# Reopen PRs that were auto-closed by require_issue_link.yml when the
# contributor was not assigned to the linked issue. When a maintainer
# assigns the contributor to the issue, this workflow finds matching
# closed PRs, verifies the issue link, and reopens them.
#
# Uses the default GITHUB_TOKEN (not a PAT or app token) so that the
# reopen and label-removal events do NOT re-trigger other workflows.
# GitHub suppresses events created by the default GITHUB_TOKEN within
# workflow runs to prevent infinite loops.

name: Reopen PR on Issue Assignment

on:
  issues:
    types: [assigned]

permissions:
  contents: read

jobs:
  reopen-linked-prs:
    runs-on: ubuntu-latest
    permissions:
      pull-requests: write

    steps:
      - name: Find and reopen matching PRs
        uses: actions/github-script@v8
        with:
          script: |
            const { owner, repo } = context.repo;
            const issueNumber = context.payload.issue.number;
            const assignee = context.payload.assignee.login;

            console.log(
              `Issue #${issueNumber} assigned to ${assignee} — searching for closed PRs to reopen`,
            );

            const q = [
              `is:pr`,
              `is:closed`,
              `author:${assignee}`,
              `label:missing-issue-link`,
              `repo:${owner}/${repo}`,
            ].join(' ');

            let data;
            try {
              ({ data } = await github.rest.search.issuesAndPullRequests({
                q,
                per_page: 30,
              }));
            } catch (e) {
              throw new Error(
                `Failed to search for closed PRs to reopen after assigning ${assignee} ` +
                `to #${issueNumber} (HTTP ${e.status ?? 'unknown'}): ${e.message}`,
              );
            }

            if (data.total_count === 0) {
              console.log('No matching closed PRs found');
              return;
            }

            console.log(`Found ${data.total_count} candidate PR(s)`);

            // Must stay in sync with the identical pattern in require_issue_link.yml
            const pattern = /(?:close[sd]?|fix(?:e[sd])?|resolve[sd]?)\s*#(\d+)/gi;

            for (const item of data.items) {
              const prNumber = item.number;
              const body = item.body || '';
              const matches = [...body.matchAll(pattern)];
              const referencedIssues = matches.map(m => parseInt(m[1], 10));

              if (!referencedIssues.includes(issueNumber)) {
                console.log(`PR #${prNumber} does not reference #${issueNumber} — skipping`);
                continue;
              }

              // Skip if already bypassed
              const labels = item.labels.map(l => l.name);
              if (labels.includes('bypass-issue-check')) {
                console.log(`PR #${prNumber} already has bypass-issue-check — skipping`);
                continue;
              }

              // Reopen first, remove label second — a closed PR that still has
              // missing-issue-link is recoverable; a closed PR with the label
              // stripped is invisible to both workflows.
              try {
                await github.rest.pulls.update({
                  owner,
                  repo,
                  pull_number: prNumber,
                  state: 'open',
                });
                console.log(`Reopened PR #${prNumber}`);
              } catch (e) {
                if (e.status === 422) {
                  // Head branch deleted — PR is unrecoverable. Notify the
                  // contributor so they know to open a new PR.
                  core.warning(`Cannot reopen PR #${prNumber}: head branch was likely deleted`);
                  try {
                    await github.rest.issues.createComment({
                      owner,
                      repo,
                      issue_number: prNumber,
                      body:
                        `You have been assigned to #${issueNumber}, but this PR could not be ` +
                        `reopened because the head branch has been deleted. Please open a new ` +
                        `PR referencing the issue.`,
                    });
                  } catch (commentErr) {
                    core.warning(
                      `Also failed to post comment on PR #${prNumber}: ${commentErr.message}`,
                    );
                  }
                  continue;
                }
                // Transient errors (rate limit, 5xx) should fail the job so
                // the label is NOT removed and the run can be retried.
                throw e;
              }

              // Remove missing-issue-link label only after successful reopen
              try {
                await github.rest.issues.removeLabel({
                  owner,
                  repo,
                  issue_number: prNumber,
                  name: 'missing-issue-link',
                });
                console.log(`Removed missing-issue-link from PR #${prNumber}`);
              } catch (e) {
                if (e.status !== 404) throw e;
              }

              // Minimize stale enforcement comment (best-effort;
              // sync w/ require_issue_link.yml minimize blocks)
              try {
                const marker = '<!-- require-issue-link -->';
                const comments = await github.paginate(
                  github.rest.issues.listComments,
                  { owner, repo, issue_number: prNumber, per_page: 100 },
                );
                const stale = comments.find(c => c.body && c.body.includes(marker));
                if (stale) {
                  await github.graphql(`
                    mutation($id: ID!) {
                      minimizeComment(input: {subjectId: $id, classifier: OUTDATED}) {
                        minimizedComment { isMinimized }
                      }
                    }
                  `, { id: stale.node_id });
                  console.log(`Minimized stale enforcement comment ${stale.id} as outdated`);
                }
              } catch (e) {
                core.warning(`Could not minimize stale comment on PR #${prNumber}: ${e.message}`);
              }
            }