Helper utility for shell scripts to read or modify configuration files like .ini, .toml or .conf

cfg

#!/bin/python3
"""
    Config-Util - Helper utility for shell scripts to read or modify
    configuration files like .ini, .toml or .conf

    Copyright (C) 2022  Jimmy Pramosi <[email protected]>

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <https://www.gnu.org/licenses/>.
"""
import io
import sys
from argparse import ArgumentParser, RawTextHelpFormatter
from configparser import ConfigParser, _UNSET
from pathlib import Path

DESCRIPTION = """
Config-Util Copyright (C) 2022  Jimmy Pramosi <[email protected]>
This program comes with ABSOLUTELY NO WARRANTY.
This is free software, and you are welcome to redistribute it under certain
conditions.
You should have received a copy of the GNU General Public License along with
this program.  If not, see <http://www.gnu.org/licenses/>.
"""

USAGE = """
    Get operations:
        cfg [OPTIONS] <FILE> <VAR-NAME>
        cfg [OPTIONS] <FILE> <[SECTION-NAME]> <VAR-NAME>
    Set operations:
        cfg [OPTIONS] <FILE> <VAR-NAME> <NEW-VALUE>
        cfg [OPTIONS] <FILE> <[SECTION-NAME]> <VAR-NAME> <NEW-VALUE>
"""

EPILOG = """
Examples:
    get variable 'timeout_secs' without section
        cfg vpn.conf timeout_secs

    set variable 'timeout_secs' without section
        cfg vpn.conf timeout_secs myprofile.ovpn

    get variable 'tun-device' with section
        cfg vpn.conf [OpenVpn] tun-device

    set variable 'tun-device' with section
        cfg vpn.conf [OpenVpn] tun-device tun0

    get variable 'select_profile' with nested section
        cfg vpn.conf [OpenVpn.profile] select_profile

    set variable 'select_profile' with nested section
        cfg vpn.conf [OpenVpn.profile] select_profile myprofile.ovpn\n
"""


def eprint(*args, **kwargs):
    print(*args, file=sys.stderr, **kwargs)


def main():
    commands = set()

    def add_argument(parser: ArgumentParser, *args, **kwargs):
        nonlocal commands
        commands.add(args[0])
        commands.add(args[1])
        parser.add_argument(*args, **kwargs)

    # parse arguments
    parser = ArgumentParser(prog="cfg", description=DESCRIPTION,
                            usage=USAGE, epilog=EPILOG, formatter_class=RawTextHelpFormatter)
    add_argument(parser, "-d", "--dump", action="store_true",
                 help="dump variable and value to stdout")
    add_argument(parser, "-q", "--quote", action="store_true",
                 help="wrap values with quotes if contains whitespace")
    add_argument(parser, "-a", "--auto-format", action="store_true",
                 help="format values automatically (quotes)")
    add_argument(parser, "-n", "--new", action="store_true",
                 help="allow creating new variables with set operation")
    add_argument(parser, "-p", "--print", action="store_true",
                 help="print file content after successful operation")
    args, _ = parser.parse_known_args()

    # clean and check args
    sys.argv[:] = [x for x in sys.argv if x not in commands]
    argn = len(sys.argv)
    if argn < 3:
        eprint(f"Invalid arguments:\n\n\t{' '.join(sys.argv)}\n\n")
        parser.print_help()
        return 1

    filepath = Path(sys.argv[1]).resolve()

    def write_string(config: ConfigParser):
        output = ""
        with io.StringIO() as ss:
            config.write(ss)
            ss.seek(0)
            output = ss.read().replace("[_]\n", "")
        return output

    def format_value(value, force_quote=False):
        if isinstance(value, str) and args.quote or force_quote or (args.auto_format and " " in value):
            value = value.replace("\"", "\\\"")
            value = f"\"{value}\""
        return value

    def dump_value(config: ConfigParser, name: str, value):
        if args.dump:
            print(f"{name}={value}")
        elif args.print:
            print(write_config(config))
        else:
            print(value)

    def read_config():
        with open(filepath, "rt", encoding="utf-8") as f:
            config_string = "[_]\n" + f.read()
        config = ConfigParser(comment_prefixes="/", allow_no_value=True)
        config.read_string(config_string)
        return config

    def write_config(config: ConfigParser):
        output = write_string(config)
        with open(filepath, "wt", encoding="utf-8") as f:
            f.write(output)

    # get value without section
    if argn == 3:
        try:
            config = read_config()
            value = format_value(config.get("_", sys.argv[2]))
            dump_value(config, sys.argv[2], value)
        except Exception as ex:
            eprint(ex)
            return 1
        return

    # get value with section
    if argn == 4 and sys.argv[2].startswith("[") and sys.argv[2].endswith("]"):
        try:
            config = read_config()
            section = sys.argv[2].removeprefix("[").removesuffix("]")
            value = format_value(config.get(
                section, sys.argv[3]))
            dump_value(config, sys.argv[2], value)
        except Exception as ex:
            eprint(ex)
            return 1
        return

    # set value without section
    if argn == 4:
        try:
            config = read_config()
            fallback = type(sys.argv[3])() if args.new else _UNSET
            rvalue = format_value(config.get(
                "_", sys.argv[2], fallback=fallback))
            value = format_value(
                sys.argv[3], isinstance(rvalue, str) and rvalue.startswith("\""))
            config.set("_", sys.argv[2], value)
            write_config(config)
            dump_value(config, sys.argv[2], value)
        except Exception as ex:
            eprint(ex)
            return 1
        return 0

    # set value with section
    if argn == 5:
        try:
            config = read_config()
            section = sys.argv[2].removeprefix("[").removesuffix("]")
            fallback = type(sys.argv[4])() if args.new else _UNSET
            rvalue = format_value(config.get(
                section, sys.argv[3], fallback=fallback))
            value = format_value(
                sys.argv[4], isinstance(rvalue, str) and rvalue.startswith("\""))
            config.set(section,
                       sys.argv[3], value)
            write_config(config)
            dump_value(config, sys.argv[3], value)
        except Exception as ex:
            eprint(ex)
            return 1
        return 0

    eprint(f"Too many arguments:\n\n\t{' '.join(sys.argv)}\n\n")
    parser.print_help()
    return 1


if __name__ == "__main__":
    main()