package io.trygvis.async;

import io.trygvis.queue.JdbcQueueService;
import io.trygvis.queue.Queue;
import io.trygvis.queue.QueueSystem;
import io.trygvis.queue.Task;
import io.trygvis.queue.TaskEffect;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.sql.Connection;
import java.sql.SQLException;
import java.util.List;

class QueueThread implements Runnable {
    private final Logger log = LoggerFactory.getLogger(getClass());

    private final QueueSystem queueSystem;

    private final JdbcQueueService queueService;

    private final SqlEffectExecutor sqlEffectExecutor;

    private final TaskEffect taskEffect;

    public final Queue queue;

    public boolean shouldRun = true;

    private boolean checkForNewTasks;

    private boolean busy;

    QueueThread(QueueSystem queueSystem, TaskEffect taskEffect, Queue queue) {
        this.queueSystem = queueSystem;
        this.sqlEffectExecutor = queueSystem.sqlEffectExecutor;
        this.queueService = queueSystem.createQueueService();
        this.taskEffect = taskEffect;
        this.queue = queue;
    }

    public void ping() {
        synchronized (this) {
            if (!busy) {
                log.info("Sending ping to " + queue);
                notify();
            } else {
                checkForNewTasks = true;
            }
        }
    }

    public void run() {
        while (shouldRun) {
            try {
                List<Task> tasks = sqlEffectExecutor.transaction(new SqlEffect<List<Task>>() {
                    @Override
                    public List<Task> doInConnection(Connection c) throws SQLException {
                        return queueSystem.createTaskDao(c).findByNameAndCompletedIsNull(queue.name);
                    }
                });

                log.info("Found {} tasks on queue {}", tasks.size(), queue.name);

                if (tasks.size() > 0) {
                    queueService.executeTask(taskEffect, tasks);
                }
            } catch (Throwable e) {
                log.warn("Error while executing tasks.", e);
            }

            synchronized (this) {
                busy = false;

                if (checkForNewTasks) {
                    log.info("Ping received!");
                    checkForNewTasks = false;
                    continue;
                }

                try {
                    wait();
                } catch (InterruptedException e) {
                    // ignore
                }

                busy = true;
            }
        }
    }
}