# This file is part of pybliographer
# 
# Copyright (C) 1998,1999,2000 Frederic GOBRY
# Email : gobry@idiap.ch
# 	   
# 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
# 
# $Id: Autoload.py,v 1.3.2.1 2000/10/17 10:40:46 fredgo Exp $

import os, string, re, gettext, sys

_ = gettext.gettext

class Loader:
    ''' An object containing the description of a loadable object '''
    
    def __init__ (self, name, regexp, module,
                  info = None, data = None):
        self.name   = name
        
        if regexp:
            self.regexp = re.compile (regexp)
        else:
            self.regexp = None
            
        self.module = module
        self.info   = info
        self.data   = data
        
        self.loaded = 0
        return

    def load (self, key = None):

        if self.regexp and key:
            if not self.regexp.search (key):
                return 0

        if self.loaded: return 1

        # ok, load the module
        try:
            exec ('import ' + self.module)
        except ImportError, err:
            print _("warning: can't import %s: %s") % \
                  (self.module, str (err))
            return 0
        
        self.is_loaded ()
        return 1


    def is_loaded (self):
        self.loaded = 1
        return


__loaders = {}

def preregister (group, name, module, regexp = None, info = None):
    ''' Register for autoloading '''

    # get info from the given group
    if __loaders.has_key (group):
        gp = __loaders [group]
    else:
        gp = {}
        __loaders [group] = gp

    lc = string.lower (name)
    # are we preregistering an existing key ?
    if gp.has_key (lc):
        return gp [lc]
    
    lo = Loader (name, regexp, module, info)
    gp [lc] = lo
    
    return lo


def register (group, name, data = None):
    ''' Register when the module is actually loaded '''

    mod = get_by_name (group, name, 0) or preregister (group, name, None)
    mod.is_loaded ()
    mod.data = data
    
    return


def get_by_regexp (group, key):
    ''' Returns a loaded module according to a key that it must match '''

    if not __loaders.has_key (group):
        return None
    
    gp = __loaders [group]
    
    for l in gp.values ():
        if l.load (key):
            return l
    
    return None


def get_by_name (group, name, load = 1):
    ''' Returns a loaded module according to its name '''
    
    if not __loaders.has_key (group):
        return None

    gp = __loaders [group]
    lc = string.lower (name)
    
    if gp.has_key (lc):
        l = gp [lc]
        if not load or l.load ():
            return l

    return None


def available (group):
    ''' Returns the list of available modules in a group '''
    
    return map (lambda x: x.name, __loaders [group].values ())


def groups ():
    ''' Returns a list of the groups '''
    return __loaders.keys ()