#!/bin/bash
#
# Install TinyPilot from a TinyPilot bundle tarball.
#
# Examples:
#  sudo install-bundle /tmp/tinypilot-community-20230103T1619Z-1.8.0-74+7623988.tgz
#  sudo install-bundle https://example.com/tinypilot-community-20230103T1619Z-1.8.0-74+7623988.tgz
#
# This script is only for development, though unlike other dev scripts, it
# installs on the device. Regular users should use the get-tinypilot.sh or
# get-tinypilot-pro.sh scripts.
#
# get-tinypilot.sh and get-tinypilot-pro.sh do not use this script because they
# can't rely on it being available locally at install time.

# Exit on unset variable.
set -u

# Exit on first error.
set -e

if (( "${EUID}" != 0 )); then
  echo "This script requires root privileges." >&2
  echo "Please re-run with sudo:" >&2
  echo "  sudo $0 $*" >&2
  exit 1
fi

print_help() {
  cat << EOF
Usage: ${0##*/} [-h] bundle_path
Install the specified TinyPilot bundle on the system.
  bundle_path: Local filesystem path or URL to TinyPilot bundle.
  -h Display this help and exit.
EOF
}

# Parse command-line arguments.
while getopts 'h' opt; do
  case "${opt}" in
    h)
      print_help
      exit
      ;;
    *)
      print_help >&2
      exit 1
  esac
done

# Ensure 'bundle_path' is given.
shift "$((OPTIND - 1))"
if (( $# == 0 )); then
  echo 'Input parameter missing: bundle_path' >&2
  exit 1
fi

# Echo commands before executing them, by default to stderr.
set -x

readonly BUNDLE_PATH="$1"

# Historically, the TinyPilot bundle was unpacked to the device's disk, where it
# persisted. Since then, we've moved to the use of a volatile RAMdisk, which
# avoids excessive writes to the filesystem. As a result, this legacy installer
# directory has been orphaned and is now removed as part of this script's
# `clean_up` function.
# https://github.com/tiny-pilot/tinypilot/issues/1357
readonly LEGACY_INSTALLER_DIR='/opt/tinypilot-updater'

# The RAMdisk size is broadly based on the combined size of the following:
# - The TinyPilot bundle archive
# - The unpacked TinyPilot bundle archive, after running the bundle's `install`
#     script
# - About 50 MiB of temporary files
# - At least a 20% safety margin
# Use the following command to help you estimate a sensible size allocation:
#   du --summarize --total --bytes "${INSTALLER_DIR}" "${BUNDLE_FILE}"
readonly RAMDISK_SIZE_MIB=560

AVAILABLE_MEMORY_MIB="$(free --mebi |
  grep --fixed-strings 'Mem:' |
  tr --squeeze-repeats ' ' |
  cut --delimiter ' ' --fields 7)"
readonly AVAILABLE_MEMORY_MIB

# Assign a provisional installation directory for our `clean_up` function.
INSTALLER_DIR='/mnt/tinypilot-installer'

# Remove temporary files & directories.
clean_up() {
  umount --lazy "${INSTALLER_DIR}" || true
  rm -rf \
    "${LEGACY_INSTALLER_DIR}" \
    "${INSTALLER_DIR}"
}

# Always clean up before exiting.
trap 'clean_up' EXIT

# Determine the installation directory. Use RAMdisk if there is enough memory,
# otherwise, fall back to regular disk.
if (( "${AVAILABLE_MEMORY_MIB}" >= "${RAMDISK_SIZE_MIB}" )); then
  # Mount volatile RAMdisk.
  # Note: `tmpfs` can use swap space when the device's physical memory is under
  # pressure. Alternatively, we could use `ramfs` which doesn't use swap space,
  # but also doesn't enforce a filesystem size limit, unlike `tmpfs`. Considering
  # that our goal is to reduce disk writes and not necessarily eliminate them
  # altogether, the possibility of using swap space is an acceptable compromise in
  # exchange for limiting memory usage.
  # https://github.com/tiny-pilot/tinypilot/issues/1357
  sudo mkdir "${INSTALLER_DIR}"
  sudo mount \
    --types tmpfs \
    --options "size=${RAMDISK_SIZE_MIB}m" \
    --source tmpfs \
    --target "${INSTALLER_DIR}" \
    --verbose
else
  # Fall back to installing from disk.
  # HACK: If we let mktemp use the default /tmp directory, the system begins
  # purging files before the end of the script for some reason. We use /var/tmp
  # as a workaround.
  INSTALLER_DIR="$(mktemp \
    --tmpdir='/var/tmp' \
    --directory)"
fi
readonly INSTALLER_DIR

# Use a temporary directory within the installer directory so that we take
# advantage of RAMdisk if we're using one.
readonly TMPDIR="${INSTALLER_DIR}/tmp"
export TMPDIR
mkdir "${TMPDIR}"

if [[ "${BUNDLE_PATH}" == http* ]]; then
  readonly BUNDLE_FILE="${INSTALLER_DIR}/bundle.tgz"
  curl "${BUNDLE_PATH}" \
    --location \
    --output "${BUNDLE_FILE}" \
    --show-error \
    --silent
else
  readonly BUNDLE_FILE="${BUNDLE_PATH}"
fi

# Extract tarball to installer directory.
tar \
  --gunzip \
  --extract \
  --file "${BUNDLE_FILE}" \
  --directory "${INSTALLER_DIR}"

# Run install.
pushd "${INSTALLER_DIR}"
./install