# koji plugin module
# Copyright (c) 2008 Red Hat
#
#    Koji is free software; you can redistribute it and/or
#    modify it under the terms of the GNU Lesser General Public
#    License as published by the Free Software Foundation; 
#    version 2.1 of the License.
#
#    This software 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
#    Lesser General Public License for more details.
#
#    You should have received a copy of the GNU Lesser General Public
#    License along with this software; if not, write to the Free Software
#    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
#
# Authors:
#       Mike McLean <mikem@redhat.com>

import imp
import koji
import sys


class PluginTracker(object):

    def __init__(self, path=None, prefix='_koji_plugin__'):
        self.searchpath = path
        #prefix should not have a '.' in it, this can cause problems.
        self.prefix = prefix
        self.plugins = {}

    def load(self, name, path=None, reload=False):
        if self.plugins.has_key(name) and not reload:
            return self.plugins[name]
        mod_name = name
        if self.prefix:
            #mod_name determines how the module is named in sys.modules
            #Using a prefix helps prevent overlap with other modules
            #(no '.' -- it causes problems)
            mod_name = self.prefix + name
        if sys.modules.has_key(mod_name) and not reload:
            raise koji.GenericError, 'module name conflict: %s' % mod_name
        if path is None:
            path = self.searchpath
        if path is None:
            raise koji.GenericError, "empty module search path"
        file, pathname, description = imp.find_module(name, self.pathlist(path))
        try:
            plugin = imp.load_module(mod_name, file, pathname, description)
        finally:
            file.close()
        self.plugins[name] = plugin
        return plugin

    def get(self, name):
        return self.plugins.get(name)

    def pathlist(self, path):
        if isinstance(path, basestring):
            return [path]
        else:
            return path


# some decorators used by plugins
def export(f):
    """a decorator that marks a function as exported

    intended to be used by plugins
    the HandlerRegistry will export the function under its own name
    """
    setattr(f, 'exported', True)
    return f

def export_as(alias):
    """returns a decorator that marks a function as exported and gives it an alias

    indended to be used by plugins
    """
    def dec(f):
        setattr(f, 'exported', True)
        setattr(f, 'export_alias', alias)
        return f
    return dec

def export_in(module, alias=None):
    """returns a decorator that marks a function as exported with a module prepended

    optionally, can also alias the function within the module
    indended to be used by plugins
    """
    def dec(f):
        if alias is None:
            alias = "%s.%s" % (module, f.__name__)
        else:
            alias = "%s.%s" % (module, alias)
        setattr(f, 'exported', True)
        setattr(f, 'export_module', module)
        setattr(f, 'export_alias', alias)
        return f
    return dec