# Copyright (C) 2009-2012 Canonical Ltd
#
# 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, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

"""Tools for dealing with the Launchpad API."""

# Importing this module will be expensive, since it imports launchpadlib and
# its dependencies. However, our plan is to only load this module when it is
# needed by a command that uses it.


import re
from urllib.parse import (
    urlparse,
    urlunparse,
    )

from ... import (
    branch,
    bedding,
    errors,
    osutils,
    trace,
    transport,
    )
from ...i18n import gettext


class LaunchpadlibMissing(errors.DependencyNotPresent):

    _fmt = ("launchpadlib is required for Launchpad API access. "
            "Please install the launchpadlib package.")

    def __init__(self, e):
        super(LaunchpadlibMissing, self).__init__(
            'launchpadlib', e)

try:
    import launchpadlib
except ImportError as e:
    raise LaunchpadlibMissing(e)

from launchpadlib.credentials import RequestTokenAuthorizationEngine
from launchpadlib.launchpad import (
    Launchpad,
    )
from launchpadlib import uris

# Declare the minimum version of launchpadlib that we need in order to work.
MINIMUM_LAUNCHPADLIB_VERSION = (1, 6, 3)


def get_cache_directory():
    """Return the directory to cache launchpadlib objects in."""
    return osutils.pathjoin(bedding.cache_dir(), 'launchpad')


def parse_launchpadlib_version(version_number):
    """Parse a version number of the style used by launchpadlib."""
    return tuple(map(int, version_number.split('.')))


def check_launchpadlib_compatibility():
    """Raise an error if launchpadlib has the wrong version number."""
    installed_version = parse_launchpadlib_version(launchpadlib.__version__)
    if installed_version < MINIMUM_LAUNCHPADLIB_VERSION:
        raise errors.DependencyNotPresent(
            'launchpadlib',
            'At least launchpadlib %s is required, but installed version is %s'
            % (MINIMUM_LAUNCHPADLIB_VERSION, installed_version))


def lookup_service_root(service_root):
    try:
        return uris.lookup_service_root(service_root)
    except ValueError:
        if service_root != 'qastaging':
            raise
        staging_root = uris.lookup_service_root('staging')
        return staging_root.replace('staging', 'qastaging')


class NoLaunchpadBranch(errors.BzrError):
    _fmt = 'No launchpad branch could be found for branch "%(url)s".'

    def __init__(self, branch):
        errors.BzrError.__init__(self, branch=branch, url=branch.base)


def get_auth_engine(base_url):
    return Launchpad.authorization_engine_factory(base_url, 'breezy')


def get_credential_store():
    return Launchpad.credential_store_factory(None)


def connect_launchpad(base_url, timeout=None, proxy_info=None,
                      version=Launchpad.DEFAULT_VERSION):
    """Log in to the Launchpad API.

    :return: The root `Launchpad` object from launchpadlib.
    """
    if proxy_info is None:
        import httplib2
        proxy_info = httplib2.proxy_info_from_environment('https')
    try:
        cache_directory = get_cache_directory()
    except EnvironmentError:
        cache_directory = None
    credential_store = get_credential_store()
    authorization_engine = get_auth_engine(base_url)
    return Launchpad.login_with(
        'breezy', base_url, cache_directory, timeout=timeout,
        credential_store=credential_store,
        authorization_engine=authorization_engine,
        proxy_info=proxy_info, version=version)



class LaunchpadBranch(object):
    """Provide bzr and lp API access to a Launchpad branch."""

    def __init__(self, lp_branch, bzr_url, bzr_branch=None, check_update=True):
        """Constructor.

        :param lp_branch: The Launchpad branch.
        :param bzr_url: The URL of the Bazaar branch.
        :param bzr_branch: An instance of the Bazaar branch.
        """
        self.bzr_url = bzr_url
        self._bzr = bzr_branch
        self._push_bzr = None
        self._check_update = check_update
        self.lp = lp_branch

    @property
    def bzr(self):
        """Return the bzr branch for this branch."""
        if self._bzr is None:
            self._bzr = branch.Branch.open(self.bzr_url)
        return self._bzr

    @property
    def push_bzr(self):
        """Return the push branch for this branch."""
        if self._push_bzr is None:
            self._push_bzr = branch.Branch.open(self.lp.bzr_identity)
        return self._push_bzr

    @staticmethod
    def plausible_launchpad_url(url):
        """Is 'url' something that could conceivably be pushed to LP?

        :param url: A URL that may refer to a Launchpad branch.
        :return: A boolean.
        """
        if url is None:
            return False
        if url.startswith('lp:'):
            return True
        regex = re.compile('([a-z]*\\+)*(bzr\\+ssh|http)'
                           '://bazaar.*.launchpad.net')
        return bool(regex.match(url))

    @staticmethod
    def candidate_urls(bzr_branch):
        """Iterate through related URLs that might be Launchpad URLs.

        :param bzr_branch: A Bazaar branch to find URLs from.
        :return: a generator of URL strings.
        """
        url = bzr_branch.get_public_branch()
        if url is not None:
            yield url
        url = bzr_branch.get_push_location()
        if url is not None:
            yield url
        url = bzr_branch.get_parent()
        if url is not None:
            yield url
        yield bzr_branch.base

    @staticmethod
    def tweak_url(url, launchpad):
        """Adjust a URL to work with staging, if needed."""
        if str(launchpad._root_uri) == uris.STAGING_SERVICE_ROOT:
            return url.replace('bazaar.launchpad.net',
                               'bazaar.staging.launchpad.net')
        elif str(launchpad._root_uri) == lookup_service_root('qastaging'):
            return url.replace('bazaar.launchpad.net',
                               'bazaar.qastaging.launchpad.net')
        return url

    @classmethod
    def from_bzr(cls, launchpad, bzr_branch, create_missing=True):
        """Find a Launchpad branch from a bzr branch."""
        check_update = True
        for url in cls.candidate_urls(bzr_branch):
            url = cls.tweak_url(url, launchpad)
            if not cls.plausible_launchpad_url(url):
                continue
            lp_branch = launchpad.branches.getByUrl(url=url)
            if lp_branch is not None:
                break
        else:
            if not create_missing:
                raise NoLaunchpadBranch(bzr_branch)
            lp_branch = cls.create_now(launchpad, bzr_branch)
            check_update = False
        return cls(lp_branch, bzr_branch.base, bzr_branch, check_update)

    @classmethod
    def create_now(cls, launchpad, bzr_branch):
        """Create a Bazaar branch on Launchpad for the supplied branch."""
        url = cls.tweak_url(bzr_branch.get_push_location(), launchpad)
        if not cls.plausible_launchpad_url(url):
            raise errors.BzrError(gettext('%s is not registered on Launchpad') %
                                  bzr_branch.base)
        bzr_branch.create_clone_on_transport(transport.get_transport(url))
        lp_branch = launchpad.branches.getByUrl(url=url)
        if lp_branch is None:
            raise errors.BzrError(gettext('%s is not registered on Launchpad') %
                                  url)
        return lp_branch

    def get_target(self):
        """Return the 'LaunchpadBranch' for the target of this one."""
        lp_branch = self.lp
        if lp_branch.project is not None:
            dev_focus = lp_branch.project.development_focus
            if dev_focus is None:
                raise errors.BzrError(gettext('%s has no development focus.') %
                                      lp_branch.bzr_identity)
            target = dev_focus.branch
            if target is None:
                raise errors.BzrError(gettext(
                    'development focus %s has no branch.') % dev_focus)
        elif lp_branch.sourcepackage is not None:
            target = lp_branch.sourcepackage.getBranch(pocket="Release")
            if target is None:
                raise errors.BzrError(gettext(
                                      'source package %s has no branch.') %
                                      lp_branch.sourcepackage)
        else:
            raise errors.BzrError(gettext(
                '%s has no associated product or source package.') %
                lp_branch.bzr_identity)
        return LaunchpadBranch(target, target.bzr_identity)

    def update_lp(self):
        """Update the Launchpad copy of this branch."""
        if not self._check_update:
            return
        with self.bzr.lock_read():
            if self.lp.last_scanned_id is not None:
                if self.bzr.last_revision() == self.lp.last_scanned_id:
                    trace.note(gettext('%s is already up-to-date.') %
                               self.lp.bzr_identity)
                    return
                graph = self.bzr.repository.get_graph()
                if not graph.is_ancestor(osutils.safe_utf8(self.lp.last_scanned_id),
                                         self.bzr.last_revision()):
                    raise errors.DivergedBranches(self.bzr, self.push_bzr)
                trace.note(gettext('Pushing to %s') % self.lp.bzr_identity)
            self.bzr.push(self.push_bzr)

    def find_lca_tree(self, other):
        """Find the revision tree for the LCA of this branch and other.

        :param other: Another LaunchpadBranch
        :return: The RevisionTree of the LCA of this branch and other.
        """
        graph = self.bzr.repository.get_graph(other.bzr.repository)
        lca = graph.find_unique_lca(self.bzr.last_revision(),
                                    other.bzr.last_revision())
        return self.bzr.repository.revision_tree(lca)


def canonical_url(object):
    """Return the canonical URL for a branch."""
    scheme, netloc, path, params, query, fragment = urlparse(
        str(object.self_link))
    path = '/'.join(path.split('/')[2:])
    netloc = netloc.replace('api.', 'code.')
    return urlunparse((scheme, netloc, path, params, query, fragment))
