"""Django database model for SatNOGS DB"""
from __future__ import absolute_import, division, print_function, \
    unicode_literals

import logging
from os import path
from uuid import uuid4

from django.conf import settings
from django.contrib.auth.models import User
from django.core.validators import MaxValueValidator, MinValueValidator
from django.db import models
from django.db.models import OuterRef, Subquery
from django.db.models.signals import post_save, pre_save
from django.utils.encoding import python_2_unicode_compatible
from django.utils.timezone import now
from markdown import markdown
from shortuuidfield import ShortUUIDField

from db.base.helpers import gridsquare

LOGGER = logging.getLogger('db')

DATA_SOURCES = ['manual', 'network', 'sids']
SATELLITE_STATUS = ['alive', 'dead', 're-entered']
TRANSMITTER_STATUS = ['active', 'inactive', 'invalid']
TRANSMITTER_TYPE = ['Transmitter', 'Transceiver', 'Transponder']
SERVICE_TYPE = [
    'Aeronautical', 'Amateur', 'Broadcasting', 'Earth Exploration', 'Fixed', 'Inter-satellite',
    'Maritime', 'Meteorological', 'Mobile', 'Radiolocation', 'Radionavigational',
    'Space Operation', 'Space Research', 'Standard Frequency and Time Signal', 'Unknown'
]


def _name_payload_frame(instance, filename):  # pylint: disable=W0613
    """Returns a unique, timestamped path and filename for a payload

    :param filename: the original filename submitted
    :returns: path string with timestamped subfolders and filename
    """
    today = now()
    folder = 'payload_frames/{0}/{1}/{2}/'.format(today.year, today.month, today.day)
    ext = 'raw'
    filename = '{0}_{1}.{2}'.format(filename, uuid4().hex, ext)
    return path.join(folder, filename)


def _gen_observer(sender, instance, created, **kwargs):  # pylint: disable=W0613
    post_save.disconnect(_gen_observer, sender=DemodData)
    try:
        qth = gridsquare(instance.lat, instance.lng)
    except Exception:  # pylint: disable=W0703
        instance.observer = 'Unknown'
    else:
        instance.observer = '{0}-{1}'.format(instance.station, qth)
    instance.save()
    post_save.connect(_gen_observer, sender=DemodData)


def _set_is_decoded(sender, instance, **kwargs):  # pylint: disable=W0613
    """Returns true if payload_decoded has data"""
    instance.is_decoded = instance.payload_decoded != ''


@python_2_unicode_compatible
class Mode(models.Model):
    """A satellite transmitter RF mode. For example: FM"""
    name = models.CharField(max_length=10, unique=True)

    def __str__(self):
        return self.name


@python_2_unicode_compatible
class Satellite(models.Model):
    """Model for all the satellites."""
    norad_cat_id = models.PositiveIntegerField()
    name = models.CharField(max_length=45)
    names = models.TextField(blank=True)
    description = models.TextField(blank=True)
    image = models.ImageField(upload_to='satellites', blank=True, help_text='Ideally: 250x250')
    tle1 = models.CharField(max_length=200, blank=True)
    tle2 = models.CharField(max_length=200, blank=True)
    tle_source = models.CharField(max_length=300, blank=True)
    status = models.CharField(
        choices=list(zip(SATELLITE_STATUS, SATELLITE_STATUS)), max_length=10, default='alive'
    )
    decayed = models.DateTimeField(null=True, blank=True)

    class Meta:
        ordering = ['norad_cat_id']

    def get_description(self):
        """Returns the markdown-processed satellite description

        :returns: the markdown-processed satellite description
        """
        return markdown(self.description)

    def get_image(self):
        """Returns an image for the satellite

        :returns: the saved image for the satellite, or a default
        """
        if self.image and hasattr(self.image, 'url'):
            image = self.image.url
        else:
            image = settings.SATELLITE_DEFAULT_IMAGE
        return image

    @property
    def transmitters(self):
        """Returns valid transmitters for this Satellite

        :returns: the valid transmitters for this Satellite
        """
        transmitters = Transmitter.objects.filter(satellite=self.id)
        return transmitters.exclude(status='invalid')

    @property
    def transmitter_suggestion_count(self):
        """Returns number of pending transmitter suggestions for this Satellite

        :returns: number of pending transmitter suggestions for this Satellite
        """
        pending_count = TransmitterSuggestion.objects.filter(satellite=self.id).count()
        return pending_count

    @property
    def telemetry_data_count(self):
        """Returns number of DemodData for this Satellite

        :returns: number of DemodData for this Satellite
        """
        data_count = DemodData.objects.filter(satellite=self.id).count()
        return data_count

    @property
    def telemetry_decoder_count(self):
        """Returns number of Telemetry objects for this Satellite

        :returns: number of Telemetry objects for this Satellite
        """
        decoder_count = Telemetry.objects.filter(satellite=self.id).exclude(decoder='').count()
        return decoder_count

    def __str__(self):
        return '{0} - {1}'.format(self.norad_cat_id, self.name)


@python_2_unicode_compatible
class TransmitterEntry(models.Model):
    """Model for satellite transmitters."""
    uuid = ShortUUIDField(db_index=True)
    description = models.TextField()
    status = models.CharField(
        choices=list(zip(TRANSMITTER_STATUS, TRANSMITTER_STATUS)), max_length=8, default='active'
    )
    type = models.CharField(
        choices=list(zip(TRANSMITTER_TYPE, TRANSMITTER_TYPE)),
        max_length=11,
        default='Transmitter'
    )
    uplink_low = models.BigIntegerField(blank=True, null=True)
    uplink_high = models.BigIntegerField(blank=True, null=True)
    uplink_drift = models.IntegerField(blank=True, null=True)
    downlink_low = models.BigIntegerField(blank=True, null=True)
    downlink_high = models.BigIntegerField(blank=True, null=True)
    downlink_drift = models.IntegerField(blank=True, null=True)
    mode = models.ForeignKey(
        Mode, blank=True, null=True, on_delete=models.SET_NULL, related_name='transmitter_entries'
    )
    invert = models.BooleanField(default=False)
    baud = models.FloatField(validators=[MinValueValidator(0)], blank=True, null=True)
    satellite = models.ForeignKey(
        Satellite, null=True, related_name='transmitter_entries', on_delete=models.SET_NULL
    )
    reviewed = models.BooleanField(default=False)
    approved = models.BooleanField(default=False)
    created = models.DateTimeField(default=now)
    citation = models.CharField(max_length=512, default='CITATION NEEDED - https://xkcd.com/285/')
    user = models.ForeignKey(User, null=True, on_delete=models.SET_NULL)
    service = models.CharField(
        choices=zip(SERVICE_TYPE, SERVICE_TYPE), max_length=34, default='Unknown'
    )

    # NOTE: future fields will need to be added to forms.py and to
    # api/serializers.py

    class Meta:
        unique_together = ("uuid", "created")
        verbose_name_plural = 'Transmitter entries'

    def __str__(self):
        return self.description

    # see https://github.com/PyCQA/pylint-django/issues/94 for why W0221
    def save(self, *args, **kwargs):  # pylint: disable=W0221
        # this assignment is needed to preserve changes made to a Transmitter
        # through the admin UI
        self.id = None  # pylint: disable=C0103, W0201
        super(TransmitterEntry, self).save()


class TransmitterSuggestionManager(models.Manager):  # pylint: disable=R0903
    """Django Manager for TransmitterSuggestions

    TransmitterSuggestions are TransmitterEntry objects that have been
    submitted (suggested) but not yet reviewed
    """

    def get_queryset(self):  # pylint: disable=R0201
        """Returns TransmitterEntries that have not been reviewed"""
        return TransmitterEntry.objects.filter(reviewed=False)


@python_2_unicode_compatible
class TransmitterSuggestion(TransmitterEntry):
    """TransmitterSuggestion is an unreviewed TransmitterEntry object"""
    objects = TransmitterSuggestionManager()

    def __str__(self):
        return self.description

    class Meta:
        proxy = True
        permissions = (('approve', 'Can approve/reject transmitter suggestions'), )


class TransmitterManager(models.Manager):  # pylint: disable=R0903
    """Django Manager for Transmitter objects"""

    def get_queryset(self):
        """Returns query of TransmitterEntries

        :returns: the latest revision of a TransmitterEntry for each
        TransmitterEntry uuid associated with this Satellite that is
        both reviewed and approved
        """
        subquery = TransmitterEntry.objects.filter(
            reviewed=True, approved=True
        ).filter(uuid=OuterRef('uuid')).order_by('-created')
        return super(TransmitterManager, self).get_queryset().filter(
            reviewed=True, approved=True
        ).filter(created=Subquery(subquery.values('created')[:1]))


@python_2_unicode_compatible
class Transmitter(TransmitterEntry):
    """Associates a generic Transmitter object with their TransmitterEntries
    that are managed by TransmitterManager
    """
    objects = TransmitterManager()

    def __str__(self):
        return self.description

    class Meta:
        proxy = True


@python_2_unicode_compatible
class Telemetry(models.Model):
    """Model for satellite telemetry decoders."""
    satellite = models.ForeignKey(
        Satellite, null=True, related_name='telemetries', on_delete=models.SET_NULL
    )
    name = models.CharField(max_length=45)
    schema = models.TextField(blank=True)
    decoder = models.CharField(max_length=20, blank=True)

    class Meta:
        ordering = ['satellite__norad_cat_id']
        verbose_name_plural = 'Telemetries'

    def __str__(self):
        return self.name


@python_2_unicode_compatible
class DemodData(models.Model):
    """Model for satellite for observation data."""
    satellite = models.ForeignKey(
        Satellite, null=True, related_name='telemetry_data', on_delete=models.SET_NULL
    )
    transmitter = models.ForeignKey(
        TransmitterEntry, null=True, blank=True, on_delete=models.SET_NULL
    )
    app_source = models.CharField(
        choices=list(zip(DATA_SOURCES, DATA_SOURCES)), max_length=7, default='sids'
    )
    data_id = models.PositiveIntegerField(blank=True, null=True)
    payload_frame = models.FileField(upload_to=_name_payload_frame, blank=True, null=True)
    payload_decoded = models.TextField(blank=True)
    payload_telemetry = models.ForeignKey(
        Telemetry, null=True, blank=True, on_delete=models.SET_NULL
    )
    station = models.CharField(max_length=45, default='Unknown')
    observer = models.CharField(max_length=60, blank=True)
    lat = models.FloatField(validators=[MaxValueValidator(90), MinValueValidator(-90)], default=0)
    lng = models.FloatField(
        validators=[MaxValueValidator(180), MinValueValidator(-180)], default=0
    )
    is_decoded = models.BooleanField(default=False, db_index=True)
    timestamp = models.DateTimeField(null=True)

    class Meta:
        ordering = ['-timestamp']

    def __str__(self):
        return 'data-for-{0}'.format(self.satellite.norad_cat_id)

    def display_frame(self):
        """Returns the contents of the saved frame file for this DemodData

        :returns: the contents of the saved frame file for this DemodData
        """
        try:
            with open(self.payload_frame.path) as frame_file:
                return frame_file.read()
        except IOError as err:
            LOGGER.error(
                err, exc_info=True, extra={
                    'payload frame path': self.payload_frame.path,
                }
            )
            return None


post_save.connect(_gen_observer, sender=DemodData)
pre_save.connect(_set_is_decoded, sender=DemodData)