Added schema migration infrastructure.

src/main/java/com/andrewlalis/perfin/data/impl/JdbcDataSourceFactory.java

@@ -2,6 +2,8 @@ package com.andrewlalis.perfin.data.impl;
 
 import com.andrewlalis.perfin.data.DataSource;
 import com.andrewlalis.perfin.data.ProfileLoadException;
+import com.andrewlalis.perfin.data.impl.migration.Migration;
+import com.andrewlalis.perfin.data.impl.migration.Migrations;
 import com.andrewlalis.perfin.data.util.FileUtil;
 import com.andrewlalis.perfin.model.Profile;
 import org.slf4j.Logger;
@@ -48,7 +50,7 @@ public class JdbcDataSourceFactory {
             log.debug("Database loaded for profile {} has schema version {}.", profileName, loadedSchemaVersion);
             if (loadedSchemaVersion < SCHEMA_VERSION) {
                 log.debug("Schema version {} is lower than the app's version {}. Performing migration.", loadedSchemaVersion, SCHEMA_VERSION);
-                // TODO: Do migration
+                migrateToCurrentSchemaVersion(profileName, loadedSchemaVersion);
             } else if (loadedSchemaVersion > SCHEMA_VERSION) {
                 log.debug("Schema version {} is higher than the app's version {}. Cannot continue.", loadedSchemaVersion, SCHEMA_VERSION);
                 throw new ProfileLoadException("Profile " + profileName + " has a database with an unsupported schema version.");
@@ -66,13 +68,7 @@ public class JdbcDataSourceFactory {
         ) {
             if (in == null) throw new IOException("Could not load database schema SQL file.");
             String schemaStr = new String(in.readAllBytes(), StandardCharsets.UTF_8);
-            List<String> statements = Arrays.stream(schemaStr.split(";"))
+            executeSqlScript(schemaStr, conn);
-                    .map(String::strip).filter(s -> !s.isBlank()).toList();
-            for (String statementText : statements) {
-                try (Statement stmt = conn.createStatement()) {
-                    stmt.executeUpdate(statementText);
-                }
-            }
             try {
                 writeCurrentSchemaVersion(profileName);
             } catch (IOException e) {
@@ -102,6 +98,63 @@ public class JdbcDataSourceFactory {
         }
     }
 
+    private void migrateToCurrentSchemaVersion(String profileName, int currentVersion) throws ProfileLoadException {
+        // Before starting, copy the database file to a backup folder.
+        Path backupDatabaseFile = getDatabaseFile(profileName).resolveSibling("migration-backup-database.mv.db");
+        try {
+            Files.copy(getDatabaseFile(profileName), backupDatabaseFile);
+        } catch (IOException e) {
+            throw new ProfileLoadException("Failed to prepare database backup prior to schema migration.", e);
+        }
+        int version = currentVersion;
+        JdbcDataSource dataSource = new JdbcDataSource(getJdbcUrl(profileName), Profile.getContentDir(profileName));
+        while (version < SCHEMA_VERSION) {
+            log.info("Migrating profile {} from version {} to version {}.", profileName, version, version + 1);
+            try {
+                Migration m = Migrations.get(version);
+                m.migrate(dataSource);
+                version++;
+            } catch (Exception e) {
+                log.error("Migration from version " + version + " to " + (version+1) + " failed!", e);
+                log.debug("Restoring database from pre-migration backup.");
+                FileUtil.deleteIfPossible(getDatabaseFile(profileName));
+                try {
+                    Files.copy(backupDatabaseFile, getDatabaseFile(profileName));
+                    FileUtil.deleteIfPossible(backupDatabaseFile);
+                } catch (IOException e2) {
+                    log.error("Failed to restore backup!", e2);
+                    throw new ProfileLoadException("Failed to restore backup after a failed migration.", e2);
+                }
+                throw new ProfileLoadException("Migration failed and data restored to pre-migration state.", e);
+            }
+        }
+        try {
+            writeCurrentSchemaVersion(profileName);
+        } catch (IOException e) {
+            log.error("Failed to write current schema version after migration.");
+            FileUtil.deleteIfPossible(getDatabaseFile(profileName));
+            try {
+                Files.copy(backupDatabaseFile, getDatabaseFile(profileName));
+                FileUtil.deleteIfPossible(backupDatabaseFile);
+            } catch (IOException e2) {
+                throw new ProfileLoadException("Failed to restore backup after failing to set schema version.", e2);
+            }
+            throw new ProfileLoadException("Failed to update the schema version file after the migration.", e);
+        }
+        FileUtil.deleteIfPossible(backupDatabaseFile);
+        log.info("Profile successfully migrated to latest version.");
+    }
+
+    private static void executeSqlScript(String script, Connection conn) throws SQLException {
+        List<String> statements = Arrays.stream(script.split(";"))
+                .map(String::strip).filter(s -> !s.isBlank()).toList();
+        for (String statementText : statements) {
+            try (Statement stmt = conn.createStatement()) {
+                stmt.executeUpdate(statementText);
+            }
+        }
+    }
+
     private static Path getDatabaseFile(String profileName) {
         return Profile.getDir(profileName).resolve("database.mv.db");
     }

src/main/java/com/andrewlalis/perfin/data/impl/migration/JdbcMigration.java

@@ -0,0 +1,15 @@
+package com.andrewlalis.perfin.data.impl.migration;
+
+import com.andrewlalis.perfin.data.DataSource;
+import com.andrewlalis.perfin.data.impl.JdbcDataSource;
+
+public interface JdbcMigration extends Migration {
+    default void migrate(DataSource dataSource) throws Exception {
+        if (dataSource instanceof JdbcDataSource ds) {
+            migrateJdbc(ds);
+        } else {
+            throw new IllegalArgumentException("This migration only accepts JDBC data sources.");
+        }
+    }
+    void migrateJdbc(JdbcDataSource dataSource) throws Exception;
+}

src/main/java/com/andrewlalis/perfin/data/impl/migration/Migration.java

@@ -0,0 +1,7 @@
+package com.andrewlalis.perfin.data.impl.migration;
+
+import com.andrewlalis.perfin.data.DataSource;
+
+public interface Migration {
+    void migrate(DataSource dataSource) throws Exception;
+}

src/main/java/com/andrewlalis/perfin/data/impl/migration/Migrations.java

@@ -0,0 +1,28 @@
+package com.andrewlalis.perfin.data.impl.migration;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+public class Migrations {
+    public static Map<Integer, Migration> getMigrations() {
+        final Map<Integer, Migration> migrations = new HashMap<>();
+        migrations.put(1, new PlainSQLMigration("/sql/migration/M1_AddBalanceRecordDeleted.sql"));
+        return migrations;
+    }
+
+    public static List<Migration> getAll() {
+        return getMigrations().entrySet().stream()
+                .sorted(Map.Entry.comparingByKey())
+                .map(Map.Entry::getValue)
+                .toList();
+    }
+
+    public static Migration get(int currentVersion) {
+        Migration selectedMigration = getMigrations().get(currentVersion);
+        if (selectedMigration == null) {
+            throw new IllegalArgumentException("No migration available from version " + currentVersion);
+        }
+        return selectedMigration;
+    }
+}

src/main/java/com/andrewlalis/perfin/data/impl/migration/PlainSQLMigration.java

@@ -0,0 +1,35 @@
+package com.andrewlalis.perfin.data.impl.migration;
+
+import com.andrewlalis.perfin.data.impl.JdbcDataSource;
+
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.util.Arrays;
+import java.util.List;
+
+public class PlainSQLMigration implements JdbcMigration {
+    private final String resourceName;
+
+    public PlainSQLMigration(String resourceName) {
+        this.resourceName = resourceName;
+    }
+
+    @Override
+    public void migrateJdbc(JdbcDataSource dataSource) throws Exception {
+        try (
+                var in = PlainSQLMigration.class.getResourceAsStream(resourceName);
+                var conn = dataSource.getConnection();
+                var stmt = conn.createStatement()
+        ) {
+            if (in == null) throw new IOException("Failed to load resource " + resourceName);
+            String sqlString = new String(in.readAllBytes(), StandardCharsets.UTF_8);
+            List<String> sqlStatements = Arrays.stream(sqlString.split(";"))
+                    .map(String::strip).filter(s -> !s.isBlank()).toList();
+            System.out.println("Running SQL Migration with " + sqlStatements.size() + " statements:");
+            for (String sqlStatement : sqlStatements) {
+                System.out.println("  Executing SQL statement:\n" + sqlStatement + "\n-----\n");
+                stmt.executeUpdate(sqlStatement);
+            }
+        }
+    }
+}

src/main/resources/sql/migration/M1_AddBalanceRecordDeleted.sql

@@ -0,0 +1,5 @@
+ALTER TABLE balance_record
+    ADD COLUMN deleted BOOLEAN NOT NULL DEFAULT FALSE AFTER currency;
+
+ALTER TABLE account_entry
+    ADD COLUMN deleted BOOLEAN NOT NULL DEFAULT FALSE AFTER currency;