#!/usr/bin/python3
"""
Set system language.

Sets the system language to the given `language`, which must be a valid locale
identifier, like "en_US.UTF-8".

Removes `/etc/locale.conf` and then uses `systemd-firstboot` from the buildhost,
with the `--locale` flag, which will write a new `/etc/locale.conf` in the
target system with `LANG={language}`.
"""


import json
import subprocess
import sys
import os

SCHEMA = """
"additionalProperties": false,
"required": ["language"],
"properties": {
  "language": {
    "type": "string",
    "description": "Locale identifier (like 'en_US.UTF-8') for system LANG"
  }
}
"""

def main(tree, options):
    language = options["language"]

    # We need to remove the /etc/locale.conf file first, because it is created while we install RPM packages.
    # systemd-firstboot expects that if /etc/locale.conf exists it is a user-defined value and does not change it, but
    # the assumption is wrong, because it contains a default value from RPM package.
    try:
        os.remove(f"{tree}/etc/locale.conf")
        print("/etc/locale.conf already exists. Replacing.")
    except FileNotFoundError:
        pass

    subprocess.run(["systemd-firstboot", f"--root={tree}", f"--locale={language}"], check=True)


if __name__ == '__main__':
    args = json.load(sys.stdin)
    r = main(args["tree"], args["options"])
    sys.exit(r)