[IN PROGRESS] Implement SQLite as a replacement for XML-based storage in saving game data

src/net/sf/freecol/common/io/FreeColSQLReader.java

@@ -0,0 +1,82 @@
+/**
+ *  Copyright (C) 2002-2022   The FreeCol Team
+ *
+ *  This file is part of FreeCol.
+ *
+ *  FreeCol is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  FreeCol is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with FreeCol.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package net.sf.freecol.common.io;
+import java.io.Closeable;
+import java.io.IOException;
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+
+/**
+ * This code creates a `FreeColSQLReader` class that connects to an
+ * SQLite database and is capable of executing queries.
+ * It maintains a connection to the SQLite file and a statement object used to
+ * execute the queries. The `ReadScopeType` is also included in the implementation,
+ * similar to the XML implementation.
+ */
+public class FreeColSQLReader implements Closeable {
+
+    private static final Logger logger = Logger.getLogger(FreeColSQLReader.class.getName());
+
+    /**
+     * Enum representing the scope of the data reading.
+     */
+    public enum ReadScopeType {
+        CLIENT, // Only the client-visible information
+        SERVER, // Full server-visible information
+        LOAD    // Absolutely everything needed to load the game state
+    }
+
+    private Connection connection;
+    private Statement statement;
+    private final ReadScopeType readScope;
+
+    public FreeColSQLReader(String dbPath, ReadScopeType scope) throws SQLException {
+        this.connection = DriverManager.getConnection("jdbc:sqlite:" + dbPath);
+        this.statement = connection.createStatement();
+        this.readScope = (scope == null) ? ReadScopeType.LOAD : scope;
+    }
+
+    /**
+     * Executes a query and returns the result set.
+     *
+     * @param query SQL query to execute.
+     * @return ResultSet containing the result of the query.
+     * @throws SQLException If the query execution fails.
+     */
+    public ResultSet executeQuery(String query) throws SQLException {
+        return statement.executeQuery(query);
+    }
+
+    @Override
+    public void close() {
+        try {
+            if (statement != null) statement.close();
+            if (connection != null) connection.close();
+        } catch (SQLException e) {
+            logger.log(Level.WARNING, "Failed to close resources", e);
+        }
+    }
+}

src/net/sf/freecol/common/io/FreeColSQLWriter.java

@@ -0,0 +1,133 @@
+/**
+ *  Copyright (C) 2002-2022   The FreeCol Team
+ *
+ *  This file is part of FreeCol.
+ *
+ *  FreeCol is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  FreeCol is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with FreeCol.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package net.sf.freecol.common.io;
+
+import java.io.Closeable;
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.PreparedStatement;
+import java.sql.SQLException;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+
+/**
+ * `FreeColSQLWriter` class to save game data into an SQLite database.
+ * It consists of the `saveGameData` method that saves general game data,
+ * player data, turn data, and tile data. Additional game components can be saved
+ * in a similar manner using prepared statements. The `close()`
+ * method ensures that the database connection is closed when done.
+ */
+public class FreeColSQLWriter implements Closeable {
+
+    private static final Logger logger = Logger.getLogger(FreeColSQLWriter.class.getName());
+
+    /**
+     * Enum representing the scope of the data writing.
+     */
+    public enum WriteScopeType {
+        CLIENT,  // Only the client-visible information
+        SERVER,  // Full server-visible information
+        SAVE     // Absolutely everything needed to save the game state
+    };
+
+    private Connection connection;
+    private WriteScopeType writeScope;
+
+    public FreeColSQLWriter(String dbPath, WriteScopeType scope) throws SQLException {
+        this.connection = DriverManager.getConnection("jdbc:sqlite:" + dbPath);
+        this.writeScope = (scope == null) ? WriteScopeType.SAVE : scope;
+    }
+
+    /**
+     * Executes an SQL update statement.
+     *
+     * @param update SQL update statement to execute.
+     * @throws SQLException If the statement execution fails.
+     */
+    public void executeUpdate(String update) throws SQLException {
+        try (PreparedStatement pstmt = connection.prepareStatement(update)) {
+            pstmt.executeUpdate();
+        }
+    }
+
+    /**
+     * Save game data to the SQLite database.
+     *
+     * @param game The Game object to save.
+     * @throws SQLException If any error occurs during saving.
+     */
+    public void saveGameData(Game game) throws SQLException {
+        // Save general game data
+        String sqlGame = "INSERT OR REPLACE INTO game (id, options) VALUES(?, ?)";
+        try (PreparedStatement pstmt = connection.prepareStatement(sqlGame)) {
+            pstmt.setInt(1, game.getId());
+            pstmt.setString(2, game.getGameOptions().toString());
+            pstmt.executeUpdate();
+        }
+
+        // Save player data
+        String sqlPlayer = "INSERT OR REPLACE INTO player (id, name, nation) VALUES(?, ?, ?)";
+        for (Player player : game.getPlayers()) {
+            try (PreparedStatement pstmt = connection.prepareStatement(sqlPlayer)) {
+                pstmt.setInt(1, player.getId());
+                pstmt.setString(2, player.getName());
+                pstmt.setString(3, player.getNation().getName());
+                pstmt.executeUpdate();
+            }
+        }
+
+        // Save turn data
+        String sqlTurn = "UPDATE game SET turn = ? WHERE id
+        // Save turn data
+        String sqlTurn = "UPDATE game SET turn = ? WHERE id = ?";
+        try (PreparedStatement pstmt = connection.prepareStatement(sqlTurn)) {
+            pstmt.setInt(1, game.getTurn());
+            pstmt.setInt(2, game.getId());
+            pstmt.executeUpdate();
+        }
+
+        // Save tile data
+        String sqlTile = "INSERT OR REPLACE INTO tile (x, y, terrain_type, owner, game_id) VALUES(?, ?, ?, ?, ?)";
+        for (Tile tile : game.getMap().getAllTiles()) {
+            try (PreparedStatement pstmt = connection.prepareStatement(sqlTile)) {
+                pstmt.setInt(1, tile.getX());
+                pstmt.setInt(2, tile.getY());
+                pstmt.setString(3, tile.getTerrainType().getName());
+                pstmt.setString(4, tile.getOwner().getName());
+                pstmt.setInt(5, game.getId());
+                pstmt.executeUpdate();
+            }
+        }
+
+        // Additional game components can be saved similarly with prepared statements
+    }
+
+    @Override
+    public void close() {
+        try {
+            if (connection != null) {
+                connection.close();
+            }
+        } catch (SQLException e) {
+            logger.log(Level.WARNING, "Failed to close resources", e);
+        }
+    }
+}

src/net/sf/freecol/common/io/FreeColXMLWriter.java

@@ -385,6 +385,7 @@ public void writeAttribute(String attributeName, Enum<?> value)
      */
     public void writeAttribute(String attributeName, Object value)
         throws XMLStreamException {
+        logger.log(Level.WARNING, "Writing attribute:" + attributeName + ", with value of: " + String.valueOf(value));
         xmlStreamWriter.writeAttribute(attributeName, String.valueOf(value));
     }
 

src/net/sf/freecol/common/model/sql/generate_sql_tables.sql

@@ -0,0 +1,84 @@
+-- Create game table
+CREATE TABLE IF NOT EXISTS game (
+    id INTEGER PRIMARY KEY,
+    difficulty TEXT,
+    mapFile TEXT,
+    gameOptions TEXT,
+    language TEXT,
+    turns INTEGER,
+    graphicalOptions TEXT,
+    soundOptions TEXT,
+    turn INTEGER
+);
+
+-- Create player table
+CREATE TABLE IF NOT EXISTS player (
+    id INTEGER PRIMARY KEY,
+    game_id INTEGER,
+    name TEXT,
+    color TEXT,
+    flag TEXT,
+    playerPreferences TEXT,
+    FOREIGN KEY (game_id) REFERENCES game (id) ON DELETE CASCADE
+);
+
+-- Create native table
+CREATE TABLE IF NOT EXISTS natives (
+    id INTEGER PRIMARY KEY,
+    game_id INTEGER,
+    name TEXT,
+    color TEXT,
+    type TEXT,
+    FOREIGN KEY (game_id) REFERENCES game (id) ON DELETE CASCADE
+);
+
+-- Create faction table
+CREATE TABLE IF NOT EXISTS factions (
+    id INTEGER PRIMARY KEY,
+    game_id INTEGER,
+    name TEXT,
+    FOREIGN KEY (game_id) REFERENCES game (id) ON DELETE CASCADE
+);
+
+-- ... The existing unit, city, and tile table creation statements remain unchanged
+
+-- Create building table
+CREATE TABLE IF NOT EXISTS building (
+    id INTEGER PRIMARY KEY,
+    game_id INTEGER,
+    city_id INTEGER,
+    type TEXT,
+    x INTEGER,
+    y INTEGER,
+    FOREIGN KEY (game_id) REFERENCES game (id) ON DELETE CASCADE,
+    FOREIGN KEY (city_id) REFERENCES city (id) ON DELETE CASCADE
+);
+
+-- Create resource (goods) table
+CREATE TABLE IF NOT EXISTS goods (
+    id INTEGER PRIMARY KEY,
+    game_id INTEGER,
+    type TEXT,
+    available INTEGER,
+    FOREIGN KEY (game_id) REFERENCES game (id) ON DELETE CASCADE
+);
+
+-- Create highscore table
+CREATE TABLE IF NOT EXISTS highScores (
+    id INTEGER PRIMARY KEY,
+    game_id INTEGER,
+    player_id INTEGER,
+    score INTEGER,
+    FOREIGN KEY (game_id) REFERENCES game (id) ON DELETE CASCADE,
+    FOREIGN KEY (player_id) REFERENCES player (id) ON DELETE CASCADE
+);
+
+-- Create foundingFathers table
+CREATE TABLE IF NOT EXISTS foundingFathers (
+    id INTEGER PRIMARY KEY,
+    game_id INTEGER,
+    name TEXT,
+    bonus TEXT,
+    improvement TEXT,
+    FOREIGN KEY (game_id) REFERENCES game (id) ON DELETE CASCADE
+);

src/net/sf/freecol/tools/FSGConverter.java

@@ -118,9 +118,9 @@ private void convertToXML(InputStream ins, OutputStream outs)
                 return;
             }
             in.reset();
-            if (!"<?xml".equals(new String(buf, StandardCharsets.UTF_8))) {
-                in = new BufferedInputStream(new GZIPInputStream(ins));
-            }
+//            if (!"<?xml".equals(new String(buf, StandardCharsets.UTF_8))) {
+//                in = new BufferedInputStream(new GZIPInputStream(ins));
+//            }
 
             // Support for XML comments has not been added:
             int indent = 0;
@@ -183,15 +183,16 @@ private static void printUsage() {
      * @param args The command-line parameters.
      */
     public static void main(String[] args) {
-        if (args.length >= 2 && args[0].endsWith("output:xml")) {
-            File in = new File(args[1]);
+        String[] actual_args = {"FSG_FILE:xml", "5c812fa4_Голландцы_1494.fsg"};
+        if (actual_args.length >= 2 && actual_args[0].endsWith("output:xml")) {
+            File in = new File(actual_args[1]);
             if (!in.exists()) {
                 printUsage();
                 System.exit(1);
             }
             File out;
-            if (args.length >= 3) {
-                out = new File(args[2]);
+            if (actual_args.length >= 3) {
+                out = new File(actual_args[2]);
             } else {
                 String name = in.getName();
                 String filename = name.replaceAll("." + FreeCol.FREECOL_SAVE_EXTENSION, ".xml");