# -*- coding: utf-8 -*-
from __future__ import unicode_literals

from datetime import timedelta

from django.conf import settings
from django.core.exceptions import ValidationError
from django.db import models
from django.template.defaultfilters import slugify
from django.utils import timezone


def validate_duration(model, max_duration=timedelta(hours=24)):
    """
    Basic sanity checks for models with a duration
    :param model: a model instance with 'start' and 'end' attributes
    :param max_duration: maximum allowed duration between start and end time
    :return:
    """
    if model.start and model.end:
        if model.start > model.end:
            raise ValidationError(
                'Start time must come before end time.',
                code='end_before_start')
        if model.end - model.start > max_duration:
            raise ValidationError('Duration too long.', code='max_duration')


def validate_time(time, field_name):
    """
    Confirm that a time is not in the future.
    :param time: a timezone aware datetime instance.
    :param field_name: the name of the field being checked.
    :return:
    """
    if time > timezone.localtime():
        raise ValidationError(
            {field_name: 'Date/time can not be in the future.'},
            code='time_invalid')


class Child(models.Model):
    model_name = 'child'
    first_name = models.CharField(max_length=255)
    last_name = models.CharField(max_length=255)
    birth_date = models.DateField(blank=False, null=False)
    slug = models.SlugField(max_length=100, unique=True, editable=False)

    objects = models.Manager()

    class Meta:
        default_permissions = ('view', 'add', 'change', 'delete')
        ordering = ['last_name', 'first_name']
        verbose_name_plural = 'Children'

    def __str__(self):
        return '{} {}'.format(self.first_name, self.last_name)

    def save(self, *args, **kwargs):
        self.slug = slugify(self)
        super(Child, self).save(*args, **kwargs)

    def name(self, reverse=False):
        if reverse:
            return '{}, {}'.format(self.last_name, self.first_name)

        return '{} {}'.format(self.first_name, self.last_name)


class DiaperChange(models.Model):
    model_name = 'diaperchange'
    child = models.ForeignKey('Child', related_name='diaper_change')
    time = models.DateTimeField(blank=False, null=False)
    wet = models.BooleanField()
    solid = models.BooleanField()
    color = models.CharField(max_length=255, blank=True, choices=[
        ('black', 'Black'),
        ('brown', 'Brown'),
        ('green', 'Green'),
        ('yellow', 'Yellow'),
    ])

    objects = models.Manager()

    class Meta:
        default_permissions = ('view', 'add', 'change', 'delete')
        ordering = ['-time']

    def __str__(self):
        return 'Diaper Change'

    def attributes(self):
        attributes = []
        if self.wet:
            attributes.append(DiaperChange._meta.get_field('wet').name)
        if self.solid:
            attributes.append(DiaperChange._meta.get_field('solid').name)
        if self.color:
            attributes.append(self.color)
        return attributes

    def clean(self):
        validate_time(self.time, 'time')

        # One or both of Wet and Solid is required.
        if not self.wet and not self.solid:
            raise ValidationError(
                'Wet and/or solid is required.', code='wet_or_solid')

        # Color is required when Solid is selected.
        if self.solid and not self.color:
            raise ValidationError(
                {'color': 'Color is required for solid diaper changes.'},
                code='solid_color_required')


class Feeding(models.Model):
    model_name = 'feeding'
    child = models.ForeignKey('Child', related_name='feeding')
    start = models.DateTimeField(blank=False, null=False)
    end = models.DateTimeField(blank=False, null=False)
    duration = models.DurationField(null=True, editable=False)
    type = models.CharField(max_length=255, choices=[
        ('breast milk', 'Breast milk'),
        ('formula', 'Formula'),
    ])
    method = models.CharField(max_length=255, choices=[
        ('bottle', 'Bottle'),
        ('left breast', 'Left breast'),
        ('right breast', 'Right breast'),
    ])
    amount = models.FloatField(blank=True, null=True)

    objects = models.Manager()

    class Meta:
        default_permissions = ('view', 'add', 'change', 'delete')
        ordering = ['-start']

    def __str__(self):
        return 'Feeding'

    def save(self, *args, **kwargs):
        if self.start and self.end:
            self.duration = self.end - self.start
        super(Feeding, self).save(*args, **kwargs)

    def clean(self):
        validate_time(self.start, 'start')
        validate_time(self.end, 'end')
        validate_duration(self)

        # "Formula" Type may only be associated with "Bottle" Method.
        if self.type == 'formula'and self.method != 'bottle':
            raise ValidationError(
                {'method':
                 'Only "Bottle" method is allowed with "Formula" type.'},
                code='bottle_formula_mismatch')


class Note(models.Model):
    model_name = 'note'
    child = models.ForeignKey('Child', related_name='note')
    note = models.TextField()
    time = models.DateTimeField(auto_now=True)

    objects = models.Manager()

    class Meta:
        default_permissions = ('view', 'add', 'change', 'delete')
        ordering = ['-time']

    def __str__(self):
        return 'Note'


class Sleep(models.Model):
    model_name = 'sleep'
    child = models.ForeignKey('Child', related_name='sleep')
    start = models.DateTimeField(blank=False, null=False)
    end = models.DateTimeField(blank=False, null=False)
    duration = models.DurationField(null=True, editable=False)

    objects = models.Manager()

    class Meta:
        default_permissions = ('view', 'add', 'change', 'delete')
        ordering = ['-start']
        verbose_name_plural = 'Sleep'

    def __str__(self):
        return 'Sleep'

    def nap(self):
        # TODO: Add a way to filter naps from Sleep.objects() easily.
        nap_start_min = timezone.datetime.strptime(
            settings.BABY_BUDDY['NAP_START_MIN'], '%H:%M').time()
        nap_start_max = timezone.datetime.strptime(
            settings.BABY_BUDDY['NAP_START_MAX'], '%H:%M').time()
        local_start_time = timezone.localtime(self.start).time()
        return nap_start_min <= local_start_time <= nap_start_max

    def save(self, *args, **kwargs):
        if self.start and self.end:
            self.duration = self.end - self.start
        super(Sleep, self).save(*args, **kwargs)

    def clean(self):
        validate_time(self.start, 'start')
        validate_time(self.end, 'end')
        validate_duration(self)


class Timer(models.Model):
    model_name = 'timer'
    name = models.CharField(max_length=255, null=True, blank=True)
    start = models.DateTimeField(
        default=timezone.now,
        blank=False,
        verbose_name='Start Time'
    )
    end = models.DateTimeField(blank=True, null=True, editable=False)
    duration = models.DurationField(null=True, editable=False)
    active = models.BooleanField(default=True, editable=False)
    user = models.ForeignKey('auth.User', related_name='timers')

    objects = models.Manager()

    class Meta:
        default_permissions = ('view', 'add', 'change', 'delete')
        ordering = ['-active', '-start', '-end']

    def __str__(self):
        return self.name or 'Timer #{}'.format(self.id)

    @classmethod
    def from_db(cls, db, field_names, values):
        instance = super(Timer, cls).from_db(db, field_names, values)
        if not instance.duration:
            instance.duration = timezone.now() - instance.start
        return instance

    def restart(self):
        """Restart the timer."""
        self.start = timezone.now()
        self.end = None
        self.duration = None
        self.active = True
        self.save()

    def stop(self, end=None):
        """Stop the timer."""
        if not self.end:
            end = timezone.now()
        self.end = end
        self.save()

    def save(self, *args, **kwargs):
        self.active = self.end is None
        self.name = self.name or None
        if self.start and self.end:
            self.duration = self.end - self.start
        else:
            self.duration = None
        super(Timer, self).save(*args, **kwargs)

    def clean(self):
        validate_time(self.start, 'start')
        if self.end:
            validate_time(self.end, 'end')
        validate_duration(self)


class TummyTime(models.Model):
    model_name = 'tummytime'
    child = models.ForeignKey('Child', related_name='tummy_time')
    start = models.DateTimeField(blank=False, null=False)
    end = models.DateTimeField(blank=False, null=False)
    duration = models.DurationField(null=True, editable=False)
    milestone = models.CharField(max_length=255, blank=True)

    objects = models.Manager()

    class Meta:
        default_permissions = ('view', 'add', 'change', 'delete')
        ordering = ['-start']

    def __str__(self):
        return 'Tummy Time'

    def save(self, *args, **kwargs):
        if self.start and self.end:
            self.duration = self.end - self.start
        super(TummyTime, self).save(*args, **kwargs)

    def clean(self):
        validate_time(self.start, 'start')
        validate_time(self.end, 'end')
        validate_duration(self)