package template;

/**
 * Abstract Class with Template Method.
 * The overall migration algorithm is fixed here; subclasses fill in
 * the source-specific steps (connect, read, transform).
 */
public abstract class DataMigration {

    // THE TEMPLATE METHOD — defines the fixed algorithm skeleton
    public final void migrate() {
        System.out.println("\n[" + getSourceName() + "] Starting migration...");
        connect();
        validate();
        int rowCount = readData();
        int transformed = transformData(rowCount);
        writeData(transformed);
        if (sendNotification()) {
            notifyStakeholders();
        }
        disconnect();
        System.out.println("[" + getSourceName() + "] Migration complete.\n");
    }

    // Abstract steps — must be implemented by each subclass
    protected abstract String getSourceName();
    protected abstract void   connect();
    protected abstract int    readData();
    protected abstract int    transformData(int rawCount);

    // Concrete steps — common to all migrations
    protected void validate() {
        System.out.println("  Validating schema compatibility...");
    }

    protected void writeData(int count) {
        System.out.println("  Writing " + count + " rows to target...");
    }

    protected void disconnect() {
        System.out.println("  Closing source connection.");
    }

    // Hook — subclasses may override to change behaviour
    protected boolean sendNotification() { return true; }

    protected void notifyStakeholders() {
        System.out.println("  Sending completion email to team.");
    }
}