#!/bin/bash

function usage() {
  cat <<EOF
  docker-backup [options] [command] [args...]

  COMMNADS:

    run:      Create a new backup (default if no options or command is passed)
    restart:  Restart all docker stacks.
    restore:  Restore from a backup, accepts argument which is path to an archive, if
              no argument is supplied, then it will use the latest backup found.

  OPTIONS:

    -h | --help:    Show this message.
    --version:      Show the version.
  
EOF
}

# ==================================================
# Variables
# ==================================================

debug=${DEBUG:-}
version=1.0.1
today=$(date +'%F')
stackdir="/etc/komodo/stacks"
backupdir="/backups"
services=($(find "$stackdir" -maxdepth 1 -mindepth 1 -type d))
# Directories to backup.
volumes=(
  "/var/lib/docker/volumes"
  "/opt"
)

# ==================================================
# Helpers
# ==================================================

function stopServices() {
  echo "Stopping services..."
  for service in "${services[@]}"; do
    cd "$service" && docker compose stop
  done
}

function startServices() {
  echo "Restarting services..."
  for service in "${services[@]}"; do
    cd "$service" && docker compose up -d
  done
}

function backupStacks() {
  echo "Backing up stacks..."
  local dir="$1/stacks"
  mkdir "$dir"
  for service in "${services[@]}"; do
    cp -r --parents "$service" "$dir"
  done
}

function backupVolumes() {
  echo "Backing up volumes..."
  local dir="$1/volumes"
  mkdir "$dir"
  for volume in "${volumes[@]}"; do
    cp -r --parents "$volume" "$dir"
  done
}

function backup() {
  echo "Creating backup..."
  tar -cvzf "/$today.tar.gz" "$1"
  cp -r "/$today.tar.gz" "$backupdir"
  # Cleanup temporary files.
  rm -rf "$1" "/$today.tar.gz"
}

function cleanBackups() {
  echo "Removing old backups..."
  # Remove backups older than 7 days.
  local dirs=($(find "$backupdir" -maxdepth 1 -mindepth 1 -name "*.tar.gz" -mtime +7))
  for dir in "${dirs[@]}"; do
    rm -rf "$dir"
  done
}

function copyIfNotDebug {
  if [ -z "$debug" ]; then
    cp -r "$1" "$2"
  else
    echo "$1 -> $2"
  fi
}

function restoreVolumes() {
  echo "Copying volumes..."
  local volumes=($(find "$1/volumes" -maxdepth 1 -mindepth 1 -type d))
  for volume in "${volumes[@]}"; do
    local dest="${volume#"$1"/volumes*}"
    copyIfNotDebug "$volume" "$dest"
  done
}

function restoreStacks() {
  echo "Copying stacks..."
  local stacks=($(find "$1/stacks" -maxdepth 1 -mindepth 1 -type d))
  for stack in "${stacks[@]}"; do
    local dest="${stack#"$1"/stacks*}"
    copyIfNotDebug "$stack" "$dest"
  done
}

function run() {
  # stop services.
  stopServices

  # Create a temporary directory.
  local temp="/$today"
  mkdir "$temp"

  # copy stack configuration.
  backupStacks "$temp"

  # copy stack configuration.
  backupVolumes "$temp"

  # Create a tar to backup.
  backup "$temp"

  # Restart services.
  startServices

  # Remove backups older than 7 days.
  cleanBackups
}

function restore() {
  # Parse the backup to use, if an argument is passed in use that as the source
  # for the backup, otherwise use the last backup.
  local archive="$1"
  if [ -z "$archive" ]; then
    echo "Backup not specified using latest backup..."
    archive=$(find /backups -maxdepth 1 -mindepth 1 -name "*.tar.gz" | sort -nr | head -1)
  fi

  local dir="${archive%*.tar.gz}"

  # unzip the archive.
  echo "Unzipping backup: $archive"
  tar -xvf "$archive"

  # copy stacks and volumes to their locations.
  restoreVolumes "$dir"
  restoreStacks "$dir"

  # cleanup
  rm -rf "$dir"

  echo "Restarting services..."
  startServices

}

# ==================================================
# MAIN
# ==================================================

function main() {

  case "$1" in
  -h | --help)
    usage && return 0
    ;;
  --version)
    echo "$version" && return 0
    ;;
  restart)
    startServices && return 0
    ;;
  restore)
    shift && restore "$@" && return 0
    ;;
  *)
    run "$@" && return 0
    ;;
  esac
}

main "$@"