#!/usr/bin/env bash

# ERR Trap Inheritance by shell functions, command substitutions, and subshells.
set -E

# Exit on Error Causes the script to immediately exit if any command returns a non-zero exit status unless that command is followed by || to explicitly handle the error.
set -e 

# Treats the use of undefined variables as an error, causing the script to exit.
set -u

# Ensures that a pipeline (a series of commands connected by |) fails if any command within it fails, rather than only failing if the last command fails.
set -o pipefail

# Cleaup script.
trap cleanup SIGINT SIGTERM ERR EXIT

# Get the script location and cd to it.
script_dir=$(cd "$(dirname "${BASH_SOURCE[0]}")" &>/dev/null && pwd -P)

# Usage error message.
usage() {
  cat <<EOF 
Usage: $(basename "${BASH_SOURCE[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 value
-p, --param     Some param description
EOF
  exit
}

# Cleaup up script iplementation. 
cleanup() {
  trap - SIGINT SIGTERM ERR EXIT
  # script cleanup here
}

# Color setup implementation. 
setup_colors() {
  if [[ -t 2 ]] && [[ -z "${NO_COLOR-}" ]] && [[ "${TERM-}" != "dumb" ]]; then
    NOFORMAT='\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
    NOFORMAT='' RED='' GREEN='' ORANGE='' BLUE='' PURPLE='' CYAN='' YELLOW=''
  fi
}

# Message helper function implementation.
msg() {
  echo >&2 -e "${1-}"
}

# Script exit implementation.
die() {
  local msg=$1
  local code=${2-1} # default exit status 1
  msg "\033[0;31m$msg\033[0m"
  exit "$code"
}

# Parameter parsing implementation.
parse_params() {
    flag=0
  param=''

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

  args=("$@")

  # check required params and arguments
  [[ -z "${param-}" ]] && die "Missing required parameter: param"
  [[ ${#args[@]} -eq 0 ]] && die "Missing script arguments"

  return 0
}
# ----- Script Start -----
# Parse parameters and setup colors for script.
parse_params "$@"
setup_colors

# Script logic example here.
msg "${GREEN}Read parameters:${NOFORMAT}"
msg "- flag: ${flag}"
msg "- param: ${param}"
msg "- arguments: ${args[*]-}"
exit 0