Provided partially the BackEnd

-DAOMessage works with the DB
-Conversation is a class that retrieves all the messages for a specific user. You only need to use its builder

src/main/java/model/DAO/DAOMessage.java

@@ -0,0 +1,114 @@
+package model.DAO;
+
+import model.entity.Message;
+
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.util.*;
+
+public class DAOMessage {
+
+    private Message getMessageFromResultSet(ResultSet resultSet) throws SQLException {
+        Message message = new Message();
+
+        message.setIdMessage(resultSet.getInt("ID_message"));
+        message.setSender(resultSet.getInt("Sender"));
+        message.setRecipient(resultSet.getInt("Recipient"));
+        message.setRead(resultSet.getBoolean("Read"));
+        message.setBody(resultSet.getString("Body"));
+        message.setSent(resultSet.getTimestamp("sent"));
+
+        return message;
+    }
+
+    /**
+     * Retrieves a list of user IDs based on the therapist ID.
+     *
+     * @param therapistId The ID of the therapist.
+     * @return A list of user IDs associated with the specified therapist.
+     */
+    public List<Integer> retrieveUserIdsByTherapist(int therapistId) {
+        Connection connection = null;
+        PreparedStatement preparedStatement = null;
+        ResultSet resultSet = null;
+
+        List<Integer> userIds = new ArrayList<>();
+
+        try {
+            connection = DAOConnection.getConnection();
+
+            // Query to retrieve user IDs associated with the specified therapist
+            String query = "SELECT ID FROM user WHERE ID_Therapist = ?";
+
+            preparedStatement = connection.prepareStatement(query);
+            preparedStatement.setInt(1, therapistId);
+
+            resultSet = preparedStatement.executeQuery();
+
+            while (resultSet.next()) {
+                int userId = resultSet.getInt("ID");
+                userIds.add(userId);
+            }
+
+        } catch (SQLException e) {
+            // Handle the exception (e.g., log or throw)
+            e.printStackTrace();
+        } finally {
+            try {
+                if (resultSet != null) resultSet.close();
+                if (preparedStatement != null) preparedStatement.close();
+                DAOConnection.releaseConnection(connection);
+            } catch (SQLException e) {
+                // Handle the exception (e.g., log or throw)
+                e.printStackTrace();
+            }
+        }
+
+        return userIds;
+    }
+
+    public Collection<Message> retrieveMessages(int userId, int contact) {
+        Connection connection = null;
+        PreparedStatement preparedStatement = null;
+        ResultSet resultSet = null;
+
+        List<Message> messages = new ArrayList<>();
+
+        try {
+            connection = DAOConnection.getConnection();
+
+            // Query to retrieve messages between the two users
+            String query = "SELECT * FROM message WHERE (Sender = ? AND Recipient = ?) OR (Sender = ? AND Recipient = ?) ORDER BY sent";
+
+            preparedStatement = connection.prepareStatement(query);
+            preparedStatement.setInt(1, userId);
+            preparedStatement.setInt(2, contact);
+            preparedStatement.setInt(3, contact);
+            preparedStatement.setInt(4, userId);
+
+            resultSet = preparedStatement.executeQuery();
+
+            while (resultSet.next()) {
+                Message message = getMessageFromResultSet(resultSet);
+                messages.add(message);
+            }
+
+        } catch (SQLException e) {
+            // Handle the exception (e.g., log or throw)
+            e.printStackTrace();
+        } finally {
+            try {
+                if (resultSet != null) resultSet.close();
+                if (preparedStatement != null) preparedStatement.close();
+                DAOConnection.releaseConnection(connection);
+            } catch (SQLException e) {
+                // Handle the exception (e.g., log or throw)
+                e.printStackTrace();
+            }
+        }
+
+        return messages;
+    }
+}

src/main/java/model/entity/Message.java

@@ -59,5 +59,17 @@ public Timestamp getSent() {
     public void setSent(Timestamp sent) {
         this.sent = sent;
     }
+
+    @Override
+    public String toString() {
+        return "Message{" +
+                //"idMessage=" + idMessage +
+                ", sender=" + sender +
+                ", recipient=" + recipient +
+                ", read=" + read +
+                //", body='" + body + '\'' +
+                //", sent=" + sent +
+                '}';
+    }
 }
 

src/main/java/model/service/message/Conversation.java

@@ -0,0 +1,70 @@
+package model.service.message;
+
+import model.DAO.DAOMessage;
+import model.entity.Message;
+import model.entity.User;
+import model.service.user.UserData;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+public class Conversation {
+    private int userId;
+    private int unreadMessages;
+    private final Map<Integer, List<Message>> conversations = new HashMap<>(); //Integer è l'ID dell'Utente con cui chatta. La lista dei messaggi è la lista dei messaggi con quell'utente
+    DAOMessage db = new DAOMessage();
+
+    public int getUserId() {
+        return userId;
+    }
+
+
+    public int getUnreadMessagesCounter() {
+        return unreadMessages;
+    }
+
+    public Map<Integer, List<Message>> getConversations() {
+        return conversations;
+    }
+
+    public Conversation(int userId){
+        this.userId = userId;
+        List<Integer> contacts= retrieveAllTheContacts(userId);
+        forEachContactRetrieveTheMessages(userId, contacts);
+        updateUnreadCounter();
+    }
+
+    private void updateUnreadCounter() {
+        unreadMessages = 0;
+        for (List<Message> messages : conversations.values()) {
+            for (Message message : messages) {
+                if (message.getRecipient() == userId && !message.isRead()) {
+                    unreadMessages++;
+                }
+            }
+        }
+    }
+
+    private void forEachContactRetrieveTheMessages(int userId, List<Integer> contacts) {
+        for (int contact : contacts) {
+            conversations.put(contact, new ArrayList<>());
+            conversations.get(contact).addAll(db.retrieveMessages(userId, contact));
+        }
+    }
+
+    private List<Integer> retrieveAllTheContacts(int userId){
+        List<Integer> contacts = new ArrayList<>();
+        UserData check = new UserData();
+        User user = check.getUserByIdOrEmail(userId);
+        if(check.isTherapist(user)) {
+            contacts.addAll(db.retrieveUserIdsByTherapist(userId));
+        }
+        else {
+            contacts.add(user.getIdTherapist());
+        }
+        contacts.add(0); //Notifications
+        return contacts;
+    }
+}