""" ``Source`` objects represent a single <Source> tag in
``sources.xml``.  Note that a single Source tag can itself describe
multiple repositories (if it uses the "url" attribute instead of
"rawurl"), and so can the ``Source`` object.  This can be the source
(har har) of some confusion.  See
:func:`Bcfg2.Server.Plugins.Packages.Collection._Collection.sourcelist`
for the proper way to get all repos from a ``Source`` object.

Source objects are aggregated into
:class:`Bcfg2.Server.Plugins.Packages.Collection._Collection`
objects, which are actually called by
:class:`Bcfg2.Server.Plugins.Packages.Packages`.  This way a more
advanced subclass can query repositories in aggregate rather than
individually, which may give faster or more accurate results.

The base ``Source`` object must be subclassed to handle each
repository type.  How you subclass ``Source`` will depend on how you
subclassed
:class:`Bcfg2.Server.Plugins.Packages.Collection._Collection`; see
:mod:`Bcfg2.Server.Plugins.Packages.Collection` for more details on
different methods for doing that.

If you are using the stock (or a near-stock)
:class:`Bcfg2.Server.Plugins.Packages.Collection._Collection` object,
then you will need to implement the following methods and attributes
in your ``Source`` subclass:

* :func:`Source.get_urls`
* :func:`Source.read_files`
* :attr:`Source.basegroups`
* :attr:`Source.ptype`

Additionally, you may want to consider overriding the following
methods and attributes:

* :func:`Source.is_virtual_package`
* :func:`Source.get_group`
* :attr:`Source.unknown_filter`
* :attr:`Source.load_state`
* :attr:`Source.save_state`

If you are overriding the ``_Collection`` object in more depth, then
you have more leeway in what you might want to override or implement
in your ``Source`` subclass.
"""

import os
import re
import sys
import Bcfg2.Server.Plugin
from Bcfg2.Compat import HTTPError, HTTPBasicAuthHandler, \
     HTTPPasswordMgrWithDefaultRealm, install_opener, build_opener, \
     urlopen, cPickle, md5


def fetch_url(url):
    """ Return the content of the given URL.

    :param url: The URL to fetch content from.
    :type url: string
    :raises: ValueError - Malformed URL
    :raises: URLError - Failure fetching URL
    :returns: string - the content of the page at the given URL """
    if '@' in url:
        mobj = re.match('(\w+://)([^:]+):([^@]+)@(.*)$', url)
        if not mobj:
            raise ValueError
        user = mobj.group(2)
        passwd = mobj.group(3)
        url = mobj.group(1) + mobj.group(4)
        auth = HTTPBasicAuthHandler(HTTPPasswordMgrWithDefaultRealm())
        auth.add_password(None, url, user, passwd)
        install_opener(build_opener(auth))
    return urlopen(url).read()


class SourceInitError(Exception):
    """ Raised when a :class:`Source` object fails instantiation. """
    pass


class Source(Bcfg2.Server.Plugin.Debuggable):
    mrepo_re = re.compile(r'/RPMS\.([^/]+)')
    pulprepo_re = re.compile(r'pulp/repos/([^/]+)')
    genericrepo_re = re.compile('https?://.*?/([^/]+)/?$')
    basegroups = []
    unknown_filter = lambda p: p.startswith("choice")

    def __init__(self, basepath, xsource, setup):
        Bcfg2.Server.Plugin.Debuggable.__init__(self)
        self.basepath = basepath
        self.xsource = xsource
        self.setup = setup
        self.essentialpkgs = set()
        self.pkgnames = set()

        try:
            self.version = xsource.find('Version').text
        except AttributeError:
            self.version = None

        self.components = [item.text for item in xsource.findall('Component')]
        self.arches = [item.text for item in xsource.findall('Arch')]
        self.blacklist = [item.text for item in xsource.findall('Blacklist')]
        self.whitelist = [item.text for item in xsource.findall('Whitelist')]

        self.server_options = dict()
        self.client_options = dict()
        opts = xsource.findall("Options")
        for el in opts:
            repoopts = dict([(k, v)
                             for k, v in el.attrib.items()
                             if k != "clientonly" and k != "serveronly"])
            if el.get("clientonly", "false").lower() == "false":
                self.server_options.update(repoopts)
            if el.get("serveronly", "false").lower() == "false":
                self.client_options.update(repoopts)

        self.gpgkeys = [el.text for el in xsource.findall("GPGKey")]

        self.essential = xsource.get('essential', 'true').lower() == 'true'
        self.recommended = xsource.get('recommended',
                                       'false').lower() == 'true'

        self.rawurl = xsource.get('rawurl', '')
        if self.rawurl and not self.rawurl.endswith("/"):
            self.rawurl += "/"
        self.url = xsource.get('url', '')
        if self.url and not self.url.endswith("/"):
            self.url += "/"
        self.version = xsource.get('version', '')

        # build the set of conditions to see if this source applies to
        # a given set of metadata
        self.conditions = []
        self.groups = []  # provided for some limited backwards compat
        for el in xsource.iterancestors():
            if el.tag == "Group":
                if el.get("negate", "false").lower() == "true":
                    self.conditions.append(lambda m, el=el:
                                           el.get("name") not in m.groups)
                else:
                    self.groups.append(el.get("name"))
                    self.conditions.append(lambda m, el=el:
                                           el.get("name") in m.groups)
            elif el.tag == "Client":
                if el.get("negate", "false").lower() == "true":
                    self.conditions.append(lambda m, el=el:
                                           el.get("name") != m.hostname)
                else:
                    self.conditions.append(lambda m, el=el:
                                           el.get("name") == m.hostname)

        self.deps = dict()
        self.provides = dict()

        self.cachefile = os.path.join(self.basepath,
                                      "cache-%s" % self.cachekey)
        if not self.rawurl:
            self.baseurl = self.url + "%(version)s/%(component)s/%(arch)s/"
        else:
            self.baseurl = self.rawurl
        self.url_map = []
        for arch in self.arches:
            if self.url:
                usettings = [dict(version=self.version, component=comp,
                                  arch=arch)
                             for comp in self.components]
            else:  # rawurl given
                usettings = [dict(version=self.version, component=None,
                                  arch=arch)]

            for setting in usettings:
                if not self.rawurl:
                    setting['baseurl'] = self.url
                else:
                    setting['baseurl'] = self.rawurl
                setting['url'] = self.baseurl % setting
            self.url_map.extend(usettings)

    @property
    def cachekey(self):
        return md5(cPickle.dumps([self.version, self.components, self.url,
                                  self.rawurl, self.arches])).hexdigest()

    def get_relevant_groups(self, metadata):
        return sorted(list(set([g for g in metadata.groups
                                if (g in self.basegroups or
                                    g in self.groups or
                                    g in self.arches)])))

    def load_state(self):
        data = open(self.cachefile)
        (self.pkgnames, self.deps, self.provides,
         self.essentialpkgs) = cPickle.load(data)

    def save_state(self):
        cache = open(self.cachefile, 'wb')
        cPickle.dump((self.pkgnames, self.deps, self.provides,
                      self.essentialpkgs), cache, 2)
        cache.close()

    def setup_data(self, force_update=False):
        should_read = True
        should_download = False
        if os.path.exists(self.cachefile):
            try:
                self.load_state()
                should_read = False
            except:
                self.logger.error("Packages: Cachefile %s load failed; "
                                  "falling back to file read" % self.cachefile)
        if should_read:
            try:
                self.read_files()
            except:
                self.logger.error("Packages: File read failed; "
                                  "falling back to file download")
                should_download = True

        if should_download or force_update:
            try:
                self.update()
                self.read_files()
            except:
                self.logger.error("Packages: Failed to load data for Source "
                                  "of %s. Some Packages will be missing." %
                                  self.urls)

    def get_repo_name(self, url_map):
        # try to find a sensible name for a repo
        if url_map['component']:
            rname = url_map['component']
        else:
            name = None
            for repo_re in (self.mrepo_re,
                            self.pulprepo_re,
                            self.genericrepo_re):
                match = repo_re.search(url_map['url'])
                if match:
                    name = match.group(1)
                    break
            if name and self.groups:
                rname = "%s-%s" % (self.groups[0], name)
            elif self.groups:
                rname = self.groups[0]
            else:
                # a global source with no reasonable name.  just use
                # the full url and let the regex below make it even
                # uglier.
                rname = url_map['url']
        # see yum/__init__.py in the yum source, lines 441-449, for
        # the source of this regex.  yum doesn't like anything but
        # string.ascii_letters, string.digits, and [-_.:].  There
        # doesn't seem to be a reason for this, because yum.
        return re.sub(r'[^A-Za-z0-9-_.:]', '-', rname)

    def __str__(self):
        if self.rawurl:
            return "%s at %s" % (self.__class__.__name__, self.rawurl)
        elif self.url:
            return "%s at %s" % (self.__class__.__name__, self.url)
        else:
            return self.__class__.__name__

    def __repr__(self):
        return str(self)

    def get_urls(self):
        return []
    urls = property(get_urls)

    def get_files(self):
        return [self.escape_url(url) for url in self.urls]
    files = property(get_files)

    def get_vpkgs(self, metadata):
        agroups = ['global'] + [a for a in self.arches
                                if a in metadata.groups]
        vdict = dict()
        for agrp in agroups:
            if agrp not in self.provides:
                self.logger.warning("%s provides no packages for %s" %
                                    (self, agrp))
                continue
            for key, value in list(self.provides[agrp].items()):
                if key not in vdict:
                    vdict[key] = set(value)
                else:
                    vdict[key].update(value)
        return vdict

    def is_virtual_package(self, metadata, package):
        """ called to determine if a package is a virtual package.
        this is only invoked if the package is not listed in the dict
        returned by get_vpkgs """
        return False

    def escape_url(self, url):
        return os.path.join(self.basepath, url.replace('/', '@'))

    def read_files(self):
        pass

    def process_files(self, deps, prov):
        self.deps['global'] = dict()
        self.provides['global'] = dict()
        for barch in deps:
            self.deps[barch] = dict()
            self.provides[barch] = dict()
        for pkgname in self.pkgnames:
            pset = set()
            for barch in deps:
                if pkgname not in deps[barch]:
                    deps[barch][pkgname] = []
                pset.add(tuple(deps[barch][pkgname]))
            if len(pset) == 1:
                self.deps['global'][pkgname] = pset.pop()
            else:
                for barch in deps:
                    self.deps[barch][pkgname] = deps[barch][pkgname]
        provided = set()
        for bprovided in list(prov.values()):
            provided.update(set(bprovided))
        for prov in provided:
            prset = set()
            for barch in prov:
                if prov not in prov[barch]:
                    continue
                prset.add(tuple(prov[barch].get(prov, ())))
            if len(prset) == 1:
                self.provides['global'][prov] = prset.pop()
            else:
                for barch in prov:
                    self.provides[barch][prov] = prov[barch].get(prov, ())
        self.save_state()

    def filter_unknown(self, unknown):
        unknown.difference_update(set([u for u in unknown
                                       if self.unknown_filter(u)]))

    def update(self):
        for url in self.urls:
            self.logger.info("Packages: Updating %s" % url)
            fname = self.escape_url(url)
            try:
                data = fetch_url(url)
                open(fname, 'w').write(data)
            except ValueError:
                self.logger.error("Packages: Bad url string %s" % url)
                raise
            except HTTPError:
                err = sys.exc_info()[1]
                self.logger.error("Packages: Failed to fetch url %s. HTTP "
                                  "response code=%s" % (url, err.code))
                raise

    def applies(self, metadata):
        # check base groups
        if not self.magic_groups_match(metadata):
            return False

        # check Group/Client tags from sources.xml
        for condition in self.conditions:
            if not condition(metadata):
                return False

        return True

    def get_arches(self, metadata):
        return ['global'] + [a for a in self.arches if a in metadata.groups]

    def get_deps(self, metadata, pkgname):
        for arch in self.get_arches(metadata):
            if pkgname in self.deps[arch]:
                return self.deps[arch][pkgname]
        return []

    def get_provides(self, metadata, required):
        for arch in self.get_arches(metadata):
            if required in self.provides[arch]:
                return self.provides[arch][required]
        return []

    def is_package(self, metadata, pkg):
        return (pkg in self.pkgnames and
                pkg not in self.blacklist and
                (len(self.whitelist) == 0 or pkg in self.whitelist))

    def get_package(self, metadata, package):
        return package

    def get_group(self, metadata, group, ptype=None):
        return []

    def magic_groups_match(self, metadata):
        """ check to see if this source applies to the given host
        metadata by checking 'magic' (base) groups only, or if magic
        groups are off """
        # we always check that arch matches
        found_arch = False
        for arch in self.arches:
            if arch in metadata.groups:
                found_arch = True
                break
        if not found_arch:
            return False

        if not self.setup.cfp.getboolean("packages", "magic_groups",
                                         default=True):
            return True
        else:
            for group in self.basegroups:
                if group in metadata.groups:
                    return True
            return False