# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# All Rights Reserved.
# Copyright (c) 2010 Citrix Systems, Inc.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

"""
Handling of VM disk images.
"""

import contextlib
import os
import shutil

from ironic_lib import disk_utils
from ironic_lib import utils as ironic_utils
from oslo_concurrency import processutils
from oslo_log import log as logging
from oslo_utils import fileutils

from ironic.common import exception
from ironic.common.glance_service import service_utils as glance_utils
from ironic.common.i18n import _
from ironic.common import image_service as service
from ironic.common import utils
from ironic.conf import CONF

LOG = logging.getLogger(__name__)


def _create_root_fs(root_directory, files_info):
    """Creates a filesystem root in given directory.

    Given a mapping of absolute path of files to their relative paths
    within the filesystem, this method copies the files to their
    destination.

    :param root_directory: the filesystem root directory.
    :param files_info: A dict containing absolute path of file to be copied
                       -> relative path within the vfat image. For example::
                        {
                        '/absolute/path/to/file' -> 'relative/path/within/root'
                        ...
                        }
    :raises: OSError, if creation of any directory failed.
    :raises: IOError, if copying any of the files failed.
    """
    for src_file, path in files_info.items():
        target_file = os.path.join(root_directory, path)
        dirname = os.path.dirname(target_file)
        if not os.path.exists(dirname):
            os.makedirs(dirname)

        shutil.copyfile(src_file, target_file)


def _umount_without_raise(mount_dir):
    """Helper method to umount without raise."""
    try:
        utils.umount(mount_dir)
    except processutils.ProcessExecutionError:
        pass


def create_vfat_image(output_file, files_info=None, parameters=None,
                      parameters_file='parameters.txt', fs_size_kib=100):
    """Creates the fat fs image on the desired file.

    This method copies the given files to a root directory (optional),
    writes the parameters specified to the parameters file within the
    root directory (optional), and then creates a vfat image of the root
    directory.

    :param output_file: The path to the file where the fat fs image needs
                        to be created.
    :param files_info: A dict containing absolute path of file to be copied
                       -> relative path within the vfat image. For example::

                        {
                        '/absolute/path/to/file' -> 'relative/path/within/root'
                        ...
                        }
    :param parameters: A dict containing key-value pairs of parameters.
    :param parameters_file: The filename for the parameters file.
    :param fs_size_kib: size of the vfat filesystem in KiB.
    :raises: ImageCreationFailed, if image creation failed while doing any
             of filesystem manipulation activities like creating dirs,
             mounting, creating filesystem, copying files, etc.
    """
    try:
        ironic_utils.dd('/dev/zero', output_file, 'count=1',
                        "bs=%dKiB" % fs_size_kib)
    except processutils.ProcessExecutionError as e:
        raise exception.ImageCreationFailed(image_type='vfat', error=e)

    with utils.tempdir() as tmpdir:

        try:
            # The label helps ramdisks to find the partition containing
            # the parameters (by using /dev/disk/by-label/ir-vfd-dev).
            # NOTE: FAT filesystem label can be up to 11 characters long.
            ironic_utils.mkfs('vfat', output_file, label="ir-vfd-dev")
            utils.mount(output_file, tmpdir, '-o', 'umask=0')
        except processutils.ProcessExecutionError as e:
            raise exception.ImageCreationFailed(image_type='vfat', error=e)

        try:
            if files_info:
                _create_root_fs(tmpdir, files_info)

            if parameters:
                parameters_file = os.path.join(tmpdir, parameters_file)
                params_list = ['%(key)s=%(val)s' % {'key': k, 'val': v}
                               for k, v in parameters.items()]
                file_contents = '\n'.join(params_list)
                utils.write_to_file(parameters_file, file_contents)

        except Exception as e:
            LOG.exception("vfat image creation failed. Error: %s", e)
            raise exception.ImageCreationFailed(image_type='vfat', error=e)

        finally:
            try:
                utils.umount(tmpdir)
            except processutils.ProcessExecutionError as e:
                raise exception.ImageCreationFailed(image_type='vfat', error=e)


def _generate_cfg(kernel_params, template, options):
    """Generates a isolinux or grub configuration file.

    Given a given a list of strings containing kernel parameters, this method
    returns the kernel cmdline string.
    :param kernel_params: a list of strings(each element being a string like
        'K=V' or 'K' or combination of them like 'K1=V1 K2 K3=V3') to be added
        as the kernel cmdline.
    :param template: the path of the config template file.
    :param options: a dictionary of keywords which need to be replaced in
                    template file to generate a proper config file.
    :returns: a string containing the contents of the isolinux configuration
        file.
    """
    options.update({'kernel_params': ' '.join(kernel_params or [])})
    return utils.render_template(template, options)


def _read_dir(root_dir, prefix_dir=None):
    """Gather files under given directory.

    :param root_dir: a directory to traverse.
    :returns: a dict mapping absolute paths to relative to the `root_dir`.
    """
    files_info = {}

    if not prefix_dir:
        prefix_dir = root_dir

    for entry in os.listdir(root_dir):
        path = os.path.join(root_dir, entry)
        if os.path.isdir(path):
            files_info.update(_read_dir(path, prefix_dir))

        else:
            files_info[path] = path[len(prefix_dir) + 1:]

    return files_info


@contextlib.contextmanager
def _collect_files(image_path):
    """Mount image and return a dictionary of paths found there.

    Mounts given image under a temporary directory, walk its contents
    and produce a dictionary of absolute->relative paths found on the
    image.

    :param image_path: ISO9660 or FAT-formatted image to mount.
    :raises: ImageCreationFailed, if image inspection failed.
    :returns: a dict mapping absolute paths to relative to the mount point.
    """
    if not image_path:
        yield {}
        return

    with utils.tempdir() as mount_dir:
        try:
            utils.mount(image_path, mount_dir, '-o', 'loop')

        except processutils.ProcessExecutionError as e:
            LOG.exception("Mounting filesystem image %(image)s "
                          "failed", {'image': image_path})
            raise exception.ImageCreationFailed(image_type='iso', error=e)

        try:
            yield _read_dir(mount_dir)

        except EnvironmentError as e:
            LOG.exception(
                "Examining image %(images)s failed: ", {'image': image_path})
            _umount_without_raise(mount_dir)
            raise exception.ImageCreationFailed(image_type='iso', error=e)

        _umount_without_raise(mount_dir)


def create_isolinux_image_for_bios(
        output_file, kernel, ramdisk, kernel_params=None, configdrive=None):
    """Creates an isolinux image on the specified file.

    Copies the provided kernel, ramdisk to a directory, generates the isolinux
    configuration file using the kernel parameters provided, and then generates
    a bootable ISO image.

    :param output_file: the path to the file where the iso image needs to be
        created.
    :param kernel: the kernel to use.
    :param ramdisk: the ramdisk to use.
    :param kernel_params: a list of strings(each element being a string like
        'K=V' or 'K' or combination of them like 'K1=V1,K2,...') to be added
        as the kernel cmdline.
    :param configdrive: ISO9660 or FAT-formatted OpenStack config drive
        image. This image will be written onto the built ISO image. Optional.
    :raises: ImageCreationFailed, if image creation failed while copying files
        or while running command to generate iso.
    """
    ISOLINUX_BIN = 'isolinux/isolinux.bin'
    ISOLINUX_CFG = 'isolinux/isolinux.cfg'
    LDLINUX_SRC_DIRS = ['/usr/lib/syslinux/modules/bios',
                        '/usr/share/syslinux']
    LDLINUX_BIN = 'isolinux/ldlinux.c32'

    options = {'kernel': '/vmlinuz', 'ramdisk': '/initrd'}

    with utils.tempdir() as tmpdir:
        files_info = {
            kernel: 'vmlinuz',
            ramdisk: 'initrd',
            CONF.isolinux_bin: ISOLINUX_BIN,
        }

        # ldlinux.c32 is required for syslinux 5.0 or later.
        if CONF.ldlinux_c32:
            ldlinux_src = CONF.ldlinux_c32
        else:
            for directory in LDLINUX_SRC_DIRS:
                ldlinux_src = os.path.join(directory, 'ldlinux.c32')
                if os.path.isfile(ldlinux_src):
                    break
            else:
                ldlinux_src = None
        if ldlinux_src:
            files_info[ldlinux_src] = LDLINUX_BIN

        with _collect_files(configdrive) as cfgdrv_files:
            files_info.update(cfgdrv_files)

            try:
                _create_root_fs(tmpdir, files_info)

            except EnvironmentError as e:
                LOG.exception("Creating the filesystem root failed.")
                raise exception.ImageCreationFailed(image_type='iso', error=e)

        cfg = _generate_cfg(kernel_params,
                            CONF.isolinux_config_template, options)

        isolinux_cfg = os.path.join(tmpdir, ISOLINUX_CFG)
        utils.write_to_file(isolinux_cfg, cfg)

        try:
            utils.execute('mkisofs', '-r', '-V',
                          'config-2' if configdrive else 'VMEDIA_BOOT_ISO',
                          '-cache-inodes', '-J', '-l', '-no-emul-boot',
                          '-boot-load-size', '4', '-boot-info-table',
                          '-b', ISOLINUX_BIN, '-o', output_file, tmpdir)
        except processutils.ProcessExecutionError as e:
            LOG.exception("Creating ISO image failed.")
            raise exception.ImageCreationFailed(image_type='iso', error=e)


def create_esp_image_for_uefi(
        output_file, kernel, ramdisk, deploy_iso=None, esp_image=None,
        kernel_params=None, configdrive=None):
    """Creates an ESP image on the specified file.

    Copies the provided kernel, ramdisk and EFI system partition image (ESP) to
    a directory, generates the grub configuration file using kernel parameters
    and then generates a bootable ISO image for UEFI.

    :param output_file: the path to the file where the iso image needs to be
        created.
    :param kernel: the kernel to use.
    :param ramdisk: the ramdisk to use.
    :param deploy_iso: deploy ISO image to extract EFI system partition image
        from. If not specified, the `esp_image` option is required.
    :param esp_image: FAT12/16/32-formatted EFI system partition image
        containing the EFI boot loader (e.g. GRUB2) for each hardware
        architecture to boot. This image will be embedded into the ISO image.
        If not specified, the `deploy_iso` option is required.
    :param kernel_params: a list of strings(each element being a string like
        'K=V' or 'K' or combination of them like 'K1=V1,K2,...') to be added
        as the kernel cmdline.
    :param configdrive: ISO9660 or FAT-formatted OpenStack config drive
        image. This image will be written onto the built ISO image. Optional.
    :raises: ImageCreationFailed, if image creation failed while copying files
        or while running command to generate iso.
    """
    EFIBOOT_LOCATION = 'boot/grub/efiboot.img'

    grub_options = {'linux': '/vmlinuz', 'initrd': '/initrd'}

    with utils.tempdir() as tmpdir:
        files_info = {
            kernel: 'vmlinuz',
            ramdisk: 'initrd',
        }

        with utils.tempdir() as mountdir:
            # Open the deploy iso used to initiate deploy and copy the
            # efiboot.img i.e. boot loader to the current temporary
            # directory.
            if deploy_iso and not esp_image:
                uefi_path_info, e_img_rel_path, grub_rel_path = (
                    _mount_deploy_iso(deploy_iso, mountdir))

                grub_cfg = os.path.join(tmpdir, grub_rel_path)

            # Use ELF boot loader provided
            elif esp_image and not deploy_iso:
                e_img_rel_path = EFIBOOT_LOCATION
                grub_rel_path = CONF.grub_config_path.lstrip(' ' + os.sep)
                grub_cfg = os.path.join(tmpdir, grub_rel_path)

                # Create an empty grub config file by copying /dev/null.
                # This is to avoid write failures when actual write of
                # config file happens. Write failures are caused if grub
                # config path does not exist on root file system.
                uefi_path_info = {
                    esp_image: e_img_rel_path,
                    '/dev/null': grub_rel_path
                }

            else:
                msg = _('Neither deploy ISO nor ESP image configured or '
                        'both of them configured')
                raise exception.ImageCreationFailed(
                    image_type='iso', error=msg)

            files_info.update(uefi_path_info)

            with _collect_files(configdrive) as cfgdrv_files:
                files_info.update(cfgdrv_files)

                try:
                    _create_root_fs(tmpdir, files_info)

                except EnvironmentError as e:
                    LOG.exception("Creating the filesystem root failed.")
                    raise exception.ImageCreationFailed(
                        image_type='iso', error=e)

                finally:
                    if deploy_iso:
                        _umount_without_raise(mountdir)

        # Generate and copy grub config file.
        grub_conf = _generate_cfg(kernel_params,
                                  CONF.grub_config_template, grub_options)
        utils.write_to_file(grub_cfg, grub_conf)

        # Create the boot_iso.
        try:
            utils.execute('mkisofs', '-r', '-V',
                          'config-2' if configdrive else 'VMEDIA_BOOT_ISO',
                          '-l', '-e', e_img_rel_path, '-no-emul-boot',
                          '-o', output_file, tmpdir)

        except processutils.ProcessExecutionError as e:
            LOG.exception("Creating ISO image failed.")
            raise exception.ImageCreationFailed(image_type='iso', error=e)


# NOTE(etingof): backward compatibility
create_isolinux_image_for_uefi = create_esp_image_for_uefi


def fetch(context, image_href, path, force_raw=False):
    # TODO(vish): Improve context handling and add owner and auth data
    #             when it is added to glance.  Right now there is no
    #             auth checking in glance, so we assume that access was
    #             checked before we got here.
    image_service = service.get_image_service(image_href,
                                              context=context)
    LOG.debug("Using %(image_service)s to download image %(image_href)s.",
              {'image_service': image_service.__class__,
               'image_href': image_href})

    with fileutils.remove_path_on_error(path):
        with open(path, "wb") as image_file:
            image_service.download(image_href, image_file)

    if force_raw:
        image_to_raw(image_href, path, "%s.part" % path)


def image_to_raw(image_href, path, path_tmp):
    with fileutils.remove_path_on_error(path_tmp):
        data = disk_utils.qemu_img_info(path_tmp)

        fmt = data.file_format
        if fmt is None:
            raise exception.ImageUnacceptable(
                reason=_("'qemu-img info' parsing failed."),
                image_id=image_href)

        backing_file = data.backing_file
        if backing_file is not None:
            raise exception.ImageUnacceptable(
                image_id=image_href,
                reason=_("fmt=%(fmt)s backed by: %(backing_file)s") %
                {'fmt': fmt, 'backing_file': backing_file})

        if fmt != "raw":
            staged = "%s.converted" % path
            LOG.debug("%(image)s was %(format)s, converting to raw",
                      {'image': image_href, 'format': fmt})
            with fileutils.remove_path_on_error(staged):
                disk_utils.convert_image(path_tmp, staged, 'raw')
                os.unlink(path_tmp)

                data = disk_utils.qemu_img_info(staged)
                if data.file_format != "raw":
                    raise exception.ImageConvertFailed(
                        image_id=image_href,
                        reason=_("Converted to raw, but format is "
                                 "now %s") % data.file_format)

                os.rename(staged, path)
        else:
            os.rename(path_tmp, path)


def image_show(context, image_href, image_service=None):
    if image_service is None:
        image_service = service.get_image_service(image_href, context=context)
    return image_service.show(image_href)


def download_size(context, image_href, image_service=None):
    return image_show(context, image_href, image_service)['size']


def converted_size(path):
    """Get size of converted raw image.

    The size of image converted to raw format can be growing up to the virtual
    size of the image.

    :param path: path to the image file.
    :returns: virtual size of the image or 0 if conversion not needed.

    """
    data = disk_utils.qemu_img_info(path)
    return data.virtual_size


def get_image_properties(context, image_href, properties="all"):
    """Returns the values of several properties of an image

    :param context: context
    :param image_href: href of the image
    :param properties: the properties whose values are required.
        This argument is optional, default value is "all", so if not specified
        all properties will be returned.
    :returns: a dict of the values of the properties. A property not on the
        glance metadata will have a value of None.
    """
    img_service = service.get_image_service(image_href, context=context)
    iproperties = img_service.show(image_href)['properties']

    if properties == "all":
        return iproperties

    return {p: iproperties.get(p) for p in properties}


def get_temp_url_for_glance_image(context, image_uuid):
    """Returns the tmp url for a glance image.

    :param context: context
    :param image_uuid: the UUID of the image in glance
    :returns: the tmp url for the glance image.
    """
    glance_service = service.GlanceImageService(context=context)
    image_properties = glance_service.show(image_uuid)
    LOG.debug('Got image info: %(info)s for image %(image_uuid)s.',
              {'info': image_properties, 'image_uuid': image_uuid})
    return glance_service.swift_temp_url(image_properties)


def create_boot_iso(context, output_filename, kernel_href,
                    ramdisk_href, deploy_iso_href=None, esp_image_href=None,
                    root_uuid=None, kernel_params=None, boot_mode=None,
                    configdrive_href=None):
    """Creates a bootable ISO image for a node.

    Given the hrefs for kernel, ramdisk, root partition's UUID and
    kernel cmdline arguments, this method fetches the kernel and ramdisk,
    and builds a bootable ISO image that can be used to boot up the
    baremetal node.

    :param context: context
    :param output_filename: the absolute path of the output ISO file
    :param kernel_href: URL or glance uuid of the kernel to use
    :param ramdisk_href: URL or glance uuid of the ramdisk to use
    :param deploy_iso_href: URL or glance UUID of the deploy ISO image
        to extract EFI system partition image. If not specified,
        the `esp_image_href` option must be present if UEFI-bootable
        ISO is desired.
    :param esp_image_href: URL or glance UUID of FAT12/16/32-formatted EFI
        system partition image containing the EFI boot loader (e.g. GRUB2)
        for each hardware architecture to boot. This image will be written
        onto the ISO image. If not specified, the `deploy_iso_href` option
        is only required for building UEFI-bootable ISO.
    :param kernel_params: a string containing whitespace separated values
        kernel cmdline arguments of the form K=V or K (optional).
    :boot_mode: the boot mode in which the deploy is to happen.
    :param configdrive_href: URL to ISO9660 or FAT-formatted OpenStack config
        drive image. This image will be embedded into the built ISO image.
        Optional.
    :raises: ImageCreationFailed, if creating boot ISO failed.
    """
    with utils.tempdir() as tmpdir:
        kernel_path = os.path.join(tmpdir, kernel_href.split('/')[-1])
        ramdisk_path = os.path.join(tmpdir, ramdisk_href.split('/')[-1])

        fetch(context, kernel_href, kernel_path)
        fetch(context, ramdisk_href, ramdisk_path)

        if configdrive_href:
            configdrive_path = os.path.join(
                tmpdir, configdrive_href.split('/')[-1])
            fetch(context, configdrive_href, configdrive_path)

        else:
            configdrive_path = None

        params = []
        if root_uuid:
            params.append('root=UUID=%s' % root_uuid)
        if kernel_params:
            params.append(kernel_params)

        if boot_mode == 'uefi':

            deploy_iso_path = esp_image_path = None

            if deploy_iso_href:
                deploy_iso_path = os.path.join(
                    tmpdir, deploy_iso_href.split('/')[-1])
                fetch(context, deploy_iso_href, deploy_iso_path)

            elif esp_image_href:
                esp_image_path = os.path.join(
                    tmpdir, esp_image_href.split('/')[-1])
                fetch(context, esp_image_href, esp_image_path)

            elif CONF.esp_image:
                esp_image_path = CONF.esp_image

            create_esp_image_for_uefi(
                output_filename, kernel_path, ramdisk_path,
                deploy_iso=deploy_iso_path, esp_image=esp_image_path,
                kernel_params=params, configdrive=configdrive_path)

        else:
            create_isolinux_image_for_bios(
                output_filename, kernel_path, ramdisk_path,
                kernel_params=params, configdrive=configdrive_path)


def is_whole_disk_image(ctx, instance_info):
    """Find out if the image is a partition image or a whole disk image.

    :param ctx: an admin context
    :param instance_info: a node's instance info dict

    :returns: True for whole disk images and False for partition images
        and None on no image_source or Error.
    """
    image_source = instance_info.get('image_source')
    if not image_source:
        return

    is_whole_disk_image = False
    if glance_utils.is_glance_image(image_source):
        try:
            iproperties = get_image_properties(ctx, image_source)
        except Exception:
            return
        is_whole_disk_image = (not iproperties.get('kernel_id')
                               and not iproperties.get('ramdisk_id'))
    else:
        # Non glance image ref
        if (not instance_info.get('kernel')
            and not instance_info.get('ramdisk')):
            is_whole_disk_image = True

    return is_whole_disk_image


def _mount_deploy_iso(deploy_iso, mountdir):
    """This function opens up the deploy iso used for deploy.

    :param deploy_iso: path to the deploy iso where its
                       contents are fetched to.
    :raises: ImageCreationFailed if mount fails.
    :returns: a tuple consisting of - 1. a dictionary containing
                                         the values as required
                                         by create_isolinux_image,
                                      2. efiboot.img relative path, and
                                      3. grub.cfg relative path.

    """
    e_img_rel_path = None
    e_img_path = None
    grub_rel_path = None
    grub_path = None

    try:
        utils.mount(deploy_iso, mountdir, '-o', 'loop')
    except processutils.ProcessExecutionError as e:
        LOG.exception("mounting the deploy iso failed.")
        raise exception.ImageCreationFailed(image_type='iso', error=e)

    try:
        for (dir, subdir, files) in os.walk(mountdir):
            if 'efiboot.img' in files:
                e_img_path = os.path.join(dir, 'efiboot.img')
                e_img_rel_path = os.path.relpath(e_img_path,
                                                 mountdir)
            if 'grub.cfg' in files:
                grub_path = os.path.join(dir, 'grub.cfg')
                grub_rel_path = os.path.relpath(grub_path,
                                                mountdir)
    except (OSError, IOError) as e:
        LOG.exception("examining the deploy iso failed.")
        _umount_without_raise(mountdir)
        raise exception.ImageCreationFailed(image_type='iso', error=e)

    # check if the variables are assigned some values or not during
    # walk of the mountdir.
    if not (e_img_path and e_img_rel_path and grub_path and grub_rel_path):
        error = (_("Deploy iso didn't contain efiboot.img or grub.cfg"))
        _umount_without_raise(mountdir)
        raise exception.ImageCreationFailed(image_type='iso', error=error)

    uefi_path_info = {e_img_path: e_img_rel_path,
                      grub_path: grub_rel_path}

    # Returning a tuple as it makes the code simpler and clean.
    # uefi_path_info: is needed by the caller for _create_root_fs to create
    # appropriate directory structures for uefi boot iso.
    # grub_rel_path: is needed to copy the new grub.cfg generated using
    # generate_cfg() to the same directory path structure where it was
    # present in deploy iso. This path varies for different OS vendors.
    # e_img_rel_path: is required by mkisofs to generate boot iso.
    return uefi_path_info, e_img_rel_path, grub_rel_path
