name: cache-prune

# Keeps the repository's total cache size below a fixed limit, so that GitHub never
# rejects a save for being over the allowance.

on:
  schedule:
    - cron: "37 */6 * * *" # every six hours at :37
  workflow_dispatch:
  workflow_call:

permissions: {}

concurrency:
  group: cache-prune

jobs:
  prune:
    runs-on: ubuntu-latest
    if: github.repository == 'go-gitea/gitea'
    permissions:
      actions: write # to delete caches
    env:
      GH_TOKEN: ${{ github.token }}
      GH_REPO: ${{ github.repository }}
    steps:
      # Keep the newest generation per key, restores never reach the older ones.
      - name: delete superseded caches
        run: |
          gh cache list --limit 1000 --json id,key,ref,createdAt |
            jq -r 'group_by([.ref, (.key | sub("(-go[0-9.]+)?-[0-9a-f]{40,64}(-[0-9]+-[0-9]+)?$"; ""))])[]
              | sort_by(.createdAt)[:-1][] | "\(.id) \(.key)"' |
            while read -r id key; do
              echo "deleting $key"
              gh cache delete "$id" || true
            done

      # Deletes least recently used first, the order GitHub itself evicts in.
      - name: delete caches over the size limit
        run: |
          caches=$(gh cache list --limit 1000 --sort last_accessed_at --order asc --json id,key,sizeInBytes)
          size=$(jq '[.[].sizeInBytes] | add // 0' <<< "$caches")
          echo "cache usage: $((size / 1000000)) MB"
          while [ "$size" -gt 6000000000 ] && read -r id bytes key; do
            echo "deleting $key"
            gh cache delete "$id" || true
            size=$((size - bytes))
          done <<< "$(jq -r '.[] | "\(.id) \(.sizeInBytes) \(.key)"' <<< "$caches")"