# This file is part of Tryton.  The COPYRIGHT file at the top level of
# this repository contains the full copyright notices and license terms.
from threading import local
from sql import Flavor

from trytond import backend
from trytond.config import config


class _AttributeManager(object):
    '''
    Manage Attribute of transaction
    '''

    def __init__(self, **kwargs):
        self.kwargs = kwargs

    def __enter__(self):
        return Transaction()

    def __exit__(self, type, value, traceback):
        for name, value in self.kwargs.iteritems():
            setattr(Transaction(), name, value)


class _Local(local):

    def __init__(self):
        # Transaction stack control
        self.transactions = []


class Transaction(object):
    '''
    Control the transaction
    '''

    _local = _Local()

    cache_keys = {'language', 'fuzzy_translation', '_datetime'}

    database = None
    readonly = False
    connection = None
    close = None
    user = None
    context = None
    create_records = None
    delete_records = None
    delete = None  # TODO check to merge with delete_records
    timestamp = None

    def __new__(cls, new=False):
        transactions = cls._local.transactions
        if new or not transactions:
            instance = super(Transaction, cls).__new__(cls)
            instance.cache = {}
            transactions.append(instance)
        else:
            instance = transactions[-1]
        return instance

    def get_cache(self):
        from trytond.cache import LRUDict
        keys = tuple(((key, self.context[key])
                for key in sorted(self.cache_keys)
                if key in self.context))
        return self.cache.setdefault((self.user, keys),
            LRUDict(config.getint('cache', 'model')))

    def start(self, database_name, user, readonly=False, context=None,
            close=False, autocommit=False):
        '''
        Start transaction
        '''
        Database = backend.get('Database')
        assert self.user is None
        assert self.database is None
        assert self.close is None
        assert self.context is None
        if not database_name:
            database = Database().connect()
        else:
            database = Database(database_name).connect()
        Flavor.set(Database.flavor)
        self.user = user
        self.database = database
        self.readonly = readonly
        self.connection = database.get_connection(readonly=readonly,
            autocommit=autocommit)
        self.close = close
        self.context = context or {}
        self.create_records = {}
        self.delete_records = {}
        self.delete = {}
        self.timestamp = {}
        self.counter = 0
        return self

    def __enter__(self):
        return self

    def __exit__(self, type, value, traceback):
        transactions = self._local.transactions
        if transactions.count(self) == 1:
            if type is None and not self.readonly:
                self.commit()
            try:
                self.rollback()
                self.database.put_connection(self.connection, self.close)
            finally:
                self.database = None
                self.readonly = False
                self.connection = None
                self.close = None
                self.user = None
                self.context = None
                self.create_records = None
                self.delete_records = None
                self.delete = None
                self.timestamp = None
        current_instance = transactions.pop()
        assert current_instance is self, transactions

    def set_context(self, context=None, **kwargs):
        if context is None:
            context = {}
        manager = _AttributeManager(context=self.context)
        self.context = self.context.copy()
        self.context.update(context)
        if kwargs:
            self.context.update(kwargs)
        return manager

    def reset_context(self):
        manager = _AttributeManager(context=self.context)
        self.context = {}
        return manager

    def set_user(self, user, set_context=False):
        if user != 0 and set_context:
            raise ValueError('set_context only allowed for root')
        manager = _AttributeManager(user=self.user,
                context=self.context)
        self.context = self.context.copy()
        if set_context:
            if user != self.user:
                self.context['user'] = self.user
        else:
            self.context.pop('user', None)
        self.user = user
        return manager

    def set_current_transaction(self, transaction):
        self._local.transactions.append(transaction)
        return transaction

    def new_transaction(self, autocommit=False, readonly=False):
        transaction = Transaction(new=True)
        return transaction.start(self.database.name, self.user,
            context=self.context, close=self.close, readonly=readonly,
            autocommit=autocommit)

    def commit(self):
        self.connection.commit()

    def rollback(self):
        for cache in self.cache.itervalues():
            cache.clear()
        self.connection.rollback()

    @property
    def language(self):
        def get_language():
            from trytond.pool import Pool
            Config = Pool().get('ir.configuration')
            return Config.get_language()
        if self.context:
            return self.context.get('language') or get_language()
        return get_language()