name: PR overlap

on:
  push:
    branches: [main]
  schedule:
    - cron: '15 * * * *'
  workflow_dispatch:

permissions: {}

concurrency:
  group: pr-overlap

jobs:
  overlap:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      pull-requests: write
    steps:
      - uses: actions/checkout@v7
        with:
          fetch-depth: 0
      - uses: actions/cache/restore@v6
        with:
          path: ${{ runner.temp }}/overlap-state.json
          key: pr-overlap-${{ github.run_id }}
          restore-keys: pr-overlap-
      - env:
          GH_TOKEN: ${{ github.token }}
          GH_REPO: ${{ github.repository }}
        run: |
          out=$RUNNER_TEMP/overlap
          state=$RUNNER_TEMP/overlap-state.json
          python3 tools/pr_overlap.py --base "${{ github.event.repository.default_branch }}" --out "$out"
          [ -s "$state" ] || echo '{}' > "$state"
          record() { jq --arg pr "$1" --arg h "$2" '.[$pr] = $h' "$state" > "$state.new" && mv "$state.new" "$state"; }
          shopt -s nullglob
          marker='<!-- pr-overlap -->'
          prev=
          for file in "$out"/*.md; do
            [ -z "$prev" ] || record "$prev" "$hash"
            pr=$(basename "$file" .md)
            hash=$(sha256sum "$file" | cut -d' ' -f1)
            prev=
            [ "$(jq -r --arg pr "$pr" '.[$pr] // empty' "$state")" = "$hash" ] && continue
            prev=$pr
            comment=$(gh api "repos/$GH_REPO/issues/$pr/comments" --paginate \
              --jq ".[] | select(.user.login == \"github-actions[bot]\" and (.body | startswith(\"$marker\"))) | [.id, .body] | @json" | head -n1)
            id=$(jq -r '.[0] // empty' <<< "${comment:-null}")
            if [ -s "$file" ]; then
              [ "$(jq -r '.[1]' <<< "${comment:-null}")" = "$(cat "$file")" ] && continue
              if [ -n "$id" ]; then
                gh api -X PATCH "repos/$GH_REPO/issues/comments/$id" -F body=@"$file" > /dev/null
              else
                gh pr comment "$pr" --body-file "$file"
              fi
            elif [ -n "$id" ]; then
              gh api -X DELETE "repos/$GH_REPO/issues/comments/$id"
            fi
          done
          [ -z "$prev" ] || record "$prev" "$hash"
          reports=$(for file in "$out"/*.md; do basename "$file" .md; done | jq -R . | jq -sc .)
          jq -c --argjson keep "$reports" 'with_entries(select(.key | IN($keep[])))' "$state" > "$state.new" && mv "$state.new" "$state"
      - if: always()
        uses: actions/cache/save@v6
        with:
          path: ${{ runner.temp }}/overlap-state.json
          key: pr-overlap-${{ github.run_id }}