name: 'Get Changed Files'
description: 'Gets the list of files changed in a pull request or push event'
inputs:
  filter:
    description: 'Optional filter pattern (e.g., "*.md" for markdown files, ".github/" for GitHub files)'
    required: false
    default: ''
  event-types:
    description: 'Comma-separated list of event types to support (pull_request, push)'
    required: false
    default: 'pull_request'
outputs:
  files:
    description: 'JSON array of changed file paths'
    value: ${{ steps.get-files.outputs.files }}
  count:
    description: 'Number of changed files'
    value: ${{ steps.get-files.outputs.count }}
runs:
  using: 'composite'
  steps:
    - name: Get changed files
      id: get-files
      uses: actions/github-script@f28e40c7f34bde8b3046d885e986cb6290c5673b # v7.1.0
      with:
        script: |
          const eventTypes = '${{ inputs.event-types }}'.split(',').map(t => t.trim());
          const filter = '${{ inputs.filter }}';
          let changedFiles = [];

          if (eventTypes.includes('pull_request') && context.eventName === 'pull_request') {
            console.log(`Getting files changed in PR #${context.payload.pull_request.number}`);

            // Fetch all files changed in the PR with pagination
            let allFiles = [];
            let page = 1;
            let fetchedCount;

            do {
              const { data: files } = await github.rest.pulls.listFiles({
                owner: context.repo.owner,
                repo: context.repo.repo,
                pull_number: context.payload.pull_request.number,
                per_page: 100,
                page: page
              });

              allFiles = allFiles.concat(files);
              fetchedCount = files.length;
              page++;
            } while (fetchedCount === 100);

            if (allFiles.length >= 100) {
              console.log(`Note: This PR has ${allFiles.length} changed files. All files fetched using pagination.`);
            }

            changedFiles = allFiles
              .filter(file => file.status === 'added' || file.status === 'modified' || file.status === 'renamed')
              .map(file => file.filename);

          } else if (eventTypes.includes('push') && context.eventName === 'push') {
            console.log(`Getting files changed in push to ${context.ref}`);

            const { data: comparison } = await github.rest.repos.compareCommits({
              owner: context.repo.owner,
              repo: context.repo.repo,
              base: context.payload.before,
              head: context.payload.after,
            });

            changedFiles = comparison.files
              .filter(file => file.status === 'added' || file.status === 'modified' || file.status === 'renamed')
              .map(file => file.filename);

          } else {
            core.setFailed(`Unsupported event type: ${context.eventName}. Supported types: ${eventTypes.join(', ')}`);
            return;
          }

          // Apply filter if provided
          if (filter) {
            const filterLower = filter.toLowerCase();
            const beforeFilter = changedFiles.length;
            changedFiles = changedFiles.filter(file => {
              const fileLower = file.toLowerCase();
              // Support simple patterns like "*.md" or ".github/"
              if (filterLower.startsWith('*.')) {
                const ext = filterLower.substring(1);
                return fileLower.endsWith(ext);
              } else {
                return fileLower.startsWith(filterLower);
              }
            });
            console.log(`Filter '${filter}' applied: ${beforeFilter} → ${changedFiles.length} files`);
          }

          // Calculate simple hash for verification
          const crypto = require('crypto');
          const filesJson = JSON.stringify(changedFiles.sort());
          const hash = crypto.createHash('sha256').update(filesJson).digest('hex').substring(0, 8);

          // Log changed files in a collapsible group
          core.startGroup(`Changed Files (${changedFiles.length} total, hash: ${hash})`);
          if (changedFiles.length > 0) {
            changedFiles.forEach(file => console.log(`  - ${file}`));
          } else {
            console.log('  (no files changed)');
          }
          core.endGroup();

          console.log(`Found ${changedFiles.length} changed files`);
          core.setOutput('files', JSON.stringify(changedFiles));
          core.setOutput('count', changedFiles.length);

branding:
  icon: 'file-text'
  color: 'blue'