#!/usr/bin/python3
"""
Bind mount service

Can (r)bind mount mounts to the tree.
"""

import os.path
import subprocess
import sys
from typing import Dict
from urllib.parse import urlparse

from osbuild import mounts

SCHEMA_2 = """
"additionalProperties": false,
"required": ["name", "type", "target"],
"properties": {
  "name": { "type": "string" },
  "type": { "type": "string" },
  "target": {
    "type": "string",
    "pattern": "^tree://"
  },
  "options": {
    "required": ["source"],
    "source": {
      "type": "string",
      "pattern": "^mount://"
    }
  }
}
"""


def parse_location(location, tree, mountroot: str) -> str:
    # we cannot use "osutil.util.parsing" here because it is too
    # tightly coupled with how arguments for stages are passed
    url = urlparse(location)
    path = url.netloc
    if url.scheme == "tree":
        return os.path.join(tree, path.rstrip("/"))
    if url.scheme == "mount":
        return os.path.join(mountroot, path.rstrip("/"))
    raise ValueError(f"unsupported schema {url.scheme} for {location}")


class BindMount(mounts.MountService):

    def __init__(self, args):
        super().__init__(args)
        self.mountpoint = ""

    def mount(self, args: Dict):
        tree = args["tree"]
        mountroot = args["root"]
        target = args["target"]
        # we cannot use args["sources"] here because the osbuild code makes
        # many assumptions about that it must link back to a "Device" so
        # we follow the pattern from org.osbuild.ostree.deployment here
        # and put it into "options"
        options = args["options"]
        source = parse_location(options.get("source"), tree, mountroot)
        self.mountpoint = parse_location(target, tree, mountroot)
        subprocess.run([
            "mount",
            "--rbind", source, self.mountpoint,
        ], check=True)

    def umount(self):
        if self.mountpoint:
            subprocess.run(["umount", "-R", "-v", self.mountpoint], check=True)
            self.mountpoint = ""

    def sync(self):
        pass


def main():
    service = BindMount.from_args(sys.argv[1:])
    service.main()


if __name__ == '__main__':
    main()