Simple bash script for running little code snippets

code.sh

#!/bin/bash

function template_from_language() {
	__PHP_TEMPLATE="<?php\n\n?>\n"
	__OBJC_TEMPLATE="#import <Foundation/Foundation.h>\n\nint main(int argc, char *argv[]) {\n\t@autoreleasepool {\n\t\t\n\t}\n\t\n\treturn 0;\n}\n"
	__JAVA_TEMPLATE="public class program {\n\tpublic static void main(String args[]) {\n\t\t\n\t}\n}\n"
	__BASH_TEMPLATE="#!/bin/bash\n\n"
	__JS_TEMPLATE="var path = require('path');\n\n"
	
	if [ -z "$1" ]
	then
		echo ""
	fi
	
	case "$1" in
	php)
		echo $__PHP_TEMPLATE
		;;
	objc)
		echo $__OBJC_TEMPLATE
		;;
	java)
		echo $__JAVA_TEMPLATE
		;;
	bash)
		echo $__BASH_TEMPLATE
		;;
	js)
		echo $__JS_TEMPLATE
		;;
	*)
		echo ""
		;;
	esac
}

function extension_from_language() {
	if [ -z "$1" ]
	then
		echo ""
	fi
	
	case "$1" in
	php)
		echo "php"
		;;
	objc)
		echo "m"
		;;
	java)
		echo "java"
		;;
	bash)
		echo "sh"
		;;
	js)
		echo "js"
		;;
	*)
		echo ""
		;;
	esac
}

function run_program_for_language() {
	if [ -z "$1" ]
	then
		return 0
	fi
	
	if [ -z "$2" ]
	then
		return 0
	fi
	
	file="$1"
	language="$2"
	
	case "$language" in
	php)
		php -f $file
		;;
	objc)
		clang -fobjc-arc -framework Foundation $file -o /tmp/program
		/tmp/program
		;;
	java)
		javac $file
		java -classpath /tmp program
		;;
	bash)
		chmod +x $file
		$file
		;;
	js)
		node $file
		;;
	*)
		return 0
		;;
	esac
}

function usage() {
	program=`basename $0`
	
	echo "USAGE: $program [options] [language]"
	echo ""
	echo "OPTIONS:"
	echo "  -e		Edit the existing code file."
	echo ""
	echo "SUPPORTED LANGUAGES:"
	echo "  Bash		(bash)"
	echo "  Java		(java)"
	echo "  JavaScript	(js)"
	echo "  Objective-C	(objc)"
	echo "  PHP		(php)"
	
	exit 0
}

language="objc"

if [ -n "$1" ]
then
	if [ "$1" == "-h" ]
	then
		usage
	elif [ "$1" != "-e" ]
	then
		language="$1"
	elif [ -n "$2" ]
	then
		language="$2"
	fi
fi

extension=$(extension_from_language $language)

if [ -z "$extension" ]
then
	echo "Invalid language specified."
	
	exit 1
fi

file="/tmp/program.$extension"
template=$(template_from_language $language)

if [ -z "$1" ]
then
	echo -e $template > $file
elif [ "$1" != "-e" ]
then
	echo -e $template > $file
fi

file_editor="$EDITOR"

if [ -z "$file_editor" ]
then
	file_editor=`which nano`
fi

$file_editor $file
run_program_for_language $file $language