#!/usr/bin/python
# $Id$

from os import stat
from stat import ST_MODE, S_ISDIR
from syslog import syslog, LOG_ERR

from Error import PublishError
from Types import Clause

import _fam

class fam(object):
    '''The fam object contains alteration monitors'''
    
    def __init__(self):
        self.fm = _fam.open()
        self.users = {}
        self.handles = {}

    def fileno(self):
        return self.fm.fileno()

    def AddMonitor(self, path, obj=None):
        m = stat(path)[ST_MODE]
        if S_ISDIR(m):
            h = self.fm.monitorDirectory(path, None)
            self.handles[h.requestID()] = h
        else:
            h = self.fm.monitorFile(path, None)
            self.handles[h.requestID()] = h
        if obj != None:
            self.users[h.requestID()] = obj
        return h.requestID()

    def HandleEvent(self):
        event = self.fm.nextEvent()
        id = event.requestID
        if self.users.has_key(id):
            self.users[id].HandleEvent(event)

class PublishedValue(object):
    def __init__(self,owner,key,value):
        self.owner=owner
        self.key=key
        self.value=value

    def Update(self,owner,value):
        if owner != self.owner:
            raise PublishError, (self.key,owner)
        self.value=value

class Core(object):
    def __init__(self, repository, structures, generators):
        self.datastore = repository
        self.fam = fam()
        self.pubspace = {}
        self.structures = []
        for structure in structures:
            s = getattr(__import__(structure),structure)
            self.structures.append(s(self, self.datastore))
        self.generators = []
        for generator in generators:
            g = getattr(__import__(generator),generator)
            self.generators.append(g(self, self.datastore))
        # we need to inventory and setup generators
        # Process generator requirements
        for g in self.generators:
            for prq in g.__requires__:
                if not self.pubspace.has_key(prq):
                    raise GeneratorError, (g.name, prq)
            g.CompleteSetup()

    def PublishValue(self,owner,key,value):
        if not self.pubspace.has_key(key):
            # This is a new entry
            self.pubspace[key]=PublishedValue(owner,key,value)
        else:
            # This is an old entry. Update can fai
            try:
                self.pubspace[key].Update(owner,value)
            except PublishError,e:
                syslog(LOG_ERR, "Publish conflict for %s. Owner %s, Modifier %s"%(key,self.pubspace[key].owner,owner))

    def ReadValue(self,key):
        if self.pubspace.has_key(key):
            return self.pubspace[key].value
        raise KeyError,key

    def GetStructures(self, metadata):
        return reduce(lambda x,y:x+y, map(lambda x:x.Construct(metadata), self.structures))

    def BindStructure(self, structure, metadata):
        for entry in structure.getchildren():
            self.Bind(entry, metadata)

    def Bind(self, entry, metadata):
        g = [x for x in self.generators if x.__provides__.get(entry.tag, {}).has_key(entry.attrib['name'])]
        if len(g) == 1:
            return g[0].__provides__[entry.tag][entry.attrib['name']](entry, metadata)
        elif len(g) > 1:
            print "Data Integrity error for %s %s"%(entry.tag, entry.attrib['name'])
        else:
            for g in self.generators:
                if hasattr(g, "FindHandler"):
                    try:
                        return g.FindHandler(entry)(entry, metadata)
                    except:
                        print g, "failed"
            raise KeyError, (entry.tag,entry.attrib['name'])