#!/bin/bash
 
BLUE='\033[34m'
GREEN='\033[32m'
BOLD='\033[1m'
NORMAL='\033[0m'
 
MARK="@COMPILECMD "
MARKSTR="${BLUE}@COMPILECMD${NORMAL}"
 
enable -n echo
 
usage() {
    IFSTR="${GREEN}<input_file>${NORMAL}"
    echo -e "${BOLD}Usage: $0 <input_file>${NORMAL}" >&2
    echo -e "\t$0 runs the value of ${MARKSTR}." >&2
    echo -e "\tThe point of this script is ease to compialation of singe source file (toy) programs." >&2
    echo -e "\tThe value of ${MARKSTR} is read from ${IFSTR} in is whatever comes after '${MARK}' until the end of the line." >&2
    echo -e "\tInside the value of ${MARKSTR} all mentions of special placeholders are replaced:" >&2
    echo -e "\t\t${BLUE}\$@${NORMAL} - ${IFSTR}"
    echo -e "\t\t${BLUE}\$*${NORMAL} - ${IFSTR} with the last extension cut off"
}
 
 
 
if [[ $# -ne 1 ]]; then
    usage
    exit 1
fi
 
if [[ $1 == "-h" ]] || [[ $1 == "--help" ]]; then
    usage
    exit 0
fi
 
 
 
input_file=$1
 
if [[ ! -f $input_file ]]; then
    echo -e "Input file '$input_file' does not exist." >&2
    exit 1
fi
 
line=$(grep "$MARK" "$input_file" | head -1)
line=${line//\$@/$input_file}
line=${line//\$\*/${input_file%.*}}
 
if [[ -n $line ]]; then
    command="${line#*@COMPILECMD }"
 
    echo "$command"
    eval "$command"
else
    echo -e "${MARKSTR} is not defined." >&2
fi