feat(dm): implement signed direct messaging with web push fallback

shine-server-db/src/main/java/shine/db/dao/ActiveSessionsDAO.java

@@ -217,6 +217,25 @@ public final class ActiveSessionsDAO {
         }
     }
 
+    public void updatePushSubscription(String sessionId, String endpoint, String p256dhKey, String authKey) throws SQLException {
+        try (Connection c = db.getConnection()) {
+            String sql = """
+                UPDATE active_sessions
+                SET push_endpoint = ?,
+                    push_p256dh_key = ?,
+                    push_auth_key = ?
+                WHERE session_id = ?
+                """;
+            try (PreparedStatement ps = c.prepareStatement(sql)) {
+                ps.setString(1, endpoint);
+                ps.setString(2, p256dhKey);
+                ps.setString(3, authKey);
+                ps.setString(4, sessionId);
+                ps.executeUpdate();
+            }
+        }
+    }
+
     // -------------------- DELETE --------------------
 
     public void deleteBySessionId(Connection c, String sessionId) throws SQLException {

shine-server-db/src/main/java/shine/db/dao/SignedDirectMessagesHistoryDAO.java

@@ -0,0 +1,47 @@
+package shine.db.dao;
+
+import shine.db.SqliteDbController;
+import shine.db.entities.SignedDirectMessageHistoryEntry;
+
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+
+public final class SignedDirectMessagesHistoryDAO {
+    private static volatile SignedDirectMessagesHistoryDAO instance;
+    private final SqliteDbController db = SqliteDbController.getInstance();
+
+    private SignedDirectMessagesHistoryDAO() {}
+
+    public static SignedDirectMessagesHistoryDAO getInstance() {
+        if (instance == null) {
+            synchronized (SignedDirectMessagesHistoryDAO.class) {
+                if (instance == null) instance = new SignedDirectMessagesHistoryDAO();
+            }
+        }
+        return instance;
+    }
+
+    public void insert(SignedDirectMessageHistoryEntry e) throws Exception {
+        try (Connection c = db.getConnection()) {
+            String sql = """
+                INSERT INTO signed_direct_messages_history (
+                    message_id, from_login, to_login, target_mode, target_session_id,
+                    message_type, time_ms, nonce, raw_packet, created_at_ms
+                ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
+                """;
+            try (PreparedStatement ps = c.prepareStatement(sql)) {
+                ps.setString(1, e.getMessageId());
+                ps.setString(2, e.getFromLogin());
+                ps.setString(3, e.getToLogin());
+                ps.setInt(4, e.getTargetMode());
+                ps.setString(5, e.getTargetSessionId());
+                ps.setInt(6, e.getMessageType());
+                ps.setLong(7, e.getTimeMs());
+                ps.setLong(8, e.getNonce());
+                ps.setBytes(9, e.getRawPacket());
+                ps.setLong(10, e.getCreatedAtMs());
+                ps.executeUpdate();
+            }
+        }
+    }
+}

shine-server-db/src/main/java/shine/db/dao/SignedDmReplayDAO.java

@@ -0,0 +1,50 @@
+package shine.db.dao;
+
+import shine.db.SqliteDbController;
+
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+
+public final class SignedDmReplayDAO {
+    private static volatile SignedDmReplayDAO instance;
+    private final SqliteDbController db = SqliteDbController.getInstance();
+
+    private SignedDmReplayDAO() {}
+
+    public static SignedDmReplayDAO getInstance() {
+        if (instance == null) {
+            synchronized (SignedDmReplayDAO.class) {
+                if (instance == null) instance = new SignedDmReplayDAO();
+            }
+        }
+        return instance;
+    }
+
+    public boolean registerUnique(String fromLogin, long timeMs, long nonce, long nowMs) throws Exception {
+        cleanupExpired(nowMs - 15L * 60L * 1000L);
+        try (Connection c = db.getConnection()) {
+            String sql = """
+                INSERT OR IGNORE INTO signed_direct_message_replay (
+                    from_login, time_ms, nonce, created_at_ms
+                ) VALUES (?, ?, ?, ?)
+                """;
+            try (PreparedStatement ps = c.prepareStatement(sql)) {
+                ps.setString(1, fromLogin);
+                ps.setLong(2, timeMs);
+                ps.setLong(3, nonce);
+                ps.setLong(4, nowMs);
+                return ps.executeUpdate() > 0;
+            }
+        }
+    }
+
+    public void cleanupExpired(long minCreatedAtMs) throws Exception {
+        try (Connection c = db.getConnection()) {
+            String sql = "DELETE FROM signed_direct_message_replay WHERE created_at_ms < ?";
+            try (PreparedStatement ps = c.prepareStatement(sql)) {
+                ps.setLong(1, minCreatedAtMs);
+                ps.executeUpdate();
+            }
+        }
+    }
+}