package io.dropwizard.logging;

import ch.qos.logback.classic.Level;
import ch.qos.logback.classic.Logger;
import ch.qos.logback.classic.filter.ThresholdFilter;
import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.core.ConsoleAppender;
import ch.qos.logback.core.Layout;
import ch.qos.logback.core.encoder.LayoutWrappingEncoder;
import io.dropwizard.logging.layout.DiscoverableLayoutFactory;

import javax.annotation.concurrent.GuardedBy;
import java.util.TimeZone;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

Utility class to configure logging before the dropwizard yml
configuration has been read, parsed, and the provided logging
strategy has been applied.

N.B. The methods in this class have run once semantics,
multiple calls are idempotent
/**
 * Utility class to configure logging before the dropwizard yml
 * configuration has been read, parsed, and the provided logging
 * strategy has been applied.
 * <p/>
 * N.B. The methods in this class have run once semantics,
 * multiple calls are idempotent
 */
public class BootstrapLogging {

    @GuardedBy("BOOTSTRAPPING_LOCK")
    private static boolean bootstrapped = false;
    private static final Lock BOOTSTRAPPING_LOCK = new ReentrantLock();

    private BootstrapLogging() {
    }

    // initially configure for WARN+ console logging
    public static void bootstrap() {
        bootstrap(Level.WARN);
    }

    public static void bootstrap(Level level) {
        bootstrap(level, DropwizardLayout::new);
    }

    public static void bootstrap(Level level, DiscoverableLayoutFactory<ILoggingEvent> layoutFactory) {
        LoggingUtil.hijackJDKLogging();

        BOOTSTRAPPING_LOCK.lock();
        try {
            if (bootstrapped) {
                return;
            }
            final Logger root = LoggingUtil.getLoggerContext().getLogger(org.slf4j.Logger.ROOT_LOGGER_NAME);
            root.detachAndStopAllAppenders();

            final Layout<ILoggingEvent> layout = layoutFactory.build(root.getLoggerContext(), TimeZone.getDefault());
            layout.start();

            final ThresholdFilter filter = new ThresholdFilter();
            filter.setLevel(level.toString());
            filter.start();

            final ConsoleAppender<ILoggingEvent> appender = new ConsoleAppender<>();
            appender.addFilter(filter);
            appender.setContext(root.getLoggerContext());

            final LayoutWrappingEncoder<ILoggingEvent> layoutEncoder = new LayoutWrappingEncoder<>();
            layoutEncoder.setLayout(layout);
            appender.setEncoder(layoutEncoder);
            appender.start();

            root.addAppender(appender);
            bootstrapped = true;
        } finally {
            BOOTSTRAPPING_LOCK.unlock();
        }
    }
}