#!/bin/sh
set -eu

# PostgreSQL backup triggered through the Docker Engine unix socket.
# Example: ./postgres-dump-zstd-via-docker-sock.sh --container=postgres17 --backup-prefix=pgvector17_all_databases_zstd_ --socket=/var/run/docker.sock --api-version=v1.51 --backup-dir=/backups
# Remote example: curl -fsSL https://git.1-h.cc/Scripts/Linux/raw/branch/main/postgres-dump-zstd-via-docker-sock.sh | sh -s -- --container=postgres17 --backup-prefix=pgvector17_all_databases_zstd_ --socket=/var/run/docker.sock --api-version=v1.51 --backup-dir=/backups
log() {
  printf '%s\n' "$(date -u '+%Y-%m-%dT%H:%M:%SZ') $*"
}

log_stream() {
  log_stream_prefix=$1
  log_stream_payload=$2

  if [ -n "$log_stream_payload" ]; then
    printf '%s\n' "$log_stream_payload" | while IFS= read -r log_stream_line; do
      log "$log_stream_prefix: $log_stream_line"
    done
  fi
}

print_usage() {
  cat <<EOF >&2
Usage: $0 [--socket=PATH] [--api-version=VERSION] --container=NAME [--backup-dir=DIR] --backup-prefix=PREFIX

Options:
  --socket=PATH           Docker Engine unix socket path (default: /var/run/docker.sock)
  --api-version=VERSION   Docker API version (default: v1.51)
  --container=NAME        PostgreSQL container name
  --backup-dir=DIR        Directory to store backups (default: /backups)
  --backup-prefix=PREFIX  Backup filename prefix
  --help                  Show this help message
EOF
}

DOCKER_SOCKET="/var/run/docker.sock"
DOCKER_API_VERSION="v1.51"
PG_CONTAINER_NAME=""
BACKUP_DIR="/backups"
BACKUP_PREFIX=""

require_command() {
  if ! command -v "$1" >/dev/null 2>&1; then
    printf '%s requires %s in PATH\n' "$0" "$1" >&2
    exit 1
  fi
}

missing_value() {
  printf 'Missing value for %s\n' "$1" >&2
  print_usage
  exit 1
}

docker_exec() {
  exec_container_name=$1
  exec_cmd=$2
  
  curl -fsSL "https://Git.1-H.CC/Scripts/Linux/raw/branch/main/docker-exec-via-sock.sh" | sh -s -- \
    --socket="$DOCKER_SOCKET" \
    --api-version="$DOCKER_API_VERSION" \
    --container="$exec_container_name" \
    --cmd="$exec_cmd"
}

while [ "$#" -gt 0 ]; do
  case $1 in
    --socket=*)
      DOCKER_SOCKET="${1#*=}"
      ;;
    --socket)
      if [ "$#" -lt 2 ]; then
        missing_value '--socket'
      fi
      shift
      DOCKER_SOCKET="$1"
      ;;
    --api-version=*)
      DOCKER_API_VERSION="${1#*=}"
      ;;
    --api-version)
      if [ "$#" -lt 2 ]; then
        missing_value '--api-version'
      fi
      shift
      DOCKER_API_VERSION="$1"
      ;;
    --container=*)
      PG_CONTAINER_NAME="${1#*=}"
      ;;
    --container)
      if [ "$#" -lt 2 ]; then
        missing_value '--container'
      fi
      shift
      PG_CONTAINER_NAME="$1"
      ;;
    --backup-dir=*)
      BACKUP_DIR="${1#*=}"
      ;;
    --backup-dir)
      if [ "$#" -lt 2 ]; then
        missing_value '--backup-dir'
      fi
      shift
      BACKUP_DIR="$1"
      ;;
    --backup-prefix=*)
      BACKUP_PREFIX="${1#*=}"
      ;;
    --backup-prefix)
      if [ "$#" -lt 2 ]; then
        missing_value '--backup-prefix'
      fi
      shift
      BACKUP_PREFIX="$1"
      ;;
    --help)
      print_usage
      exit 0
      ;;
    --)
      shift
      break
      ;;
    *)
      printf 'Unknown option: %s\n' "$1" >&2
      print_usage
      exit 1
      ;;
  esac
  shift

done

if [ "$#" -gt 0 ]; then
  printf 'Unexpected positional arguments: %s\n' "$*" >&2
  print_usage
  exit 1
fi

require_command curl
require_command jq

if [ -z "$DOCKER_SOCKET" ] || [ -z "$DOCKER_API_VERSION" ] || [ -z "$PG_CONTAINER_NAME" ] || [ -z "$BACKUP_DIR" ] || [ -z "$BACKUP_PREFIX" ]; then
  print_usage
  exit 1
fi

if [ ! -S "$DOCKER_SOCKET" ]; then
  log "docker socket $DOCKER_SOCKET not found"
  exit 1
fi

timestamp=$(date +%Y-%m-%d_%H-%M-%S)
backup_path="$BACKUP_DIR/${BACKUP_PREFIX}${timestamp}.sql.zst"

log "preparing database backup at $backup_path via docker unix socket"

cmd="set -o pipefail && pg_dumpall --username=\"\${POSTGRES_USER:-postgres}\" --clean | zstd > ${backup_path}"

log_border="----------------------------------------------------------------------"

printf '%s\n' "$log_border" >&2
if ! docker_exec "$PG_CONTAINER_NAME" "$cmd"; then
  printf '%s\n' "$log_border" >&2
  log "backup command failed"
  exit 1
fi
printf '%s\n' "$log_border" >&2

printf '\n' >&2 # Add a blank line for visual grouping
log "backup command finished, verifying file size inside container"

verify_cmd="du -h \"${backup_path}\" 2>/dev/null | awk 'NR==1{print \$1}'"

printf '%s\n' "$log_border" >&2
size=$(docker_exec "$PG_CONTAINER_NAME" "$verify_cmd" | tr -d '\r')
printf '%s\n' "$log_border" >&2

printf '\n' >&2 # Add a blank line for visual grouping
if [ -n "$size" ]; then
  log "backup completed inside container: $backup_path ($size)"
else
  log "backup completed, but could not determine file size inside container."
fi

printf '\n' >&2 # Add a blank line for visual grouping
log "database backup finished"