Initial implementation of DB upgrader

src/zutil/db/DBUpgradeHandler.java

@@ -0,0 +1,89 @@
+package zutil.db;
+
+import zutil.db.handler.ListSQLResult;
+import zutil.log.LogUtil;
+
+import java.sql.SQLException;
+import java.util.List;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+/**
+ * This class will take a reference DB and alter
+ * the source DB to have the same structure.
+ * NOTE: only works with sqllite
+ *
+ * Created by Ziver
+ */
+public class DBUpgradeHandler {
+    private static final Logger logger = LogUtil.getLogger();
+
+    private DBConnection reference;
+    private DBConnection target;
+
+
+    public DBUpgradeHandler(DBConnection reference){
+        this.reference = reference;
+    }
+
+    public void setTargetDB(DBConnection db){
+        this.target = db;
+    }
+
+    public void upgrade() throws SQLException {
+        /*
+        - beginTransaction
+        - run a table creation with if not exists (we are doing an upgrade, so the table might not exists yet, it will fail alter and drop)
+        - put in a list the existing columns List<String> columns = DBUtils.GetColumns(db, TableName);
+        - backup table (ALTER table " + TableName + " RENAME TO 'temp_"                    + TableName)
+        - create new table (the newest table creation schema)
+        - get the intersection with the new columns, this time columns taken from the upgraded table (columns.retainAll(DBUtils.GetColumns(db, TableName));)
+        - restore data (String cols = StringUtils.join(columns, ",");
+                    db.execSQL(String.format(
+                            "INSERT INTO %s (%s) SELECT %s from temp_%s",
+                            TableName, cols, cols, TableName));
+        )
+        - remove backup table (DROP table 'temp_" + TableName)
+        - setTransactionSuccessful
+         */
+        try {
+            target.exec("BEGIN IMMEDIATE TRANSACTION");
+
+            upgradeCreateTabels();
+            upgradeAlterTables();
+            upgradeDeleteTables();
+
+            target.exec("COMMIT TRANSACTION");
+        } catch(SQLException e){
+            try {
+                target.exec("ROLLBACK TRANSACTION");
+            } catch (SQLException secondary_e) {
+                logger.log(Level.SEVERE, null, secondary_e);
+            }
+            throw e;
+        }
+    }
+
+
+
+    private void upgradeCreateTabels() throws SQLException {
+        List<String> refTables = reference.exec("SELECT name FROM sqlite_master WHERE type='table';", new ListSQLResult<String>());
+        List<String> targetTables = reference.exec("SELECT name FROM sqlite_master WHERE type='table';", new ListSQLResult<String>());
+
+        for(String table : refTables){
+            if(!targetTables.contains(table)){
+                logger.fine("Creating new table: "+ table);
+
+            }
+        }
+    }
+
+    private void upgradeAlterTables() throws SQLException {
+        logger.fine("Altering table: ");
+        //RAGMA table_info([tablename]);
+    }
+
+    private void upgradeDeleteTables() throws SQLException {
+        logger.fine("Deleting table: ");
+    }
+}