package io.trygvis.persistence.sql;

import javax.persistence.Cache;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.PersistenceException;
import javax.persistence.PersistenceUnitUtil;
import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.metamodel.Metamodel;
import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Map;

import static java.util.Collections.emptyMap;

public abstract class SqlEntityManagerFactory implements EntityManagerFactory {

    public final SqlUnit sqlUnit;

    private final DataSource dataSource;

    protected SqlEntityManagerFactory(SqlUnit sqlUnit, DataSource dataSource) {
        this.sqlUnit = sqlUnit;
        this.dataSource = dataSource;
    }

    // -----------------------------------------------------------------------
    //
    // -----------------------------------------------------------------------

    protected abstract EntityManager createEntityManager(Connection c);

    // -----------------------------------------------------------------------
    //
    // -----------------------------------------------------------------------

    @Override
    public EntityManager createEntityManager() {
        return createEntityManager(emptyMap());
    }

    @Override
    public EntityManager createEntityManager(Map map) {
        try {
            Connection c = dataSource.getConnection();
            return createEntityManager(c);
        } catch (SQLException e) {
            throw new PersistenceException("Could not get connection", e);
        }
    }

    @Override
    public CriteriaBuilder getCriteriaBuilder() {
        throw new UnsupportedOperationException();
    }

    @Override
    public Metamodel getMetamodel() {
        throw new UnsupportedOperationException();
    }

    @Override
    public boolean isOpen() {
        return true;
    }

    @Override
    public void close() {
    }

    @Override
    public Map<String, Object> getProperties() {
        return emptyMap();
    }

    @Override
    public Cache getCache() {
        return new NoOpCache();
    }

    @Override
    public PersistenceUnitUtil getPersistenceUnitUtil() {
        throw new UnsupportedOperationException();
    }

    private static class NoOpCache implements Cache {
        @Override
        public boolean contains(Class cls, Object primaryKey) {
            return false;
        }

        @Override
        public void evict(Class cls, Object primaryKey) {
        }

        @Override
        public void evict(Class cls) {
        }

        @Override
        public void evictAll() {
        }
    }
}