#!/usr/bin/env bash
# Delete the binary assets of every release except the newest KEEP ones.
#
# Gitea has no asset retention, so 9 assets x ~57 MB per tag pile up forever on
# the host disk (sow-tools #52). Nothing consumes an old asset: CI takes the
# Crucible binary from the Nix flake, and every deleted file is reproducible
# from its tag. Tags, source archives, release notes and the releases
# themselves are never touched — only attachments.
#
# Nothing is excluded, SHA256SUMS and the wrappers included: the checksums are
# only meaningful next to the binaries they cover, and the drift-check reads
# the wrappers from the latest release, which always stays complete.
#
# Best-effort by design: a stale asset is cheaper than a blocked release, so
# every API failure is a warning, never a non-zero exit.
#
# Env:
#   API    repo API base, e.g. https://git.example/api/v1/repos/owner/repo  [required]
#   TOKEN  Gitea token with releases:write                                  [required]
#   KEEP   how many newest releases stay complete (default 2)
set -uo pipefail

: "${API:?set API}"
: "${TOKEN:?set TOKEN}"
keep="${KEEP:-2}"
auth="Authorization: token ${TOKEN}"
per_page=50

warn() { echo "prune-release-assets: $*" >&2; }

# Walk every page so an old backlog is cleared, not only the tag that fell out
# of the window on this run. Each page already embeds its releases' assets, so
# no follow-up request per release is needed.
releases='[]'
page=1
while :; do
  body="$(curl -fsS -H "$auth" "${API}/releases?limit=${per_page}&page=${page}&draft=false")" || {
    warn "listing releases failed on page ${page}; pruning what was listed so far"
    break
  }
  count="$(jq 'length' <<<"$body")" || { warn "unreadable release page ${page}"; break; }
  releases="$(jq -s 'add' <(printf '%s' "$releases") <(printf '%s' "$body"))"
  # A short page is the last one; this also stops a server that ignores `page`.
  (( count < per_page )) && break
  page=$(( page + 1 ))
done

# Sort here rather than trusting the response order, and skip drafts in case
# the server ignored `draft=false` — a draft must not consume a keep slot and
# strip the binaries off the newest real release.
mapfile -t stale < <(jq -r --argjson keep "$keep" '
  [.[] | select(.draft != true)]
  | sort_by(.created_at) | reverse | .[$keep:]
  | .[] | "\(.id) \(.assets // [] | map(.id) | join(","))"
' <<<"$releases")

(( ${#stale[@]} )) || { echo "prune-release-assets: nothing older than the newest ${keep} releases"; exit 0; }

for line in "${stale[@]}"; do
  id="${line%% *}"
  assets="${line#* }"
  for asset in ${assets//,/ }; do
    echo "deleting asset ${asset} of release ${id}"
    curl -fsS -X DELETE -H "$auth" "${API}/releases/${id}/assets/${asset}" >/dev/null \
      || warn "deleting asset ${asset} of release ${id} failed"
  done
done