import inspect


def error_not_async(func):
    if not inspect.iscoroutinefunction(func):
        lines, start = inspect.getsourcelines(func)

        fdef_index = 0
        while fdef_index < len(lines) and not lines[fdef_index].strip().startswith(
            "def"
        ):
            fdef_index += 1

        if fdef_index < len(lines):
            line_num = start + fdef_index

            fdef_content = lines[fdef_index].strip()

            ERROR_HEADER = "\033[1m\033[91m[FATAL_EXECUTION_ERROR]: Non-Asynchronous Route Detected\033[0m"

            ERROR_BODY = (
                f"\n"
                f'--> File "{inspect.getsourcefile(func)}", line {line_num}, in {func.__name__}\n\n'
                f"\033[1m[CONSTRAINT_VIOLATION]\033[0m\n"
                f"  Synchronous function used where an async coroutine was required.\n"
                f"  \033[93mCode Traceback:\033[0m\n"
                f"  {line_num}: \033[93m{fdef_content}\033[0m\n\n"
                f"\033[1m[SUGGESTED_PATCH]\033[0m\n"
                f"  Apply the 'async' keyword to the function signature:\n"
                f"  {line_num}: \033[92masync {fdef_content}\033[0m"
            )

            raise RuntimeError(ERROR_HEADER + ERROR_BODY)

        else:
            raise RuntimeError(
                "\033[1m\033[91m[FATAL_EXECUTION_ERROR]: Non-Asynchronous Route Detected\033[0m"
            )