#!/bin/sh
set -eu

helper_image='qdrant/qdrant:v1.18.2@sha256:75eab8c4ba42096724fdcfde8b4de0b5713d529dde32f285a1f86fdcb2c9e50c'
archive_format='thothii-qdrant-backup-v1'
volume_role='qdrant-data'

usage() {
  echo "usage: $0 --project-name NAME --output FILE" >&2
  exit 2
}

project_name=
output=
while [ "$#" -gt 0 ]; do
  case "$1" in
    --project-name) project_name=${2-}; shift 2 ;;
    --output) output=${2-}; shift 2 ;;
    *) usage ;;
  esac
done

[ -n "$project_name" ] && [ -n "$output" ] || usage
[ ! -e "$output" ] || { echo "refusing to overwrite existing backup: $output" >&2; exit 2; }

output_dir=$(dirname "$output")
output_name=$(basename "$output")
[ -d "$output_dir" ] || { echo "backup destination directory does not exist" >&2; exit 2; }

expected_volume_name="${project_name}_${volume_role}"
script_dir=$(CDPATH= cd "$(dirname "$0")" && pwd)
. "$script_dir/lib/vector-operation-lock.sh"
vector_operation_lock_init

resolve_volume() {
  names=$(docker volume ls \
    --filter "label=com.docker.compose.project=$project_name" \
    --filter "label=com.docker.compose.volume=$volume_role" \
    --format '{{.Name}}')
  count=$(printf '%s\n' "$names" | sed '/^$/d' | wc -l | tr -d ' ')
  [ "$count" -eq 1 ] || {
    echo "expected exactly one qdrant-data volume for compose project $project_name" >&2
    exit 2
  }
  resolved=$(printf '%s\n' "$names" | sed -n '/./{p;q;}')
  [ "$resolved" = "$expected_volume_name" ] || {
    echo "unexpected qdrant-data volume name: $resolved" >&2
    exit 2
  }
  printf '%s\n' "$resolved"
}

validate_volume_metadata() {
  metadata=$(docker volume inspect --format '{{ .Name }} {{ index .Labels "com.docker.compose.project" }} {{ index .Labels "com.docker.compose.volume" }}' "$1")
  set -- $metadata
  [ "${1-}" = "$expected_volume_name" ] || { echo "volume metadata name mismatch" >&2; exit 2; }
  [ "${2-}" = "$project_name" ] || { echo "volume metadata project label mismatch" >&2; exit 2; }
  [ "${3-}" = "$volume_role" ] || { echo "volume metadata role label mismatch" >&2; exit 2; }
}

restart_qdrant=0
temporary_output=
cleanup() {
  status=$?
  trap - EXIT HUP INT TERM
  if [ -n "${temporary_output:-}" ] && [ -e "${temporary_output:-}" ]; then
    rm -f "$temporary_output"
  fi
  if [ "$restart_qdrant" -eq 1 ]; then
    if ! docker compose --project-name "$project_name" start qdrant >/dev/null; then
      echo "Unable to restart Qdrant after backup" >&2
      [ "$status" -ne 0 ] || status=1
    fi
  fi
  if ! release_vector_operation_lock; then
    [ "$status" -ne 0 ] || status=1
  fi
  exit "$status"
}
trap cleanup EXIT HUP INT TERM

acquire_vector_operation_lock
volume_name=$(resolve_volume)
validate_volume_metadata "$volume_name"
running_container=$(docker compose --project-name "$project_name" ps --status running -q qdrant)

if [ -n "$running_container" ]; then
  restart_qdrant=1
  docker compose --project-name "$project_name" stop qdrant >/dev/null
fi

umask 077
temporary_output=$(mktemp "$output_dir/.${output_name}.tmp.XXXXXX")
created_utc=$(date -u +"%Y-%m-%dT%H:%M:%SZ")

docker run --rm \
  --mount "type=volume,src=$volume_name,dst=/qdrant-data,readonly" \
  --mount "type=bind,src=$output_dir,dst=/backup" \
  "$helper_image" \
  /bin/sh -eu -c '
    archive_format=$1
    project_name=$2
    volume_name=$3
    volume_role=$4
    helper_image=$5
    created_utc=$6
    output_name=$7
    staging=$(mktemp -d /tmp/qdrant-backup.XXXXXX)
    trap "rm -rf \"$staging\"" EXIT HUP INT TERM
    mkdir -p "$staging/payload"
    cat >"$staging/manifest.env" <<EOF
format=$archive_format
project_name=$project_name
volume_name=$volume_name
volume_role=$volume_role
helper_image=$helper_image
created_utc=$created_utc
    EOF
    cp -R /qdrant-data/. "$staging/payload"/
    tar -C "$staging" -cf "/backup/$output_name" manifest.env payload
  ' sh "$archive_format" "$project_name" "$volume_name" "$volume_role" "$helper_image" "$created_utc" "$(basename "$temporary_output")"

if ! ln "$temporary_output" "$output"; then
  echo "refusing to replace backup destination created concurrently: $output" >&2
  exit 2
fi
rm -f "$temporary_output"
temporary_output=
echo "Qdrant backup written from $volume_name to $output"