#!/usr/bin/env bash
set -euo pipefail

MINIMUM_FREE_GIB="${MINIMUM_FREE_GIB:-10}"
IMAGE_REPOSITORY="${IMAGE_REPOSITORY:-*/copse/jyotisha}"
KEEP_IMAGE_SHA="${KEEP_IMAGE_SHA:-}"

if ! [[ "$MINIMUM_FREE_GIB" =~ ^[0-9]+$ ]]; then
  echo "MINIMUM_FREE_GIB must be a whole number of GiB" >&2
  exit 1
fi

DOCKER_ROOT="$(docker info --format '{{.DockerRootDir}}')"
if [ -z "$DOCKER_ROOT" ] || [ ! -d "$DOCKER_ROOT" ]; then
  echo "unable to resolve the Docker root directory to measure" >&2
  exit 1
fi

free_gib() {
  df -Pk "$DOCKER_ROOT" | awk 'NR == 2 { printf "%d", $4 / 1048576 }'
}

BEFORE_GIB="$(free_gib)"
echo "docker root $DOCKER_ROOT has ${BEFORE_GIB} GiB free before reclaim"

# Every reclaim below is restricted to resources no container currently holds,
# so a quality-gate job running concurrently on this runner keeps its fixtures.
docker container prune --force --filter until=6h
docker volume ls --quiet --filter 'name=^jyotisha-postgres-' --filter dangling=true |
  xargs -r docker volume rm
docker network prune --force --filter until=6h
docker image prune --force

# Exact-SHA release images are immutable in the registry once published, so the
# runner's local copies are rebuildable cache rather than release state.
KEEP_TAG_SHA="${KEEP_IMAGE_SHA:-no-image-to-keep}"
STALE_IMAGES="$(docker image ls --format '{{.Repository}}:{{.Tag}}' \
  --filter "reference=$IMAGE_REPOSITORY:api-*" \
  --filter "reference=$IMAGE_REPOSITORY:web-*" |
  grep -v -F -e "api-$KEEP_TAG_SHA" -e "web-$KEEP_TAG_SHA" || true)"
if [ -n "$STALE_IMAGES" ]; then
  printf '%s\n' "$STALE_IMAGES" | xargs -r docker image rm || true
fi

docker builder prune --force --all

AFTER_GIB="$(free_gib)"
echo "docker root $DOCKER_ROOT has ${AFTER_GIB} GiB free after reclaim"
docker system df

if [ "$AFTER_GIB" -lt "$MINIMUM_FREE_GIB" ]; then
  echo "runner kept only ${AFTER_GIB} GiB free; PostgreSQL fixtures and image builds need at least ${MINIMUM_FREE_GIB} GiB" >&2
  exit 1
fi

echo "runner disk reclaimed"