From 45b4bfba0deaeec80b8e653cfc0cdf641a3f3e2d Mon Sep 17 00:00:00 2001
From: yushijinhun <yushijinhun@gmail.com>
Date: Sun, 8 Jul 2018 15:21:46 +0800
Subject: [PATCH] Allow to turn on debug mode for specified loggers

---
 .../authlibinjector/AuthlibInjector.java      |  2 +-
 .../yushi/authlibinjector/util/Logging.java   | 48 +++++++++++++------
 2 files changed, 35 insertions(+), 15 deletions(-)

diff --git a/src/main/java/moe/yushi/authlibinjector/AuthlibInjector.java b/src/main/java/moe/yushi/authlibinjector/AuthlibInjector.java
index b50230f..4841f2c 100644
--- a/src/main/java/moe/yushi/authlibinjector/AuthlibInjector.java
+++ b/src/main/java/moe/yushi/authlibinjector/AuthlibInjector.java
@@ -51,7 +51,7 @@ public final class AuthlibInjector {
 	public static final String PROP_DISABLE_HTTPD = "authlibinjector.httpd.disable";
 
 	/**
-	 * Whether to turn on debug logging.
+	 * The name of loggers to have debug level turned on.
 	 */
 	public static final String PROP_DEBUG = "authlibinjector.debug";
 
diff --git a/src/main/java/moe/yushi/authlibinjector/util/Logging.java b/src/main/java/moe/yushi/authlibinjector/util/Logging.java
index a0fd8bf..81e832a 100644
--- a/src/main/java/moe/yushi/authlibinjector/util/Logging.java
+++ b/src/main/java/moe/yushi/authlibinjector/util/Logging.java
@@ -4,6 +4,10 @@ import static moe.yushi.authlibinjector.AuthlibInjector.PROP_DEBUG;
 import java.io.PrintWriter;
 import java.io.StringWriter;
 import java.text.MessageFormat;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.function.Predicate;
+import java.util.logging.Filter;
 import java.util.logging.Formatter;
 import java.util.logging.Level;
 import java.util.logging.LogRecord;
@@ -13,25 +17,25 @@ import java.util.logging.StreamHandler;
 public final class Logging {
 	private Logging() {}
 
-	public static final Logger ROOT = Logger.getLogger("moe.yushi.authlibinjector");
-	public static final Logger LAUNCH = Logger.getLogger("moe.yushi.authlibinjector.launch");
-	public static final Logger CONFIG = Logger.getLogger("moe.yushi.authlibinjector.config");
-	public static final Logger TRANSFORM = Logger.getLogger("moe.yushi.authlibinjector.transform");
-	public static final Logger HTTPD = Logger.getLogger("moe.yushi.authlibinjector.httpd");
+	private static final String PREFIX = "moe.yushi.authlibinjector";
+
+	public static final Logger ROOT = Logger.getLogger(PREFIX);
+	public static final Logger LAUNCH = Logger.getLogger(PREFIX + ".launch");
+	public static final Logger CONFIG = Logger.getLogger(PREFIX + ".config");
+	public static final Logger TRANSFORM = Logger.getLogger(PREFIX + ".transform");
+	public static final Logger HTTPD = Logger.getLogger(PREFIX + ".httpd");
 
 	public static void init() {
 		initRootLogger();
-		initLoggingLevels();
 	}
 
 	private static void initRootLogger() {
-		ROOT.setLevel(Level.INFO);
+		ROOT.setLevel(Level.ALL);
 		ROOT.setUseParentHandlers(false);
 		StreamHandler handler = new StreamHandler(System.err, new Formatter() {
 			private String convertLoggerName(String loggerName) {
-				final String prefix = "moe.yushi.authlibinjector";
-				if (loggerName.startsWith(prefix)) {
-					return "authlib-injector" + loggerName.substring(prefix.length());
+				if (loggerName.startsWith(PREFIX)) {
+					return "authlib-injector" + loggerName.substring(PREFIX.length());
 				} else {
 					return loggerName;
 				}
@@ -63,14 +67,30 @@ public final class Logging {
 			}
 		};
 		handler.setLevel(Level.ALL);
-		handler.setFilter(null);
+		handler.setFilter(createFilter());
 		ROOT.addHandler(handler);
 	}
 
-	private static void initLoggingLevels() {
-		if ("true".equals(System.getProperty(PROP_DEBUG))) {
-			ROOT.setLevel(Level.ALL);
+	private static Predicate<String> createDebugLoggerNamePredicate() {
+		String argument = System.getProperty(PROP_DEBUG);
+		if (argument == null) {
+			return any -> false;
+		} else {
+			Set<String> debugLoggers = new HashSet<>();
+			for (String element : argument.split(",")) {
+				if (element.equals("true") || element.equals("all")) {
+					return loggerName -> loggerName.startsWith(PREFIX);
+				} else {
+					debugLoggers.add(PREFIX + "." + element);
+				}
+			}
+			return debugLoggers::contains;
 		}
 	}
 
+	private static Filter createFilter() {
+		Predicate<String> namePredicate = createDebugLoggerNamePredicate();
+		return log -> log.getLevel().intValue() >= Level.INFO.intValue() || namePredicate.test(log.getLoggerName());
+	}
+
 }