#!/usr/bin/env bash
#
# Purge the entire BunnyCDN pull zone.
#
# `purge_cdn_cache.sh` purges the five index files by URL, which is right after
# a normal update: new packages arrive at new URLs, so only the index is stale.
#
# A rebuild is different. It replaces an object *in place*: a package whose
# build failed was published as its CRAN source, and the rebuilt binary takes
# exactly the same URL. The zone caches tarballs for ~370 days
# (`cache_expiration_time` in cdn.tf), so without a purge every client keeps
# receiving the source tarball for up to a year, and nothing about it looks
# wrong from the outside.
#
# Purging per URL would mean one API call per replaced package -- ~13.5k per
# arch against a rate-limited endpoint, where a single missed call leaves a
# silently stale package. One zone purge is a single call regardless of how many
# objects were replaced. The cost is a cold cache for everything else, which is
# why this is not used by the daily update path.
#
# The public hostnames currently use separate pull zones, so callers must pass
# every zone that serves the repository. A zone can be identified by its
# numeric ID or by one of its hostnames; hostname lookup avoids persisting IDs
# that change when a zone is recreated.
#
# Usage:
#   purge_cdn_zone.sh <BUNNYNET_API_KEY> <pull_zone> [<pull_zone>...]
#
set -euo pipefail

if (($# < 2)); then
  echo "usage: $0 <api_key> <pull_zone> [<pull_zone>...]" >&2
  exit 2
fi

api_key="$1"
shift

resolve_zone_id() {
  local zone="$1"
  local response_file
  local zone_id

  if [[ "${zone}" =~ ^[0-9]+$ ]]; then
    echo "${zone}"
    return
  fi

  response_file=$(mktemp)
  curl -sS -o "${response_file}" \
    -H "AccessKey: ${api_key}" \
    "https://api.bunny.net/pullzone"
  zone_id=$(
    jq -r --arg hostname "${zone}" \
      '(.Items // .)[] | select(any(.Hostnames[]?; .Value == $hostname)) | .Id' \
      "${response_file}"
  )
  rm -f "${response_file}"

  if [[ -z "${zone_id}" ]]; then
    echo "Could not find BunnyCDN pull zone for hostname ${zone}" >&2
    exit 1
  fi

  echo "${zone_id}"
}

for zone in "$@"; do
  zone_id=$(resolve_zone_id "${zone}")
  echo "Purging BunnyCDN pull zone ${zone_id}"

  response_file="/tmp/purge_zone_response_${zone_id}.txt"
  status=$(
    curl -sS -o "${response_file}" -w '%{http_code}' -X POST \
      -H "AccessKey: ${api_key}" \
      -H "Content-Length: 0" \
      "https://api.bunny.net/pullzone/${zone_id}/purgeCache"
  )

  if [[ "${status}" != "200" && "${status}" != "204" ]]; then
    echo "Purge of pull zone ${zone_id} failed with HTTP ${status}:" >&2
    cat "${response_file}" >&2
    exit 1
  fi

  echo "Purged pull zone ${zone_id} (HTTP ${status})"
done