from typing import Dict, List, Optional
import os
from shutil import rmtree
from pathlib import Path
from importlib_resources import read_text
from customer_local_ops.util.helpers import create_file
from customer_local_ops.util.execute import runCommand, RunCommandResult


APT_PUBLIC_KEYS = [
    '61EE28720129F5F3'  # http://packages.panopta.com/deb
]


class PackageManager:
    # List of command-line arguments to install packages.
    # Packages to install are appended when command is run.
    # See install().
    INSTALL_ARGS = None  # type: List[str]

    def _env(self) -> Optional[Dict[str, str]]:
        """Environment variables to send to subprocess.

        This version copies the environment from the parent process.
        """
        return None

    def install(self, *packages: str, tag: str = None) -> RunCommandResult:
        """Install one or more packages.

        :param *pkg_spec: one or more specifications of packages to install
        :param tag: optional identifier included in logs
        :returns: result of installation command as (exit_code, stdout, stderr)
        """
        if not packages:
            raise ValueError('At least one package is required')

        cmd = self.INSTALL_ARGS + list(packages)
        if tag is None:
            tag = 'install %s' % str(packages)
        return runCommand(cmd, tag, env=self._env())

    def update_indices(self) -> RunCommandResult:
        """Update local package indices from remote sources.

        Not all package managers need this, so this version does nothing and
        returns a fake success result.

        :returns: result of update command as (exit_code, stdout, stderr)
        """
        return 0, '', ''


class Apt(PackageManager):
    INSTALL_ARGS = ['apt-get', 'install', '-y']

    def _env(self) -> Optional[Dict[str, str]]:
        """Environment variables to send to subprocess.

        We set DEBIAN_FRONTEND to ensure user is not prompted to answer any
        questions during installation.
        """
        env = os.environ.copy()
        env['DEBIAN_FRONTEND'] = 'noninteractive'
        env['APT_KEY_DONT_WARN_ON_DANGEROUS_USAGE'] = '1'
        return env

    def update_indices(self) -> RunCommandResult:
        for key in APT_PUBLIC_KEYS:
            cmd = ['apt-key', 'adv', '--keyserver', 'hkp://keyserver.ubuntu.com:80', '--recv-keys', key]
            runCommand(cmd, 'apt-key get public keys', env=self._env())

        cmd = ['apt-get', 'update', '-y', '-o', 'Acquire::ForceIPv4=true']
        return runCommand(cmd, 'apt-get update', env=self._env())


class AptEOL(Apt):
    TMP_DIRS = [
                '/tmp/tmp_apt',
                '/tmp/tmp_apt/source.list.d',
                '/tmp/tmp_apt/tmp_apt_cache',
                '/tmp/tmp_apt/tmp_apt_lists'
        ]
    TMP_SOURCE_LIST = '/tmp/tmp_apt/source.list'
    LINUX_EOL_DISTROS = ['Debian8', 'Ubuntu1604']
    APT_CONF_PATH = '/etc/apt/apt.conf'
    RES_PACKAGE = 'customer_local_ops.operating_system.resources'

    def __init__(self, os_name: str):
        if os_name not in self.LINUX_EOL_DISTROS:
            raise ValueError('Invalid Linux distributive name was provided - %s.' % os_name)

        self.os_name = os_name

    def _add_tmp_source_list_dirs(self) -> None:
        """
        Add folder structure for temporary APT config \n
        Fill source.list file with mirrors for provided Linux distributive

        :returns: None
        """
        for dir_path in self.TMP_DIRS:
            Path(dir_path).mkdir(parents=True, exist_ok=True)

        mirrors_list = self.os_name.lower() + '_mirrors.repo'

        mirrors_list_content = read_text(
                                self.RES_PACKAGE,
                                mirrors_list)
        create_file(self.TMP_SOURCE_LIST, mirrors_list_content)

    def _add_tmp_apt_config(self) -> None:
        """
        Fill apt.conf file with a new config

        :returns: None
        """
        apt_config_content = read_text(
                                self.RES_PACKAGE,
                                'tmp_apt_config.repo')
        create_file(self.APT_CONF_PATH, apt_config_content)

    def _clear_apt_conf(self) -> None:
        """
        Delete apt.conf file

        :returns: None
        """
        os.remove(self.APT_CONF_PATH)

    def _clear_tmp_apt_folders(self) -> None:
        """
        Delete all tmp folders used for apt update

        :returns: None
        """
        rmtree(self.TMP_DIRS[0])

    def update_indices(self) -> RunCommandResult:
        """
        Run both _add_tmp_source_list_dirs and _add_tmp_apt_config methods

        :returns: run update_indices method for super class if no errors; otherwise raise RuntimeError
        """
        try:
            self._add_tmp_source_list_dirs()
            self._add_tmp_apt_config()
        except (PermissionError, IOError, OSError) as ex:
            raise RuntimeError('An error occurred during file operation with tmp source list: ' + str(ex)) from ex

        return super().update_indices()

    def install(self, *packages: str, tag: str = None) -> RunCommandResult:
        result = super().install(*packages, tag=tag)

        try:
            self._clear_apt_conf()
            self._clear_tmp_apt_folders()
        except (PermissionError, IOError, OSError) as ex:
            raise RuntimeError('An error occurred during clear apt.conf file: ' + str(ex)) from ex

        return result


class Yum(PackageManager):
    INSTALL_ARGS = ['yum', 'install', '-y']