<?xml version="1.0"?>
<!--
  ~ Licensed to the Apache Software Foundation (ASF) under one or more
  ~ contributor license agreements.  See the NOTICE file distributed with
  ~ this work for additional information regarding copyright ownership.
  ~ The ASF licenses this file to You 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
  ~
  ~    http://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.
  ~
  -->
<!DOCTYPE module PUBLIC
        "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
        "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">

<!-- This is a checkstyle configuration file. For descriptions of
what the following rules do, please see the checkstyle configuration
page at http://checkstyle.sourceforge.net/config.html -->

<module name="Checker">
    <property name="severity" value="error"/>

    <module name="Header">
        <property name="headerFile" value="tools/maven/checkstyle-header.txt"/>
        <property name="fileExtensions" value="java"/>
    </module>

    <module name="FileTabCharacter">
        <!-- Checks that there are no tab characters in the file. -->
    </module>

    <module name="RegexpSingleline">
        <!-- Checks that TODOs don't have stuff in parenthesis, e.g., username. -->
        <property name="format" value="((//.*)|(\*.*))TODO\(" />
        <property name="message" value="TODO comments must not include usernames." />
        <property name="severity" value="error" />
    </module>

    <module name="RegexpSingleline">
        <property name="format" value="\s+$"/>
        <property name="message" value="Trailing whitespace"/>
        <property name="severity" value="error"/>
    </module>

    <module name="RegexpSingleline">
        <property name="format" value="Throwables.propagate\("/>
        <property name="message" value="Throwables.propagate is deprecated"/>
        <property name="severity" value="error"/>
    </module>

    <!-- Prevent *Tests.java as tools may not pick them up -->
    <module name="RegexpOnFilename">
        <property name="fileNamePattern" value=".*Tests\.java$" />
    </module>

    <!--
        LENGTH and CODING CHECKS
        -->

    <module name="LineLength">
        <!-- Checks if a line is too long. -->
        <property name="max" value="120"/>
        <property name="severity" value="error"/>

        <!--
          The default ignore pattern exempts the following elements:
            - import statements
            - long URLs inside comments
        -->

        <property name="ignorePattern"
                  value="^(package .*;\s*)|(import .*;\s*)|( *\* .*https?://.*)$"/>
    </module>

    <!-- Check that every module has a package-info.java -->
    <!--<module name="JavadocPackage"/>-->

    <!-- All Java AST specific tests live under TreeWalker module. -->
    <module name="TreeWalker">

        <module name="TodoComment">
            <!-- Checks that disallowed strings are not used in comments.  -->
            <property name="format" value="(FIXME)|(XXX)|(@author)" />
        </module>

        <!--
        ANNOTATIONS CHECKS
        -->

        <module name="MissingDeprecated" />

        <!--
        IMPORT CHECKS
        -->

        <module name="RedundantImport">
            <!-- Checks for redundant import statements. -->
            <property name="severity" value="error"/>
            <message key="import.redundancy"
                     value="Redundant import {0}."/>
        </module>

        <module name="ImportOrder">
            <!-- Checks for out of order import statements. -->
            <property name="severity" value="error"/>
            <property name="groups" value="org.apache.streampipes,*,javax,java,scala"/>
            <property name="separated" value="true"/>
            <property name="sortStaticImportsAlphabetically" value="true"/>
            <property name="option" value="bottom"/>
            <property name="tokens" value="STATIC_IMPORT, IMPORT"/>
            <message key="import.ordering"
                     value="Import {0} appears after other imports that it should precede"/>
        </module>

        <module name="AvoidStarImport">
            <property name="severity" value="error"/>
        </module>

        <module name="IllegalImport">
            <property name="illegalPkgs" value="autovalue.shaded, avro.shaded, com.google.api.client.repackaged, com.google.appengine.repackaged, io.netty.util.internal"/>
        </module>

        <module name="RedundantModifier">
            <!-- Checks for redundant modifiers on various symbol definitions.
              See: http://checkstyle.sourceforge.net/config_modifier.html#RedundantModifier
            -->
            <property name="tokens" value="METHOD_DEF, VARIABLE_DEF, ANNOTATION_FIELD_DEF, INTERFACE_DEF, CLASS_DEF, ENUM_DEF"/>
        </module>

        <!--
            IllegalImport cannot blacklist classes, and c.g.api.client.util is used for some shaded
            code and some useful code. So we need to fall back to Regexp.
        -->
        <module name="RegexpSinglelineJava">
            <property name="format" value="com\.google\.api\.client\.util\.(ByteStreams|Charsets|Collections2|Joiner|Lists|Maps|Objects|Preconditions|Sets|Strings|Throwables)"/>
        </module>

        <!--
             Require static importing from Preconditions.
        -->
        <module name="RegexpSinglelineJava">
            <property name="format" value="^import com.google.common.base.Preconditions;$"/>
            <property name="message" value="Static import functions from Guava Preconditions"/>
        </module>

        <module name="UnusedImports">
            <property name="severity" value="error"/>
            <property name="processJavadoc" value="true"/>
            <message key="import.unused"
                     value="Unused import: {0}."/>
        </module>

        <!--
        JAVADOC CHECKS
        -->

        <!-- Checks for Javadoc comments.                     -->
        <!-- See http://checkstyle.sf.net/config_javadoc.html -->
        <!--<module name="JavadocMethod">-->
            <!--<property name="scope" value="protected"/>-->
            <!--<property name="severity" value="error"/>-->
            <!--<property name="allowMissingJavadoc" value="true"/>-->
            <!--<property name="allowMissingParamTags" value="true"/>-->
            <!--<property name="allowMissingReturnTag" value="true"/>-->
            <!--<property name="allowMissingThrowsTags" value="true"/>-->
            <!--<property name="allowThrowsTagsForSubclasses" value="true"/>-->
            <!--<property name="allowUndeclaredRTE" value="true"/>-->
        <!--</module>-->

        <!-- Check that paragraph tags are used correctly in Javadoc. -->
        <!--<module name="JavadocParagraph"/>-->

        <!--<module name="JavadocType">-->
            <!--<property name="scope" value="protected"/>-->
            <!--<property name="severity" value="error"/>-->
            <!--<property name="allowMissingParamTags" value="true"/>-->
        <!--</module>-->

        <!--<module name="JavadocStyle">-->
            <!--<property name="severity" value="error"/>-->
            <!--<property name="checkHtml" value="true"/>-->
        <!--</module>-->

        <!--
        NAMING CHECKS
        -->

        <!-- Item 38 - Adhere to generally accepted naming conventions -->

        <module name="PackageName">
            <!-- Validates identifiers for package names against the
              supplied expression. -->
            <!-- Here the default checkstyle rule restricts package name parts to
              seven characters, this is not in line with common practice at Google.
            -->
            <property name="format" value="^[a-z]+(\.[a-z][a-z0-9]{1,})*$"/>
            <property name="severity" value="error"/>
        </module>

        <module name="TypeNameCheck">
            <!-- Validates static, final fields against the
            expression "^[A-Z][a-zA-Z0-9]*$". -->
            <metadata name="altname" value="TypeName"/>
            <property name="severity" value="error"/>
        </module>

        <module name="ConstantNameCheck">
            <!-- Validates non-private, static, final fields against the supplied
            public/package final fields "^[A-Z][A-Z0-9]*(_[A-Z0-9]+)*$". -->
            <metadata name="altname" value="ConstantName"/>
            <property name="applyToPublic" value="true"/>
            <property name="applyToProtected" value="true"/>
            <property name="applyToPackage" value="true"/>
            <property name="applyToPrivate" value="false"/>
            <property name="format" value="^([A-Z][A-Z0-9]*(_[A-Z0-9]+)*|FLAG_.*)$"/>
            <message key="name.invalidPattern"
                     value="Variable ''{0}'' should be in ALL_CAPS (if it is a constant) or be private (otherwise)."/>
            <property name="severity" value="error"/>
        </module>

        <module name="StaticVariableNameCheck">
            <!-- Validates static, non-final fields against the supplied
            expression "^[a-z][a-zA-Z0-9]*_?$". -->
            <metadata name="altname" value="StaticVariableName"/>
            <property name="applyToPublic" value="true"/>
            <property name="applyToProtected" value="true"/>
            <property name="applyToPackage" value="true"/>
            <property name="applyToPrivate" value="true"/>
            <property name="format" value="^[a-z][a-zA-Z0-9]*_?$"/>
            <property name="severity" value="error"/>
        </module>

        <module name="MemberNameCheck">
            <!-- Validates non-static members against the supplied expression. -->
            <metadata name="altname" value="MemberName"/>
            <property name="applyToPublic" value="true"/>
            <property name="applyToProtected" value="true"/>
            <property name="applyToPackage" value="true"/>
            <property name="applyToPrivate" value="true"/>
            <property name="format" value="^[a-z][a-zA-Z0-9]*$"/>
            <property name="severity" value="error"/>
        </module>

        <module name="MethodNameCheck">
            <!-- Validates identifiers for method names. -->
            <metadata name="altname" value="MethodName"/>
            <property name="format" value="^[a-z][a-zA-Z0-9]*(_[a-zA-Z0-9]+)*$"/>
            <property name="severity" value="error"/>
        </module>

        <module name="ParameterName">
            <!-- Validates identifiers for method parameters against the
              expression "^[a-z][a-zA-Z0-9]*$". -->
            <property name="severity" value="error"/>
        </module>

        <module name="LocalFinalVariableName">
            <!-- Validates identifiers for local final variables against the
              expression "^[a-z][a-zA-Z0-9]*$". -->
            <property name="severity" value="error"/>
        </module>

        <module name="LocalVariableName">
            <!-- Validates identifiers for local variables against the
              expression "^[a-z][a-zA-Z0-9]*$". -->
            <property name="severity" value="error"/>
        </module>

        <!-- Type parameters must be either one of the four blessed letters
        T, K, V, W, X or else be capital-case terminated with a T,
        such as MyGenericParameterT -->
        <module name="ClassTypeParameterName">
            <property name="format" value="^(((T|K|V|W|X)[0-9]*)|([A-Z][a-z][a-zA-Z]*T))$"/>
            <property name="severity" value="error"/>
        </module>

        <module name="MethodTypeParameterName">
            <property name="format" value="^(((T|K|V|W|X)[0-9]*)|([A-Z][a-z][a-zA-Z]*T))$"/>
            <property name="severity" value="error"/>
        </module>

        <module name="InterfaceTypeParameterName">
            <property name="format" value="^(((T|K|V|W|X)[0-9]*)|([A-Z][a-z][a-zA-Z]*T))$"/>
            <property name="severity" value="error"/>
        </module>

        <module name="LeftCurly">
            <!-- Checks for placement of the left curly brace ('{'). -->
            <property name="severity" value="error"/>
        </module>

        <module name="RightCurly">
            <!-- Checks right curlies on CATCH, ELSE, and TRY blocks are on
            the same line. e.g., the following example is fine:
            <pre>
              if {
                ...
              } else
            </pre>
            -->
            <!-- This next example is not fine:
            <pre>
              if {
                ...
              }
              else
            </pre>
            -->
            <property name="option" value="same"/>
            <property name="severity" value="error"/>
        </module>

        <!-- Checks for braces around if and else blocks -->
        <module name="NeedBraces">
            <property name="severity" value="error"/>
            <property name="tokens" value="LITERAL_IF, LITERAL_ELSE, LITERAL_FOR, LITERAL_WHILE, LITERAL_DO"/>
        </module>

        <module name="UpperEll">
            <!-- Checks that long constants are defined with an upper ell.-->
            <property name="severity" value="error"/>
        </module>

        <module name="FallThrough">
            <!-- Warn about falling through to the next case statement.  Similar to
            javac -Xlint:fallthrough, but the check is suppressed if a single-line comment
            on the last non-blank line preceding the fallen-into case contains 'fall through' (or
            some other variants that we don't publicized to promote consistency).
            -->
            <property name="reliefPattern"
                      value="fall through|Fall through|fallthru|Fallthru|falls through|Falls through|fallthrough|Fallthrough|No break|NO break|no break|continue on"/>
            <property name="severity" value="error"/>
        </module>

        <!-- Checks for over-complicated boolean expressions. -->
        <module name="SimplifyBooleanExpression"/>

        <!-- Detects empty statements (standalone ";" semicolon). -->
        <module name="EmptyStatement"/>

        <!--
        MODIFIERS CHECKS
        -->

        <module name="ModifierOrder">
            <!-- Warn if modifier order is inconsistent with JLS3 8.1.1, 8.3.1, and
                 8.4.3.  The prescribed order is:
                 public, protected, private, abstract, static, final, transient, volatile,
                 synchronized, native, strictfp
              -->
            <property name="severity" value="error"/>
        </module>


        <!--
        WHITESPACE CHECKS
        -->
        <module name="EmptyLineSeparator">
            <property name="allowNoEmptyLineBetweenFields" value="false"/>
            <property name="allowMultipleEmptyLines" value="true"/>
            <property name="allowMultipleEmptyLinesInsideClassMembers" value="true"/>
            <property name="tokens" value="IMPORT,CLASS_DEF,INTERFACE_DEF,STATIC_INIT,
                                     INSTANCE_INIT,ENUM_DEF,CTOR_DEF" />
            <!-- we don't want blank lines between member variables, so don't use VARIABLE_DEF -->
            <!-- eventually add: METHOD_DEF -->
        </module>

        <module name="WhitespaceAround">
            <!-- Checks that various tokens are surrounded by whitespace.
                 This includes most binary operators and keywords followed
                 by regular or curly braces.
            -->
            <property name="tokens" value="ASSIGN, BAND, BAND_ASSIGN, BOR,
        BOR_ASSIGN, BSR, BSR_ASSIGN, BXOR, BXOR_ASSIGN, COLON, DIV, DIV_ASSIGN,
        EQUAL, GE, GT, LAND, LE, LITERAL_CATCH, LITERAL_DO, LITERAL_ELSE,
        LITERAL_FINALLY, LITERAL_FOR, LITERAL_IF, LITERAL_RETURN,
        LITERAL_SYNCHRONIZED, LITERAL_TRY, LITERAL_WHILE, LOR, LT, MINUS,
        MINUS_ASSIGN, MOD, MOD_ASSIGN, NOT_EQUAL, PLUS, PLUS_ASSIGN, QUESTION,
        SL, SL_ASSIGN, SR_ASSIGN, STAR, STAR_ASSIGN"/>
            <property name="severity" value="error"/>
        </module>

        <module name="WhitespaceAfter">
            <!-- Checks that commas, semicolons and typecasts are followed by
                 whitespace.
            -->
            <property name="tokens" value="COMMA, SEMI, TYPECAST"/>
        </module>

        <module name="NoWhitespaceAfter">
            <!-- Checks that there is no whitespace after various unary operators.
                 Linebreaks are allowed.
            -->
            <property name="tokens" value="BNOT, DEC, DOT, INC, LNOT, UNARY_MINUS,
        UNARY_PLUS"/>
            <property name="allowLineBreaks" value="true"/>
            <property name="severity" value="error"/>
        </module>

        <module name="NoWhitespaceBefore">
            <!-- Checks that there is no whitespace before various unary operators.
                 Linebreaks are allowed.
            -->
            <property name="tokens" value="SEMI, DOT, POST_DEC, POST_INC"/>
            <property name="allowLineBreaks" value="true"/>
            <property name="severity" value="error"/>
        </module>

        <module name="OperatorWrap">
            <!-- Checks that operators like + and ? appear at newlines rather than
                 at the end of the previous line.
            -->
            <property name="option" value="NL"/>
            <property name="tokens" value="BAND, BOR, BSR, BXOR, DIV, EQUAL,
        GE, GT, LAND, LE, LITERAL_INSTANCEOF, LOR, LT, MINUS, MOD,
        NOT_EQUAL, PLUS, QUESTION, SL, SR, STAR "/>
        </module>

        <module name="OperatorWrap">
            <!-- Checks that assignment operators are at the end of the line. -->
            <property name="option" value="eol"/>
            <property name="tokens" value="ASSIGN"/>
        </module>

        <module name="ParenPad">
            <!-- Checks that there is no whitespace before close parens or after
                 open parens.
            -->
            <property name="severity" value="error"/>
        </module>

        <module name="Indentation">
            <property name="basicOffset" value="2"/>
            <property name="braceAdjustment" value="2"/>
            <property name="caseIndent" value="2"/>
            <property name="throwsIndent" value="4"/>
            <property name="lineWrappingIndentation" value="4"/>
            <property name="arrayInitIndent" value="2"/>
        </module>
    </module>
</module>
