Determine the used language of an `.scpt` file

osagetlang.sh

#!/usr/bin/env bash

function usage {
	echo "Usage: $(basename $0) $1 [-n|-i|-a]

Arguments:
  -n or --name:  show name of language (default)
  -i or --id:    show id of language
  -a or --all:   show 'id:name' of language 
  -e or --error: (for TESTING) to generate an AppleScript error"
}

scpt_file=".*\.scpt$"
if [[ $# -lt 1 || ! $1 =~ .*\.scpt$ ]]; then
	usage "applescript-file.scpt"
	exit 1
fi
if [[ $1 =~ ^/.* ]]; then
	INPUT_FILE=$1
else
	INPUT_FILE=$(pwd)/$1
fi
if [[ ! -f $INPUT_FILE ]]; then
	echo "File '$INPUT_FILE' doesn't exist"
	exit 2
fi
if [[ $# -gt 1 ]]; then
	ALL=0 PROPERTY=id
	case $2 in
		-n | --name)  PROPERTY=name;;
		-i | --id)    ;;
		-a | --all)   ALL=1;;
		-e | --error) PROPERTY="generate_error";;
		-h | -? | --help) usage $1; exit 0;;
		*) echo "Unknown argument '$2'"; exit 3;;
	esac
else
	PROPERTY=name
fi

osascript <<AS_EOF
set scpt_file to POSIX file "${INPUT_FILE}"
try
	tell application "Script Editor"
		set scpt_doc to open scpt_file
		set lang to language of scpt_doc
		close scpt_doc without saving
	end tell
	if "${ALL}" = "1" then
		set result to (id of lang) & ":" & (name of lang)
	else
		set result to ${PROPERTY} of lang
	end if
	do shell script "echo " & quoted form of result
on error err_msg number err_nr
	set msg to "AppleScript error #" & err_nr & ": " & err_msg
	do shell script "echo " & quoted form of msg
end
AS_EOF