Add Flyway, run db migration in local PostgreSQL db

First step in my plan to switch away from MySQL.

src/main/java/config/ServerConfig.java

@@ -12,6 +12,15 @@ public class ServerConfig {
     public String DB_PASS;
     public int INIT_CONNECTION_POOL_TIMEOUT;
 
+    // PostgreSQL database configuration
+    public String PG_DB_NAME;
+    public String PG_DB_HOST;
+    public String PG_DB_SCHEMA;
+    public String PG_DB_ADMIN_USERNAME;
+    public String PG_DB_ADMIN_PASSWORD;
+    public String PG_DB_USERNAME;
+    public String PG_DB_PASSWORD;
+
     //Login Configuration
     public int WORLDS;
     public int WLDLIST_SIZE;

src/main/java/database/PgDatabaseConfig.java

@@ -0,0 +1,30 @@
+package database;
+
+import java.time.Duration;
+
+public record PgDatabaseConfig(
+        String databaseName, String host, String schema,
+        String adminUsername, String adminPassword,
+        String username, String password,
+        Duration poolInitTimeout
+) {
+    public PgDatabaseConfig {
+        verifyNotBlank(databaseName);
+        verifyNotBlank(host);
+        verifyNotBlank(schema);
+        verifyNotBlank(adminUsername);
+        verifyNotBlank(adminPassword);
+        verifyNotBlank(username);
+        verifyNotBlank(password);
+    }
+
+    private void verifyNotBlank(String value) {
+        if (value == null || value.isBlank()) {
+            throw new IllegalArgumentException("Missing or blank value in PG database config");
+        }
+    }
+
+    public String getJdbcUrl() {
+        return "jdbc:postgresql://%s:5432/%s".formatted(host, databaseName);
+    }
+}

src/main/java/database/migration/FlywayRunner.java

@@ -0,0 +1,22 @@
+package database.migration;
+
+import database.PgDatabaseConfig;
+import org.flywaydb.core.Flyway;
+import org.flywaydb.core.api.FlywayException;
+
+public class FlywayRunner {
+    private final PgDatabaseConfig dbConfig;
+
+    public FlywayRunner(PgDatabaseConfig dbConfig) {
+        this.dbConfig = dbConfig;
+    }
+
+    public void migrate() throws FlywayException {
+        Flyway flyway = Flyway.configure()
+                .dataSource(dbConfig.getJdbcUrl(), dbConfig.adminUsername(), dbConfig.adminPassword())
+                .schemas(dbConfig.schema())
+                .createSchemas(true)
+                .load();
+        flyway.migrate();
+    }
+}

src/main/java/net/server/Server.java

@@ -31,11 +31,14 @@ import client.inventory.ItemFactory;
 import client.inventory.manipulator.CashIdGenerator;
 import client.newyear.NewYearCardRecord;
 import client.processor.npc.FredrickProcessor;
+import config.ServerConfig;
 import config.YamlConfig;
 import constants.game.GameConstants;
 import constants.inventory.ItemConstants;
 import constants.net.OpcodeConstants;
 import constants.net.ServerConstants;
+import database.PgDatabaseConfig;
+import database.migration.FlywayRunner;
 import database.note.NoteDao;
 import net.ChannelDependencies;
 import net.PacketProcessor;
@@ -840,6 +843,8 @@ public class Server {
             Runtime.getRuntime().addShutdownHook(new Thread(shutdown(false)));
         }
 
+        runDatabaseMigration();
+
         if (!DatabaseConnection.initializeConnectionPool()) {
             throw new IllegalStateException("Failed to initiate a connection to the database");
         }
@@ -922,6 +927,22 @@ public class Server {
         }
     }
 
+    private void runDatabaseMigration() {
+        PgDatabaseConfig pgDbConfig = readPgDbConfig();
+        FlywayRunner flywayRunner = new FlywayRunner(pgDbConfig);
+        flywayRunner.migrate();
+    }
+
+    private PgDatabaseConfig readPgDbConfig() {
+        final ServerConfig serverConfig = YamlConfig.config.server;
+        return new PgDatabaseConfig(
+                serverConfig.PG_DB_NAME, serverConfig.PG_DB_HOST, serverConfig.PG_DB_SCHEMA,
+                serverConfig.PG_DB_ADMIN_USERNAME, serverConfig.PG_DB_ADMIN_PASSWORD,
+                serverConfig.PG_DB_USERNAME, serverConfig.PG_DB_PASSWORD,
+                Duration.ofSeconds(serverConfig.INIT_CONNECTION_POOL_TIMEOUT)
+        );
+    }
+
     private ChannelDependencies registerChannelDependencies() {
         NoteService noteService = new NoteService(new NoteDao());
         FredrickProcessor fredrickProcessor = new FredrickProcessor(noteService);