from types import StringTypes
import time
import re

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 PLC.Storage.AlchemyObject import AlchemyObj
from PLC.Faults import *
from PLC.Parameter import Parameter, Mixed
from PLC.Filter import Filter
from PLC.Debug import profile
from PLC.Nodes import Node
from PLC.Persons import Person, Persons
from PLC.Timestamp import Timestamp

class Slice(AlchemyObj):
    """
    Representation of a row in the slices table. To use, optionally
    instantiate with a dict of values. Update as you would a
    dict. Commit to the database with sync().To use, instantiate
    with a dict of values.
    """

    tablename = 'slices'
 
    fields = {
        'id': Parameter(int, "Slice identifier", primary_key=True),
        'site_id': Parameter(int, "Identifier of the site to which this slice belongs"),
        'name': Parameter(str, "Slice name", max = 32),
        'url': Parameter(str, "URL further describing this slice", max = 254, nullok = True),
        'description': Parameter(str, "Slice description", max = 2048, nullok = True),
        'max_nodes': Parameter(int, "Maximum number of nodes that can be assigned to this slice"),
        'creator_person_id': Parameter(int, "Identifier of the account that created this slice"),
        'created': Parameter(int, "Date and time when slice was created, in seconds since UNIX epoch", ro = True),
        'expires': Parameter(int, "Date and time when slice expires, in seconds since UNIX epoch"),
        'node_ids': Parameter([int], "List of nodes in this slice", ro = True),
        'person_ids': Parameter([int], "List of accounts that can use this slice", ro = True),
        }
    tags = {}

    def validate_name(self, name):
        # N.B.: Responsibility of the caller to ensure that login_base
        # portion of the slice name corresponds to a valid site, if
        # desired.

        # 1. Lowercase.
        # 2. Begins with login_base (letters or numbers).
        # 3. Then single underscore after login_base.
        # 4. Then letters, numbers, or underscores.
        good_name = r'^[a-z0-9]+_[a-zA-Z0-9_]+$'
        if not name or \
           not re.match(good_name, name):
            raise PLCInvalidArgument, "Invalid slice name"

        conflicts = Slices(self.api, [name])
        for slice in conflicts:
            if 'id' not in self or self['id'] != slice.id:
                raise PLCInvalidArgument, "Slice name already in use, %s"%name

        return name

    def validate_expires(self, expires):
        # N.B.: Responsibility of the caller to ensure that expires is
        # not too far into the future.
        check_future = not ('is_deleted' in self and self['is_deleted'])
        return Timestamp.sql_validate( expires, check_future = check_future)

    #add_person = Row.add_object(Person, 'slice_person')
    #remove_person = Row.remove_object(Person, 'slice_person')

    #add_node = Row.add_object(Node, 'slice_node')
    #remove_node = Row.remove_object(Node, 'slice_node')

    #add_to_node_whitelist = Row.add_object(Node, 'node_slice_whitelist')
    #delete_from_node_whitelist = Row.remove_object(Node, 'node_slice_whitelist')

    def sync(self, commit = True, validate=True):
        """
        Add or update a slice.
        """
        AlchemyObj.sync(self, commit, validate)
        if 'id' not in self:
            # Before a new slice is added, delete expired slices
            expired = Slices(self.api, expires = -int(time.time()))
            for slice in expired:
                slice.delete(commit)
            Slice().insert(dict(self))

    def delete(self, commit = True):
        """
        Delete existing slice.
        """

        assert 'slice_id' in self

        # Clean up miscellaneous join tables
        for table in self.join_tables:
            self.api.db.do("DELETE FROM %s WHERE slice_id = %d" % \
                           (table, self['slice_id']))

        # Mark as deleted
        self['is_deleted'] = True
        self.sync(commit)


class Slices(list):
    """
    Representation of row(s) from the slices table in the
    database.
    """

    def __init__(self, api, slice_filter = None, columns = None, expires = int(time.time())):
         
        # the view that we're selecting upon: start with view_slices
        if not slice_filter:
            slices = Slice().select()
        elif isinstance (slice_filter, StringTypes):
            slices = Slice().select(filter={'name': slice_filter})
        elif isinstance(slice_filter, dict):
            slices = Slice().select(filter=slice_filter)
        elif isinstance(slice_filter, (list, tuple, set)):
            slices = Slice().select()
            slices = [slice for slice in slices if slice.id in slice_filter]
        else:
            raise PLCInvalidArgument, "Wrong slice filter %r"%slice_filter

        for slice in slices:
            self.append(slice)