import datetime

import decimal

from time import time

from django.utils.hashcompat import md5_constructor

class CursorDebugWrapper(object):

    def __init__(self, cursor, db):

        self.cursor = cursor

        self.db = db # Instance of a BaseDatabaseWrapper subclass

    def execute(self, sql, params=()):

        start = time()

        try:

            return self.cursor.execute(sql, params)

        finally:

            stop = time()

            sql = self.db.ops.last_executed_query(self.cursor, sql, params)

            self.db.queries.append({

                'sql': sql,

                'time': "%.3f" % (stop - start),

            })

    def executemany(self, sql, param_list):

        start = time()

        try:

            return self.cursor.executemany(sql, param_list)

        finally:

            stop = time()

            self.db.queries.append({

                'sql': '%s times: %s' % (len(param_list), sql),

                'time': "%.3f" % (stop - start),

            })

    def __getattr__(self, attr):

        if attr in self.__dict__:

            return self.__dict__[attr]

        else:

            return getattr(self.cursor, attr)

    def __iter__(self):

        return iter(self.cursor)

###############################################

# Converters from database (string) to Python #

###############################################

def typecast_date(s):

    return s and datetime.date(*map(int, s.split('-'))) or None # returns None if s is null

def typecast_time(s): # does NOT store time zone information

    if not s: return None

    hour, minutes, seconds = s.split(':')

    if '.' in seconds: # check whether seconds have a fractional part

        seconds, microseconds = seconds.split('.')

    else:

        microseconds = '0'

    return datetime.time(int(hour), int(minutes), int(seconds), int(float('.'+microseconds) * 1000000))

def typecast_timestamp(s): # does NOT store time zone information

    # "2005-07-29 15:48:00.590358-05"

    # "2005-07-29 09:56:00-05"

    if not s: return None

    if not ' ' in s: return typecast_date(s)

    d, t = s.split()

    # Extract timezone information, if it exists. Currently we just throw

    # it away, but in the future we may make use of it.

    if '-' in t:

        t, tz = t.split('-', 1)

        tz = '-' + tz

    elif '+' in t:

        t, tz = t.split('+', 1)

        tz = '+' + tz

    else:

        tz = ''

    dates = d.split('-')

    times = t.split(':')

    seconds = times[2]

    if '.' in seconds: # check whether seconds have a fractional part

        seconds, microseconds = seconds.split('.')

    else:

        microseconds = '0'

    return datetime.datetime(int(dates[0]), int(dates[1]), int(dates[2]),

        int(times[0]), int(times[1]), int(seconds), int(float('.'+microseconds) * 1000000))

def typecast_boolean(s):

    if s is None: return None

    if not s: return False

    return str(s)[0].lower() == 't'

def typecast_decimal(s):

    if s is None or s == '':

        return None

    return decimal.Decimal(s)

###############################################

# Converters from Python to database (string) #

###############################################

def rev_typecast_boolean(obj, d):

    return obj and '1' or '0'

def rev_typecast_decimal(d):

    if d is None:

        return None

    return str(d)

def truncate_name(name, length=None):

    """Shortens a string to a repeatable mangled version with the given length.

    """

    if length is None or len(name) <= length:

        return name

    hash = md5_constructor(name).hexdigest()[:4]

    return '%s%s' % (name[:length-4], hash)

def format_number(value, max_digits, decimal_places):

    """

    Formats a number into a string with the requisite number of digits and

    decimal places.

    """

    if isinstance(value, decimal.Decimal):

        context = decimal.getcontext().copy()

        context.prec = max_digits

        return u'%s' % str(value.quantize(decimal.Decimal(".1") ** decimal_places, context=context))

    else:

        return u"%.*f" % (decimal_places, value)