name: Label Issues by OS

on:
  issues:
    types:
      - opened
      - edited
      - reopened

permissions:
  issues: write

jobs:
  apply-os-label:
    runs-on: ubuntu-latest
    timeout-minutes: 5
    steps:
      - name: Apply OS label from issue form
        uses: actions/github-script@v8
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            const issue = context.payload.issue;
            const body = issue.body || "";
            const osMatch = body.match(/^### Operating system\s+(.+)$/m);

            if (!osMatch) {
              core.info("No operating system field found. Skipping.");
              return;
            }

            const selectedOs = osMatch[1].trim().toLowerCase();
            const osLabelMap = {
              macos: "os:macos",
              windows: "os:Windows",
              linux: "os:linux",
            };

            const desiredLabel = osLabelMap[selectedOs];
            if (!desiredLabel) {
              core.info(`No OS label configured for "${selectedOs}". Skipping.`);
              return;
            }

            const managedLabels = Object.values(osLabelMap);
            const existingLabels = issue.labels.map((label) =>
              typeof label === "string" ? label : label.name,
            );
            const labelsToKeep = existingLabels.filter(
              (label) => !managedLabels.includes(label),
            );
            const nextLabels = [...new Set([...labelsToKeep, desiredLabel])];

            await github.rest.issues.setLabels({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: issue.number,
              labels: nextLabels,
            });

            core.info(`Applied label ${desiredLabel} to issue #${issue.number}.`);