"""
Copyright 2018 Oliver Smith

This file is part of pmbootstrap.

pmbootstrap 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.

pmbootstrap 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 pmbootstrap.  If not, see <http://www.gnu.org/licenses/>.
"""
import glob
import json
import logging
import os
import time

import pmb.helpers.mount
import pmb.helpers.run
import pmb.chroot


def init(args):
    if not os.path.isdir("/sys/module/loop"):
        pmb.helpers.run.root(args, ["modprobe", "loop"])
    loopdevices = [loopdev for loopdev in glob.glob("/dev/loop*") if not os.path.isdir(loopdev)]
    for loopdev in loopdevices:
        pmb.helpers.mount.bind_blockdevice(args, loopdev,
                                           args.work + "/chroot_native/" + loopdev)


def mount(args, img_path):
    """
    :param img_path: Path to the img file inside native chroot.
    """
    logging.debug("(native) mount " + img_path + " (loop)")

    # Try to mount multiple times (let the kernel module initialize #1594)
    for i in range(0, 5):
        # Retry
        if i > 0:
            logging.debug("loop module might not be initialized yet, retry in"
                          " one second...")
            time.sleep(1)

        # Mount and return on success
        init(args)

        losetup_cmd = ["losetup", "-f", img_path]
        sector_size = args.deviceinfo["rootfs_image_sector_size"]
        if sector_size:
            losetup_cmd += ["-b", str(int(sector_size))]

        pmb.chroot.root(args, losetup_cmd, check=False)
        if device_by_back_file(args, img_path):
            return

    # Failure: raise exception
    raise RuntimeError("Failed to mount loop device: " + img_path)


def device_by_back_file(args, back_file):
    """
    Get the /dev/loopX device, that points to a specific image file.
    """

    # Get list from losetup
    losetup_output = pmb.chroot.root(args, ["losetup", "--json",
                                            "--list"], output_return=True)
    if not losetup_output:
        return None

    # Find the back_file
    losetup = json.loads(losetup_output)
    for loopdevice in losetup["loopdevices"]:
        if loopdevice["back-file"] == back_file:
            return loopdevice["name"]
    return None


def umount(args, img_path):
    """
    :param img_path: Path to the img file inside native chroot.
    """
    device = device_by_back_file(args, img_path)
    if not device:
        return
    logging.debug("(native) umount " + device)
    pmb.chroot.root(args, ["losetup", "-d", device])