name: PR Test Builds

# Runs after "Build firmware" completes. Uses workflow_run (rather than
# pull_request directly) so that secrets are available even for PRs from forks.
#
# Requires a repository secret PR_BUILDS_TOKEN with Contents: write access
# to iNavFlight/pr-test-builds (fine-grained PAT or classic PAT with repo scope).
on:
  workflow_run:
    workflows: ["Build firmware"]
    types: [completed]

jobs:
  publish:
    runs-on: ubuntu-latest
    # Only act on pull_request-triggered runs that succeeded.
    if: >
      github.event.workflow_run.event == 'pull_request' &&
      github.event.workflow_run.conclusion == 'success'
    # Prevent concurrent runs for the same PR branch racing on the
    # release delete/create cycle.
    concurrency:
      group: pr-test-build-${{ github.event.workflow_run.head_repository.full_name }}-${{ github.event.workflow_run.head_branch }}
      cancel-in-progress: true
    permissions:
      actions: read          # to download artifacts from the triggering workflow run
      issues: write          # github.rest.issues.* endpoints used to post PR comments
      pull-requests: write   # to post the PR comment

    steps:
      - name: Download PR number
        uses: actions/download-artifact@v4
        with:
          name: pr-number
          run-id: ${{ github.event.workflow_run.id }}
          github-token: ${{ secrets.GITHUB_TOKEN }}

      - name: Read PR number
        id: pr
        run: |
          PR_NUM=$(tr -dc '0-9' < pr_number.txt)
          if [ -z "$PR_NUM" ]; then
            echo "::error::Invalid PR number in artifact"
            exit 1
          fi
          echo "number=${PR_NUM}" >> $GITHUB_OUTPUT

      - name: Download firmware artifacts
        uses: actions/download-artifact@v4
        with:
          pattern: matrix-inav-*
          merge-multiple: true
          path: hexes
          run-id: ${{ github.event.workflow_run.id }}
          github-token: ${{ secrets.GITHUB_TOKEN }}

      - name: Get build info
        id: info
        run: |
          COUNT=$(find hexes -name '*.hex' -type f | wc -l)
          if [ "$COUNT" -eq 0 ]; then
            echo "::error::No .hex files found in downloaded artifacts"
            exit 1
          fi
          echo "count=${COUNT}" >> $GITHUB_OUTPUT
          echo "short_sha=$(echo '${{ github.event.workflow_run.head_sha }}' | cut -c1-7)" >> $GITHUB_OUTPUT

      # Delete the previous release for this PR (if any) so assets are replaced
      # cleanly on each new commit. --cleanup-tag removes the old tag so it is
      # recreated fresh pointing to the new commit.
      - name: Delete existing PR release
        env:
          GH_TOKEN: ${{ secrets.PR_BUILDS_TOKEN }}
        run: |
          gh release delete "pr-${{ steps.pr.outputs.number }}" \
            --repo iNavFlight/pr-test-builds --cleanup-tag --yes 2>/dev/null || true

      - name: Create PR release
        env:
          GH_TOKEN: ${{ secrets.PR_BUILDS_TOKEN }}
          PR_NUMBER: ${{ steps.pr.outputs.number }}
          SHORT_SHA: ${{ steps.info.outputs.short_sha }}
          HEX_COUNT: ${{ steps.info.outputs.count }}
          REPO: ${{ github.repository }}
        run: |
          PR_URL="https://github.com/${REPO}/pull/${PR_NUMBER}"
          printf '%s\n\n%s\n\n%s\n' \
            "Test build for [PR #${PR_NUMBER}](${PR_URL}) — commit \`${SHORT_SHA}\`" \
            "**${HEX_COUNT} targets built.** Find your board's \`.hex\` file by name (e.g. \`MATEKF405SE.hex\`)." \
            "> Development build for testing only. Use Full Chip Erase when flashing." \
            > release-notes.md
          gh release create "pr-${PR_NUMBER}" hexes/*.hex \
            --repo iNavFlight/pr-test-builds \
            --prerelease \
            --title "PR #${PR_NUMBER} (${SHORT_SHA})" \
            --notes-file release-notes.md

      - name: Post or update PR comment
        uses: actions/github-script@v7
        env:
          PR_NUMBER: ${{ steps.pr.outputs.number }}
          SHORT_SHA: ${{ steps.info.outputs.short_sha }}
          HEX_COUNT: ${{ steps.info.outputs.count }}
        with:
          script: |
            const prNumber = parseInt(process.env.PR_NUMBER, 10);
            if (isNaN(prNumber)) throw new Error(`Invalid PR number: ${process.env.PR_NUMBER}`);
            const shortSha  = process.env.SHORT_SHA;
            const count     = process.env.HEX_COUNT;
            const releaseUrl = `https://github.com/iNavFlight/pr-test-builds/releases/tag/pr-${prNumber}`;

            const body = [
              '<!-- pr-test-build -->',
              '**Test firmware build ready** — commit `' + shortSha + '`',
              '',
              `[Download firmware for PR #${prNumber}](${releaseUrl})`,
              '',
              `${count} targets built. Find your board's \`.hex\` file by name on that page ` +
              '(e.g. `MATEKF405SE.hex`). Files are individually downloadable — no GitHub login required.',
              '',
              '> Development build for testing only. Use Full Chip Erase when flashing.',
            ].join('\n');

            const comments = await github.paginate(
              github.rest.issues.listComments,
              {
                owner: context.repo.owner,
                repo:  context.repo.repo,
                issue_number: prNumber,
              }
            );

            const existing = comments.find(c =>
              c.user.type === 'Bot' && c.body.includes('<!-- pr-test-build -->')
            );

            if (existing) {
              await github.rest.issues.updateComment({
                owner:      context.repo.owner,
                repo:       context.repo.repo,
                comment_id: existing.id,
                body,
              });
            } else {
              await github.rest.issues.createComment({
                owner:        context.repo.owner,
                repo:         context.repo.repo,
                issue_number: prNumber,
                body,
              });
            }