java-linter.yml

name: java-linter

on:
  pull_request:
    branches: [ main ]
    paths:
      - '**.java'

permissions:
  contents: read
  pull-requests: write
  checks: write

jobs:
  java-lint-and-review:
    runs-on: ubuntu-latest
    
    steps:
      - name: Checkout code
        uses: actions/checkout@v4
        with:
          fetch-depth: 0
          token: ${{ secrets.GITHUB_TOKEN }}

      - name: Fetch PR base branch
        if: github.event_name == 'pull_request'
        run: |
          git fetch origin ${{ github.event.pull_request.base.ref }}:refs/remotes/origin/${{ github.event.pull_request.base.ref }}

      - name: Detect build tool
        id: detect-build
        run: |
          if [ -f "pom.xml" ]; then
            echo "build_tool=maven" >> $GITHUB_OUTPUT
            echo "Build tool: Maven"
          elif [ -f "build.gradle" ] || [ -f "build.gradle.kts" ]; then
            echo "build_tool=gradle" >> $GITHUB_OUTPUT
            echo "Build tool: Gradle"
          else
            echo "build_tool=none" >> $GITHUB_OUTPUT
            echo "No build tool detected"
          fi

      - name: Set up JDK 17
        uses: actions/setup-java@v4
        with:
          java-version: '17'
          distribution: 'temurin'
          cache: ${{ steps.detect-build.outputs.build_tool != 'none' && steps.detect-build.outputs.build_tool || '' }}

      - name: Cache dependencies
        uses: actions/cache@v3
        if: steps.detect-build.outputs.build_tool != 'none'
        with:
          path: |
            ~/.m2/repository
            ~/.gradle/caches
            ~/.gradle/wrapper
          key: ${{ runner.os }}-${{ steps.detect-build.outputs.build_tool }}-${{ hashFiles('**/pom.xml', '**/*.gradle*', '**/gradle-wrapper.properties') }}
          restore-keys: |
            ${{ runner.os }}-${{ steps.detect-build.outputs.build_tool }}-

      - name: Install Checkstyle
        run: |
          mkdir -p $HOME/tools
          cd $HOME/tools
          wget https://github.com/checkstyle/checkstyle/releases/download/checkstyle-10.12.5/checkstyle-10.12.5-all.jar
          echo "CHECKSTYLE_JAR=$HOME/tools/checkstyle-10.12.5-all.jar" >> $GITHUB_ENV

      - name: Download Google Java Format
        run: |
          cd $HOME/tools
          wget https://github.com/google/google-java-format/releases/download/v1.19.1/google-java-format-1.19.1-all-deps.jar
          echo "FORMATTER_JAR=$HOME/tools/google-java-format-1.19.1-all-deps.jar" >> $GITHUB_ENV

      - name: Create Checkstyle Configuration
        run: |
          cat > checkstyle.xml << 'EOF'
          <?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">
            <property name="charset" value="UTF-8"/>
            <property name="severity" value="warning"/>
            <property name="fileExtensions" value="java"/>
            
            <!-- Line length check - must be under Checker -->
            <module name="LineLength">
              <property name="max" value="120"/>
              <property name="ignorePattern" value="^package.*|^import.*|a href|href|http://|https://|ftp://"/>
            </module>
            
            <module name="TreeWalker">
              <module name="OuterTypeFilename"/>
              <module name="IllegalTokenText">
                <property name="tokens" value="STRING_LITERAL, CHAR_LITERAL"/>
                <property name="format" value="\\u00(09|0(a|A)|0(c|C)|0(d|D)|22|27|5(C|c))|\\(0(10|11|12|14|15|42|47)|134)"/>
              </module>
              <module name="AvoidEscapedUnicodeCharacters">
                <property name="allowEscapesForControlCharacters" value="true"/>
                <property name="allowByTailComment" value="true"/>
                <property name="allowNonPrintableEscapes" value="true"/>
              </module>
              <module name="AvoidStarImport"/>
              <module name="OneTopLevelClass"/>
              <module name="NoLineWrap"/>
              <module name="EmptyBlock">
                <property name="option" value="TEXT"/>
                <property name="tokens" value="LITERAL_TRY, LITERAL_FINALLY, LITERAL_IF, LITERAL_ELSE, LITERAL_SWITCH"/>
              </module>
              <module name="NeedBraces"/>
              <module name="LeftCurly"/>
              <module name="RightCurly">
                <property name="option" value="alone"/>
                <property name="tokens" value="CLASS_DEF, METHOD_DEF, CTOR_DEF, LITERAL_FOR, LITERAL_WHILE, STATIC_INIT, INSTANCE_INIT"/>
              </module>
              <module name="WhitespaceAround">
                <property name="allowEmptyConstructors" value="true"/>
                <property name="allowEmptyMethods" value="true"/>
                <property name="allowEmptyTypes" value="true"/>
                <property name="allowEmptyLoops" value="true"/>
              </module>
              <module name="OneStatementPerLine"/>
              <module name="MultipleVariableDeclarations"/>
              <module name="ArrayTypeStyle"/>
              <module name="MissingSwitchDefault"/>
              <module name="FallThrough"/>
              <module name="UpperEll"/>
              <module name="ModifierOrder"/>
              <module name="EmptyLineSeparator">
                <property name="allowNoEmptyLineBetweenFields" value="true"/>
              </module>
              <module name="SeparatorWrap">
                <property name="tokens" value="DOT"/>
                <property name="option" value="nl"/>
              </module>
              <module name="SeparatorWrap">
                <property name="tokens" value="COMMA"/>
                <property name="option" value="EOL"/>
              </module>
              <module name="PackageName">
                <property name="format" value="^[a-z]+(\.[a-z][a-z0-9]*)*$"/>
              </module>
              <module name="TypeName"/>
              <module name="MemberName">
                <property name="format" value="^[a-z][a-z0-9][a-zA-Z0-9]*$"/>
              </module>
              <module name="ParameterName">
                <property name="format" value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$"/>
              </module>
              <module name="CatchParameterName">
                <property name="format" value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$"/>
              </module>
              <module name="LocalVariableName">
                <property name="tokens" value="VARIABLE_DEF"/>
                <property name="format" value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$"/>
              </module>
              <module name="ClassTypeParameterName">
                <property name="format" value="(^[A-Z][0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
              </module>
              <module name="MethodTypeParameterName">
                <property name="format" value="(^[A-Z][0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
              </module>
              <module name="InterfaceTypeParameterName">
                <property name="format" value="(^[A-Z][0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
              </module>
              <module name="NoFinalizer"/>
              <module name="GenericWhitespace"/>
              <module name="Indentation">
                <property name="basicOffset" value="2"/>
                <property name="braceAdjustment" value="0"/>
                <property name="caseIndent" value="2"/>
                <property name="throwsIndent" value="4"/>
                <property name="lineWrappingIndentation" value="4"/>
                <property name="arrayInitIndent" value="2"/>
              </module>
              <module name="AbbreviationAsWordInName">
                <property name="ignoreFinal" value="false"/>
                <property name="allowedAbbreviationLength" value="1"/>
              </module>
              <module name="OverloadMethodsDeclarationOrder"/>
              <module name="VariableDeclarationUsageDistance"/>
              <module name="MethodParamPad"/>
              <module name="NoWhitespaceBefore">
                <property name="tokens" value="COMMA, SEMI, POST_INC, POST_DEC, DOT, ELLIPSIS, METHOD_REF"/>
                <property name="allowLineBreaks" value="true"/>
              </module>
              <module name="ParenPad"/>
              <module name="OperatorWrap">
                <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, METHOD_REF"/>
              </module>
              <module name="AnnotationLocation">
                <property name="tokens" value="CLASS_DEF, INTERFACE_DEF, ENUM_DEF, METHOD_DEF, CTOR_DEF"/>
              </module>
              <module name="AnnotationLocation">
                <property name="tokens" value="VARIABLE_DEF"/>
                <property name="allowSamelineMultipleAnnotations" value="true"/>
              </module>
              <module name="NonEmptyAtclauseDescription"/>
              <module name="MethodName">
                <property name="format" value="^[a-z][a-z0-9][a-zA-Z0-9_]*$"/>
              </module>
              <module name="EmptyCatchBlock">
                <property name="exceptionVariableName" value="expected"/>
              </module>
              <module name="CommentsIndentation"/>
            </module>
          </module>
          EOF

      - name: Get changed Java files
        id: changed-files
        run: |
          if [ "${{ github.event_name }}" = "pull_request" ]; then
            BASE_SHA="${{ github.event.pull_request.base.sha }}"
            HEAD_SHA="${{ github.sha }}"
            
            echo "Comparing $BASE_SHA...$HEAD_SHA"
            
            MERGE_BASE=$(git merge-base $BASE_SHA $HEAD_SHA)
            echo "Merge base: $MERGE_BASE"
            
            git diff --name-only --diff-filter=ACMRT $MERGE_BASE $HEAD_SHA | grep '\.java$' > changed_files.txt || true
          else
            if git rev-parse HEAD^ >/dev/null 2>&1; then
              git diff --name-only --diff-filter=ACMRT HEAD^ HEAD | grep '\.java$' > changed_files.txt || true
            else
              git diff-tree --no-commit-id --name-only --diff-filter=ACMRT -r HEAD | grep '\.java$' > changed_files.txt || true
            fi
          fi
          
          if [ -s changed_files.txt ]; then
            echo "has_changes=true" >> $GITHUB_OUTPUT
            echo "Changed Java files:"
            cat changed_files.txt
          else
            echo "has_changes=false" >> $GITHUB_OUTPUT
            echo "No Java files changed"
          fi

      - name: Run Checkstyle
        if: steps.changed-files.outputs.has_changes == 'true'
        run: |
          mkdir -p reports
          java -jar $CHECKSTYLE_JAR -c checkstyle.xml $(cat changed_files.txt | tr '\n' ' ') -f xml -o reports/checkstyle-result.xml || true
          java -jar $CHECKSTYLE_JAR -c checkstyle.xml $(cat changed_files.txt | tr '\n' ' ') || true

      - name: Run SpotBugs
        if: steps.changed-files.outputs.has_changes == 'true' && steps.detect-build.outputs.build_tool == 'maven'
        continue-on-error: true
        run: |
          mvn clean compile spotbugs:spotbugs || true

      - name: Run SpotBugs (Gradle)
        if: steps.changed-files.outputs.has_changes == 'true' && steps.detect-build.outputs.build_tool == 'gradle'
        continue-on-error: true
        run: |
          if grep -q "spotbugs" build.gradle* 2>/dev/null; then
            ./gradlew spotbugsMain || true
          else
            echo "SpotBugs not configured in Gradle project"
          fi

      - name: Format Java files
        if: steps.changed-files.outputs.has_changes == 'true'
        run: |
          mkdir -p formatted
          while IFS= read -r file; do
            if [ -f "$file" ]; then
              echo "Formatting $file..."
              java -jar $FORMATTER_JAR --replace "$file"
            fi
          done < changed_files.txt

      - name: Generate diff and suggestions
        if: steps.changed-files.outputs.has_changes == 'true'
        id: generate-diff
        run: |
          mkdir -p suggestions
          
          cat > suggestions/review.md << 'HEADER'
          ## 🔍 Java Code Review Results
          
          ### Summary
          This automated review checks your Java code for:
          - **Style violations** (Checkstyle)
          - **Code formatting** (Google Java Format)
          - **Best practices**
          
          ---
          
          HEADER
          
          if git diff --quiet; then
            echo "no_changes=true" >> $GITHUB_OUTPUT
            echo "✅ **All files are properly formatted!**" >> suggestions/review.md
          else
            echo "no_changes=false" >> $GITHUB_OUTPUT
            echo "### 📝 Formatting Changes Required" >> suggestions/review.md
            echo "" >> suggestions/review.md
            
            while IFS= read -r file; do
              if [ -f "$file" ] && ! git diff --quiet "$file"; then
                echo "#### \`$file\`" >> suggestions/review.md
                echo "" >> suggestions/review.md
                echo "<details>" >> suggestions/review.md
                echo "<summary>View suggested changes</summary>" >> suggestions/review.md
                echo "" >> suggestions/review.md
                echo '```diff' >> suggestions/review.md
                git diff "$file" >> suggestions/review.md
                echo '```' >> suggestions/review.md
                echo "" >> suggestions/review.md
                echo "</details>" >> suggestions/review.md
                echo "" >> suggestions/review.md
              fi
            done < changed_files.txt
          fi
          
          if [ -f "reports/checkstyle-result.xml" ]; then
            ERROR_COUNT=$(grep -o '<error' reports/checkstyle-result.xml | wc -l)
            if [ "$ERROR_COUNT" -gt 0 ]; then
              echo "" >> suggestions/review.md
              echo "### ⚠️ Checkstyle Issues Found: $ERROR_COUNT" >> suggestions/review.md
              echo "" >> suggestions/review.md
              echo "<details>" >> suggestions/review.md
              echo "<summary>View Checkstyle violations</summary>" >> suggestions/review.md
              echo "" >> suggestions/review.md
              java -jar $CHECKSTYLE_JAR -c checkstyle.xml $(cat changed_files.txt | tr '\n' ' ') 2>&1 | head -100 >> suggestions/review.md || true
              echo "" >> suggestions/review.md
              echo "</details>" >> suggestions/review.md
            fi
          fi
          
          cat >> suggestions/review.md << 'FOOTER'
          
          ---
          
          ### 💡 Recommendations
          
          1. **Apply formatting**: Run `google-java-format` on your files
          2. **Fix Checkstyle issues**: Address the violations mentioned above
          3. **Review best practices**: Ensure your code follows Java conventions
          
          ### 🛠️ How to Fix Locally
          
          ```bash
          # Download Google Java Format
          wget https://github.com/google/google-java-format/releases/download/v1.19.1/google-java-format-1.19.1-all-deps.jar
          
          # Format your Java files
          java -jar google-java-format-1.19.1-all-deps.jar --replace src/**/*.java
          ```
          
          Or use your IDE plugin:
          - **IntelliJ IDEA**: Install "google-java-format" plugin
          - **Eclipse**: Install "google-java-format" plugin
          - **VS Code**: Install "Language Support for Java" extension
          
          FOOTER

      - name: Comment PR with review
        if: github.event_name == 'pull_request' && steps.changed-files.outputs.has_changes == 'true'
        uses: actions/github-script@v7
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            const fs = require('fs');
            const reviewContent = fs.readFileSync('suggestions/review.md', 'utf8');
            
            const { data: comments } = await github.rest.issues.listComments({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.issue.number,
            });
            
            const botComment = comments.find(comment => 
              comment.user.type === 'Bot' && 
              comment.body.includes('🔍 Java Code Review Results')
            );
            
            if (botComment) {
              await github.rest.issues.updateComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                comment_id: botComment.id,
                body: reviewContent
              });
            } else {
              await github.rest.issues.createComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: context.issue.number,
                body: reviewContent
              });
            }

      - name: Upload formatted files as artifact
        if: steps.changed-files.outputs.has_changes == 'true' && steps.generate-diff.outputs.no_changes == 'false'
        uses: actions/upload-artifact@v4
        with:
          name: formatted-java-files
          path: |
            **/*.java
          retention-days: 7

      - name: Upload Checkstyle report
        if: steps.changed-files.outputs.has_changes == 'true' && hashFiles('reports/checkstyle-result.xml') != ''
        uses: actions/upload-artifact@v4
        with:
          name: checkstyle-report
          path: reports/checkstyle-result.xml
          retention-days: 14

      - name: Create check run
        if: steps.changed-files.outputs.has_changes == 'true'
        uses: actions/github-script@v7
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            const fs = require('fs');
            let conclusion = 'success';
            let summary = '✅ All checks passed!';
            
            if (fs.existsSync('reports/checkstyle-result.xml')) {
              const content = fs.readFileSync('reports/checkstyle-result.xml', 'utf8');
              const errorCount = (content.match(/<error/g) || []).length;
              
              if (errorCount > 0) {
                conclusion = 'failure';
                summary = `❌ Found ${errorCount} Checkstyle violations`;
              }
            }
            
            if ('${{ steps.generate-diff.outputs.no_changes }}' === 'false') {
              conclusion = 'failure';
              summary += '\n❌ Code formatting issues detected';
            }
            
            await github.rest.checks.create({
              owner: context.repo.owner,
              repo: context.repo.repo,
              name: 'Java Lint & Format Check',
              head_sha: context.sha,
              status: 'completed',
              conclusion: conclusion,
              output: {
                title: 'Java Code Quality Check',
                summary: summary
              }
            });

      - name: Fail if issues found
        if: steps.changed-files.outputs.has_changes == 'true' && steps.generate-diff.outputs.no_changes == 'false'
        run: |
          echo "❌ Code formatting or style issues detected!"
          echo "Please review the PR comment for detailed suggestions."
          exit 1