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/*
 * Copyright 2019-2021 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package nl.altindag.log;

import ch.qos.logback.classic.Level;
import ch.qos.logback.classic.Logger;
import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.core.Appender;
import ch.qos.logback.core.filter.Filter;
import ch.qos.logback.core.read.ListAppender;
import nl.altindag.log.model.LogEvent;
import nl.altindag.log.util.JavaUtilLoggingLoggerUtils;
import org.slf4j.LoggerFactory;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Optional;

import static java.util.stream.Collectors.collectingAndThen;
import static java.util.stream.Collectors.toList;
import static nl.altindag.log.util.Mappers.toLogEvent;
import static org.slf4j.Logger.ROOT_LOGGER_NAME;

/**
 * @author Hakan Altindag
 */
public final class LogCaptor implements AutoCloseable {

    private static final Map LOG_LEVEL_CONTAINER = new HashMap<>();

    private final Logger logger;
    private final Appender appender;
    private final List eventList = Collections.synchronizedList(new ArrayList<>());

    private LogCaptor(String loggerName) {
        org.slf4j.Logger slf4jLogger = LoggerFactory.getLogger(loggerName);
        if (!(slf4jLogger instanceof Logger)) {
            throw new IllegalArgumentException(
                    String.format("SLF4J Logger implementation should be of the type [%s] but found [%s]. " +
                                  "Please remove any other SLF4J implementations during the test phase from your classpath of your project. " +
                                  "See here for an example configurations: https://github.com/Hakky54/log-captor#using-log-captor-alongside-with-other-logging-libraries",
                                  Logger.class.getName(), slf4jLogger.getClass().getName()
                    )
            );
        }

        logger = (Logger) slf4jLogger;
        appender = createAppender(eventList);
        appender.start();
        logger.addAppender(appender);

        JavaUtilLoggingLoggerUtils.redirectToSlf4j(loggerName);
        LOG_LEVEL_CONTAINER.putIfAbsent(logger.getName(), logger.getEffectiveLevel());
    }

    private static ListAppender createAppender(List dst) {
        ListAppender listAppender = new ListAppender<>();
        listAppender.setName("log-captor");
        listAppender.list = dst;
        return listAppender;
    }

    /**
     * Captures all log messages
     *
     * @return LogCaptor instance for the root logger
     */
    public static LogCaptor forRoot() {
        return new LogCaptor(ROOT_LOGGER_NAME);
    }

    /**
     * Captures log messages for the provided class
     *
     * @param clazz Class for capturing
     * @return LogCaptor instance for the provided class
     */
    public static LogCaptor forClass(Class clazz) {
        return new LogCaptor(clazz.getName());
    }

    /**
     * Captures log messages for the provided logger name
     *
     * @param name Logger name for capturing
     * @return LogCaptor instance for the provided logger name
     */
    public static LogCaptor forName(String name) {
        return new LogCaptor(name);
    }

    public List getLogs() {
        synchronized (eventList) {
            return eventList.stream()
                    .map(ILoggingEvent::getFormattedMessage)
                    .collect(collectingAndThen(toList(), Collections::unmodifiableList));
        }
    }

    public List getInfoLogs() {
        return getLogs(Level.INFO);
    }

    public List getDebugLogs() {
        return getLogs(Level.DEBUG);
    }

    public List getWarnLogs() {
        return getLogs(Level.WARN);
    }

    public List getErrorLogs() {
        return getLogs(Level.ERROR);
    }

    public List getTraceLogs() {
        return getLogs(Level.TRACE);
    }

    private List getLogs(Level level) {
        synchronized (eventList) {
            return eventList.stream()
                    .filter(logEvent -> logEvent.getLevel() == level)
                    .map(ILoggingEvent::getFormattedMessage)
                    .collect(collectingAndThen(toList(), Collections::unmodifiableList));
        }
    }

    public List getLogEvents() {
        synchronized (eventList) {
            return eventList.stream()
                    .map(toLogEvent())
                    .collect(collectingAndThen(toList(), Collections::unmodifiableList));
        }
    }

    public void addFilter(Filter filter) {
        appender.addFilter(filter);
        filter.start();
    }

    /**
     * Overrides the log level property of the target logger. This may result that the overridden property
     * of the target logger is still active even though a new instance of {@link LogCaptor} has been created.
     * To roll-back to the initial state use: {@link LogCaptor#resetLogLevel()}
     *
     * This option will implicitly include the following log levels: WARN and ERROR
     */
    public void setLogLevelToInfo() {
        logger.setLevel(Level.INFO);
    }

    /**
     * Overrides the log level property of the target logger. This may result that the overridden property
     * of the target logger is still active even though a new instance of {@link LogCaptor} has been created.
     * To roll-back to the initial state use: {@link LogCaptor#resetLogLevel()}
     *
     * This option will implicitly include the following log levels: INFO, WARN and ERROR
     */
    public void setLogLevelToDebug() {
        logger.setLevel(Level.DEBUG);
    }

    /**
     * Overrides the log level property of the target logger. This may result that the overridden property
     * of the target logger is still active even though a new instance of {@link LogCaptor} has been created.
     * To roll-back to the initial state use: {@link LogCaptor#resetLogLevel()}
     *
     * This option will implicitly include the following log levels: INFO, DEBUG, WARN and ERROR
     */
    public void setLogLevelToTrace() {
        logger.setLevel(Level.TRACE);
    }

    /**
     * Overrides the log level property of the target logger. This may result that the overridden property
     * of the target logger is still active even though a new instance of {@link LogCaptor} has been created.
     * To roll-back to the initial state use: {@link LogCaptor#resetLogLevel()}
     */
    public void disableLogs() {
        logger.setLevel(Level.OFF);
    }

    /**
     * Resets the log level of the target logger to the initial value which was available before
     * changing it with {@link LogCaptor#setLogLevelToInfo()}, {@link LogCaptor#setLogLevelToDebug()} or with {@link LogCaptor#setLogLevelToTrace()}
     */
    public void resetLogLevel() {
        Optional.ofNullable(LOG_LEVEL_CONTAINER.get(logger.getName()))
                .ifPresent(logger::setLevel);
    }

    public void clearLogs() {
        eventList.clear();
    }

    @Override
    public void close() {
        logger.detachAppender(appender);
        appender.stop();
    }

}