pre-run

#!/bin/sh -u
# -u: Treat unset variables as an error when performing parameter expansion.
# If expansion is attempted on an unset interactive, exits with a non-zero status.
#
# Process executed before application manager execution
#
# Author: Loan Lassalle <https://github.com/lassalleloan>

# Current version of StevenBlack/hosts source files
CURRENT_VERSION="$(sed -En 's/^CURRENT_VERSION=([0-9]+([.][0-9]+)*)(( |#).*)?$/\1/p' .conf)"

# Default verbosity level
VERBOSITY="$(sed -En 's/^VERBOSITY=([0-9]{1})(( |#).*)?$/\1/p' .conf)"

# Display a banner
banner() {
  printf "Pre-run script\n"
}

# Usage of the script
usage() {
  printf "Usage: pre-run [--verbosity (0 | 1 | 2)]\n"
  printf "\n"
  printf "Process executed before run-app execution\n"
  printf "\n"
  printf "Version: 1.0.0, build deadbeef\n"
  printf "\n"
  printf "Author:\n"
  printf "  Loan Lassalle - <https://github.com/lassalleloan>\n"
  printf "\n"
  printf "Options:\n"
  printf "  -v, --verbosity (0 | 1 | 2)     Level of verbosity: no ouput, step information (default), all information\n"
  printf "  -h, --help                      Help on how to use this script\n"
}

# Check for updates
check_updates() {
  local current_version="$1"
  local verbosity="$2"

  # Retrieve the latest version number of StevenBlack/hosts source files
  local latest_version="$(curl --silent https://raw.githubusercontent.com/StevenBlack/hosts/master/package.json | \
    sed -En 's/^[ ]*"version": "([0-9]+([.][0-9]+)*)",$/\1/p')"

  # Check if the latest version number has been retrieved
  if [ -z "$latest_version" ]; then
    latest_version="0.0.0"
  fi

  if [ "$verbosity" -ne 0 ]; then
    printf "Checking for updates\n"
  fi

  if [ "$verbosity" -eq 2 ]; then
    printf "Current version: %*s\n" 12 "$current_version"
    printf "Latest version: %*s\n" 13 "$latest_version"
  fi

  # Check if the latest version is greater than the current version
  if [ ! -f src/etc/hosts ] || \
    [ ! -s src/etc/hosts ] || \
    [ "$(printf '%s\n' "$current_version" "$latest_version" | \
      sort -rV | \
      head -n 1)" != "$current_version" ]; then

    # Update the lastest version in .conf file
    sed -i '' -E "/^LATEST_VERSION=$current_version(( |#).*)?$/ s/$current_version/$latest_version/" \
      .conf

    # Audit system
    if [ "$verbosity" -eq 0 ]; then
      printf "%s\tinfo\tupgrade\t%s\t%s\t\"New version available\"\n" \
        "$(date -u +%FT%TZ)" "$current_version" "$latest_version" >> .log
    fi
  else

    # Audit system
    if [ "$verbosity" -eq 0 ]; then
      printf "%s\tinfo\tupdate\t" "$(date -u +%FT%TZ)" >> .log

      if [ "$latest_version" = "0.0.0" ]; then
        printf "%s\t%s\t\"Lastest version number not retrieved\"\n" \
          "$current_version" "$latest_version" >> .log
      else
        printf "%s\t%s\t\"No new version available\"\n" "$current_version" "$latest_version" >> .log
      fi
    fi

    # Stop all future process
    exit 1
  fi
}

# Check if it is an integer
exit_if_not_integer() {
  local variable="$1"

  if ! echo "$variable" | grep -Eq  "^[0-9]{1}$"; then
    printf "%s: not a integer\n" "$variable"
    usage
    exit 1
  fi
}

# Main
for arg in "$@"; do
  shift
  case "$arg" in
    "--verbosity")
      set -- "$@" "-v"
      ;;
    "--help")
      set -- "$@" "-h"
      ;;
    "--"*)
      set -- "$@" "-?"
      ;;
    *)
      set -- "$@" "$arg"
  esac
done

while getopts ":v:h" option; do
  case $option in
    v)
      VERBOSITY=$OPTARG
      exit_if_not_integer "$VERBOSITY"
      ;;
    h)
      usage
      exit
      ;;
    :)
      printf "%s: required argument\n" "$OPTARG"
      exit 1
      ;;
    \?)
      printf "%s: invalid option\n" "$OPTARG"
      usage
      exit 1
      ;;
  esac
done

if [ "$VERBOSITY" -ne 0 ]; then
  banner
fi

# Check for updates
check_updates "$CURRENT_VERSION" "$VERBOSITY"