#!/usr/bin/python3
"""
Configure the kernel command-line parameters

Configures the kernel boot parameters, also known as the kernel
command line.

https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html
"""

import json
import os
import sys

SCHEMA = """
"additionalProperties": false,
"properties": {
  "root_fs_uuid": {
    "description": "UUID of the root filesystem image",
    "type": "string",
    "oneOf": [
      { "pattern": "^[0-9A-Za-z]{8}(-[0-9A-Za-z]{4}){3}-[0-9A-Za-z]{12}$",
        "examples": ["9c6ae55b-cf88-45b8-84e8-64990759f39d"] },
      { "pattern": "^[0-9A-Za-z]{4}-[0-9A-Za-z]{4}$",
        "examples": ["6699-AFB5"] }
    ]
  },
  "kernel_opts": {
    "description": "Additional kernel boot options",
    "type": "string",
    "default": ""
  }
}
"""


def main(tree, options):
    root_fs_uuid = options.get("root_fs_uuid", "")
    additional = options.get("kernel_opts", "")

    params = []

    if root_fs_uuid:
        params += [f"root=UUID={root_fs_uuid}"]

    if additional:
        params += [additional]

    base = os.path.join(tree, "etc/kernel")
    os.makedirs(base, exist_ok=True)

    with open(f"{base}/cmdline", "w") as f:
        f.write(" ".join(filter(len, params)))

    return 0


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