name: Milestone Sync
on:
  pull_request_target:
    types:
      - opened
      - reopened
      - ready_for_review
      - edited
      - milestoned
      - closed
    branches:
      - develop

permissions:
  issues: write
  pull-requests: write

concurrency:
  group: milestone-sync-${{ github.event.pull_request.number }}

jobs:
  milestone-sync:
    if: github.repository_owner == 'GameServerManagers'
    runs-on: ubuntu-latest
    steps:
      - name: Set PR milestone and update linked issues
        uses: actions/github-script@v9
        with:
          script: |
            const { owner, repo } = context.repo;
            const pr = context.payload.pull_request;
            const action = context.payload.action;
            const fixedLabel = 'status: fixed in develop';

            if (action === 'closed' && !pr.merged) {
              return;
            }

            let milestone = pr.milestone;
            if (!milestone && ['opened', 'reopened', 'ready_for_review'].includes(action)) {
              const open = await github.paginate(github.rest.issues.listMilestones, { owner, repo, state: 'open', per_page: 100 });
              open.sort((a, b) => {
                if (a.due_on && b.due_on) return a.due_on.localeCompare(b.due_on);
                if (a.due_on) return -1;
                if (b.due_on) return 1;
                return a.number - b.number;
              });
              if (open.length === 0) {
                core.warning('No open milestone to assign.');
              } else {
                milestone = open[0];
                await github.rest.issues.update({ owner, repo, issue_number: pr.number, milestone: milestone.number });
                core.info(`Set PR #${pr.number} milestone to ${milestone.title}.`);
              }
            }

            const body = (pr.body || '').replace(/<!--[\s\S]*?-->/g, '');
            const issueRef = /\b(close[sd]?|fix(?:e[sd])?|resolve[sd]?|related to):?\s+(?:([\w.-]+)\/([\w.-]+))?#(\d+)/gi;
            const issues = new Map();
            for (const m of body.matchAll(issueRef)) {
              if (m[2] && (m[2].toLowerCase() !== owner.toLowerCase() || m[3].toLowerCase() !== repo.toLowerCase())) {
                continue;
              }
              const number = Number(m[4]);
              const closing = !/^related to$/i.test(m[1]);
              issues.set(number, issues.get(number) || closing);
            }

            for (const [number, closing] of issues) {
              let issue;
              try {
                ({ data: issue } = await github.rest.issues.get({ owner, repo, issue_number: number }));
              } catch (error) {
                core.warning(`Could not read #${number}: ${error.message}`);
                continue;
              }
              if (issue.pull_request) {
                continue;
              }

              if (milestone && issue.milestone?.number !== milestone.number) {
                if (issue.milestone && !pr.merged) {
                  core.info(`#${number} is in ${issue.milestone.title}; it will move to ${milestone.title} when this PR merges.`);
                } else {
                  await github.rest.issues.update({ owner, repo, issue_number: number, milestone: milestone.number });
                  core.info(`Set #${number} milestone to ${milestone.title}.`);
                }
              }

              if (pr.merged && closing && issue.state === 'open' && !issue.labels.some((l) => (l.name || l) === fixedLabel)) {
                await github.rest.issues.addLabels({ owner, repo, issue_number: number, labels: [fixedLabel] });
                core.info(`Labelled #${number} "${fixedLabel}".`);
              }
            }