/**
 * {@link Endpoint @Endpoint} to expose a collection of {@link LoggerConfiguration}s.
 *
 * @author Ben Hale
 * @author Phillip Webb
 * @author HaiTao Zhang
 * @since 2.0.0
 */
@Endpoint(id = "loggers")
public class LoggersEndpoint {
    private final LoggingSystem loggingSystem;
    private final LoggerGroups loggerGroups;
    /**
     * Create a new {@link LoggersEndpoint} instance.
     * @param loggingSystem the logging system to expose
     * @param loggerGroups the logger group to expose
     */
    public LoggersEndpoint(LoggingSystem loggingSystem, LoggerGroups loggerGroups) {
        Assert.notNull(loggingSystem, "LoggingSystem must not be null");
        Assert.notNull(loggerGroups, "LoggerGroups must not be null");
        this.loggingSystem = loggingSystem;
        this.loggerGroups = loggerGroups;
    }
    //......
}

@ReadOperation
    public Map<String, Object> loggers() {
        Collection<LoggerConfiguration> configurations = this.loggingSystem.getLoggerConfigurations();
        if (configurations == null) {
            return Collections.emptyMap();
        }
        Map<String, Object> result = new LinkedHashMap<>();
        result.put("levels", getLevels());
        result.put("loggers", getLoggers(configurations));
        result.put("groups", getGroups());
        return result;
    }
    private NavigableSet<LogLevel> getLevels() {
        Set<LogLevel> levels = this.loggingSystem.getSupportedLogLevels();
        return new TreeSet<>(levels).descendingSet();
    }
    private Map<String, LoggerLevels> getLoggers(Collection<LoggerConfiguration> configurations) {
        Map<String, LoggerLevels> loggers = new LinkedHashMap<>(configurations.size());
        for (LoggerConfiguration configuration : configurations) {
            loggers.put(configuration.getName(), new SingleLoggerLevels(configuration));
        }
        return loggers;
    }
    private Map<String, LoggerLevels> getGroups() {
        Map<String, LoggerLevels> groups = new LinkedHashMap<>();
        this.loggerGroups.forEach((group) -> groups.put(group.getName(),
                new GroupLoggerLevels(group.getConfiguredLevel(), group.getMembers())));
        return groups;
    }

@ReadOperation
    public LoggerLevels loggerLevels(@Selector String name) {
        Assert.notNull(name, "Name must not be null");
        LoggerGroup group = this.loggerGroups.get(name);
        if (group != null) {
            return new GroupLoggerLevels(group.getConfiguredLevel(), group.getMembers());
        }
        LoggerConfiguration configuration = this.loggingSystem.getLoggerConfiguration(name);
        return (configuration != null) ? new SingleLoggerLevels(configuration) : null;
    }

@WriteOperation
    public void configureLogLevel(@Selector String name, @Nullable LogLevel configuredLevel) {
        Assert.notNull(name, "Name must not be empty");
        LoggerGroup group = this.loggerGroups.get(name);
        if (group != null && group.hasMembers()) {
            group.configureLogLevel(configuredLevel, this.loggingSystem::setLogLevel);
            return;
        }
        this.loggingSystem.setLogLevel(name, configuredLevel);
    }