# Copyright 2023 VyOS maintainers and contributors <maintainers@vyos.io>
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library 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
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library.  If not, see <http://www.gnu.org/licenses/>.

from pathlib import Path
from re import MULTILINE, compile as re_compile
from typing import Union
from uuid import uuid5, NAMESPACE_URL, UUID

from vyos.template import render
from vyos.utils.process import cmd, rc_cmd
from vyos.system import disk

# Define variables
GRUB_DIR_MAIN: str = '/boot/grub'
GRUB_CFG_MAIN: str = f'{GRUB_DIR_MAIN}/grub.cfg'
GRUB_DIR_VYOS: str = f'{GRUB_DIR_MAIN}/grub.cfg.d'
CFG_VYOS_HEADER: str = f'{GRUB_DIR_VYOS}/00-vyos-header.cfg'
CFG_VYOS_MODULES: str = f'{GRUB_DIR_VYOS}/10-vyos-modules-autoload.cfg'
CFG_VYOS_VARS: str = f'{GRUB_DIR_VYOS}/20-vyos-defaults-autoload.cfg'
CFG_VYOS_COMMON: str = f'{GRUB_DIR_VYOS}/25-vyos-common-autoload.cfg'
CFG_VYOS_PLATFORM: str = f'{GRUB_DIR_VYOS}/30-vyos-platform-autoload.cfg'
CFG_VYOS_MENU: str = f'{GRUB_DIR_VYOS}/40-vyos-menu-autoload.cfg'
CFG_VYOS_OPTIONS: str = f'{GRUB_DIR_VYOS}/50-vyos-options.cfg'
GRUB_DIR_VYOS_VERS: str = f'{GRUB_DIR_VYOS}/vyos-versions'

TMPL_VYOS_VERSION: str = 'grub/grub_vyos_version.j2'
TMPL_GRUB_VARS: str = 'grub/grub_vars.j2'
TMPL_GRUB_MAIN: str = 'grub/grub_main.j2'
TMPL_GRUB_MENU: str = 'grub/grub_menu.j2'
TMPL_GRUB_MODULES: str = 'grub/grub_modules.j2'
TMPL_GRUB_OPTS: str = 'grub/grub_options.j2'
TMPL_GRUB_COMMON: str = 'grub/grub_common.j2'

# prepare regexes
REGEX_GRUB_VARS: str = r'^set (?P<variable_name>.+)=[\'"]?(?P<variable_value>.*)(?<![\'"])[\'"]?$'
REGEX_GRUB_MODULES: str = r'^insmod (?P<module_name>.+)$'
REGEX_KERNEL_CMDLINE: str = r'^BOOT_IMAGE=/(?P<boot_type>boot|live)/((?P<image_version>.+)/)?vmlinuz.*$'


def install(drive_path: str, boot_dir: str, efi_dir: str, id: str = 'VyOS') -> None:
    """Install GRUB for both BIOS and EFI modes (hybrid boot)

    Args:
        drive_path (str): path to a drive where GRUB must be installed
        boot_dir (str): a path to '/boot' directory
        efi_dir (str): a path to '/boot/efi' directory
    """
    commands: list[str] = [
        f'grub-install --no-floppy --target=i386-pc --boot-directory={boot_dir} \
            {drive_path} --force',
        f'grub-install --no-floppy --recheck --target=x86_64-efi \
            --force-extra-removable --boot-directory={boot_dir} \
            --efi-directory={efi_dir} --bootloader-id="{id}" \
            --no-uefi-secure-boot'
    ]
    for command in commands:
        cmd(command)


def gen_version_uuid(version_name: str) -> str:
    """Generate unique ID from version name

    Use UUID5 / NAMESPACE_URL with prefix `uuid5-`

    Args:
        version_name (str): version name

    Returns:
        str: generated unique ID
    """
    ver_uuid: UUID = uuid5(NAMESPACE_URL, version_name)
    ver_id: str = f'uuid5-{ver_uuid}'
    return ver_id


def version_add(version_name: str,
                root_dir: str = '',
                boot_opts: str = '') -> None:
    """Add a new VyOS version to GRUB loader configuration

    Args:
        vyos_version (str): VyOS version name
        root_dir (str): an optional path to the root directory.
        Defaults to empty.
        boot_opts (str): an optional boot options for Linux kernel.
        Defaults to empty.
    """
    if not root_dir:
        root_dir = disk.find_persistence()
    version_config: str = f'{root_dir}/{GRUB_DIR_VYOS_VERS}/{version_name}.cfg'
    render(
        version_config, TMPL_VYOS_VERSION, {
            'version_name': version_name,
            'version_uuid': gen_version_uuid(version_name),
            'boot_opts': boot_opts
        })


def version_del(vyos_version: str, root_dir: str = '') -> None:
    """Delete a VyOS version from GRUB loader configuration

    Args:
        vyos_version (str): VyOS version name
        root_dir (str): an optional path to the root directory.
        Defaults to empty.
    """
    if not root_dir:
        root_dir = disk.find_persistence()
    version_config: str = f'{root_dir}/{GRUB_DIR_VYOS_VERS}/{vyos_version}.cfg'
    Path(version_config).unlink(missing_ok=True)


def version_list(root_dir: str = '') -> list[str]:
    """Generate a list with installed VyOS versions

    Args:
        root_dir (str): an optional path to the root directory.
        Defaults to empty.

    Returns:
        list: A list with versions names

    N.B. coreutils stat reports st_birthtime, but not available in
    Path.stat()/os.stat()
    """
    if not root_dir:
        root_dir = disk.find_persistence()
    versions_files = Path(f'{root_dir}/{GRUB_DIR_VYOS_VERS}').glob('*.cfg')
    versions_order: dict[str, int] = {}
    for file in versions_files:
        p = Path(root_dir).joinpath('boot').joinpath(file.stem)
        command = f'stat -c %W {p.as_posix()}'
        rc, out = rc_cmd(command)
        if rc == 0:
            versions_order[file.stem] = int(out)
    versions_order = sorted(versions_order, key=versions_order.get, reverse=True)
    versions_list: list[str] = list(versions_order)

    return versions_list


def read_env(env_file: str = '') -> dict[str, str]:
    """Read GRUB environment

    Args:
        env_file (str, optional): a path to grub environment file.
        Defaults to empty.

    Returns:
        dict: dictionary with GRUB environment
    """
    if not env_file:
        root_dir: str = disk.find_persistence()
        env_file = f'{root_dir}/{GRUB_DIR_MAIN}/grubenv'

    env_content: str = cmd(f'grub-editenv {env_file} list').splitlines()
    regex_filter = re_compile(r'^(?P<variable_name>.*)=(?P<variable_value>.*)$')
    env_dict: dict[str, str] = {}
    for env_item in env_content:
        search_result = regex_filter.fullmatch(env_item)
        if search_result:
            search_result_dict: dict[str, str] = search_result.groupdict()
            variable_name: str = search_result_dict.get('variable_name', '')
            variable_value: str = search_result_dict.get('variable_value', '')
            if variable_name and variable_value:
                env_dict.update({variable_name: variable_value})
    return env_dict


def get_cfg_ver(root_dir: str = '') -> int:
    """Get current version of GRUB configuration

    Args:
        root_dir (str, optional): an optional path to the root directory.
        Defaults to empty.

    Returns:
        int: a configuration version
    """
    if not root_dir:
        root_dir = disk.find_persistence()

    cfg_ver: str = vars_read(f'{root_dir}/{CFG_VYOS_HEADER}').get(
            'VYOS_CFG_VER')
    if cfg_ver:
        cfg_ver_int: int = int(cfg_ver)
    else:
        cfg_ver_int: int = 0
    return cfg_ver_int


def write_cfg_ver(cfg_ver: int, root_dir: str = '') -> None:
    """Write version number of GRUB configuration

    Args:
        cfg_ver (int): a version number to write
        root_dir (str, optional): an optional path to the root directory.
        Defaults to empty.

    Returns:
        int: a configuration version
    """
    if not root_dir:
        root_dir = disk.find_persistence()

    vars_file: str = f'{root_dir}/{CFG_VYOS_HEADER}'
    vars_current: dict[str, str] = vars_read(vars_file)
    vars_current['VYOS_CFG_VER'] = str(cfg_ver)
    vars_write(vars_file, vars_current)


def vars_read(grub_cfg: str) -> dict[str, str]:
    """Read variables from a GRUB configuration file

    Args:
        grub_cfg (str): a path to the GRUB config file

    Returns:
        dict: a dictionary with variables and values
    """
    vars_dict: dict[str, str] = {}
    regex_filter = re_compile(REGEX_GRUB_VARS)
    try:
        config_text: list[str] = Path(grub_cfg).read_text().splitlines()
    except FileNotFoundError:
        return vars_dict
    for line in config_text:
        search_result = regex_filter.fullmatch(line)
        if search_result:
            search_dict = search_result.groupdict()
            variable_name: str = search_dict.get('variable_name', '')
            variable_value: str = search_dict.get('variable_value', '')
            if variable_name and variable_value:
                vars_dict.update({variable_name: variable_value})
    return vars_dict


def modules_read(grub_cfg: str) -> list[str]:
    """Read modules list from a GRUB configuration file

    Args:
        grub_cfg (str): a path to the GRUB config file

    Returns:
        list: a list with modules to load
    """
    mods_list: list[str] = []
    regex_filter = re_compile(REGEX_GRUB_MODULES, MULTILINE)
    try:
        config_text = Path(grub_cfg).read_text()
    except FileNotFoundError:
        return mods_list
    mods_list = regex_filter.findall(config_text)

    return mods_list


def modules_write(grub_cfg: str, mods_list: list[str]) -> None:
    """Write modules list to a GRUB configuration file (overwrite everything)

    Args:
        grub_cfg (str): a path to GRUB configuration file
        mods_list (list): a list with modules to load
    """
    render(grub_cfg, TMPL_GRUB_MODULES, {'mods_list': mods_list})


def vars_write(grub_cfg: str, grub_vars: dict[str, str]) -> None:
    """Write variables to a GRUB configuration file (overwrite everything)

    Args:
        grub_cfg (str): a path to GRUB configuration file
        grub_vars (dict): a dictionary with new variables
    """
    render(grub_cfg, TMPL_GRUB_VARS, {'vars': grub_vars})


def set_default(version_name: str, root_dir: str = '') -> None:
    """Set version as default boot entry

    Args:
        version_name (str): versio name
        root_dir (str, optional): an optional path to the root directory.
        Defaults to empty.
    """
    if not root_dir:
        root_dir = disk.find_persistence()

    vars_file = f'{root_dir}/{CFG_VYOS_VARS}'
    vars_current = vars_read(vars_file)
    vars_current['default'] = gen_version_uuid(version_name)
    vars_write(vars_file, vars_current)


def common_write(root_dir: str = '', grub_common: dict[str, str] = {}) -> None:
    """Write common GRUB configuration file (overwrite everything)

    Args:
        root_dir (str, optional): an optional path to the root directory.
        Defaults to empty.
    """
    if not root_dir:
        root_dir = disk.find_persistence()
    common_config = f'{root_dir}/{CFG_VYOS_COMMON}'
    render(common_config, TMPL_GRUB_COMMON, grub_common)


def create_structure(root_dir: str = '') -> None:
    """Create GRUB directories structure

    Args:
        root_dir (str, optional): an optional path to the root directory.
        Defaults to ''.
    """
    if not root_dir:
        root_dir = disk.find_persistence()

    Path(f'{root_dir}/GRUB_DIR_VYOS_VERS').mkdir(parents=True, exist_ok=True)


def set_console_type(console_type: str, root_dir: str = '') -> None:
    """Write default console type to GRUB configuration

    Args:
        console_type (str): a default console type
        root_dir (str, optional): an optional path to the root directory.
        Defaults to empty.
    """
    if not root_dir:
        root_dir = disk.find_persistence()

    vars_file: str = f'{root_dir}/{CFG_VYOS_VARS}'
    vars_current: dict[str, str] = vars_read(vars_file)
    vars_current['console_type'] = str(console_type)
    vars_write(vars_file, vars_current)

def set_console_speed(console_speed: str, root_dir: str = '') -> None:
    """Write default console speed to GRUB configuration

    Args:
        console_speed (str): default console speed
        root_dir (str, optional): an optional path to the root directory.
        Defaults to empty.
    """
    if not root_dir:
        root_dir = disk.find_persistence()

    vars_file: str = f'{root_dir}/{CFG_VYOS_VARS}'
    vars_current: dict[str, str] = vars_read(vars_file)
    vars_current['console_speed'] = str(console_speed)
    vars_write(vars_file, vars_current)