stale_preview_removal.yml

name: Doc Preview Cleanup

on:
  schedule:
    - cron: "0 0 1 * *"

jobs:
  doc-preview-cleanup:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout gh-pages branch
        uses: actions/checkout@v4
        with:
          ref: gh-pages
      - uses: julia-actions/setup-julia@v2
      - name: Check for stale PR previews
        shell: julia {0}
        run: |
          using Pkg
          Pkg.activate(; temp=true)
          Pkg.add(["HTTP", "JSON3"])

          using HTTP
          using JSON3
          using Dates

          repo = ENV["GITHUB_REPOSITORY"]
          retention_days = 14

          pr_previews = map(filter(startswith("PR"), readdir("previews"))) do dir
              parse(Int, match(r"PR(\d*)", dir)[1])
          end

          function all_prs()
              query_prs(page) = JSON3.read(HTTP.get("https://api.github.com/repos/$repo/pulls?per_page=100;page=$(page)").body)
              prs = []
              page = 1
              while true
                  page_prs = query_prs(page)
                  isempty(page_prs) && break
                  append!(prs, page_prs)
                  page += 1
              end
              return prs
          end
          open_within_threshold = map(x -> x.number, filter(all_prs()) do pr
              time = DateTime(pr.updated_at[1:19], ISODateTimeFormat)
              return pr.state == "open" && Dates.days(now() - time) <= retention_days
          end)

          stale_previews = setdiff(pr_previews, open_within_threshold)
          @info "Found $(length(stale_previews)) stale previews"

          if isempty(stale_previews)
              @info "No stale previews"
              exit(0)
          end

          for pr in stale_previews
              path = joinpath("previews", "PR$pr")
              @info "Removing $path"
              run(`git rm -rf $path`)
          end
      - name: Push changes
        run: |
          git config user.name "Documenter.jl"
          git config user.email "documenter@juliadocs.github.io"
          git commit -m "delete preview"
          git branch gh-pages-new $(echo "delete history" | git commit-tree HEAD^{tree})
          git push --force origin gh-pages-new:gh-pages