#
# image.py: Support methods for CD/DVD and ISO image installations.
#
# Copyright (C) 2007  Red Hat, Inc.  All rights reserved.
#
# This program 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 2 of the License, or
# (at your option) any later version.
#
# This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
#

from pyanaconda import isys
import os, os.path, stat, tempfile

from pyanaconda.errors import errorHandler, ERROR_RAISE, InvalidImageSizeError, MissingImageError

import blivet.util
import blivet.arch
from blivet.errors import FSError

import logging
log = logging.getLogger("anaconda")

_arch = blivet.arch.get_arch()

def findFirstIsoImage(path):
    """
    Find the first iso image in path
    This also supports specifying a specific .iso image

    Returns the basename of the image
    """
    try:
        os.stat(path)
    except OSError:
        return None

    arch = _arch

    if os.path.isfile(path) and path.endswith(".iso"):
        files = [os.path.basename(path)]
        path = os.path.dirname(path)
    else:
        files = os.listdir(path)

    for fn in files:
        what = path + '/' + fn
        log.debug("Checking %s", what)
        if not isys.isIsoImage(what):
            continue

        log.debug("mounting %s on /mnt/install/cdimage", what)
        try:
            blivet.util.mount(what, "/mnt/install/cdimage", fstype="iso9660", options="ro")
        except OSError:
            continue

        if not os.access("/mnt/install/cdimage/.discinfo", os.R_OK):
            blivet.util.umount("/mnt/install/cdimage")
            continue

        log.debug("Reading .discinfo")
        f = open("/mnt/install/cdimage/.discinfo")
        f.readline() # skip timestamp
        f.readline() # skip release description
        discArch = f.readline().strip() # read architecture
        f.close()

        log.debug("discArch = %s", discArch)
        if discArch != arch:
            log.warning("findFirstIsoImage: architectures mismatch: %s, %s",
                        discArch, arch)
            blivet.util.umount("/mnt/install/cdimage")
            continue

        # If there's no repodata, there's no point in trying to
        # install from it.
        if not os.access("/mnt/install/cdimage/repodata", os.R_OK):
            log.warning("%s doesn't have repodata, skipping", what)
            blivet.util.umount("/mnt/install/cdimage")
            continue

        # warn user if images appears to be wrong size
        if os.stat(what)[stat.ST_SIZE] % 2048:
            log.warning("%s appears to be corrupted", what)
            exn = InvalidImageSizeError("size is not a multiple of 2048 bytes", what)
            if errorHandler.cb(exn) == ERROR_RAISE:
                raise exn

        log.info("Found disc at %s", fn)
        blivet.util.umount("/mnt/install/cdimage")
        return fn

    return None

def mountImage(isodir, tree):
    while True:
        if os.path.isfile(isodir):
            image = isodir
        else:
            image = findFirstIsoImage(isodir)
            if image is None:
                exn = MissingImageError()
                if errorHandler.cb(exn) == ERROR_RAISE:
                    raise exn
                else:
                    continue

            image = os.path.normpath("%s/%s" % (isodir, image))

        try:
            blivet.util.mount(image, tree, fstype='iso9660', options="ro")
        except OSError:
            exn = MissingImageError()
            if errorHandler.cb(exn) == ERROR_RAISE:
                raise exn
            else:
                continue
        else:
            break

# Return the first Device instance containing valid optical install media
# for this product.
def opticalInstallMedia(devicetree):
    retval = None

    # Search for devices identified as cdrom along with any other
    # device that has an iso9660 filesystem. This will catch USB media
    # created from ISO images.
    for dev in set([d for d in devicetree.devices if d.type == "cdrom"] + \
            [d for d in devicetree.devices if d.format.type == "iso9660"]):
        if not dev.controllable:
            continue

        devicetree.handle_format(None, dev)
        if not hasattr(dev.format, "mount"):
            # no mountable media
            continue

        mountpoint = tempfile.mkdtemp()
        try:
            try:
                dev.format.mount(mountpoint=mountpoint)
            except FSError:
                continue

            try:
                if not verifyMedia(mountpoint):
                    continue
            finally:
                dev.format.unmount(mountpoint=mountpoint)
        finally:
            os.rmdir(mountpoint)

        retval = dev
        break

    return retval

# Return a generator yielding Device instances that may have HDISO install
# media somewhere.  Candidate devices are simply any that we can mount.
def potentialHdisoSources(devicetree):
    return (d for d in devicetree.devices
            if d.type == "partition" and d.format.exists and d.format.mountable)

def verifyMedia(tree, timestamp=None):
    if os.access("%s/.discinfo" % tree, os.R_OK):
        f = open("%s/.discinfo" % tree)

        newStamp = f.readline().strip()
        # Next is the description, which we just want to throw away.
        f.readline()
        arch = f.readline().strip()
        f.close()

        if timestamp is not None:
            if newStamp == timestamp and arch == _arch:
                return True
        else:
            if arch == _arch:
                return True

    return False