#!/usr/bin/env bash

# Example Bash Shell Script
# from https://betterdev.blog/minimal-safe-bash-script-template/

set -Eeuo pipefail

cd "$(dirname "${BASH_SOURCE[0]}")" >/dev/null 2>&1

# declare globals as readonly
readonly SCRIPT_NAME
SCRIPT_NAME="$(basename "$0")"

trap cleanup SIGINT SIGTERM ERR EXIT

usage() {
  cat <<EOF
Usage: $(basename "$0") [-h] [-v] [-f] -p param_value arg1 [arg2...]

Script description here.

Available options:

-h, --help      Print this help and exit
-v, --verbose   Print script debug info
-f, --flag      Some flag description
-p, --param     Some param description
EOF
  exit
}

cleanup() {
  trap - SIGINT SIGTERM ERR EXIT
  # script cleanup here
}

setup_colors() {
  if [[ -t 2 ]] && [[ -z ${NO_COLOR-} ]] && [[ ${TERM-} != "dumb" ]]; then
    NOCOLOR='\033[0m' RED='\033[0;31m' GREEN='\033[0;32m' ORANGE='\033[0;33m' BLUE='\033[0;34m' PURPLE='\033[0;35m' CYAN='\033[0;36m' YELLOW='\033[1;33m'
  else
    # shellcheck disable=SC2034
    NOCOLOR='' RED='' GREEN='' ORANGE='' BLUE='' PURPLE='' CYAN='' YELLOW=''
  fi
}

# you only need one of the following two functions
# simple function to redirect output to stderr (good)
msg() {
  echo >&2 -e "${1-}"
}

# more structured logging (better)
log() {
  local -r level="$1"
  local -r message="$2"
  local -r timestamp=$(date +"%Y-%m-%d %H:%M:%S")

  # colorize your log output here, if desired
  echo >&2 -e "${timestamp} [${level}] [$SCRIPT_NAME] ${message}"
}

die() {
  local msg=$1
  local code=${2-1} # default exit status 1
  log "FATAL" "$msg"
  exit "$code"
}

assert_not_empty() {
  local -r arg_name="$1"
  local -r arg_value="$2"

  if [[ -z $arg_value ]]; then
    log "ERROR" "The value for '$arg_name' cannot be empty"
    exit 1
  fi
}

assert_is_installed() {
  local -r name="$1"

  if [[ ! $(command -v "$name") ]]; then
    log "ERROR" "The binary '$name' is required by this script but is not installed or in the system's PATH."
    exit 1
  fi
}

parse_params() {
  while :; do
    case "${1-}" in
    -h | --help)
      usage
      ;;
    -v | --verbose)
      set -x
      ;;
    --no-color)
      NO_COLOR=1
      ;;
    -f | --flag) # example flag
      # FLAG=1
      ;;
    -p | --param) # example named parameter
      assert_not_empty "--param", "${2-}"
      PARAM="${2-}"
      shift
      ;;
    -?*)
      die "Unknown option: $1"
      ;;
    *)
      break
      ;;
    esac
    shift
  done

  # check required params and arguments
  assert_is_installed "bash"

  return 0
}

# default values of variables set from parse_params
# to avoid having these variables here, you will need to define the work of
# the script as another function that takes arguments and call it with local
# variables declared in parse_params:
#
# run() {
#  local -r flag=$1
# }
#
# parse_params() {
#   local flag=0
#    ...
#   run $flag
# }
FLAG=0
PARAM=''
readonly ARGS=("$@")

parse_params "$@"
setup_colors

# script logic here

log "INFO" "${RED}Read parameters:${NOCOLOR}"
log "INFO" "- flag: ${FLAG}"
log "INFO" "- param: ${PARAM}"
log "INFO" "- arguments: ${ARGS[*]-}"