package mineplex.reportserver;

import java.util.logging.Level;
import java.util.logging.Logger;

import org.apache.commons.lang3.Validate;
import org.apache.commons.lang3.time.DurationFormatUtils;
import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;

/**
 * Establishes and maintains a connection to Redis.
 */
public class RedisConnectionHandler implements Runnable
{
	private final String _name;
	private final JedisPool _jedisPool;
	private final RedisCommandHandler _handler;
	private final String[] _channels;
	private final Logger _logger;

	private long _lastConnectionMillis = -1;
	private Throwable _lastThrowable = null;

	public RedisConnectionHandler(String name, JedisPool jedisPool, RedisCommandHandler handler, String[] channels, Logger logger)
	{
		_name = name;
		_jedisPool = jedisPool;
		_handler = handler;
		_channels = channels;
		_logger = logger;

		Validate.isTrue(channels.length > 0, "Must provide at least one channel.");
	}

	@Override
	public void run()
	{
		while (!Thread.interrupted())
		{
			try
			{
				registerChannelHandlers();
			}
			catch (Throwable e)
			{
				// Only log new errors (prevents same error being spammed)
				if (_lastThrowable == null || !e.getClass().equals(_lastThrowable.getClass()))
				{
					if (_lastThrowable == null) // connection just failed
					{
						_lastConnectionMillis = System.currentTimeMillis();
					}

					_logger.log(Level.SEVERE, prefixMessage(
							"Exception in Redis connection"
									+ (_lastConnectionMillis != -1 ? " (no connection for " + getLastConnectionDuration() + ")" : "")
									+ ", attempting to regain connection."
							), e);

					_lastThrowable = e;
				}

				try
				{
					Thread.sleep(1000 * 5);
				}
				catch (InterruptedException ignored) {}
			}
		}

		_jedisPool.destroy();
		_logger.warning("Thread interrupted, end of connection.");
	}

	private void registerChannelHandlers()
	{
		try (Jedis jedis = _jedisPool.getResource())
		{
			connectionEstablished();
			jedis.subscribe(_handler, _channels);
		}
	}

	private void connectionEstablished()
	{
		// subscribe blocks so we need to do all this before
		_logger.info(
				_lastThrowable == null
						? prefixMessage("Connected.")
						: prefixMessage(String.format("Connected after %s.", getLastConnectionDuration()))
		);

		_lastThrowable = null;
	}

	private String prefixMessage(String message)
	{
		return String.format("[%s] %s", _name, message);
	}

	private String getLastConnectionDuration()
	{
		return DurationFormatUtils.formatDurationWords(System.currentTimeMillis() - _lastConnectionMillis, true, true);
	}
}