#!/usr/bin/env bash

#
# wrapacker - https://github.com/elasticdog/packer-arch
#
# A script to automatically ensure the latest ISO download URL and optionally
# use a mirror from the provided country in order to build an Arch Linux box
# using Packer.
#
# Copyright (c) 2015 Aaron Bull Schaefer <aaron@elasticdog.com>
# This source code is provided under the terms of the ICS License
# that can be be found in the LICENSE file.
#

##### Constants

# country codes supported by https://www.archlinux.org/mirrorlist/
readonly VALID_COUNTRIES=(AT AU BD BE BG BR BY CA CH CL CN CO CZ DE DK EC ES FR GB GR HR HU ID IE IL IN IR IS IT JP KR KZ LT LU LV MK NC NL NO NZ PH PL PT RO RS RU SE SG SK TR TW UA US VN ZA)

if command -v packer-io > /dev/null 2>&1; then
  # Older arch linux versions called the packer binary packer-io.
  readonly PACKER_BIN='packer-io'
else
  readonly PACKER_BIN='packer'
fi

VALID_TIME_UNITS=(ns us ms s m h)

##### Functions

# print a message to stderr
warn() {
  local fmt="$1"
  shift
  printf "wrapacker: $fmt\n" "$@" >&2
}

# print a message to stderr and exit with either
# the given status or that of the most recent command
die() {
  local st="$?"
  if [[ "$1" != *[^0-9]* ]]; then
    st="$1"
    shift
  fi
  warn "$@"
  exit "$st"
}

# test the VALID_COUNTRIES array for membership of the given value
validate_country() {
  local haystack="VALID_COUNTRIES[@]"
  local needle=$1
  local found=1
  for element in "${!haystack}"; do
    if [[ $element == "$needle" ]]; then
      found=0
      break
    fi
  done
  return $found
}

# print this script's usage message to stderr
usage() {
  cat <<-EOF >&2
  usage: wrapacker [-c COUNTRY] [-p PROVIDER] [-t TIMEOUT] [-w] [-o ON-ERROR ACTION] [-f] [-d] [-h]
EOF
}

# print the list of valid countries to stderr
print_valid_countries() {
  printf '\n*** VALID COUNTRY CODES ***\n\n' >&2
  for country in "${VALID_COUNTRIES[@]}"; do
    printf '%-6s\n' "$country"
  done | column >&2
}

# print the list of valid providers to stderr
print_valid_providers() {
  printf '\n*** VALID PROVIDERS ***\n\n' >&2
  for provider in {parallels,virtualbox,vmware,libvirt}; do
    printf '%-6s\n' "$provider"
  done | column >&2
}

# print the list of valid time units to stderr
print_valid_time_units() {
  printf '\n*** VALID TIME UNITS ***\n\n' >&2
  for units in "${VALID_TIME_UNITS[@]}"; do
    printf '%-6s\n' "$units"
  done | column >&2
}

# print the list of valid on-error actions to stderr
print_valid_on_error_actions() {
  printf '\n*** VALID ON-ERROR ACTIONS ***\n\n' >&2
  for action in {cleanup,abort,ask}; do
    printf '%-6s\n' "$action"
  done | column >&2
}

# print this script's help message to stdout
help() {
  cat <<-EOF

  NAME
       wrapacker -- wrap packer to build arch with custom mirror settings

  SYNOPSIS
       wrapacker [options...]

  DESCRIPTION

       wrapacker will automatically ensure the latest ISO download URL and
       will optionally use a mirror from the provided country in order to
       build an Arch Linux box using Packer.

  OPTIONS
       -c, --country=COUNTRY
              the country code to download from;
              defaults to the kernel.org US mirror

       -p, --provider=PROVIDER
              the packer provider to build with;
              defaults to virtualbox

       -t, --timeout=TIMEOUT
              sets the amount of time packer will wait for trying ssh login;
              defaults to 20m

       -w, --skip-write-zeros
              don't inflate the disk to improve virtual disk compaction

       -o, --on-error=ACTION
              error handling if the build fails;
              defaults to cleanup

       -f, --force
              force a build to continue if artifacts exist; deletes existing artifacts

       -d, --dry-run
              do not actually perform the build, just show what would run

       -h, --help
              view this help message

       -e, --headless
              do not run the build in the GUI
              only works with --provider=virtualbox

  AUTHOR
       Aaron Bull Schaefer <aaron@elasticdog.com>

EOF
}


##### Main

# check for dependencies
for cmd in {awk,curl,sed,tr}; do
  command -v $cmd > /dev/null || die "required command \"$cmd\" was not found"
done

# reset all variables that might be set
country=''
provider=''
dry_run=false
timeout=''
skip_write_zeros=false
on_error=''
force=false
headless=false

# parse command line options
while [[ $1 != '' ]]; do
  case $1 in
    -c | --country)
      country=$(echo "$2" | tr '[:lower:]' '[:upper:]')
      shift
      ;;
    --country=*)
      country=$(echo "${1#*=}" | tr '[:lower:]' '[:upper:]')
      ;;
    -p | --provider)
      provider=$2
      shift
      ;;
    --provider=*)
      provider=${1#*=}
      ;;
    -t | --timeout)
      timeout=$2
      shift
      ;;
    --timeout=*)
      timeout=${1#*=}
      ;;
    -w | --skip-write-zeros)
      skip_write_zeros=true
      ;;
    -o | --on-error)
      on_error=$2
      shift
      ;;
    --on-error=*)
      on_error=${1#*=}
      ;;
    -f | --force)
      force=true
      ;;
    -d| --dry-run)
      dry_run=true
      ;;
    -h | --help | -\?)
      help
      print_valid_countries
      print_valid_providers
      print_valid_time_units
      print_valid_on_error_actions
      exit 0
      ;;
    -e| --headless)
      headless=true
      ;;
    --*)
      warn "unknown option -- ${1#--}"
      usage
      exit 1
      ;;
    *)
      warn "unknown option -- ${1#-}"
      usage
      exit 1
      ;;
  esac
  shift
done

if [[ $provider ]]; then
  case $(echo "$provider" | tr '[:upper:]' '[:lower:]') in
    parallels | parallels-iso)
      PACKER_PROVIDER='parallels-iso'
      ;;
    virtualbox | virtualbox-iso)
      PACKER_PROVIDER='virtualbox-iso'
      ;;
    vmware | vmware-iso)
      PACKER_PROVIDER='vmware-iso'
      ;;
    libvirt | qemu)
      PACKER_PROVIDER='qemu'
      ;;
    *)
      warn "unknown provider -- ${provider}"
      usage
      print_valid_providers
      exit 1
      ;;
  esac
else
  PACKER_PROVIDER='virtualbox-iso'
fi

if [[ $country ]]; then
  if validate_country "$country"; then
    MIRRORLIST="https://archlinux.org/mirrorlist/?country=${country}&protocol=http&protocol=https&ip_version=4&use_mirror_status=on"
    MIRROR=$(curl -s "$MIRRORLIST" | awk '/#Server/{ print $3; exit }' | sed 's|/$repo.*||')
  else
    warn 'INVALID COUNTRY SPECIFIED - %s' "$country"
    usage
    print_valid_countries
    exit 1
  fi
else
  MIRROR='https://mirrors.kernel.org/archlinux'
  country='US'
fi

ISO_CHECKSUM_URL="${MIRROR}/iso/latest/sha256sums.txt"
ISO_NAME=$(curl -sL "$ISO_CHECKSUM_URL" | awk '/-x86_64.iso/{ print $2 }' | tail -n 1)
ISO_URL="${MIRROR}/iso/latest/${ISO_NAME}"

if [[ $timeout ]]; then
  if [[ "$timeout" =~ ^[0-9]+(ns|us|ms|s|m|h)$ ]]; then
    SSH_TIMEOUT=$timeout
  else
    warn 'INVALID TIME UNITS SPECIFIED or MISSING UNIT - %s' "$timeout"
    usage
    print_valid_time_units
    exit 1
  fi
else
  SSH_TIMEOUT='20m'
fi

if [[ $skip_write_zeros = true ]]; then
  WRITE_ZEROS="false"
else
  WRITE_ZEROS="true"
fi

if [[ $on_error ]]; then
  case $(echo "$on_error" | tr '[:upper:]' '[:lower:]') in
    cleanup)
      ON_ERROR='cleanup'
      ;;
    abort)
      ON_ERROR='abort'
      ;;
    ask)
      ON_ERROR='ask'
      ;;
    *)
      warn "unknown on-error action -- ${on_error}"
      usage
      print_valid_on_error_actions
      exit 1
      ;;
  esac
else
  ON_ERROR='cleanup'
fi

if [[ $dry_run = true ]]; then
  if [[ $force = true ]]; then
cat <<-EOF
  $PACKER_BIN build \\
    -only=$PACKER_PROVIDER \\
    -var "iso_url=$ISO_URL" \\
    -var "iso_checksum_url=$ISO_CHECKSUM_URL" \\
    -var "ssh_timeout=$SSH_TIMEOUT" \\
    -var "country=$country" \\
    -var "headless=$headless" \\
    -var "write_zeros=$WRITE_ZEROS" \\
    -on-error=$ON_ERROR \\
    -force \\
    arch-template.json
EOF
  else
cat <<-EOF
  $PACKER_BIN build \\
    -only=$PACKER_PROVIDER \\
    -var "iso_url=$ISO_URL" \\
    -var "iso_checksum_url=$ISO_CHECKSUM_URL" \\
    -var "ssh_timeout=$SSH_TIMEOUT" \\
    -var "country=$country" \\
    -var "headless=$headless" \\
    -var "write_zeros=$WRITE_ZEROS" \\
    -on-error=$ON_ERROR \\
    arch-template.json
EOF
  fi
else
  if [[ $force = true ]]; then
    $PACKER_BIN build \
      -only=$PACKER_PROVIDER \
      -var "iso_url=$ISO_URL" \
      -var "iso_checksum_url=$ISO_CHECKSUM_URL" \
      -var "ssh_timeout=$SSH_TIMEOUT" \
      -var "country=$country" \
      -var "headless=$headless" \
      -var "write_zeros=$WRITE_ZEROS" \
      -on-error=$ON_ERROR \
      -force \
      arch-template.json
  else
    $PACKER_BIN build \
      -only=$PACKER_PROVIDER \
      -var "iso_url=$ISO_URL" \
      -var "iso_checksum_url=$ISO_CHECKSUM_URL" \
      -var "ssh_timeout=$SSH_TIMEOUT" \
      -var "country=$country" \
      -var "headless=$headless" \
      -var "write_zeros=$WRITE_ZEROS" \
      -on-error=$ON_ERROR \
      arch-template.json
  fi
fi

exit $?