"""Read disk hardware info from system."""
import logging
from pathlib import Path
import shutil
from typing import Union

from ..coresys import CoreSys, CoreSysAttributes
from ..exceptions import HardwareNotFound
from .const import UdevSubsystem
from .data import Device

_LOGGER: logging.Logger = logging.getLogger(__name__)

_MOUNTINFO: Path = Path("/proc/self/mountinfo")
_BLOCK_DEVICE_CLASS = "/sys/class/block/{}"
_BLOCK_DEVICE_EMMC_LIFE_TIME = "/sys/block/{}/device/life_time"


class HwDisk(CoreSysAttributes):
    """Representation of an interface to disk utils."""

    def __init__(self, coresys: CoreSys):
        """Init hardware object."""
        self.coresys = coresys

    def is_used_by_system(self, device: Device) -> bool:
        """Return true if this is a system partition."""
        if device.subsystem != UdevSubsystem.DISK:
            return False

        # Root
        if device.minor == 0:
            for child in device.children:
                try:
                    device = self.sys_hardware.get_by_path(child)
                except HardwareNotFound:
                    continue
                if device.subsystem == UdevSubsystem.DISK:
                    if device.attributes.get("ID_FS_LABEL", "").startswith("hassos"):
                        return True
            return False

        # Partition
        if device.minor > 0 and device.attributes.get("ID_FS_LABEL", "").startswith(
            "hassos"
        ):
            return True

        return False

    def get_disk_total_space(self, path: Union[str, Path]) -> float:
        """Return total space (GiB) on disk for path."""
        total, _, _ = shutil.disk_usage(path)
        return round(total / (1024.0**3), 1)

    def get_disk_used_space(self, path: Union[str, Path]) -> float:
        """Return used space (GiB) on disk for path."""
        _, used, _ = shutil.disk_usage(path)
        return round(used / (1024.0**3), 1)

    def get_disk_free_space(self, path: Union[str, Path]) -> float:
        """Return free space (GiB) on disk for path."""
        _, _, free = shutil.disk_usage(path)
        return round(free / (1024.0**3), 1)

    def _get_mountinfo(self, path: str) -> str:
        mountinfo = _MOUNTINFO.read_text(encoding="utf-8")
        for line in mountinfo.splitlines():
            mountinfoarr = line.split()
            if mountinfoarr[4] == path:
                return mountinfoarr
        return None

    def _get_mount_source(self, path: str) -> str:
        mountinfoarr = self._get_mountinfo(path)

        if mountinfoarr is None:
            return None

        # Find optional field separator
        optionsep = 6
        while mountinfoarr[optionsep] != "-":
            optionsep += 1
        return mountinfoarr[optionsep + 2]

    def _try_get_emmc_life_time(self, device_name: str) -> float:
        # Get eMMC life_time
        life_time_path = Path(_BLOCK_DEVICE_EMMC_LIFE_TIME.format(device_name))

        if not life_time_path.exists():
            return None

        # JEDEC health status DEVICE_LIFE_TIME_EST_TYP_A/B
        emmc_life_time = life_time_path.read_text(encoding="utf-8").split()

        if len(emmc_life_time) < 2:
            return None

        # Type B life time estimate represents the user partition.
        life_time_value = int(emmc_life_time[1], 16)

        # 0=Not defined, 1-10=0-100% device life time used, 11=Exceeded
        if life_time_value == 0:
            return None

        if life_time_value == 11:
            logging.warning(
                "eMMC reports that its estimated life-time has been exceeded!"
            )
            return 100.0

        # Return the pessimistic estimate (0x02 -> 10%-20%, return 20%)
        return life_time_value * 10.0

    def get_disk_life_time(self, path: Union[str, Path]) -> float:
        """Return life time estimate of the underlying SSD drive."""
        mount_source = self._get_mount_source(str(path))
        if mount_source == "overlay":
            return None

        mount_source_path = Path(mount_source)
        if not mount_source_path.is_block_device():
            return None

        # This looks a bit funky but it is more or less what lsblk is doing to get
        # the parent dev reliably

        # Get class device...
        mount_source_device_part = Path(
            _BLOCK_DEVICE_CLASS.format(mount_source_path.name)
        )

        # ... resolve symlink and get parent device from that path.
        mount_source_device_name = mount_source_device_part.resolve().parts[-2]

        # Currently only eMMC block devices supported
        return self._try_get_emmc_life_time(mount_source_device_name)