# -*- coding: utf-8 -*-
from datetime import datetime
from sqlalchemy import Column, Integer, Float, DateTime, String, ForeignKey
from sqlalchemy.orm import relationship, backref
from sqlalchemy.ext.declarative import declarative_base

ModelBase = declarative_base()

class Sensor(ModelBase):
    __tablename__ = 'sensor'
    
    id = Column(Integer, primary_key=True)
    name = Column(String)
    description = Column(String, default="")

    def __init__(self, name, description=""):
        self.name = name
        self.description = description
        
    def __repr__(self):
        return "<Sensor('%s','%s','%s')>" % (self.id, self.name, self.description)

# http://www.sqlalchemy.org/docs/05/reference/ext/declarative.html#inheritance-configuration
class Value(ModelBase):
    __tablename__ = 'value'

    id = Column(Integer, primary_key=True)
    timestamp = Column(DateTime)
    sensor_id = Column(Integer, ForeignKey("sensor.id"))
    sensor = relationship(Sensor, backref=backref('values', order_by=timestamp))

    discriminator = Column('type', String(50))
    __mapper_args__ = {'polymorphic_on': discriminator}

    def __init__(self, sensor, timestamp=datetime.now()):
        self.timestamp = timestamp
        self.sensor  = sensor

    def __repr__(self):
        return "<Value('%s','%s','%s','%s'>" % (self.id, self.sensor, self.value, self.timestamp)

    def value(self):
        raise NotImplementedException()

class ValueFloat(Value):
    __mapper_args__ = {'polymorphic_identity': 'float'}
    value_float = Column(Float(precision=4))
    
    def __init__(self, sensor, value, timestamp=datetime.now()):
        Value.__init__(self, sensor, timestamp)
        self.value_float = value

    def value(self):
        return self.value_float

class ValueInt(Value):
    __mapper_args__ = {'polymorphic_identity': 'int'}
    value_int = Column(Integer)

    def __init__(self, sensor, value, timestamp=datetime.now()):
        Value.__init__(self, sensor, timestamp)
        self.value_int = value

    def value(self):
        return self.value_int

class ValueString(Value):
    __mapper_args__ = {'polymorphic_identity': 'string'}
    value_string = Column(String)

    def __init__(self, sensor, value, timestamp=datetime.now()):
        Value.__init__(self, sensor, timestamp)
        self.value_string = value

    def value(self):
        return self.value_string


class EbusPacketSQL(object):
    def __init__(self,session):
        self.session = session

    def get_values(self,packet):
        packet_description = packet.get_packet_description()
        sensor_name = packet._get_source_name()
        sensor = self.session.query(Sensor) \
            .filter(Sensor.name==sensor_name)
        
        if packet is None:
            return

        for field in packet_description.fields:
            name = field.name
            offset = int(field.offset)
            if not name:
                continue
            elif field.tag == "bit":
                yield ValueInt(sensor, \
                                   fields.Bit(name, offset).value())
            elif field.tag == "byte":
                yield ValueInt(sensor, \
                                   fields.Byte(name, offset).value())
            elif field.tag == "word":
                yield ValueInt(sensor, \
                                   fields.Word(name, offset).value())
            elif field.tag == "data1b":
                yield ValueInt(sensor, \
                                   fields.Data1b(name, offset).value())
            elif field.tag == "data1c":
                yield ValueInt(sensor, \
                                   fields.Data1c(name, offset).value())
            elif field.tag == "data2b":
                yield ValueInt(sensor, \
                                   fields.Data2b(name, offset).value())
            elif field.tag == "data2c":
                yield ValueInt(sensor, 
                               fields.Data2c(name, offset).value())
            elif field.tag == "bcd":
                yield ValueString(sensor,
                                  fields.Bcd(name, offset).value())
            elif field.tag == "byteEnum":
                options = dict(map(lambda opt: ( int(opt.get("value")[2:],16), opt.get("name")),
                                   field.xpath("./option")))
                yield ValueString(sensor,
                                  fields.ByteEnum(name, offset, options).value())
            else:
                print "Unsupported field-type %s" % (name)