import datetime

dateformat = '%Y-%m-%dT%H:%M:%S'

datepattern = '0000-00-00T00:00:00'

def any_to_str(s):

  return '' if s is None else str(s)

def date_to_str(date):

    return date.strftime(dateformat).rjust(len(datepattern), '0')

def set_timezone(date, tz = datetime.timezone.utc):

    return datetime.datetime(

        year        = date.year,

        month       = date.month,

        day         = date.day,

        hour        = date.hour,

        minute      = date.minute,

        second      = date.second,

        microsecond = date.microsecond,

        tzinfo      = tz )

def str_to_date(s):

    return set_timezone( datetime.datetime.strptime(s, date_format) )

class Type:

  def from_raw(self, value):

    return None

  def from_db(self, connection, value):

    return value

  def to_db(self, connection, value):

    return connection.escape(self.from_raw(value))

class Int(Type):

  def from_raw(self, value):

    return int(value if value else 0)

class String(Type):

  def from_raw(self, value):

    return any_to_str(value)

  def to_db(self, connection, value):

    return "'" + connection.escape_string(self.from_raw(value)) + "'"

class Float(Type):

  def from_raw(self, value):

    return float(value if value else 0)

class Date(Type):

  def from_raw(self, value):

    return str_to_date(date_to_str(value) if type(value) is datetime.datetime else any_to_str(value))

  def from_db(self, connection, value):

    return set_timezone(value)

class Field(Type):

  def from_raw(self, value):

    result = any_to_str(value)

    assert(result.isidentifier())

    return result

  def to_db(self, connection, value):

    return '`' + connection.escape_string(self.from_raw(value)) + '`'

class Table(Type):

  def from_raw(self, value):

    result = any_to_str(value)

    assert(result.isidentifier())

    return result

  def from_db(self, connection, value):

    value = any_to_str(value)

    prefix = connection.pool.server.config['db']['prefix']

    assert value.startswith(prefix)

    return self.from_raw(value[len(prefix):])

  def to_db(self, connection, value):

    return '`' + connection.escape_string( connection.pool.server.config['db']['prefix'] + self.from_raw(value)) + '`'

class Query(Type):

  def from_raw(self, value):

    assert type(value) is str

    return value

  def from_db(self, connection, value):

    assert type(value) is str

    return value

  def to_db(self, connection, value):

    return self.from_raw(value)

tint    = Int()

tstring = String()

tfloat  = Float()

tdate   = Date()

tfield  = Field()

ttable  = Table()

tquery  = Query()

bytype = {

  int   : tint,

  str   : tstring,

  float : tfloat,

  datetime.datetime: tdate,

}

bychar = {

  'd': tint,

  's': tstring,

  'f': tfloat,

  'D': tdate,

  'F': tfield,

  'T': ttable,

  'Q': tquery,

}