from datetime import datetime

from sqlalchemy import or_, and_ 
from sqlalchemy import Column, Integer, String, DateTime
from sqlalchemy import Table, Column, MetaData, join, ForeignKey
from sqlalchemy.orm import relationship, backref
from sqlalchemy.orm import column_property
from sqlalchemy.orm import object_mapper
from sqlalchemy.orm import validates
from sqlalchemy.ext.declarative import declarative_base

from sfa.storage.record import Record
from sfa.util.sfalogging import logger
from sfa.util.sfatime import utcparse, datetime_to_string
from sfa.util.xml import XML 
from sfa.util.py23 import StringType

from sfa.trust.gid import GID

##############################
Base = declarative_base()

####################
# dicts vs objects
####################
# historically the front end to the db dealt with dicts, so the code was only dealing with dicts
# sqlalchemy however offers an object interface, meaning that you write obj.id instead of obj['id']
# which is admittedly much nicer
# however we still need to deal with dictionaries if only for the xmlrpc layer
# 
# here are a few utilities for this 
# 
# (*) first off, when an old pieve of code needs to be used as-is, if only temporarily, the simplest trick
# is to use obj.__dict__
# this behaves exactly like required, i.e. obj.__dict__['field']='new value' does change obj.field
# however this depends on sqlalchemy's implementation so it should be avoided 
#
# (*) second, when an object needs to be exposed to the xmlrpc layer, we need to convert it into a dict
# remember though that writing the resulting dictionary won't change the object
# essentially obj.__dict__ would be fine too, except that we want to discard alchemy private keys starting with '_'
# 2 ways are provided for that:
# . dict(obj)
# . obj.todict()
# the former dict(obj) relies on __iter__() and next() below, and does not rely on the fields names
# although it seems to work fine, I've found cases where it issues a weird python error that I could not get right
# so the latter obj.todict() seems more reliable but more hacky as is relies on the form of fields, so this can probably be improved
#
# (*) finally for converting a dictionary into an sqlalchemy object, we provide
# obj.load_from_dict(dict)

class AlchemyObj(Record):
    def __iter__(self): 
        self._i = iter(object_mapper(self).columns)
        return self 
    def next(self): 
        n = self._i.next().name
        return n, getattr(self, n)

#    # only intended for debugging 
#    def inspect (self, logger, message=""):
#        logger.info("%s -- Inspecting AlchemyObj -- attrs"%message)
#        for k in dir(self):
#            if not k.startswith('_'):
#                logger.info ("  %s: %s"%(k,getattr(self,k)))
#        logger.info("%s -- Inspecting AlchemyObj -- __dict__"%message)
#        d=self.__dict__
#        for (k,v) in d.iteritems():
#            logger.info("[%s]=%s"%(k,v))


##############################
# various kinds of records are implemented as an inheritance hierarchy
# RegRecord is the base class for all actual variants
# a first draft was using 'type' as the discriminator for the inheritance
# but we had to define another more internal column (classtype) so we 
# accomodate variants in types like authority+am and the like

class RegRecord(Base, AlchemyObj):
    __tablename__       = 'records'
    record_id           = Column (Integer, primary_key=True)
    # this is the discriminator that tells which class to use
    classtype           = Column (String)
    # in a first version type was the discriminator
    # but that could not accomodate for 'authority+sa' and the like
    type                = Column (String)
    hrn                 = Column (String)
    gid                 = Column (String)
    authority           = Column (String)
    peer_authority      = Column (String)
    pointer             = Column (Integer, default=-1)
    date_created        = Column (DateTime)
    last_updated        = Column (DateTime)
    # use the 'type' column to decide which subclass the object is of
    __mapper_args__     = { 'polymorphic_on' : classtype }

    fields = [ 'type', 'hrn', 'gid', 'authority', 'peer_authority' ]
    def __init__ (self, type=None, hrn=None, gid=None, authority=None, peer_authority=None, 
                  pointer=None, dict=None):
        if type:                                self.type=type
        if hrn:                                 self.hrn=hrn
        if gid: 
            if isinstance(gid, StringType):     self.gid=gid
            else:                               self.gid=gid.save_to_string(save_parents=True)
        if authority:                           self.authority=authority
        if peer_authority:                      self.peer_authority=peer_authority
        if pointer:                             self.pointer=pointer
        if dict:                                self.load_from_dict (dict)

    def __repr__(self):
        result="<Record id=%s, type=%s, hrn=%s, authority=%s" % \
                (self.record_id, self.type, self.hrn, self.authority)
#        for extra in ('pointer', 'email', 'name'):
#        for extra in ('email', 'name'):
# displaying names at this point it too dangerous, because of unicode
        for extra in ('email'):
            if hasattr(self, extra):
                result += " {}={},".format(extra, getattr(self, extra))
        # skip the uniform '--- BEGIN CERTIFICATE --' stuff
        if self.gid:
            result+=" gid=%s..."%self.gid[28:36]
        else:
            result+=" nogid"
        result += ">"
        return result

    # shortcut - former implem. was record-based
    def get (self, field, default):
        return getattr(self,field,default)

    @validates ('gid')
    def validate_gid (self, key, gid):
        if gid is None:                     return
        elif isinstance(gid, StringType):   return gid
        else:                               return gid.save_to_string(save_parents=True)

    def validate_datetime (self, key, incoming):
        if isinstance (incoming, datetime):
            return incoming
        elif isinstance (incoming, (int, float)):
            return datetime.fromtimestamp (incoming)
        else:
            logger.info("Cannot validate datetime for key %s with input %s"%\
                        (key,incoming))

    @validates ('date_created')
    def validate_date_created (self, key, incoming):
        return self.validate_datetime (key, incoming)

    @validates ('last_updated')
    def validate_last_updated (self, key, incoming):
        return self.validate_datetime (key, incoming)

    # xxx - there might be smarter ways to handle get/set'ing gid using validation hooks 
    def get_gid_object (self):
        if not self.gid:        return None
        else:                   return GID(string=self.gid)

    def just_created (self):
        now = datetime.utcnow()
        self.date_created = now
        self.last_updated = now

    def just_updated (self):
        now = datetime.utcnow()
        self.last_updated = now

#################### cross-relations tables
# authority x user (pis) association
authority_pi_table = \
    Table ( 'authority_pi', Base.metadata,
            Column ('authority_id', Integer, ForeignKey ('records.record_id'), primary_key=True),
            Column ('pi_id', Integer, ForeignKey ('records.record_id'), primary_key=True),
            )
# slice x user (researchers) association
slice_researcher_table = \
    Table ( 'slice_researcher', Base.metadata,
            Column ('slice_id', Integer, ForeignKey ('records.record_id'), primary_key=True),
            Column ('researcher_id', Integer, ForeignKey ('records.record_id'), primary_key=True),
            )

##############################
# all subclasses define a convenience constructor with a default value for type, 
# and when applicable a way to define local fields in a kwd=value argument
####################
class RegAuthority(RegRecord):
    __tablename__       = 'authorities'
    __mapper_args__     = { 'polymorphic_identity' : 'authority' }
    record_id           = Column (Integer, ForeignKey ("records.record_id"), primary_key=True)
    #### extensions come here
    name                = Column ('name', String)
    #### extensions come here
    reg_pis             = relationship \
        ('RegUser',
         secondary = authority_pi_table,
         primaryjoin = RegRecord.record_id==authority_pi_table.c.authority_id,
         secondaryjoin = RegRecord.record_id==authority_pi_table.c.pi_id,
         backref = 'reg_authorities_as_pi',
        )
    
    def __init__ (self, **kwds):
        # handle local settings
        if 'name' in kwds:
            self.name = kwds.pop('name')
        # fill in type if not previously set
        if 'type' not in kwds:
            kwds['type']='authority'
        # base class constructor
        RegRecord.__init__(self, **kwds)

    # no proper data yet, just hack the typename
    def __repr__ (self):
        result = RegRecord.__repr__(self).replace("Record", "Authority")
# here again trying to display names that can be utf8 is too dangerous        
#        result.replace(">", " name={}>".format(self.name))
        return result

    def update_pis (self, pi_hrns, dbsession):
        # strip that in case we have <researcher> words </researcher>
        pi_hrns = [ x.strip() for x in pi_hrns ]
        request = dbsession.query(RegUser).filter(RegUser.hrn.in_(pi_hrns))
        logger.info("RegAuthority.update_pis: %d incoming pis, %d matches found"\
                    % (len(pi_hrns), request.count()))
        pis = dbsession.query(RegUser).filter(RegUser.hrn.in_(pi_hrns)).all()
        self.reg_pis = pis

####################
class RegSlice(RegRecord):
    __tablename__       = 'slices'
    __mapper_args__     = { 'polymorphic_identity' : 'slice' }
    record_id           = Column (Integer, ForeignKey ("records.record_id"), primary_key=True)
    #### extensions come here
    reg_researchers     = relationship \
        ('RegUser', 
         secondary=slice_researcher_table,
         primaryjoin=RegRecord.record_id==slice_researcher_table.c.slice_id,
         secondaryjoin=RegRecord.record_id==slice_researcher_table.c.researcher_id,
         backref='reg_slices_as_researcher',
        )

    def __init__ (self, **kwds):
        if 'type' not in kwds:
            kwds['type']='slice'
        RegRecord.__init__(self, **kwds)

    def __repr__ (self):
        return RegRecord.__repr__(self).replace("Record", "Slice")

    def update_researchers (self, researcher_hrns, dbsession):
        # strip that in case we have <researcher> words </researcher>
        researcher_hrns = [ x.strip() for x in researcher_hrns ]
        request = dbsession.query (RegUser).filter(RegUser.hrn.in_(researcher_hrns))
        logger.info ("RegSlice.update_researchers: %d incoming researchers, %d matches found"\
                     % (len(researcher_hrns), request.count()))
        researchers = dbsession.query (RegUser).filter(RegUser.hrn.in_(researcher_hrns)).all()
        self.reg_researchers = researchers

    # when dealing with credentials, we need to retrieve the PIs attached to a slice
    # WARNING: with the move to passing dbsessions around, we face a glitch here because this
    # helper function is called from the trust/ area that
    def get_pis (self):
        from sqlalchemy.orm import sessionmaker
        Session = sessionmaker()
        dbsession = Session.object_session(self)
        from sfa.util.xrn import get_authority
        authority_hrn = get_authority(self.hrn)
        auth_record = dbsession.query(RegAuthority).filter_by(hrn=authority_hrn).first()
        return auth_record.reg_pis
        
    @validates ('expires')
    def validate_expires (self, key, incoming):
        return self.validate_datetime (key, incoming)

####################
class RegNode(RegRecord):
    __tablename__       = 'nodes'
    __mapper_args__     = { 'polymorphic_identity' : 'node' }
    record_id           = Column (Integer, ForeignKey ("records.record_id"), primary_key=True)
    
    def __init__(self, **kwds):
        if 'type' not in kwds:
            kwds['type']='node'
        RegRecord.__init__(self, **kwds)

    def __repr__ (self):
        return RegRecord.__repr__(self).replace("Record", "Node")

####################
class RegUser(RegRecord):
    __tablename__       = 'users'
    # these objects will have type='user' in the records table
    __mapper_args__     = { 'polymorphic_identity' : 'user' }
    record_id           = Column (Integer, ForeignKey ("records.record_id"), primary_key=True)
    #### extensions come here
    email               = Column ('email', String)
    # can't use name 'keys' here because when loading from xml we're getting
    # a 'keys' tag, and assigning a list of strings in a reference column like this crashes
    reg_keys            = relationship \
        ('RegKey', backref='reg_user',
         cascade = "all, delete, delete-orphan",
        )
    
    # so we can use RegUser (email=.., hrn=..) and the like
    def __init__ (self, **kwds):
        # handle local settings
        if 'email' in kwds:
            self.email = kwds.pop('email')
        if 'type' not in kwds:
            kwds['type'] = 'user'
        RegRecord.__init__(self, **kwds)

    # append stuff at the end of the record __repr__
    def __repr__ (self): 
        result = RegRecord.__repr__(self).replace("Record", "User")
        result.replace(">", " email={}>".format(self.email))
        return result

    @validates('email') 
    def validate_email(self, key, address):
        assert '@' in address
        return address

####################
# xxx tocheck : not sure about eager loading of this one
# meaning, when querying the whole records, we expect there should
# be a single query to fetch all the keys 
# or, is it enough that we issue a single query to retrieve all the keys 
class RegKey(Base):
    __tablename__       = 'keys'
    key_id              = Column (Integer, primary_key=True)
    record_id           = Column (Integer, ForeignKey ("records.record_id"))
    key                 = Column (String)
    pointer             = Column (Integer, default = -1)
    
    def __init__ (self, key, pointer=None):
        self.key = key
        if pointer:
            self.pointer = pointer

    def __repr__ (self):
        result = "<key id=%s key=%s..." % (self.key_id, self.key[8:16],)
        try:    result += " user=%s" % self.reg_user.record_id
        except: result += " no-user"
        result += ">"
        return result

class SliverAllocation(Base,AlchemyObj):
    __tablename__       = 'sliver_allocation'
    sliver_id           = Column(String, primary_key=True)
    client_id           = Column(String)
    component_id        = Column(String)
    slice_urn           = Column(String)
    allocation_state    = Column(String)

    def __init__(self, **kwds):
        if 'sliver_id' in kwds:
            self.sliver_id = kwds['sliver_id']
        if 'client_id' in kwds:
            self.client_id = kwds['client_id']
        if 'component_id' in kwds:
            self.component_id = kwds['component_id']
        if 'slice_urn' in kwds:
            self.slice_urn = kwds['slice_urn']
        if 'allocation_state' in kwds:
            self.allocation_state = kwds['allocation_state']

    def __repr__(self):
        result = "<sliver_allocation sliver_id=%s allocation_state=%s"\
                 % (self.sliver_id, self.allocation_state)
        return result

    @validates('allocation_state')
    def validate_allocation_state(self, key, state):
        allocation_states = ['geni_unallocated', 'geni_allocated', 'geni_provisioned']
        assert state in allocation_states
        return state

    @staticmethod    
    def set_allocations(sliver_ids, state, dbsession):
        if not isinstance(sliver_ids, list):
            sliver_ids = [sliver_ids]
        sliver_state_updated = {}
        constraint = SliverAllocation.sliver_id.in_(sliver_ids)
        sliver_allocations = dbsession.query (SliverAllocation).filter(constraint)
        sliver_ids_found = []
        for sliver_allocation in sliver_allocations:
            sliver_allocation.allocation_state = state
            sliver_ids_found.append(sliver_allocation.sliver_id)

        # Some states may not have been updated becuase no sliver allocation state record
        # exists for the sliver. Insert new allocation records for these slivers and set
        # it to geni_allocated.
        sliver_ids_not_found = set(sliver_ids).difference(sliver_ids_found)
        for sliver_id in sliver_ids_not_found:
            record = SliverAllocation(sliver_id=sliver_id, allocation_state=state)
            dbsession.add(record)
        dbsession.commit()

    @staticmethod
    def delete_allocations(sliver_ids, dbsession):
        if not isinstance(sliver_ids, list):
            sliver_ids = [sliver_ids]
        constraint = SliverAllocation.sliver_id.in_(sliver_ids)
        sliver_allocations = dbsession.query(SliverAllocation).filter(constraint)
        for sliver_allocation in sliver_allocations:
            dbsession.delete(sliver_allocation)
        dbsession.commit()
    
    def sync(self, dbsession):
        constraints = [SliverAllocation.sliver_id == self.sliver_id]
        results = dbsession.query(SliverAllocation).filter(and_(*constraints))
        records = []
        for result in results:
            records.append(result) 
        
        if not records:
            dbsession.add(self)
        else:
            record = records[0]
            record.sliver_id = self.sliver_id
            record.client_id  = self.client_id
            record.component_id  = self.component_id
            record.slice_urn  = self.slice_urn
            record.allocation_state = self.allocation_state
        dbsession.commit()    
        

##############################
# although the db needs of course to be reachable for the following functions
# the schema management functions are here and not in alchemy
# because the actual details of the classes need to be known
# migrations: this code has no notion of the previous versions
# of the data model nor of migrations
# sfa.storage.migrations.db_init uses this when starting from
# a fresh db only
def init_tables(engine):
    logger.info("Initializing db schema from current/latest model")
    Base.metadata.create_all(engine)

def drop_tables(engine):
    logger.info("Dropping tables from current/latest model")
    Base.metadata.drop_all(engine)

##############################
# create a record of the right type from either a dict or an xml string
def make_record (dict=None, xml=""):
    if dict is None: dict={}
    if dict:    return make_record_dict (dict)
    elif xml:   return make_record_xml (xml)
    else:       raise Exception("make_record has no input")

# convert an incoming record - typically from xmlrpc - into an object
def make_record_dict (record_dict):
    assert ('type' in record_dict)
    type = record_dict['type'].split('+')[0]
    if type == 'authority':
        result = RegAuthority (dict=record_dict)
    elif type == 'user':
        result = RegUser (dict=record_dict)
    elif type == 'slice':
        result = RegSlice (dict=record_dict)
    elif type == 'node':
        result = RegNode (dict=record_dict)
    else:
        logger.debug("Untyped RegRecord instance")
        result = RegRecord (dict=record_dict)
    logger.info("converting dict into Reg* with type=%s"%type)
    logger.info("returning=%s"%result)
    # xxx todo
    # register non-db attributes in an extensions field
    return result
        
def make_record_xml (xml_str):
    xml = XML(xml_str)
    xml_dict = xml.todict()
    logger.info("load from xml, keys=%s"%xml_dict.keys())
    return make_record_dict (xml_dict)

####################
# augment local records with data from builtin relationships
# expose related objects as a list of hrns
# we pick names that clearly won't conflict with the ones used in the old approach,
# were the relationships data came from the testbed side
# for each type, a dict of the form {<field-name-exposed-in-record>:<alchemy_accessor_name>}
# so after that, an 'authority' record will e.g. have a 'reg-pis' field with the hrns of its pi-users
augment_map = {'authority': {'reg-pis' : 'reg_pis',},
               'slice': {'reg-researchers' : 'reg_researchers',},
               'user': {'reg-pi-authorities' : 'reg_authorities_as_pi',
                        'reg-slices' : 'reg_slices_as_researcher',},
           }


# xxx mystery
# the way we use sqlalchemy might be a little wrong
# in any case what has been observed is that (Reg)Records as returned by an sqlalchemy
# query not always have their __dict__ properly adjusted
# typically a RegAuthority object would have its object.name set properly, but
# object.__dict__ has no 'name' key
# which is an issue because we rely on __dict__ for many things, in particular this
# is what gets exposed to the drivers (this is historical and dates back before sqlalchemy)
# so it is recommended to always run this function that will make sure
# that such built-in fields are properly set in __dict__ too
# 
def augment_with_sfa_builtins(local_record):
    # don't ruin the import of that file in a client world
    from sfa.util.xrn import Xrn
    # add a 'urn' field
    setattr(local_record, 'reg-urn', Xrn(xrn=local_record.hrn, type=local_record.type).urn)
    # users have keys and this is needed to synthesize 'users' sent over to CreateSliver
    fields_to_check = []
    if local_record.type == 'user':
        user_keys = [ key.key for key in local_record.reg_keys ]
        setattr(local_record, 'reg-keys', user_keys)
        fields_to_check = ['email']
    elif local_record.type == 'authority':
        fields_to_check = ['name']
    for field in fields_to_check:
        if not field in local_record.__dict__:
            logger.debug("augment_with_sfa_builtins: hotfixing missing '{}' in {}"
                         .format(field, local_record.hrn))
            local_record.__dict__[field] = getattr(local_record, field)
    # search in map according to record type
    type_map = augment_map.get(local_record.type, {})
    # use type-dep. map to do the job
    for (field_name, attribute) in type_map.items():
        # get related objects
        related_records = getattr(local_record, attribute, [])
        hrns = [ r.hrn for r in related_records ]
        setattr (local_record, field_name, hrns)