package io.trygvis.async;

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;

public class SqlEffectExecutor {

    private final DataSource dataSource;

    public SqlEffectExecutor(DataSource dataSource) {
        this.dataSource = dataSource;
    }

    public <A> A transaction(SqlEffect<A> effect) {
/*
        int pid;

        try (Connection c = dataSource.getConnection()) {

            try (Statement statement = c.createStatement()) {
                ResultSet rs = statement.executeQuery("SELECT pg_backend_pid()");
                rs.next();
                pid = rs.getInt(1);
            }

            System.out.println("pid = " + pid);

            try {
                effect.doInConnection(c);
                c.commit();
            } catch (SQLException e) {
                c.rollback();
                e.printStackTrace();
            } finally {
                System.out.println("Closing pid=" + pid);
                try {
                    c.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        } catch (SQLException e) {
            e.printStackTrace();
            throw new SqlExecutionException(e);
        }
*/

        try (Connection c = dataSource.getConnection()) {
            boolean ok = false;
            try {
                A a = effect.doInConnection(c);
                c.commit();
                ok = true;
                return a;
            } finally {
                if (!ok) {
                    c.rollback();
                }
            }
        } catch (SQLException e) {
            throw new SqlExecutionException(e);
        }
    }

    public void transaction(final SqlEffect.Void effect) {
        transaction(new SqlEffect<Object>() {
            @Override
            public Object doInConnection(Connection c) throws SQLException {
                effect.doInConnection(c);
                return null;
            }
        });
    }

    public static class SqlExecutionException extends RuntimeException {
        public final SQLException exception;

        public SqlExecutionException(SQLException ex) {
            super(ex);
            this.exception = ex;
        }
    }
}