pr-validation.yml

name: PR Validation

on:
  pull_request:
    branches: [master]

permissions:
  contents: read
  pull-requests: write

jobs:
  validate-algorithms:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Setup Node.js
        uses: actions/setup-node@v4
        with:
          node-version: '20'

      - name: Install dependencies
        run: npm install

      - name: Detect changed algorithm directories
        id: changes
        run: |
          # Get list of changed files compared to base branch
          CHANGED=$(git diff --name-only origin/${{ github.base_ref }}...HEAD -- 'algorithms/')

          if [ -z "$CHANGED" ]; then
            echo "dirs=" >> "$GITHUB_OUTPUT"
            echo "has_changes=false" >> "$GITHUB_OUTPUT"
            exit 0
          fi

          # Extract unique algorithm directories (algorithms/{category}/{slug})
          DIRS=$(echo "$CHANGED" | sed -n 's|\(algorithms/[^/]*/[^/]*\)/.*|\1|p' | sort -u)
          echo "has_changes=true" >> "$GITHUB_OUTPUT"

          # Write dirs to a file for the next step
          echo "$DIRS" > /tmp/changed-dirs.txt
          echo "Detected changed algorithm directories:"
          cat /tmp/changed-dirs.txt

      - name: Validate changed algorithms
        if: steps.changes.outputs.has_changes == 'true'
        id: validate
        run: |
          VALID_CATEGORIES="sorting searching graph dynamic-programming trees strings math greedy backtracking divide-and-conquer bit-manipulation geometry cryptography data-structures"
          VALID_DIFFICULTIES="beginner intermediate advanced"
          REQUIRED_META_FIELDS="name slug category difficulty complexity"

          ERRORS=""
          WARNINGS=""
          PASS=true

          while IFS= read -r dir; do
            [ -z "$dir" ] && continue
            echo "Checking: $dir"

            # Extract category and slug
            CATEGORY=$(echo "$dir" | cut -d'/' -f2)
            SLUG=$(echo "$dir" | cut -d'/' -f3)

            # Check metadata.yaml exists
            if [ ! -f "$dir/metadata.yaml" ]; then
              ERRORS="$ERRORS\n- \`$dir\`: Missing \`metadata.yaml\`"
              PASS=false
              continue
            fi

            # Validate category
            if ! echo "$VALID_CATEGORIES" | grep -qw "$CATEGORY"; then
              ERRORS="$ERRORS\n- \`$dir\`: Invalid category \`$CATEGORY\`"
              PASS=false
            fi

            # Check README.md exists
            if [ ! -f "$dir/README.md" ]; then
              ERRORS="$ERRORS\n- \`$dir\`: Missing \`README.md\`"
              PASS=false
            fi

            # Check tests/cases.yaml exists
            if [ ! -f "$dir/tests/cases.yaml" ]; then
              ERRORS="$ERRORS\n- \`$dir\`: Missing \`tests/cases.yaml\`"
              PASS=false
            else
              # Check for at least 1 test case
              TEST_COUNT=$(grep -c "^\s*- name:" "$dir/tests/cases.yaml" 2>/dev/null || echo "0")
              if [ "$TEST_COUNT" -lt 1 ]; then
                ERRORS="$ERRORS\n- \`$dir\`: \`tests/cases.yaml\` has no test cases"
                PASS=false
              fi
            fi

            # Validate metadata fields using node
            node -e "
              const fs = require('fs');
              const YAML = require('yaml');
              const meta = YAML.parse(fs.readFileSync('$dir/metadata.yaml', 'utf-8'));
              const required = '$REQUIRED_META_FIELDS'.split(' ');
              const missing = required.filter(f => !meta || meta[f] === undefined || meta[f] === null || meta[f] === '');
              if (missing.length > 0) {
                console.log('MISSING:' + missing.join(','));
              }
              const validDiff = '$VALID_DIFFICULTIES'.split(' ');
              if (meta && meta.difficulty && !validDiff.includes(meta.difficulty)) {
                console.log('BAD_DIFFICULTY:' + meta.difficulty);
              }
            " 2>/dev/null | while IFS= read -r line; do
              if echo "$line" | grep -q "^MISSING:"; then
                FIELDS=$(echo "$line" | sed 's/^MISSING://')
                echo "::error::$dir: metadata.yaml missing required fields: $FIELDS"
              fi
              if echo "$line" | grep -q "^BAD_DIFFICULTY:"; then
                DIFF=$(echo "$line" | sed 's/^BAD_DIFFICULTY://')
                echo "::error::$dir: Invalid difficulty '$DIFF'"
              fi
            done

          done < /tmp/changed-dirs.txt

          # Build summary
          {
            echo "## PR Validation Results"
            echo ""
            if [ "$PASS" = true ]; then
              echo "All checks passed."
            else
              echo "### Errors"
              echo ""
              echo -e "$ERRORS"
            fi
          } > /tmp/validation-summary.md

          echo "pass=$PASS" >> "$GITHUB_OUTPUT"

      - name: Comment on PR
        if: steps.changes.outputs.has_changes == 'true'
        uses: actions/github-script@v7
        with:
          script: |
            const fs = require('fs');
            const body = fs.readFileSync('/tmp/validation-summary.md', 'utf-8');

            // Find existing bot comment to update
            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(c =>
              c.user.type === 'Bot' && c.body.includes('PR Validation Results')
            );

            if (botComment) {
              await github.rest.issues.updateComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                comment_id: botComment.id,
                body,
              });
            } else {
              await github.rest.issues.createComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: context.issue.number,
                body,
              });
            }

      - name: Fail if validation errors
        if: steps.validate.outputs.pass == 'false'
        run: |
          echo "Validation failed. See PR comment for details."
          exit 1

      - name: Run full structure validation
        run: node scripts/validate-structure.mjs