#!/bin/bash

name="whichhead"
version="1.0"
read -r -d '' help_message <<-EOF
	Print the first 10 lines from a program
	Usage: whichhead [PROGRAM ..] [OPTIONS]
	Options:
	 -h, --help        print this message
	 -n N, --number=N  print the first N lines (Default: 10)
	 -q, --quiet       suppress error messages
	 -v, --verbose     show additional messages
	 -V, --version     print version number and exit
EOF

source /usr/local/lib/mylib.bash

positional=()
num_lines=10
quiet=0
verbose=0

while [[ $# -gt 0 ]]; do
  case $1 in

  -h|--help)
    help_msg
    shift
    ;;

  -n|--number)
    if ! is_natural "$2"; then
      error_msg "Cannot set number of lines to '${2}' (not an integer >= 0)"
    fi
    debug_msg "Setting number of lines to ${2} (was ${num_lines})"
    num_lines="$2"
    shift; shift
    ;;

  -q|--quiet)
    debug_msg "Setting quiet option to 1 (was ${quiet})"
    quiet=1
    shift
    ;;

  -v|--verbose)
    debug_msg "Setting verbose option to 1 (was ${verbose})"
    verbose=1
    shift
    ;;

  -V|--version)
    version_msg
    ;;

  *)
    debug_msg "Argument '${1}' added to positional array"
    positional+=("$1")
    shift
    ;;
  esac
done

# main routine
code=0
for target in "${positional[@]}"; do
  abs_target=$(command -v "$target")
  if [[ -z $abs_target ]]; then
    nonfatal_error_msg "No such program '${target}'"
    code=1
  else
    /usr/bin/head "$abs_target" -n "$num_lines"
  fi
done

# return stored code
exit "$code"