#!/usr/bin/env python3
#
# Copyright 2023 VyOS maintainers and contributors <maintainers@vyos.io>
#
# This file is part of VyOS.
#
# VyOS 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.
#
# VyOS 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
# VyOS. If not, see <https://www.gnu.org/licenses/>.

from argparse import ArgumentParser, Namespace
from pathlib import Path
from shutil import rmtree
from sys import exit
from typing import Optional

from vyos.system import disk, grub, image, compat
from vyos.utils.io import ask_yes_no, select_entry

SET_IMAGE_LIST_MSG: str = 'The following images are available:'
SET_IMAGE_PROMPT_MSG: str = 'Select an image to set as default:'
DELETE_IMAGE_LIST_MSG: str = 'The following images are installed:'
DELETE_IMAGE_PROMPT_MSG: str = 'Select an image to delete:'
MSG_DELETE_IMAGE_RUNNING: str = 'Currently running image cannot be deleted; reboot into another image first'
MSG_DELETE_IMAGE_DEFAULT: str = 'Default image cannot be deleted; set another image as default first'

def annotated_list(images_list: list[str]) -> list[str]:
    """Annotate list of images with additional info

    Args:
        images_list (list[str]): a list of image names

    Returns:
        list[str]: a list of image names with additional info
    """
    index_running: int = None
    index_default: int = None
    try:
        index_running = images_list.index(image.get_running_image())
        index_default = images_list.index(image.get_default_image())
    except ValueError:
        pass
    if index_running is not None:
        images_list[index_running] += ' (running)'
    if index_default is not None:
        images_list[index_default] += ' (default boot)'
    return images_list

@compat.grub_cfg_update
def delete_image(image_name: Optional[str] = None,
                 no_prompt: bool = False) -> None:
    """Remove installed image files and boot entry

    Args:
        image_name (str): a name of image to delete
    """
    available_images: list[str] = annotated_list(grub.version_list())
    if image_name is None:
        if no_prompt:
            exit('An image name is required for delete action')
        else:
            image_name = select_entry(available_images,
                                      DELETE_IMAGE_LIST_MSG,
                                      DELETE_IMAGE_PROMPT_MSG)
    if image_name == image.get_running_image():
        exit(MSG_DELETE_IMAGE_RUNNING)
    if image_name == image.get_default_image():
        exit(MSG_DELETE_IMAGE_DEFAULT)
    if image_name not in available_images:
        exit(f'The image "{image_name}" cannot be found')
    persistence_storage: str = disk.find_persistence()
    if not persistence_storage:
        exit('Persistence storage cannot be found')

    if (not no_prompt and
        not ask_yes_no(f'Do you really want to delete the image {image_name}?',
                       default=False)):
        exit()

    # remove files and menu entry
    version_path: Path = Path(f'{persistence_storage}/boot/{image_name}')
    try:
        rmtree(version_path)
        grub.version_del(image_name, persistence_storage)
        print(f'The image "{image_name}" was successfully deleted')
    except Exception as err:
        exit(f'Unable to remove the image "{image_name}": {err}')


@compat.grub_cfg_update
def set_image(image_name: Optional[str] = None,
              prompt: bool = True) -> None:
    """Set default boot image

    Args:
        image_name (str): an image name
    """
    available_images: list[str] = annotated_list(grub.version_list())
    if image_name is None:
        if not prompt:
            exit('An image name is required for set action')
        else:
            image_name = select_entry(available_images,
                                      SET_IMAGE_LIST_MSG,
                                      SET_IMAGE_PROMPT_MSG)
    if image_name == image.get_default_image():
        exit(f'The image "{image_name}" already configured as default')
    if image_name not in available_images:
        exit(f'The image "{image_name}" cannot be found')
    persistence_storage: str = disk.find_persistence()
    if not persistence_storage:
        exit('Persistence storage cannot be found')

    # set default boot image
    try:
        grub.set_default(image_name, persistence_storage)
        print(f'The image "{image_name}" is now default boot image')
    except Exception as err:
        exit(f'Unable to set default image "{image_name}": {err}')


@compat.grub_cfg_update
def rename_image(name_old: str, name_new: str) -> None:
    """Rename installed image

    Args:
        name_old (str): old name
        name_new (str): new name
    """
    if name_old == image.get_running_image():
        exit('Currently running image cannot be renamed')
    available_images: list[str] = grub.version_list()
    if name_old not in available_images:
        exit(f'The image "{name_old}" cannot be found')
    if name_new in available_images:
        exit(f'The image "{name_new}" already exists')
    if not image.validate_name(name_new):
        exit(f'The image name "{name_new}" is not allowed')

    persistence_storage: str = disk.find_persistence()
    if not persistence_storage:
        exit('Persistence storage cannot be found')

    if not ask_yes_no(
            f'Do you really want to rename the image {name_old} '
            f'to the {name_new}?',
            default=False):
        exit()

    try:
        # replace default boot item
        if name_old == image.get_default_image():
            grub.set_default(name_new, persistence_storage)

        # rename files and dirs
        old_path: Path = Path(f'{persistence_storage}/boot/{name_old}')
        new_path: Path = Path(f'{persistence_storage}/boot/{name_new}')
        old_path.rename(new_path)

        # replace boot item
        grub.version_del(name_old, persistence_storage)
        grub.version_add(name_new, persistence_storage)

        print(f'The image "{name_old}" was renamed to "{name_new}"')
    except Exception as err:
        exit(f'Unable to rename image "{name_old}" to "{name_new}": {err}')


def list_images() -> None:
    """Print list of available images for CLI hints"""
    images_list: list[str] = grub.version_list()
    for image_name in images_list:
        print(image_name)


def parse_arguments() -> Namespace:
    """Parse arguments

    Returns:
        Namespace: a namespace with parsed arguments
    """
    parser: ArgumentParser = ArgumentParser(description='Manage system images')
    parser.add_argument('--action',
                        choices=['delete', 'set', 'rename', 'list'],
                        required=True,
                        help='action to perform with an image')
    parser.add_argument('--no-prompt', action='store_true',
                        help='perform action non-interactively')
    parser.add_argument(
        '--image-name',
        help=
        'a name of an image to add, delete, install, rename, or set as default')
    parser.add_argument('--image-new-name', help='a new name for image')
    args: Namespace = parser.parse_args()
    # Validate arguments
    if args.action == 'rename' and (not args.image_name or
                                    not args.image_new_name):
        exit('Both old and new image names are required for rename action')

    return args


if __name__ == '__main__':
    try:
        args: Namespace = parse_arguments()
        if args.action == 'delete':
            delete_image(args.image_name, args.no_prompt)
        if args.action == 'set':
            set_image(args.image_name)
        if args.action == 'rename':
            rename_image(args.image_name, args.image_new_name)
        if args.action == 'list':
            list_images()

        exit()

    except KeyboardInterrupt:
        print('Stopped by Ctrl+C')
        exit()

    except Exception as err:
        exit(f'{err}')