#!/bin/bash
#
# Administers a device manager installation.
#
# This script is a thin wrapper on top of the deviced commands.  Its main
# purpose is to set up the installation by fetches the binaries required for a
# device manager installation from a few possible sources and setting up the
# setuid helper.

set -e

usage() {
  echo "usage:"
  echo
  echo "Install device manager:"
  echo "VANADIUM_DEVICE_DIR=<installation dir> ./devicex install [<binary source>] [ args for installer... ] [ -- args for device manager...]"
  echo "  Possible values for <binary source>:"
  echo "     unspecified: get binaries from local repository"
  echo "     /path/to/binaries: get binaries from local filesystem"
  echo "     http://host/path: get binaries from HTTP server"
  echo
  echo "Uninstall device manager:"
  echo "VANADIUM_DEVICE_DIR=<installation dir> ./devicex uninstall"
  echo
  echo "Start device manager:"
  echo "VANADIUM_DEVICE_DIR=<installation dir> ./devicex start"
  echo
  echo "Stop device manager:"
  echo "VANADIUM_DEVICE_DIR=<installation dir> ./devicex stop"
}

readonly BIN_NAMES=(deviced suidhelper agentd inithelper)

###############################################################################
# Copies one binary from source to destination.
# Arguments:
#   name of the binary
#   source dir of binary
#   destination dir of binary
# Returns:
#   None
###############################################################################
copy_binary() {
  local -r BIN_NAME="$1"
  local -r BIN_SRC_DIR="$2"
  local -r BIN_DEST_DIR="$3"
  local -r SOURCE="${BIN_SRC_DIR}/${BIN_NAME}"
  if [[ -x "${SOURCE}" ]]; then
    local -r DESTINATION="${BIN_DEST_DIR}/${BIN_NAME}"
    cp "${SOURCE}" "${DESTINATION}"
    chmod 700 "${DESTINATION}"
  else
    echo "couldn't find ${SOURCE}"
    exit 1
  fi
}

###############################################################################
# Fetches binaries needed by device manager installation.
# Globals:
#   BIN_NAMES
#   VANADIUM_ROOT
# Arguments:
#   destination for binaries
#   source of binaries
# Returns:
#   None
###############################################################################
get_binaries() {
  local -r BIN_INSTALL="$1"
  local -r BIN_SOURCE="$2"

  local bin_names_str=""
  for bin_name in "${BIN_NAMES[@]}"; do
    bin_names_str+=" ${bin_name}"
  done

  # If source is not specified, try to look for it in the repository.
  if [[ -z "${BIN_SOURCE}" ]]; then
    if [[ -z "${VANADIUM_ROOT}" ]]; then
      echo 'ERROR: binary source not specified and no local repository available'
      exit 1
    fi
    local -r REPO_BIN_DIR="${VANADIUM_ROOT}/release/go/bin"
    echo "Fetching binaries:${bin_names_str} from build repository: ${REPO_BIN_DIR} ..."
    for bin_name in "${BIN_NAMES[@]}"; do
      copy_binary "${bin_name}" "${REPO_BIN_DIR}" "${BIN_INSTALL}"
    done
    return
  fi

  # If the source is specified as an existing local filesystem path,
  # look for the binaries there.
  if [[ -d "${BIN_SOURCE}" ]]; then
      echo "Fetching binaries:${bin_names_str} locally from: ${BIN_SOURCE} ..."
      for bin_name in "${BIN_NAMES[@]}"; do
        copy_binary "${bin_name}" "${BIN_SOURCE}" "${BIN_INSTALL}"
      done
      return
  fi

  # If the source looks like a URL, use HTTP to fetch.
  local -r URL_REGEXP='^(https?|ftp|file)://'
  if [[ "${BIN_SOURCE}" =~ ${URL_REGEXP} ]]; then
    echo "Fetching binaries:${bin_names_str} remotely from: ${BIN_SOURCE} ..."
    for bin_name in "${BIN_NAMES[@]}"; do
      local DEST="${BIN_INSTALL}/${bin_name}"
      curl -f -o "${DEST}" "${BIN_SOURCE}/${bin_name}"
      chmod 700 "${DEST}"
    done
    return
  fi

  echo 'ERROR: couldn'"'"'t fetch binaries.'
  exit 1
}

###############################################################################
# Installs device manager: fetches binaries, configures suidhelper, calls the
# self-install command on deviced.
# Globals:
#   VANADIUM_DEVICE_DIR
# Arguments:
#   source of binaries (optional)
#   args for self-install command and for device manager (optional)
# Returns:
#   None
###############################################################################
install() {
  if [[ -e "${VANADIUM_DEVICE_DIR}" ]]; then
    echo "${VANADIUM_DEVICE_DIR} already exists!"
    exit 1
  fi
  mkdir -m 700 "${VANADIUM_DEVICE_DIR}"
  local -r BIN_INSTALL="${VANADIUM_DEVICE_DIR}/bin"
  mkdir -m 700 "${BIN_INSTALL}"

  # Fetch the binaries.
  if [[ $# = 0 || "$1" == --* ]]; then
    local -r BIN_SOURCE=""
  else
    local -r BIN_SOURCE="$1"
    shift
  fi
  get_binaries "${BIN_INSTALL}" "${BIN_SOURCE}"
  for bin_name in "${BIN_NAMES[@]}"; do
    local BINARY="${BIN_INSTALL}/${bin_name}"
    if [[ ! -s "${BINARY}" ]]; then
      echo "${BINARY} is empty."
      exit 1
    fi
  done
  echo "Binaries are in ${BIN_INSTALL}."

  # Set up the suidhelper.
  echo "Configuring helpers ..."
  local SINGLE_USER=false
  local INIT_MODE=false
  for ARG in $*; do
    if [[ ${ARG} = "--" ]]; then
      break
    elif [[ ${ARG} = "--single_user" || ${ARG} = "--single_user=true" ]]; then
      SINGLE_USER=true
    elif [[ ${ARG} = "--init_mode" || ${ARG} = "--init_mode=true" ]]; then
      INIT_MODE=true
    fi
  done
  local -r SETUID_SCRIPT="${BIN_INSTALL}/suidhelper"
  if [[ ${SINGLE_USER} == false ]]; then
    sudo bash -c "chown root:root \"${SETUID_SCRIPT}\"; chmod 4551 \"${SETUID_SCRIPT}\""
  fi
  local -r INIT_SCRIPT="${BIN_INSTALL}/inithelper"
  if [[ ${INIT_MODE} == true ]]; then
    sudo bash -c "chown root:root \"${INIT_SCRIPT}\"; chmod 4551 \"${INIT_SCRIPT}\""
  fi
  echo "Helpers configured."

  # Install the device manager.
  echo "Installing device manager under ${VANADIUM_DEVICE_DIR} ..."
  "${BIN_INSTALL}/deviced" install --suid_helper="${SETUID_SCRIPT}" --agent="${BIN_INSTALL}/agentd" --init_helper="${INIT_SCRIPT}" "$@"
  echo "Device manager installed."
}

###############################################################################
# Uninstalls device manager: calls the uninstall command of deviced and removes
# the installation.
# Globals:
#   VANADIUM_DEVICE_DIR
# Arguments:
#   None
# Returns:
#   None
###############################################################################
uninstall() {
  if [[ ! -d "${VANADIUM_DEVICE_DIR}" ]]; then
    echo "${VANADIUM_DEVICE_DIR} is not a directory!"
    exit 1
  fi
  local -r BIN_INSTALL="${VANADIUM_DEVICE_DIR}/bin"
  echo "Uninstalling device manager from ${VANADIUM_DEVICE_DIR} ..."
  "${BIN_INSTALL}/deviced" uninstall
   echo "Device manager uninstalled."
   # Any data created underneath "${VANADIUM_DEVICE_DIR}" by the "deviced
   # install" command would have been cleaned up already by "deviced uninstall".
   # However, install() created "${VANADIUM_DEVICE_DIR}", so uninstall() needs
   # to remove it (as well as data created by install(), like bin/*).
   rm -rf "${VANADIUM_DEVICE_DIR}"
   echo "Removed ${VANADIUM_DEVICE_DIR}"
}

###############################################################################
# Starts device manager: calls the start command of deviced.
# Globals:
#   VANADIUM_DEVICE_DIR
# Arguments:
#   None
# Returns:
#   None
###############################################################################
start() {
  if [[ ! -d "${VANADIUM_DEVICE_DIR}" ]]; then
    echo "${VANADIUM_DEVICE_DIR} is not a directory!"
    exit 1
  fi
  local -r BIN_INSTALL="${VANADIUM_DEVICE_DIR}/bin"
  "${BIN_INSTALL}/deviced" start
}

###############################################################################
# Stops device manager: calls the stop command of deviced.
# Globals:
#   VANADIUM_DEVICE_DIR
# Arguments:
#   None
# Returns:
#   None
###############################################################################
stop() {
  if [[ ! -d "${VANADIUM_DEVICE_DIR}" ]]; then
    echo "${VANADIUM_DEVICE_DIR} is not a directory!"
    exit 1
  fi
  local -r BIN_INSTALL="${VANADIUM_DEVICE_DIR}/bin"
  "${BIN_INSTALL}/deviced" stop
}

main() {
  if [[ -z "${VANADIUM_DEVICE_DIR}" ]]; then
    echo 'No local device installation dir specified!'
    usage
    exit 1
  fi
  if [[ -e "${VANADIUM_DEVICE_DIR}" && ! -d "${VANADIUM_DEVICE_DIR}" ]]; then
    echo "${VANADIUM_DEVICE_DIR} is not a directory!"
    usage
    exit 1
  fi

  if [[ $# = 0 ]]; then
    echo 'No command specified!'
    usage
    exit 1
  fi
  local -r COMMAND="$1"
  shift
  case "${COMMAND}" in
    install)
      install "$@"
      ;;
    uninstall)
      uninstall
      ;;
    start)
      start
      ;;
    stop)
      stop
      ;;
    *)
      echo "Unrecognized command: ${COMMAND}!"
      usage
      exit 1
  esac
}

main "$@"