name: Validate PR Title

on:
  pull_request:
    types: [opened, edited, synchronize, reopened]

jobs:
  validate-pr-title:
    name: Validate PR Title Format
    runs-on: ubuntu-latest
    steps:
      - name: Check PR Title Format
        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
        with:
          script: |
            const title = context.payload.pull_request.title;
            
            // Valid PR types based on pull_request_template.md
            const validTypes = ['fix', 'feature', 'improvement', 'breaking', 'docs', 'chore', 'feat'];
            
            // Regex pattern: type(optional-scope): short description
            // - Type must be one of the valid types
            // - Scope is optional, must be in parentheses, lowercase alphanumeric with hyphens
            // - Followed by colon, space, and description (must start with lowercase letter)
            const pattern = new RegExp(`^(${validTypes.join('|')})(\\([a-z0-9-]+\\))?: [a-z].+$`);
            
            if (!pattern.test(title)) {
              const errorMessage = `
            ❌ **Invalid PR Title Format**
            
            Your PR title: \`${title}\`
            
            **Expected format:** \`type(scope): short description\` (description must start with lowercase)
            
            **Valid types:**
            - \`fix\` - Bug fixes
            - \`feature\` - New features
            - \`improvement\` - Enhancements to existing features
            - \`breaking\` - Breaking changes
            - \`docs\` - Documentation updates
            - \`chore\` - Maintenance tasks
            
            **Scope:** Optional, short identifier in parentheses (e.g., \`(api)\`, \`(auth)\`, \`(ui)\`)
            
            **Examples:**
            - \`fix: prevent crash on sync\`
            - \`fix(api): handle null response from auth endpoint\`
            - \`docs(cli): update installation guide\`
            `;
              
              core.setFailed(errorMessage);
            } else {
              console.log(`✅ PR title is valid: "${title}"`);
            }