html or plain text).
      *
      * @param message The message to send.
      * @param mimeType The mime type of the message to send: text/html or
@@ -299,6 +320,45 @@ public class MetaContactChatTransport
     }
 
     /**
+     * Sends <tt>message</tt> as a message correction through this transport,
+     * specifying the mime type (html or plain text) and the id of the
+     * message to replace.
+     * 
+     * @param message The message to send.
+     * @param mimeType The mime type of the message to send: text/html or
+     * text/plain.
+     * @param correctedMessageUID The ID of the message being corrected by
+     * this message.
+     */
+    public void correctInstantMessage(String message, String mimeType,
+            String correctedMessageUID)
+    {
+        if (!allowsMessageCorrections())
+        {
+            return;
+        }
+
+        OperationSetMessageCorrection mcOpSet = contact.getProtocolProvider()
+                .getOperationSet(OperationSetMessageCorrection.class);
+
+        Message msg;
+        if (mimeType.equals(OperationSetBasicInstantMessaging.HTML_MIME_TYPE)
+                && mcOpSet.isContentTypeSupported(
+                OperationSetBasicInstantMessaging.HTML_MIME_TYPE))
+        {
+            msg = mcOpSet.createMessage(message,
+                    OperationSetBasicInstantMessaging.HTML_MIME_TYPE,
+                    "utf-8", "");
+        }
+        else
+        {
+            msg = mcOpSet.createMessage(message);
+        }
+
+        mcOpSet.correctMessage(contact, msg, correctedMessageUID);
+    }
+
+    /**
      * Determines whether this chat transport supports the supplied content type
      *
      * @param contentType the type we want to check
diff --git a/src/net/java/sip/communicator/impl/gui/main/chat/conference/AdHocConferenceChatTransport.java b/src/net/java/sip/communicator/impl/gui/main/chat/conference/AdHocConferenceChatTransport.java
index 195ea78..48a27dd 100644
--- a/src/net/java/sip/communicator/impl/gui/main/chat/conference/AdHocConferenceChatTransport.java
+++ b/src/net/java/sip/communicator/impl/gui/main/chat/conference/AdHocConferenceChatTransport.java
@@ -316,4 +316,31 @@ public class AdHocConferenceChatTransport
         // TODO Auto-generated method stub
         return 0;
     }
+
+    /**
+     * Returns <tt>true</tt> if this chat transport supports message
+     * corrections and false otherwise.
+     * 
+     * @return <tt>true</tt> if this chat transport supports message
+     * corrections and false otherwise.
+     */
+    public boolean allowsMessageCorrections()
+    {
+        return false;
+    }
+
+    /**
+     * Sends <tt>message</tt> as a message correction through this transport,
+     * specifying the mime type (html or plain text) and the id of the
+     * message to replace.
+     * 
+     * @param message The message to send.
+     * @param mimeType The mime type of the message to send: text/html or
+     * text/plain.
+     * @param correctedMessageUID The ID of the message being corrected by
+     * this message.
+     */
+    public void correctInstantMessage(String message, String mimeType,
+            String correctedMessageUID)
+    {}
 }
diff --git a/src/net/java/sip/communicator/impl/gui/main/chat/conference/ConferenceChatTransport.java b/src/net/java/sip/communicator/impl/gui/main/chat/conference/ConferenceChatTransport.java
index d4f196a..e2bd0e5 100644
--- a/src/net/java/sip/communicator/impl/gui/main/chat/conference/ConferenceChatTransport.java
+++ b/src/net/java/sip/communicator/impl/gui/main/chat/conference/ConferenceChatTransport.java
@@ -318,4 +318,31 @@ public class ConferenceChatTransport
     {
         return chatRoom;
     }
+
+    /**
+     * Sends <tt>message</tt> as a message correction through this transport,
+     * specifying the mime type (html or plain text) and the id of the
+     * message to replace.
+     * 
+     * @param message The message to send.
+     * @param mimeType The mime type of the message to send: text/html or
+     * text/plain.
+     * @param correctedMessageUID The ID of the message being corrected by
+     * this message.
+     */
+	public void correctInstantMessage(String message, String mimeType,
+            String correctedMessageUID)
+    {}
+
+    /**
+     * Returns <code>true</code> if this chat transport supports message
+     * corrections and false otherwise.
+     * 
+     * @return <code>true</code> if this chat transport supports message
+     * corrections and false otherwise.
+     */
+    public boolean allowsMessageCorrections()
+    {
+        return false;
+    }
 }
diff --git a/src/net/java/sip/communicator/impl/gui/main/chat/history/HistoryWindow.java b/src/net/java/sip/communicator/impl/gui/main/chat/history/HistoryWindow.java
index 0a109b6..2c2b216 100644
--- a/src/net/java/sip/communicator/impl/gui/main/chat/history/HistoryWindow.java
+++ b/src/net/java/sip/communicator/impl/gui/main/chat/history/HistoryWindow.java
@@ -278,8 +278,11 @@ public class HistoryWindow
                                 .getAccountDisplayName(protocolProvider),
                             evt.getTimestamp(),
                             Chat.OUTGOING_MESSAGE,
+                            null,
                             evt.getSourceMessage().getContent(),
-                            evt.getSourceMessage().getContentType());
+                            evt.getSourceMessage().getContentType(),
+                            evt.getSourceMessage().getMessageUID(),
+                            null);
                 }
                 else if(o instanceof MessageReceivedEvent)
                 {
@@ -290,8 +293,11 @@ public class HistoryWindow
                         evt.getSourceContact().getDisplayName(),
                         evt.getTimestamp(),
                         Chat.INCOMING_MESSAGE,
+                        null,
                         evt.getSourceMessage().getContent(),
-                        evt.getSourceMessage().getContentType());
+                        evt.getSourceMessage().getContentType(),
+                        evt.getSourceMessage().getMessageUID(),
+                        null);
                 }
                 else if(o instanceof ChatRoomMessageReceivedEvent)
                 {
diff --git a/src/net/java/sip/communicator/impl/gui/main/contactlist/ContactListPane.java b/src/net/java/sip/communicator/impl/gui/main/contactlist/ContactListPane.java
index 2f9e23b..9243cb9 100644
--- a/src/net/java/sip/communicator/impl/gui/main/contactlist/ContactListPane.java
+++ b/src/net/java/sip/communicator/impl/gui/main/contactlist/ContactListPane.java
@@ -238,8 +238,8 @@ public class ContactListPane
 
         if(metaContact != null)
         {
-            messageReceived(protocolContact,
-                metaContact, message, eventType, evt.getTimestamp());
+            messageReceived(protocolContact, metaContact, message, eventType,
+                    evt.getTimestamp(), evt.getCorrectedMessageUID());
         }
         else
         {
@@ -266,7 +266,8 @@ public class ContactListPane
                                  final MetaContact metaContact,
                                  final Message message,
                                  final int eventType,
-                                 final long timestamp)
+                                 final long timestamp,
+                                 final String correctedMessageUID)
     {
         if(!SwingUtilities.isEventDispatchThread())
         {
@@ -274,8 +275,8 @@ public class ContactListPane
             {
                 public void run()
                 {
-                    messageReceived(protocolContact,
-                        metaContact, message, eventType, timestamp);
+                    messageReceived(protocolContact, metaContact, message,
+                            eventType, timestamp, correctedMessageUID);
                 }
             });
             return;
@@ -315,7 +316,9 @@ public class ContactListPane
             timestamp,
             messageType,
             message.getContent(),
-            message.getContentType());
+            message.getContentType(),
+            message.getMessageUID(),
+            correctedMessageUID);
 
         chatWindowManager.openChat(chatPanel, false);
 
@@ -361,7 +364,9 @@ public class ContactListPane
                 evt.getTimestamp(),
                 Chat.OUTGOING_MESSAGE,
                 msg.getContent(),
-                msg.getContentType());
+                msg.getContentType(),
+                msg.getMessageUID(),
+                evt.getCorrectedMessageUID());
         }
     }
 
@@ -429,7 +434,9 @@ public class ContactListPane
                 System.currentTimeMillis(),
                 Chat.OUTGOING_MESSAGE,
                 sourceMessage.getContent(),
-                sourceMessage.getContentType());
+                sourceMessage.getContentType(),
+                sourceMessage.getMessageUID(),
+                evt.getCorrectedMessageUID());
 
         chatPanel.addErrorMessage(
                 metaContact.getDisplayName(),
diff --git a/src/net/java/sip/communicator/impl/protocol/jabber/MessageJabberImpl.java b/src/net/java/sip/communicator/impl/protocol/jabber/MessageJabberImpl.java
index f502d2b..d417ebc 100755
--- a/src/net/java/sip/communicator/impl/protocol/jabber/MessageJabberImpl.java
+++ b/src/net/java/sip/communicator/impl/protocol/jabber/MessageJabberImpl.java
@@ -33,4 +33,21 @@ public class MessageJabberImpl
     {
         super(content, contentType, contentEncoding, subject);
     }
+    
+    /**
+     * Creates an instance of this Message with the specified parameters.
+     * 
+     * @param content the text content of the message.
+     * @param contentType a MIME string indicating the content type of the
+     *            <tt>content</tt> String.
+     * @param contentEncoding a MIME String indicating the content encoding of
+     *            the <tt>content</tt> String.
+     * @param subject the subject of the message or null for empty.
+     * @param 
+     */
+    public MessageJabberImpl(String content, String contentType,
+        String contentEncoding, String subject, String messageUID)
+    {
+        super(content, contentType, contentEncoding, subject, messageUID);
+    }
 }
diff --git a/src/net/java/sip/communicator/impl/protocol/jabber/OperationSetBasicInstantMessagingJabberImpl.java b/src/net/java/sip/communicator/impl/protocol/jabber/OperationSetBasicInstantMessagingJabberImpl.java
index 3b14c28..ff7763a 100644
--- a/src/net/java/sip/communicator/impl/protocol/jabber/OperationSetBasicInstantMessagingJabberImpl.java
+++ b/src/net/java/sip/communicator/impl/protocol/jabber/OperationSetBasicInstantMessagingJabberImpl.java
@@ -9,6 +9,7 @@ package net.java.sip.communicator.impl.protocol.jabber;
 import java.util.*;
 
 import net.java.sip.communicator.impl.protocol.jabber.extensions.mailnotification.*;
+import net.java.sip.communicator.impl.protocol.jabber.extensions.messagecorrection.*;
 import net.java.sip.communicator.service.protocol.*;
 import net.java.sip.communicator.service.protocol.Message;
 import net.java.sip.communicator.service.protocol.event.*;
@@ -34,6 +35,7 @@ import org.jivesoftware.smackx.packet.*;
  */
 public class OperationSetBasicInstantMessagingJabberImpl
     extends AbstractOperationSetBasicInstantMessaging
+    implements OperationSetMessageCorrection
 {
     /**
      * Our class logger
@@ -129,6 +131,13 @@ public class OperationSetBasicInstantMessagingJabberImpl
         this.jabberProvider = provider;
         provider.addRegistrationStateChangeListener(
                         new RegistrationStateListener());
+
+        ProviderManager man = ProviderManager.getInstance();
+        MessageCorrectionExtensionProvider extProvider =
+                new MessageCorrectionExtensionProvider();
+        man.addExtensionProvider(MessageCorrectionExtension.ELEMENT_NAME,
+                MessageCorrectionExtension.NAMESPACE,
+                extProvider);
     }
 
     /**
@@ -159,6 +168,13 @@ public class OperationSetBasicInstantMessagingJabberImpl
         return new MessageJabberImpl(content, contentType, encoding, subject);
     }
 
+    private Message createMessage(String content, String contentType,
+            String messageUID)
+    {
+        return new MessageJabberImpl(content, contentType,
+                DEFAULT_MIME_ENCODING, null, messageUID);
+    }
+
     /**
      * Determines wheter the protocol provider (or the protocol itself) support
      * sending and receiving offline messages. Most often this method would
@@ -350,18 +366,18 @@ public class OperationSetBasicInstantMessagingJabberImpl
     }
 
     /**
-     * Sends the <tt>message</tt> to the destination indicated by the
-     * <tt>to</tt> contact.
-     *
-     * @param to the <tt>Contact</tt> to send <tt>message</tt> to
-     * @param message the <tt>Message</tt> to send.
-     * @throws java.lang.IllegalStateException if the underlying stack is
-     * not registered and initialized.
-     * @throws java.lang.IllegalArgumentException if <tt>to</tt> is not an
-     * instance of ContactImpl.
+     * Helper function used to send a message to a contact, with the given
+     * extensions attached.
+     * 
+     * @param to The contact to send the message to.
+     * @param message The message to send.
+     * @param extensions The XMPP extensions that should be attached to the
+     * message before sending.
+     * @return The MessageDeliveryEvent that resulted after attempting to
+     * send this message, so the calling function can modify it if needed.
      */
-    public void sendInstantMessage(Contact to, Message message)
-        throws IllegalStateException, IllegalArgumentException
+    private MessageDeliveredEvent sendMessage(Contact to, Message message,
+            PacketExtension[] extensions)
     {
         if( !(to instanceof ContactJabberImpl) )
            throw new IllegalArgumentException(
@@ -382,8 +398,14 @@ public class OperationSetBasicInstantMessagingJabberImpl
 
             Chat chat = obtainChatInstance(toJID);
 
+            msg.setPacketID(message.getMessageUID());
             msg.setTo(toJID);
 
+            for (PacketExtension ext : extensions)
+            {
+                msg.addExtension(ext);
+            }
+
             if (logger.isTraceEnabled())
                 logger.trace("Will send a message to:" + toJID
                             + " chat.jid=" + chat.getParticipant()
@@ -396,7 +418,7 @@ public class OperationSetBasicInstantMessagingJabberImpl
                 = messageDeliveryPendingTransform(msgDeliveryPendingEvt);
 
             if (msgDeliveryPendingEvt == null)
-                return;
+                return null;
 
             String content = msgDeliveryPendingEvt
                                     .getSourceMessage().getContent();
@@ -421,7 +443,7 @@ public class OperationSetBasicInstantMessagingJabberImpl
                 // this is plain text so keep it as it is.
                 msg.setBody(content);
             }
-
+            
             //msg.addExtension(new Version());
 
             MessageEventManager.
@@ -434,16 +456,53 @@ public class OperationSetBasicInstantMessagingJabberImpl
 
             // msgDeliveredEvt = messageDeliveredTransform(msgDeliveredEvt);
 
-            if (msgDeliveredEvt != null)
-                fireMessageEvent(msgDeliveredEvt);
+            return msgDeliveredEvt;
         }
         catch (XMPPException ex)
         {
-            logger.error("message not send", ex);
+            logger.error("message not sent", ex);
+            return null;
         }
     }
 
     /**
+     * Sends the <tt>message</tt> to the destination indicated by the
+     * <tt>to</tt> contact.
+     *
+     * @param to the <tt>Contact</tt> to send <tt>message</tt> to
+     * @param message the <tt>Message</tt> to send.
+     * @throws java.lang.IllegalStateException if the underlying stack is
+     * not registered and initialized.
+     * @throws java.lang.IllegalArgumentException if <tt>to</tt> is not an
+     * instance of ContactImpl.
+     */
+    public void sendInstantMessage(Contact to, Message message)
+        throws IllegalStateException, IllegalArgumentException
+    {
+        MessageDeliveredEvent msgDelivered =
+                sendMessage(to, message, new PacketExtension[0]);
+        fireMessageEvent(msgDelivered);
+    }
+
+    /**
+     * Replaces the message with ID <tt>correctedMessageUID</tt> sent to
+     * the contact <tt>to</tt> with the message <tt>message</tt>
+     * 
+     * @param to The contact to send the message to.
+     * @param message The new message.
+     * @param correctedMessageUID The ID of the message being replaced.
+     */
+    public void correctMessage(Contact to, Message message,
+            String correctedMessageUID)
+    {
+        PacketExtension[] exts = new PacketExtension[1];
+        exts[0] = new MessageCorrectionExtension(correctedMessageUID);
+        MessageDeliveredEvent msgDelivered = sendMessage(to, message, exts);
+        msgDelivered.setCorrectedMessageUID(correctedMessageUID);
+        fireMessageEvent(msgDelivered);
+    }
+
+    /**
      * Utility method throwing an exception if the stack is not properly
      * initialized.
      *
@@ -581,7 +640,8 @@ public class OperationSetBasicInstantMessagingJabberImpl
                              + msg.toXML());
             }
 
-            Message newMessage = createMessage(msg.getBody());
+            Message newMessage = createMessage(msg.getBody(),
+                    DEFAULT_MIME_TYPE, msg.getPacketID());
 
             //check if the message is available in xhtml
             PacketExtension ext = msg.getExtension(
@@ -619,11 +679,20 @@ public class OperationSetBasicInstantMessagingJabberImpl
                     receivedMessage =
                             receivedMessage.replaceAll("&apos;", "&#39;");
 
-                    newMessage =
-                        createMessage(receivedMessage, HTML_MIME_TYPE);
+                    newMessage = createMessage(receivedMessage,
+                            HTML_MIME_TYPE, msg.getPacketID());
                 }
             }
 
+            PacketExtension correctionExtension =
+                    msg.getExtension(MessageCorrectionExtension.NAMESPACE);
+            String correctedMessageUID = null;
+            if (correctionExtension != null)
+            {
+                correctedMessageUID = ((MessageCorrectionExtension)
+                        correctionExtension).getCorrectedMessageUID();
+            }
+
             Contact sourceContact
                 = opSetPersPresence.findContactByID(fromUserID);
 
@@ -652,6 +721,7 @@ public class OperationSetBasicInstantMessagingJabberImpl
                 MessageDeliveryFailedEvent ev
                     = new MessageDeliveryFailedEvent(newMessage,
                                                      sourceContact,
+                                                     correctedMessageUID,
                                                      errorResultCode);
 
                 // ev = messageDeliveryFailedTransform(ev);
@@ -681,9 +751,8 @@ public class OperationSetBasicInstantMessagingJabberImpl
                     .createVolatileContact(fromUserID);
             }
 
-            MessageReceivedEvent msgReceivedEvt
-                = new MessageReceivedEvent(
-                    newMessage, sourceContact , System.currentTimeMillis() );
+            MessageReceivedEvent msgReceivedEvt = new MessageReceivedEvent(
+                    newMessage, sourceContact, correctedMessageUID);
 
             // msgReceivedEvt = messageReceivedTransform(msgReceivedEvt);
 
diff --git a/src/net/java/sip/communicator/impl/protocol/jabber/OperationSetContactCapabilitiesJabberImpl.java b/src/net/java/sip/communicator/impl/protocol/jabber/OperationSetContactCapabilitiesJabberImpl.java
index b030dfb..35d7f83 100644
--- a/src/net/java/sip/communicator/impl/protocol/jabber/OperationSetContactCapabilitiesJabberImpl.java
+++ b/src/net/java/sip/communicator/impl/protocol/jabber/OperationSetContactCapabilitiesJabberImpl.java
@@ -9,6 +9,7 @@ package net.java.sip.communicator.impl.protocol.jabber;
 import java.util.*;
 
 import net.java.sip.communicator.impl.protocol.jabber.extensions.caps.*;
+import net.java.sip.communicator.impl.protocol.jabber.extensions.messagecorrection.*;
 import net.java.sip.communicator.service.protocol.*;
 import net.java.sip.communicator.service.protocol.event.*;
 import net.java.sip.communicator.util.*;
@@ -70,6 +71,7 @@ public class OperationSetContactCapabilitiesJabberImpl
     static
     {
         OFFLINE_OPERATION_SETS.add(OperationSetBasicInstantMessaging.class);
+        OFFLINE_OPERATION_SETS.add(OperationSetMessageCorrection.class);
 
         OPERATION_SETS_TO_FEATURES.put(
                 OperationSetBasicTelephony.class,
@@ -98,6 +100,13 @@ public class OperationSetContactCapabilitiesJabberImpl
                     ProtocolProviderServiceJabberImpl.URN_XMPP_JINGLE_RTP_VIDEO
                 });
 
+        OPERATION_SETS_TO_FEATURES.put(
+                OperationSetMessageCorrection.class,
+                new String[]
+                {
+                    MessageCorrectionExtension.NAMESPACE
+                });
+
         CAPS_OPERATION_SETS_TO_FEATURES.put(
                 OperationSetBasicTelephony.class,
                 new String[]
diff --git a/src/net/java/sip/communicator/impl/protocol/jabber/ProtocolProviderServiceJabberImpl.java b/src/net/java/sip/communicator/impl/protocol/jabber/ProtocolProviderServiceJabberImpl.java
index 4a2c4c6..3a8197d 100644
--- a/src/net/java/sip/communicator/impl/protocol/jabber/ProtocolProviderServiceJabberImpl.java
+++ b/src/net/java/sip/communicator/impl/protocol/jabber/ProtocolProviderServiceJabberImpl.java
@@ -25,6 +25,7 @@ import net.java.sip.communicator.impl.protocol.jabber.extensions.inputevt.*;
 import net.java.sip.communicator.impl.protocol.jabber.extensions.jingle.*;
 import net.java.sip.communicator.impl.protocol.jabber.extensions.jingleinfo.*;
 import net.java.sip.communicator.impl.protocol.jabber.extensions.keepalive.*;
+import net.java.sip.communicator.impl.protocol.jabber.extensions.messagecorrection.*;
 import net.java.sip.communicator.impl.protocol.jabber.extensions.version.*;
 import net.java.sip.communicator.impl.protocol.jabber.sasl.*;
 import net.java.sip.communicator.service.certificate.*;
@@ -1787,6 +1788,10 @@ public class ProtocolProviderServiceJabberImpl
             if(versionManager == null)
                 versionManager = new VersionManager(this);
 
+            supportedFeatures.add(MessageCorrectionExtension.NAMESPACE);
+            addSupportedOperationSet(OperationSetMessageCorrection.class,
+                    basicInstantMessaging);
+
             isInitialized = true;
         }
     }
diff --git a/src/net/java/sip/communicator/impl/protocol/jabber/extensions/messagecorrection/MessageCorrectionExtension.java b/src/net/java/sip/communicator/impl/protocol/jabber/extensions/messagecorrection/MessageCorrectionExtension.java
new file mode 100644
index 0000000..12e3c4a
--- /dev/null
+++ b/src/net/java/sip/communicator/impl/protocol/jabber/extensions/messagecorrection/MessageCorrectionExtension.java
@@ -0,0 +1,109 @@
+/*
+ * Jitsi, the OpenSource Java VoIP and Instant Messaging client.
+ *
+ * Distributable under LGPL license.
+ * See terms of license at gnu.org.
+ */
+package net.java.sip.communicator.impl.protocol.jabber.extensions.messagecorrection;
+
+import org.jivesoftware.smack.packet.*;
+
+/**
+ * Represents an XMPP Message correction extension, as defined in XEP-308.
+ *
+ * @author Ivan Vergiliev
+ */
+public class MessageCorrectionExtension
+    implements PacketExtension
+{
+    /**
+     * The XMPP namespace that this extension belongs to.
+     */
+    public static final String NAMESPACE = "urn:xmpp:message-correct:0";
+    
+    /**
+     * The XMPP namespace that Swift IM use to send message corrections.
+     * Temporary until they start using the standard one.
+     */
+    public static final String SWIFT_NAMESPACE =
+            "http://swift.im/protocol/replace";
+    
+    /**
+     * The XML element name of this extension.
+     */
+    public static final String ELEMENT_NAME = "replace";
+    
+    /**
+     * Name of the attribute that specifies the ID of the message
+     * being corrected.
+     */
+    public static final String ID_ATTRIBUTE_NAME = "id";
+  
+    /**
+     * The ID of the message being corrected.
+     */
+    private String correctedMessageUID;
+
+    /**
+     * Creates a new message correction extension that corrects the
+     * message specified by the passed ID.
+     * 
+     * @param correctedMessageUID The ID of the message being corrected.
+     */
+    public MessageCorrectionExtension(String correctedMessageUID)
+    {
+        this.correctedMessageUID = correctedMessageUID;
+    }
+
+    /**
+     * Returns the XML element name of this extension.
+     * 
+     * @return The XML element name of this extension.
+     */
+    public String getElementName()
+    {
+        return ELEMENT_NAME;
+    }
+
+    /**
+     * Returns the XML namespace this extension belongs to.
+     * 
+     * @return The XML namespace this extension belongs to.
+     */
+    public String getNamespace()
+    {
+        return NAMESPACE;
+    }
+
+    /**
+     * Construct an XML element representing this extension;
+     * has the form '<replace id="..." xmlns="...">'.
+     * 
+     * @return An XML representation of this extension.
+     */
+    public String toXML()
+    {
+        return "<" + ELEMENT_NAME + " id='" + correctedMessageUID
+                + "' xmlns='" + NAMESPACE + "' />";
+    }
+
+    /**
+     * Returns the correctedMessageUID The UID of the message being corrected.
+     * 
+     * @return the correctedMessageUID The UID of the message being corrected.
+     */
+    public String getCorrectedMessageUID()
+    {
+        return correctedMessageUID;
+    }
+
+    /**
+     * Sets the UID of the message being corrected.
+     * 
+     * @param correctedMessageUID The UID of the message being corrected.
+     */
+    public void setCorrectedMessageUID(String correctedMessageUID)
+    {
+        this.correctedMessageUID = correctedMessageUID;
+    }
+}
diff --git a/src/net/java/sip/communicator/impl/protocol/jabber/extensions/messagecorrection/MessageCorrectionExtensionProvider.java b/src/net/java/sip/communicator/impl/protocol/jabber/extensions/messagecorrection/MessageCorrectionExtensionProvider.java
new file mode 100644
index 0000000..81ac147
--- /dev/null
+++ b/src/net/java/sip/communicator/impl/protocol/jabber/extensions/messagecorrection/MessageCorrectionExtensionProvider.java
@@ -0,0 +1,46 @@
+/*
+ * Jitsi, the OpenSource Java VoIP and Instant Messaging client.
+ *
+ * Distributable under LGPL license.
+ * See terms of license at gnu.org.
+ */
+package net.java.sip.communicator.impl.protocol.jabber.extensions.messagecorrection;
+
+import org.jivesoftware.smack.packet.*;
+import org.jivesoftware.smack.provider.*;
+import org.xmlpull.v1.*;
+
+/**
+ * Creates Smack packet extensions by parsing <replace /> tags
+ * from incoming XMPP packets.
+ *
+ * @author Ivan Vergiliev
+ */
+public class MessageCorrectionExtensionProvider
+    implements PacketExtensionProvider
+{
+
+    /**
+     * Creates a new correction extension by parsing an XML element.
+     * 
+     * @param parser An XML parser.
+     * @return A new MesssageCorrectionExtension parsed from the XML.
+     * @throws Exception if an error occurs parsing the XML.
+     */
+    public PacketExtension parseExtension(XmlPullParser parser) throws Exception
+    {
+        MessageCorrectionExtension res = new MessageCorrectionExtension(null);
+
+        do
+        {
+            if (parser.getEventType() == XmlPullParser.START_TAG)
+            {
+                res.setCorrectedMessageUID(parser.getAttributeValue(
+                        null, MessageCorrectionExtension.ID_ATTRIBUTE_NAME));
+            }
+        }
+        while (parser.next() != XmlPullParser.END_TAG);
+
+        return res;
+    }
+}
diff --git a/src/net/java/sip/communicator/service/protocol/AbstractMessage.java b/src/net/java/sip/communicator/service/protocol/AbstractMessage.java
index a623dd0..620bf78 100644
--- a/src/net/java/sip/communicator/service/protocol/AbstractMessage.java
+++ b/src/net/java/sip/communicator/service/protocol/AbstractMessage.java
@@ -68,7 +68,7 @@ public abstract class AbstractMessage
         setEncoding(encoding);
         setContent(content);
 
-        this.messageUID = messageUID;
+        this.messageUID = messageUID == null ? createMessageUID() : messageUID;
     }
 
     protected String createMessageUID()
diff --git a/src/net/java/sip/communicator/service/protocol/OperationSetMessageCorrection.java b/src/net/java/sip/communicator/service/protocol/OperationSetMessageCorrection.java
new file mode 100644
index 0000000..01c095f
--- /dev/null
+++ b/src/net/java/sip/communicator/service/protocol/OperationSetMessageCorrection.java
@@ -0,0 +1,27 @@
+/*
+ * Jitsi, the OpenSource Java VoIP and Instant Messaging client.
+ *
+ * Distributable under LGPL license.
+ * See terms of license at gnu.org.
+ */
+package net.java.sip.communicator.service.protocol;
+
+/**
+ * Provides functionality for correcting instant messages.
+ *
+ * @author Ivan Vergiliev
+ */
+public interface OperationSetMessageCorrection
+    extends OperationSetBasicInstantMessaging
+{  
+    /**
+     * Replaces the message with ID <tt>correctedMessageUID</tt> sent to
+     * the contact <tt>to</tt> with the message <tt>message</tt>
+     * 
+     * @param to The contact to send the message to.
+     * @param message The new message.
+     * @param correctedMessageUID The ID of the message being replaced.
+     */
+    public void correctMessage(Contact to, Message message,
+            String correctedMessageUID);
+}
diff --git a/src/net/java/sip/communicator/service/protocol/event/MessageDeliveredEvent.java b/src/net/java/sip/communicator/service/protocol/event/MessageDeliveredEvent.java
index 0ffc91b..17a6e0a 100644
--- a/src/net/java/sip/communicator/service/protocol/event/MessageDeliveredEvent.java
+++ b/src/net/java/sip/communicator/service/protocol/event/MessageDeliveredEvent.java
@@ -33,6 +33,12 @@ public class MessageDeliveredEvent
       * A timestamp indicating the exact date when the event occurred.
       */
      private final long timestamp;
+     
+     /**
+      * The ID of the message being corrected, or null if this was a new message
+      * and not a message correction.
+      */
+     private String correctedMessageUID;
 
      /**
       * Constructor.
@@ -44,6 +50,21 @@ public class MessageDeliveredEvent
      {
          this(source, to, System.currentTimeMillis());
      }
+     
+     /**
+      * Creates a <tt>MessageDeliveredEvent</tt> representing delivery of the
+      * <tt>source</tt> message to the specified <tt>to</tt> contact.
+      *
+      * @param source the <tt>Message</tt> whose delivery this event represents.
+      * @param to the <tt>Contact</tt> that this message was sent to.
+      * @param correctedMessageUID The ID of the message being corrected.
+      */
+     public MessageDeliveredEvent(Message source, Contact to,
+             String correctedMessageUID)
+     {
+         this(source, to, System.currentTimeMillis());
+         this.correctedMessageUID = correctedMessageUID;
+     }
 
      /**
       * Creates a <tt>MessageDeliveredEvent</tt> representing delivery of the
@@ -93,4 +114,26 @@ public class MessageDeliveredEvent
          return timestamp;
      }
 
+    /**
+     * Returns the ID of the message being corrected, or null if this was a
+     * new message and not a message correction.
+     *
+     * @return the ID of the message being corrected, or null if this was a
+     * new message and not a message correction.
+     */
+    public String getCorrectedMessageUID()
+    {
+        return correctedMessageUID;
+    }
+    
+    /**
+     * Sets the ID of the message being corrected to the passed ID.
+     * 
+     * @param correctedMessageUID The ID of the message being corrected.
+     */
+    public void setCorrectedMessageUID(String correctedMessageUID)
+    {
+        this.correctedMessageUID = correctedMessageUID;
+    }
+
 }
diff --git a/src/net/java/sip/communicator/service/protocol/event/MessageDeliveryFailedEvent.java b/src/net/java/sip/communicator/service/protocol/event/MessageDeliveryFailedEvent.java
index cba4101..e0f60a3 100644
--- a/src/net/java/sip/communicator/service/protocol/event/MessageDeliveryFailedEvent.java
+++ b/src/net/java/sip/communicator/service/protocol/event/MessageDeliveryFailedEvent.java
@@ -75,6 +75,12 @@ public class MessageDeliveryFailedEvent
      private final long timestamp;
 
      /**
+      * The ID of the message being corrected, or null if this was a new message
+      * and not a message correction.
+      */
+     private String correctedMessageUID;
+
+     /**
       * Constructor.
       *
       * @param source the message
@@ -87,6 +93,23 @@ public class MessageDeliveryFailedEvent
      {
          this(source, to, errorCode, System.currentTimeMillis(), null);
      }
+     
+     /**
+      * Constructor.
+      *
+      * @param source the message
+      * @param to the "to" contact
+      * @param correctedMessageUID The ID of the message being corrected.
+      * @param errorCode error code
+      */
+     public MessageDeliveryFailedEvent(Message source,
+                                       Contact to,
+                                       String correctedMessageUID,
+                                       int errorCode)
+     {
+         this(source, to, errorCode, System.currentTimeMillis(), null);
+         this.correctedMessageUID = correctedMessageUID;
+     }
 
      /**
       * Creates a <tt>MessageDeliveryFailedEvent</tt> indicating failure of
@@ -190,4 +213,14 @@ public class MessageDeliveryFailedEvent
     {
         return reasonPhrase;
     }
+
+    /**
+     * Sets the ID of the message being corrected to the passed ID.
+     * 
+     * @param correctedMessageUID The ID of the message being corrected.
+     */
+    public String getCorrectedMessageUID()
+    {
+        return correctedMessageUID;
+    }
 }
diff --git a/src/net/java/sip/communicator/service/protocol/event/MessageReceivedEvent.java b/src/net/java/sip/communicator/service/protocol/event/MessageReceivedEvent.java
index 959101b..cd15cf6 100644
--- a/src/net/java/sip/communicator/service/protocol/event/MessageReceivedEvent.java
+++ b/src/net/java/sip/communicator/service/protocol/event/MessageReceivedEvent.java
@@ -55,6 +55,12 @@ public class MessageReceivedEvent
      * The type of message event that this instance represents.
      */
     private int eventType = -1;
+    
+    /**
+     * The ID of the message being corrected, or null if this is a new message
+     * and not a correction.
+     */
+    private String correctedMessageUID = null;
 
     /**
      * Creates a <tt>MessageReceivedEvent</tt> representing reception of the
@@ -77,6 +83,23 @@ public class MessageReceivedEvent
      *
      * @param source the <tt>Message</tt> whose reception this event represents.
      * @param from the <tt>Contact</tt> that has sent this message.
+     * @param timestamp the exact date when the event ocurred.
+     */
+    public MessageReceivedEvent(Message source, Contact from,
+            String correctedMessageUID)
+    {
+       this(source, from, System.currentTimeMillis(),
+               CONVERSATION_MESSAGE_RECEIVED);
+       this.correctedMessageUID = correctedMessageUID;
+    }
+
+    /**
+     * Creates a <tt>MessageReceivedEvent</tt> representing reception of the
+     * <tt>source</tt> message received from the specified <tt>from</tt>
+     * contact.
+     *
+     * @param source the <tt>Message</tt> whose reception this event represents.
+     * @param from the <tt>Contact</tt> that has sent this message.
      * @param timestamp the exact date when the event occurred.
      * @param eventType the type of message event that this instance represents
      * (one of the XXX_MESSAGE_RECEIVED static fields).
@@ -92,10 +115,10 @@ public class MessageReceivedEvent
     }
 
     /**
-     * Returns a reference to the <tt>Contact</tt> that has send the
+     * Returns a reference to the <tt>Contact</tt> that has sent the
      * <tt>Message</tt> whose reception this event represents.
      *
-     * @return a reference to the <tt>Contact</tt> that has send the
+     * @return a reference to the <tt>Contact</tt> that has sent the
      * <tt>Message</tt> whose reception this event represents.
      */
     public Contact getSourceContact()
@@ -135,4 +158,16 @@ public class MessageReceivedEvent
     {
         return eventType;
     }
+
+    /**
+     * Returns the correctedMessageUID The ID of the message being corrected,
+     * or null if this is a new message and not a correction.
+     * 
+     * @return the correctedMessageUID The ID of the message being corrected,
+     * or null if this is a new message and not a correction.
+     */
+    public String getCorrectedMessageUID()
+    {
+        return correctedMessageUID;
+    }
 }