from __future__ import unicode_literals

from django import forms
from django.db import models
from django.db.models import signals

from .config import settings
from .utils import get_backend, max_cropping
from .widgets import ImageCropWidget


class ImageCropField(models.ImageField):
    def formfield(self, **kwargs):
        defaults = {'widget': ImageCropWidget}
        defaults.update(kwargs)
        return super(ImageCropField, self).formfield(**defaults)

    def south_field_triple(self):  # pragma: no cover
        """
        Return a suitable description of this field for South.
        """
        # We'll just introspect ourselves, since we inherit.
        from south.modelsinspector import introspector
        field_class = "django.db.models.fields.files.ImageField"
        args, kwargs = introspector(self)
        return (field_class, args, kwargs)


class ImageRatioField(models.CharField):
    def __init__(self, image_field, size='0x0', free_crop=False,
                 adapt_rotation=False, allow_fullsize=False, verbose_name=None,
                 help_text=None, hide_image_field=False,
                 size_warning=settings.IMAGE_CROPPING_SIZE_WARNING):
        if '__' in image_field:
            self.image_field, self.image_fk_field = image_field.split('__')
        else:
            self.image_field, self.image_fk_field = image_field, None
        self.width, self.height = list(map(int, size.split('x')))
        self.free_crop = free_crop
        self.adapt_rotation = adapt_rotation
        self.allow_fullsize = allow_fullsize
        self.size_warning = size_warning
        self.hide_image_field = hide_image_field
        self.box_max_width = settings.IMAGE_CROPPING_THUMB_SIZE[0]
        self.box_max_height = settings.IMAGE_CROPPING_THUMB_SIZE[1]
        field_kwargs = {
            'max_length': 255,
            'default': '',
            'blank': True,
            'verbose_name': verbose_name,
            'help_text': help_text
        }
        super(ImageRatioField, self).__init__(**field_kwargs)

    def deconstruct(self):  # pragma: no cover
        """
        Needed for Django 1.7+ migrations. Generate args and kwargs from current
        field values.
        """
        if self.image_fk_field:
            image_field = '%s__%s' % (self.image_field, self.image_fk_field)
        else:
            image_field = self.image_field

        args = (image_field, '%dx%d' % (self.width, self.height))
        kwargs = {
            'free_crop': self.free_crop,
            'adapt_rotation': self.adapt_rotation,
            'allow_fullsize': self.allow_fullsize,
            'verbose_name': self.verbose_name,
            'help_text': self.help_text,
            'hide_image_field': self.hide_image_field,
            'size_warning': self.size_warning,
        }
        return self.name, 'image_cropping.fields.ImageRatioField', args, kwargs

    def contribute_to_class(self, cls, name, **kwargs):
        super(ImageRatioField, self).contribute_to_class(cls, name, **kwargs)
        if not cls._meta.abstract:
            # attach a list of fields that are referenced by the ImageRatioField
            # so we can set the correct widget in the ModelAdmin
            if not hasattr(cls, 'crop_fields'):
                cls.add_to_class('crop_fields', {})
            cls.crop_fields[self.image_field] = {
                'fk_field': self.image_fk_field,
                'hidden': self.hide_image_field,
            }

            # attach ratiofields to cls
            if not hasattr(cls, 'ratio_fields'):
                cls.add_to_class('ratio_fields', [])
            cls.ratio_fields.append(name)

            signals.pre_save.connect(self.initial_cropping, sender=cls)

    def initial_cropping(self, sender, instance, *args, **kwargs):
        for ratiofieldname in getattr(instance, 'ratio_fields', []):
            # cropping already set?
            if getattr(instance, ratiofieldname):
                continue

            # get image
            ratiofield = instance._meta.get_field(ratiofieldname)
            image = getattr(instance, ratiofield.image_field)
            if ratiofield.image_fk_field and image:  # image is ForeignKey
                # get the imagefield
                image = getattr(image, ratiofield.image_fk_field)
            if not image:
                continue

            # calculate initial cropping
            width, height = (100, 100)
            try:
                width, height = (image.width, image.height)
            except AttributeError:
                width, height = get_backend().get_size(image)

            try:
                # handle corrupt or accidentally removed images
                box = max_cropping(ratiofield.width, ratiofield.height,
                                   width, height,
                                   free_crop=ratiofield.free_crop)
                box = ','.join(map(lambda i: str(i), box))
            except IOError:
                box = ''
            setattr(instance, ratiofieldname, box)

    def formfield(self, *args, **kwargs):
        ratio = self.width / float(self.height) if not self.free_crop else 0

        kwargs['widget'] = forms.TextInput(attrs={
            'data-min-width': self.width,
            'data-min-height': self.height,
            'data-box-max-width': self.box_max_width,
            'data-box-max-height': self.box_max_height,
            'data-ratio': str(ratio),
            'data-image-field': self.image_field,
            'data-my-name': self.name,
            'data-jquery-url': settings.IMAGE_CROPPING_JQUERY_URL,
            'data-adapt-rotation': str(self.adapt_rotation).lower(),
            'data-allow-fullsize': str(self.allow_fullsize).lower(),
            'data-size-warning': str(self.size_warning).lower(),
            'class': 'image-ratio',
        })
        return super(ImageRatioField, self).formfield(*args, **kwargs)

    def south_field_triple(self):  # pragma: no cover
        """
        Return a suitable description of this field for South.
        """
        # We'll just introspect ourselves, since we inherit.
        from south.modelsinspector import introspector
        field_class = "django.db.models.fields.CharField"
        args, kwargs = introspector(self)
        return (field_class, args, kwargs)