package io.trygvis.queue;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Timestamp;
import java.sql.Types;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Date;
import java.util.List;

import static java.util.Arrays.asList;

public class TaskDao {

    private final Connection connection;

    public static final String fields = "id, parent, queue, scheduled, last_run, run_count, completed, arguments";

    public TaskDao(Connection connection) {
        this.connection = connection;
    }

    public long insert(String queue, Date scheduled, String arguments) throws SQLException {
        return insert(null, queue, scheduled, arguments);
    }

    public long insert(Long parent, String queue, Date scheduled, String arguments) throws SQLException {
        String sql = "INSERT INTO task(id, parent, run_count, queue, scheduled, arguments) " +
                "VALUES(nextval('task_seq'), ?, 0, ?, ?, ?)";
        try (PreparedStatement stmt = connection.prepareStatement(sql)) {
            int i = 1;
            if (parent == null) {
                stmt.setNull(i++, Types.BIGINT);
            } else {
                stmt.setLong(i++, parent);
            }
            stmt.setString(i++, queue);
            stmt.setTimestamp(i++, new Timestamp(scheduled.getTime()));
            stmt.setString(i, arguments);
            stmt.executeUpdate();
        }
        try (PreparedStatement stmt = connection.prepareStatement("SELECT currval('task_seq')")) {
            ResultSet rs = stmt.executeQuery();
            rs.next();
            return rs.getLong(1);
        }
    }

    public Task findById(long id) throws SQLException {
        try (PreparedStatement stmt = connection.prepareStatement("SELECT " + fields + " FROM task WHERE id=?")) {
            ResultSet rs = stmt.executeQuery();
            return rs.next() ? mapRow(rs) : null;
        }
    }

    public List<Task> findByNameAndCompletedIsNull(String name) throws SQLException {
        try (PreparedStatement stmt = connection.prepareStatement("SELECT " + fields + " FROM task WHERE queue=? AND completed IS NULL")) {
            int i = 1;
            stmt.setString(i, name);
            ResultSet rs = stmt.executeQuery();
            List<Task> list = new ArrayList<>();
            while (rs.next()) {
                list.add(mapRow(rs));
            }
            return list;
        }
    }

    public void update(Task task) throws SQLException {
        try (PreparedStatement stmt = connection.prepareStatement("UPDATE task SET scheduled=?, last_run=?, run_count=?, completed=? WHERE id=?")) {
            int i = 1;
            stmt.setTimestamp(i++, new Timestamp(task.scheduled.getTime()));
            setTimestamp(stmt, i++, task.lastRun);
            stmt.setInt(i++, task.runCount);
            setTimestamp(stmt, i++, task.completed);
            stmt.setLong(i, task.id);
            stmt.executeUpdate();
        }
    }

    private static void setTimestamp(PreparedStatement stmt, int parameterIndex, Date date) throws SQLException {
        if (date == null) {
            stmt.setNull(parameterIndex, Types.TIMESTAMP);
        } else {
            stmt.setTimestamp(parameterIndex, new Timestamp(date.getTime()));
        }
    }

    public Task mapRow(ResultSet rs) throws SQLException {
        String arguments = rs.getString(8);
        return new Task(
                rs.getLong(1),
                rs.getLong(2),
                rs.getString(3),
                rs.getTimestamp(4),
                rs.getTimestamp(5),
                rs.getInt(6),
                rs.getTimestamp(7),
                arguments != null ? asList(arguments.split(" ")) : Collections.<String>emptyList());
    }
}