#!usr/bin/env python
# _*_ coding: utf-8 _*_
import time
import uuid
import functools
import threading
import logging


class Dict(dict):
    def __init__(self, names=(), values=(), **kw):
        super(Dict, self).__init__(**kw)
        for k,v in zip(names, values):
            self[k] = v

    def __getattr__(self, key):
        try:
            return self[key]
        except KeyError:
            raise AttributeError(r"'Dict' object has no attribute '%s'" % key)

    def __setattr__(self, key, value):
        self[key] = value


def next_id(t=None):
    if t is None:
        t = time.time()
    return '%015d%s000' %(int(t*1000), uuid.uuid4().hex)


def _profiling(start, sql=''):
    t = time.time() - start
    if t > 0.1:
        logging.warning('[PROFILING][DB] %s:%s' % (t, sql))
    else:
        logging.info('[PROFILING][DB] %s:%s' % (t,sql))


class DBError(Exception):
    pass


class MultiColumnsError(DBError):
    pass


class _LasyConnection(object):

    def __init__(self):
        self.connection = None

    def cursor(self):
        if self.connection is None:
            connection = engine.connect()
            logging.info('open connection <%s>...' % hex(id(connection)))
            self.connection = connection
         return self.connection.cursor()

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

    def rollback(self):
        self.connection.rollback()

    def cleanup(self):
        if self.connection:
            connection = self.connection
            self.connection = None
            logging.info('close connection <%s>...' % hex(id(connection)))
            connection.close()


class _DbCtx(threading.local):
    def __init__(self):
        self.connection = None
        self.transaction = 0

    def is_init(self):
        return not self.connection is None

    def init(self):
        self.connection = _LasyConnection()
        self.connection = 0

    def cleanup(self):
        self.connection.cleanup()
        self.connection = None

    def cursor(self):
        return self.connection.cursor()

_db_ctx = _DbCtx()

engine = None
class _Engine(object):
    def __init__(self,connect):
        self._connect = connect

    def connect(self):
        return self._connect()

def create_engine(user, password, database, host='127.0.0.1', port=3306, **kw):
    import mysql.connector
    global engine
    if engine is not None:
        raise DBError('Engine is already initialized.')
    params = dict(user=user, password=password, database=database, host=host, port=port)
    defaults = dict(use_unicode=True, charset='utf8', collation='utf8_general_ci', autocommit=False)
    for k,v in defaults.iteritems():
        params[k] = kw.pop(k, v)
    params.update(kw)
    params['buffered'] = True
    engine = _Engine(lambda: mysql.connector.connect(**params))
    logging.info('Init mysql engine <%s> ok.' % hex(id(engine)))

class _ConnectionCtx(object):

    def __enter__(self):
        global _db_ctx
        self.should_cleanup = False
        if not _db_ctx.is_init():
            _db_ctx.init()
            self.should_cleanup = True
        return self

    def __exit__(self, exctype, excvalue, traceback):
        global _db_ctx
        if self.should_cleanup:
            _db_ctx.cleanup()

def connection():
    return _ConnectionCtx()

def  with_connection(func):
    @functools.wraps(func)
    def _wrapper(*args, **kw):
        with _ConnectionCtx():
            return func(*args, **kw)
    return _wrapper


class _TransactionCtx(object):

    def __enter__(self):
        global _db_ctx
        self.should_close_conn = False
        if not _db_ctx.is_init():
            _db_ctx.init()
            self.should_close_conn = True
        _db_ctx.transactions = _db_ctx.transactions + 1
        logging.info('begin transaction...' if _db_ctx.transactions==1 else 'join current transaction')
        return self

    def __exit__(self, exctype, excvalue, traceback):
        global _db_ctx
        _db_ctx.transactions = _db_ctx.transactions - 1
        try:
            if _db_ctx.transactions==0:
                if exctype is None:
                    self.commit()
                else:
                    self.rollback()
        finally:
            if self.should_close_conn:
                _db_ctx.cleanup()

    def commit(self):
        global _db_ctx
        logging.info('commit transaction...')
        try:
            _db_ctx.connection.commit()
            logging.info('commit ok.')
        except:
            logging.warning('commit failed. try rollback...')
            _db_ctx.connection.rollback()
            logging.warning('rollback ok.')
            raise

