just.bash

#!/usr/bin/env bash

# Name:         just (Just a UNIX Shell script Template [with bash features])
# Version:      0.0.9
# Release:      1
# License:      CC-BA (Creative Commons By Attribution)
#               http://creativecommons.org/licenses/by/4.0/legalcode
# Group:        System
# Source:       N/A
# URL:          https://github.com/lateralblast/just
# Distribution: UNIX
# Vendor:       UNIX
# Packager:     Richard Spindler <richard@lateralblast.com.au>
# Description:  A template for writing shell scripts

# Insert some shellcheck disables
# Depending on your requirements, you may want to add/remove disables
# shellcheck disable=SC2034
# shellcheck disable=SC1090
# shellcheck disable=SC2129

# Grab script args for some initial processing

script_args="$*"
script_file="$0"
script_name="just"
script_file=$( realpath "$script_file" )
script_path=$( dirname "$script_file" )
module_path="$script_path/modules"
script_bin=$( basename "$script_file" )

# Create arrays for options and actions

declare -A options 
declare -A defaults 
declare -a option_flags
declare -a action_flags

# Set defaults

set_defaults () {
  defaults["verbose"]="false"
  defaults["actions"]="false"
  defaults["options"]="false"
  defaults["strict"]="false"
  defaults["dryrun"]="false"
  defaults["debug"]="false"
  defaults["force"]="false"
  defaults["yes"]="false"
  for default in "${!defaults[@]}"; do
    value="${defaults[${default}]}"
    options["$default"]="$value"
  done
  os_name=$( uname -s )
  if [ "$os_name" = "Linux" ]; then
    os_distro=$( lsb_release -i -s 2> /dev/null )
  fi
}

set_defaults

# Verbose message

verbose_message () {
  message="$1"
  format="$2"
  if [ "$format" = "verbose" ]; then
    echo "$message"
  else
    if [ "${options['verbose']}" = "true" ]; then
      if [[ "$format" =~ ing$ ]]; then
        format="${format^}"
      else
        if [[ "$format" =~ t$ ]]; then
          format="${format^}ing"
        else
          if [[ "$format" =~ e$ ]]; then
            format="${format::-1}"
            format="${format^}ing"
          fi
        fi
      fi 
      echo -e "$format:\t\t$message"
    fi
  fi
}


# Enable verbose mode

if [[ "$script_args" =~ "verbose" ]]; then
  options["verbose"]="true"
  verbose_message "verbose to true" "set"
fi

# Load modules

if [ -d "$module_path" ]; then
  modules=$( find "$module_path" -name "*.sh" )
  for module in $modules; do
    if [[ "$script_args" =~ "verbose" ]]; then
     verbose_message "Module $module" "load"
    fi
    . "$module"
  done
fi

# Reset defaults based on command line options

reset_defaults () {
  if [ "${options['debug']}" = "true" ]; then
    verbose_message "Enabling debug mode" "notice"
    set -x
  fi
  if [ "${options['strict']}" = "true" ]; then
    verbose_message "Enabling strict mode" "notice"
    set -u
  fi
  if [ "${options['dryrun']}" = "true" ]; then
    verbose_message "Enabling dryrun mode" "notice"
  fi
}

# Selective exit (don't exit when we're running in dryrun mode)

do_exit () {
  if [ "${options['dryrun']}" = "false" ]; then
    exit
  fi
}

# check value (make sure that command line arguments that take values have values)

check_value () {
  parameter="$1"
  value="$2"
  if [[ "$value" =~ "--" ]]; then
    verbose_message "Value '$value' for parameter '$parameter' looks like a parameter" "verbose"
    echo ""
    if [ "${options['force']}" = "false" ]; then
      do_exit
    fi
  else
    if [ "$value" = "" ]; then
      verbose_message "No value given for parameter $parameter" "verbose"
      echo ""
      if [[ "$parameter" =~ "option" ]]; then
        print_options
      else
        if [[ "$parameter" =~ "action" ]]; then
          print_actions
        else
          print_help
        fi
      fi
      exit
    fi
  fi
}

# Execute command

execute_command () {
  command="$1"
  privilege="$2"
  if [ "$privilege" = "su" ]; then
    command="sudo sh -c \"$command\""
  fi
  if [ "${options['verbose']}" = "true" ]; then
    verbose_message "$command" "execute"
  fi
  if [ "${options['dryrun']}" = "false" ]; then
    eval "$command"
  fi
}

# Print help/usage insformation

print_help () {
  script_help=$( grep -A1 "# switch" "$script_file" |sed "s/^--//g" |sed "s/# switch//g" | tr -s " " |grep -Ev "=|echo" |sed "s/#/ /g" | sed "/^\s*$/d" )
  echo "Usage: $script_bin --switch [value]"
  echo ""
  echo "switches:"
  echo "--------"
  echo "$script_help"
  echo ""
}

# Print actions

print_actions () {
  script_actions=$( grep -A1 "# action" "$script_file" |sed "s/^--//g" |sed "s/# action//g" | tr -s " " |grep -Ev "=|echo" |sed "s/#/ /g" |sed "/^\s*$/d" )
  echo "Usage: $script_bin --action(s) [value]"
  echo ""
  echo "actions:"
  echo "-------"
  echo "$script_actions"
  echo ""
}

# Print options

print_options () {
  script_options=$( grep -A1 "# option" "$script_file" |sed "s/^--//g" |sed "s/# option//g" | tr -s " " |grep -Ev "=|echo" |sed "s/#/ /g" |sed "/^\s*$/d" )
  echo "Usage: $script_bin --option(s) [value]"
  echo ""
  echo "options:"
  echo "-------"
  echo "$script_options"
  echo ""
}

# Print Usage

print_usage () {
  usage="$1"
  case $usage in
    all|full)
      print_help
      print_actions
      print_options
      ;;
    help)
      print_help
      ;;
    action*)
      print_actions
      ;;
    option*)
      print_options
      ;;
    *)
      print_help
      shift
      ;;
  esac
}

# Print version information

print_version () {
  script_vers=$( grep '^# Version' < "$0" | awk '{print $3}' )
  echo "$script_vers"
}

# Run Shellcheck

check_shellcheck () {
  bin_test=$( command -v shellcheck | grep -c shellcheck )
  if [ ! "$bin_test" = "0" ]; then
    shellcheck "$script_file"
  fi
}

# Do some early command line argument processing

if [ "$script_args" = "" ]; then
  print_help
  exit
fi

# Handle options

process_options () {
  option_flag="$1"
  if [[ "$option_flag" =~ ^no ]]; then
    option_flag="${option_flag:2}"
    value="false"
  else
    value="true"
  fi
  options["$option_flag"]="true"
  verbose_message "$option_flag to $value" "set"
}

# Print environment

print_environment () {
  echo "Environment (Options):"
  for option in "${!options[@]}"; do
    value="${options[${option}]}"
    echo -e "Option $option\tis set to $value"
  done
}


# Print defaults

print_defaults () {
  echo "Defaults:"
  for default in "${!defaults[@]}"; do
    value="${defaults[${default}]}"
    echo -e "Default $default\tis set to $value"
  done
}


# Handle actions

process_actions () {
  actions="$1"
  case $actions in
    help)                 # action
      # Print actions help
      print_actions
      exit
      ;;
    version)              # action
      # Print version
      print_version
      exit
      ;;
    printenv*)             # action
      # Print environment 
      print_environment
      exit
      ;;
    printdefaults)        # action
      # Print defaults 
      print_defaults
      exit
      ;;
    shellcheck)           # action
      # Shellcheck script
      check_shellcheck
      exit
      ;;
    *)
      print_actions
      exit
      ;;
  esac
}

# Handle command line arguments

while test $# -gt 0; do
  case $1 in
    --action*)            # switch
      # Action to perform
      check_value "$1" "$2"
      action_flags+=("$2")
      options["actions"]="true"
      shift 2
      ;;
    --debug)              # switch
      # Enable debug mode
      options["debug"]="true"
      shift
      ;;
    --force)              # switch
      # Enable force mode
      options["force"]="true"
      shift
      ;;
    --strict)             # switch
      # Enable strict mode
      options["strict"]="true"
      shift
      ;;
    --verbose)            # switch
      # Enable verbos e mode
      options["verbose"]="true"
      shift
      ;;
    --version|-V)         # switch
      # Print version information
      print_version
      exit
      ;;
    --option*)            # switch
      # Action to perform
      check_value "$1" "$2"
      option_flags+=("$2")
      options["options"]="true"
      shift 2
      ;;
    --usage*)             # switch
      # Action to perform
      check_value "$1" "$2"
      usage="$2"
      print_usage "$usage"
      shift 2
      exit
      ;;
    --help|-h)            # switch
      # Print help information
      print_help
      shift
      exit
      ;;
    *)
      print_help
      shift
      exit
      ;;
  esac
done

# Process options

if [ "${options['options']}" = "true" ]; then
  for option_flag in "${option_flags[@]}"; do
    if [[ "$option_flag" =~ "," ]]; then
      IFS="," read -r -a array <<< "$option_flag"
      for option in "${array[@]}"; do
        process_options "$option"
      done
    else
      process_options "$option_flag"
    fi
  done
fi

# Reset defaults based on switches

reset_defaults

# Process actions

if [ "${options['actions']}" = "true" ]; then
  for action_flag in "${action_flags[@]}"; do
    if [[ "$action_flag" =~ "," ]]; then
      IFS="," read -r -a array <<< "$action_flag"
      for action in "${array[@]}"; do
        process_actions "$action"
      done
    else
      process_actions "$action_flag"
    fi
  done
fi