#!/usr/bin/env bash

# This is a pre-allocated string of 39 chars of whitespace
# DO NOT CHANGE THIS without great care - it will break header length
# calculations
LENS=(                                       )
export SELF             # Absolute path to the installer script (me!)
export TMP              # Path to tmp install staging directory
export PAYLOAD          # Path to the extracted payload directory
export NOCLEANUP=0      # Do not clean up deploy resources. Useful for debugging
export EXTRACTONLY=0    # Execute extract, skipping deployment and cleanup
export DECOMPRESS='{{ DECOMPRESS }}' # Command to decompress data

# Header:    0
# runscript: 1
# payload:   2
extract_chunk_index() {
  local src="${1}"
  local dest="${2}"
  local index="${3}"
  local skip=0  # Byte count to skip into source
  local of      # Output path with 'of=' prefix. Only used if dest is not '-'

  for (( i = 0; i < index; i++ )); do
    skip=$(( skip + LENS[$i] ))
  done

  [ "${dest}" != '-' ] && of="of=${dest}"
  # Extract the requested chunk index
  dd bs=${LENS[$index]} count=1 iflag=skip_bytes skip=${skip} \
    if=${src} ${of} 2>/dev/null
}

extract_header() {
  extract_chunk_index "${SELF}" "${TMP}/header.sh" 0
}

extract_libinstall() {
  extract_chunk_index "${SELF}" '-' 1 | ${DECOMPRESS} | tar -C "${TMP}" -x
}

extract_runscript() {
  extract_chunk_index "${SELF}" '-' 2 | ${DECOMPRESS} > "${TMP}/run.sh"
}

extract_payload() {
  extract_chunk_index "${SELF}" '-' 3 | ${DECOMPRESS} | tar -C "${TMP}" -x
  export PAYLOAD="${TMP}/pkg"
}


main() {
  local args=(${@})

  SELFDIR="$(cd $(dirname ${0}) && pwd)"
  SELF="${SELFDIR}/$(basename ${0})"
  TMP="$(mktemp -d /tmp/installer-XXXXXXX)"

  extract_header
  extract_libinstall
  extract_runscript

  cd "${TMP}"

  source libinstall/template.sh
  source libinstall/ensure.sh
  source libinstall/colorize.sh

  source run.sh

  for (( i = 0; i < ${#args[@]}; i++ )); do
    # NOTE: Do not support short switches here to reduce the probability of
    #       conflicting with  a switch provided by the downstream run.sh
    if [ "${args[$i]}" = '--extract-only' ]; then
      export EXTRACTONLY=1
      export NOCLEANUP=1
    fi
  done

  if [ "${EXTRACTONLY}" = '1' ]; then
    printf 'Extracting...\n'
    extract_payload
    printf 'Installation payload available at "%s"\n' "${TMP}/pkg"
    printf 'Skipping cleanup\n'
    return 0
  elif [ "$(type -t deploy)" == 'function' ]; then
    # Function 'deploy' is provided by run.sh
    deploy ${@}
  else
    printf "ERROR: Deploy function not found.\n"
  fi

  # Cleanup
  if [ "${NOCLEANUP}" -ne 0 ]; then
    rm -rf "${TMP}"
  fi
}

main ${@}
exit 0