From 37690058d260f5673876f78e6ec75364cfd3e59c Mon Sep 17 00:00:00 2001
From: Stypox <stypox@pm.me>
Date: Wed, 16 Mar 2022 22:53:21 +0100
Subject: [PATCH] Add checkstyle to extractor gradle project

With respect to NewPipe's checkstyle.xml, checkstyle is disabled for javadoc comments. There is no need for strict rules over comments here in the extractor, as sometimes javadocs are just needed to clarify a small thing and having empty/meaningless @param or @throws is useless.
---
 build.gradle              |   1 +
 checkstyle/checkstyle.xml | 189 ++++++++++++++++++++++++++++++++++++++
 extractor/build.gradle    |  20 +++-
 3 files changed, 209 insertions(+), 1 deletion(-)
 create mode 100644 checkstyle/checkstyle.xml

diff --git a/build.gradle b/build.gradle
index 3cc6fa0c4..ebac57210 100644
--- a/build.gradle
+++ b/build.gradle
@@ -30,6 +30,7 @@ allprojects {
         nanojsonVersion = "1d9e1aea9049fc9f85e68b43ba39fe7be1c1f751"
         spotbugsVersion = "4.6.0"
         junitVersion = "5.8.2"
+        checkstyleVersion = "9.3" // do not use latest version (10.0) as it requires compile SDK 11
     }
 }
 
diff --git a/checkstyle/checkstyle.xml b/checkstyle/checkstyle.xml
new file mode 100644
index 000000000..4a82f6be3
--- /dev/null
+++ b/checkstyle/checkstyle.xml
@@ -0,0 +1,189 @@
+<?xml version="1.0"?>
+<!DOCTYPE module PUBLIC
+          "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
+          "https://checkstyle.org/dtds/configuration_1_3.dtd">
+<module name="Checker">
+    <!--
+        If you set the basedir property below, then all reported file
+        names will be relative to the specified directory. See
+        https://checkstyle.org/5.x/config.html#Checker
+
+        <property name="basedir" value="${basedir}"/>
+    -->
+    <property name="severity" value="error"/>
+
+    <property name="fileExtensions" value="java, properties, xml"/>
+
+    <!-- Excludes all 'module-info.java' files              -->
+    <!-- See https://checkstyle.org/config_filefilters.html -->
+    <module name="BeforeExecutionExclusionFileFilter">
+        <property name="fileNamePattern" value="module\-info\.java$"/>
+    </module>
+
+    <!-- https://checkstyle.org/config_filters.html#SuppressionFilter -->
+    <module name="SuppressionFilter">
+        <property name="file" value="${config_loc}/suppressions.xml" />
+        <property name="optional" value="true"/>
+    </module>
+
+    <!-- Checks that a package-info.java file exists for each package.     -->
+    <!-- See https://checkstyle.org/config_javadoc.html#JavadocPackage -->
+    <!--<module name="JavadocPackage"/>-->
+
+    <!-- Checks whether files end with a new line.                        -->
+    <!-- See https://checkstyle.org/config_misc.html#NewlineAtEndOfFile -->
+    <module name="NewlineAtEndOfFile"/>
+
+    <!-- Checks that property files contain the same keys.         -->
+    <!-- See https://checkstyle.org/config_misc.html#Translation -->
+    <module name="Translation"/>
+
+    <!-- Checks for Size Violations.                    -->
+    <!-- See https://checkstyle.org/config_sizes.html -->
+    <module name="FileLength"/>
+    <module name="LineLength">
+      <property name="max" value="100"/>
+      <property name="fileExtensions" value="java"/>
+    </module>
+
+    <!-- Checks for whitespace                               -->
+    <!-- See https://checkstyle.org/config_whitespace.html -->
+    <module name="FileTabCharacter"/>
+
+    <!-- Miscellaneous other checks.                   -->
+    <!-- See https://checkstyle.org/config_misc.html -->
+    <module name="RegexpSingleline">
+       <property name="format" value="\s+$"/>
+       <property name="minimum" value="0"/>
+       <property name="maximum" value="0"/>
+       <property name="message" value="Line has trailing spaces."/>
+    </module>
+
+    <!-- Checks for Headers                                -->
+    <!-- See https://checkstyle.org/config_header.html   -->
+    <!-- <module name="Header"> -->
+    <!--   <property name="headerFile" value="${checkstyle.header.file}"/> -->
+    <!--   <property name="fileExtensions" value="java"/> -->
+    <!-- </module> -->
+
+    <module name="SuppressWarningsFilter" />
+
+    <module name="TreeWalker">
+        <!-- Checks for Javadoc comments.                     -->
+        <!-- See https://checkstyle.org/config_javadoc.html -->
+        <module name="InvalidJavadocPosition"/>
+        <module name="JavadocMethod">
+            <property name="allowMissingParamTags" value="true"/>
+            <property name="allowMissingReturnTag" value="true"/>
+        </module>
+        <module name="JavadocType"/>
+        <!--<module name="JavadocVariable"/>-->
+        <module name="JavadocStyle">
+            <property name="checkFirstSentence" value="false"/>
+        </module>
+        <!--<module name="MissingJavadocMethod"/>-->
+
+        <!-- Checks for Naming Conventions.                  -->
+        <!-- See https://checkstyle.org/config_naming.html -->
+        <module name="ConstantName"/>
+        <module name="LocalFinalVariableName"/>
+        <module name="LocalVariableName"/>
+        <module name="MemberName">
+            <property name="format" value="^(TAG|DEBUG|[a-z][a-zA-Z0-9]*)$"/>
+        </module>
+        <module name="MethodName"/>
+        <module name="PackageName"/>
+        <module name="ParameterName"/>
+        <module name="StaticVariableName"/>
+        <module name="TypeName"/>
+
+        <!-- Checks for imports                              -->
+        <!-- See https://checkstyle.org/config_import.html -->
+        <module name="AvoidStarImport"/>
+        <module name="IllegalImport"/> <!-- defaults to sun.* packages -->
+        <module name="RedundantImport"/>
+        <module name="UnusedImports"/>
+
+        <!-- Checks for Size Violations.                    -->
+        <!-- See https://checkstyle.org/config_sizes.html -->
+        <module name="MethodLength">
+            <property name="severity" value="warning"/>
+        </module>
+        <module name="ParameterNumber">
+            <property name="severity" value="warning"/>
+        </module>
+
+        <!-- Checks for whitespace                               -->
+        <!-- See https://checkstyle.org/config_whitespace.html -->
+        <module name="EmptyForIteratorPad"/>
+        <module name="GenericWhitespace"/>
+        <module name="MethodParamPad"/>
+        <module name="NoWhitespaceAfter"/>
+        <module name="NoWhitespaceBefore"/>
+        <module name="OperatorWrap"/>
+        <module name="ParenPad"/>
+        <module name="TypecastParenPad"/>
+        <module name="WhitespaceAfter"/>
+        <module name="WhitespaceAround"/>
+
+        <!-- Modifier Checks                                    -->
+        <!-- See https://checkstyle.org/config_modifiers.html -->
+        <module name="ModifierOrder"/>
+        <module name="RedundantModifier"/>
+
+        <!-- Checks for blocks. You know, those {}'s         -->
+        <!-- See https://checkstyle.org/config_blocks.html -->
+        <module name="AvoidNestedBlocks"/>
+        <module name="EmptyBlock"/>
+        <module name="LeftCurly"/>
+        <module name="NeedBraces"/>
+        <module name="RightCurly"/>
+
+        <!-- Checks for common coding problems               -->
+        <!-- See https://checkstyle.org/config_coding.html -->
+        <module name="EmptyStatement"/>
+        <module name="EqualsHashCode">
+            <property name="severity" value="warning"/>
+        </module>
+        <module name="HiddenField">
+            <property name="ignoreConstructorParameter" value="true"/>
+            <property name="ignoreSetter" value="true"/>
+        </module>
+        <module name="IllegalInstantiation"/>
+        <module name="InnerAssignment"/>
+        <!--<module name="MagicNumber"/>-->
+        <!--<module name="MissingSwitchDefault">
+            <property name="severity" value="warning"/>
+        </module>-->
+        <module name="MultipleVariableDeclarations"/>
+        <module name="SimplifyBooleanExpression"/>
+        <module name="SimplifyBooleanReturn"/>
+        <module name="FinalLocalVariable">
+            <property name="tokens" value="VARIABLE_DEF,PARAMETER_DEF"/>
+            <property name="validateEnhancedForLoopVariable" value="true"/>
+        </module>
+
+        <!-- Checks for class design                         -->
+        <!-- See https://checkstyle.org/config_design.html -->
+        <!--<module name="DesignForExtension"/>-->
+        <module name="FinalClass"/>
+        <module name="HideUtilityClassConstructor"/>
+        <module name="InterfaceIsType"/>
+        <!--<module name="VisibilityModifier">
+            <property name="ignoreAnnotationCanonicalNames" value="State,ColumnInfo"/>
+            <property name="severity" value="warning"/>
+        </module>-->
+
+        <!-- Miscellaneous other checks.                   -->
+        <!-- See https://checkstyle.org/config_misc.html -->
+        <module name="ArrayTypeStyle"/>
+        <module name="FinalParameters"/>
+        <!--<module name="TodoComment">
+            <property name="format" value="(TODO:|FIXME:)"/>
+            <property name="severity" value="warning"/>
+        </module>-->
+        <module name="UpperEll"/>
+
+        <module name="SuppressWarningsHolder" />
+    </module>
+</module>
diff --git a/extractor/build.gradle b/extractor/build.gradle
index a9b5f7f3e..70b51a338 100644
--- a/extractor/build.gradle
+++ b/extractor/build.gradle
@@ -1,9 +1,25 @@
+plugins {
+    id 'checkstyle'
+}
+
 test {
-//  Pass on downloader type to tests for different CI jobs. See DownloaderFactory.java and ci.yml
+    // Pass on downloader type to tests for different CI jobs. See DownloaderFactory.java and ci.yml
     if (System.properties.containsKey('downloader')) {
         systemProperty('downloader', System.getProperty('downloader'))
     }
     useJUnitPlatform()
+    dependsOn checkstyleMain // run checkstyle when testing
+}
+
+checkstyle {
+    getConfigDirectory().set(rootProject.file("checkstyle"))
+    ignoreFailures false
+    showViolations true
+    toolVersion checkstyleVersion
+}
+
+checkstyleTest {
+    enabled false // do not checkstyle test files
 }
 
 dependencies {
@@ -15,6 +31,8 @@ dependencies {
     implementation "com.github.spotbugs:spotbugs-annotations:$spotbugsVersion"
     implementation 'org.nibor.autolink:autolink:0.10.0'
 
+    checkstyle "com.puppycrawl.tools:checkstyle:$checkstyleVersion"
+
     testImplementation platform("org.junit:junit-bom:$junitVersion")
     testImplementation 'org.junit.jupiter:junit-jupiter-api'
     testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine'