/.github/workflows/pr-validation.yml

name: PR Validation

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

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

jobs:
  validate:
    name: Validate PR Requirements
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v6

      - name: Validate PR requirements
        uses: actions/github-script@v9
        with:
          script: |
            const pr = context.payload.pull_request;
            const prBody = pr.body || '';
            const prAuthor = pr.user.login;

            // Extract issue numbers from PR description
            // Matches patterns like: Fixes #123, Closes #456, Relates to #789, etc.
            const issuePattern = /(?:fixes?|closes?|resolves?|relates?\s+to|see|refs?)\s+#(\d+)/gi;
            const matches = [...prBody.matchAll(issuePattern)];
            const issueNumbers = [...new Set(matches.map(m => parseInt(m[1])))];

            const warnings = [];

            if (issueNumbers.length === 0) {
              warnings.push('❌ **No linked issue found**: This PR does not reference any issue. Please link to an issue using "Fixes #123" or "Closes #123" in the PR description.');
            } else {
              // Check each linked issue
              for (const issueNumber of issueNumbers) {
                try {
                  const issue = await github.rest.issues.get({
                    owner: context.repo.owner,
                    repo: context.repo.repo,
                    issue_number: issueNumber
                  });

                  if (issue.data.state === 'closed') {
                    warnings.push(`⚠️ **Issue #${issueNumber} is closed**: The linked issue #${issueNumber} is already closed. Please ensure you're linking to the correct issue.`);
                  }

                  // Check if PR author is assigned to the issue
                  const assignees = issue.data.assignees.map(a => a.login);
                  if (assignees.length === 0) {
                    warnings.push(`⚠️ **Issue #${issueNumber} has no assignee**: This issue has not been assigned to anyone. Please wait for a maintainer to assign it to you before submitting a PR.`);
                  } else if (!assignees.includes(prAuthor)) {
                    warnings.push(`⚠️ **Assignment mismatch**: You (@${prAuthor}) are not assigned to issue #${issueNumber}. The issue is assigned to: ${assignees.map(a => `@${a}`).join(', ')}. Please wait for a maintainer to assign the issue to you.`);
                  }

                  // Check if issue has triage label (indicating it might not be approved yet)
                  const labels = issue.data.labels.map(l => l.name);
                  if (labels.includes('triage')) {
                    warnings.push(`ℹ️ **Issue #${issueNumber} is still in triage**: This issue may not have been reviewed and approved by a maintainer yet. Please ensure the issue has been approved before submitting a PR.`);
                  }
                } catch (error) {
                  if (error.status === 404) {
                    warnings.push(`❌ **Issue #${issueNumber} not found**: The linked issue #${issueNumber} does not exist. Please check the issue number.`);
                  } else {
                    warnings.push(`⚠️ **Error checking issue #${issueNumber}**: ${error.message}`);
                  }
                }
              }
            }

            // Post comment if there are warnings
            if (warnings.length > 0) {
              const commentBody = '## ⚠️ PR Validation Warnings\n\n' +
                warnings.join('\n\n') + '\n\n' +
                '---\n\n' +
                '**Note**: This PR can remain open, but please address these issues to ensure a smooth review process. For more information, see our [Contributing Guide](https://github.com/kornia/kornia/blob/main/CONTRIBUTING.md).';

              // Check if we already posted a comment
              const comments = await github.rest.issues.listComments({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: pr.number
              });

              const botComment = comments.data.find(
                c => c.user.type === 'Bot' && c.body.includes('PR Validation Warnings')
              );

              if (botComment) {
                // Update existing comment
                await github.rest.issues.updateComment({
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                  comment_id: botComment.id,
                  body: commentBody
                });
              } else {
                // Create new comment
                await github.rest.issues.createComment({
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                  issue_number: pr.number,
                  body: commentBody
                });
              }
            } else {
              // Remove any existing warning comments if validation passes
              const comments = await github.rest.issues.listComments({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: pr.number
              });

              const botComment = comments.data.find(
                c => c.user.type === 'Bot' && c.body.includes('PR Validation Warnings')
              );

              if (botComment) {
                await github.rest.issues.deleteComment({
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                  comment_id: botComment.id
                });
              }
            }