import os
import random
import shutil
import zipfile

from datetime import datetime
from inspect import isclass

from django.db import models
from django.db.models.signals import post_init
from django.conf import settings
from django.core.files.base import ContentFile
from django.core.urlresolvers import reverse
from django.template.defaultfilters import slugify
from django.utils.functional import curry
from django.utils.translation import ugettext_lazy as _
from django.contrib.auth.models import User
from django.contrib.sites.managers import CurrentSiteManager
from django.contrib.sites.models import Site
from django_extensions.db.models import TimeStampedModel
from django_extensions.db.fields import AutoSlugField

from darkroom.managers import * 
from directory.models import Town, Place
from taggit.managers import TaggableManager
from taggit.models import Tag

# Required PIL classes may or may not be available from the root namespace
# depending on the installation method used.
try:
    import Image
    import ImageFile
    import ImageFilter
    import ImageEnhance
except ImportError:
    try:
        from PIL import Image
        from PIL import ImageFile
        from PIL import ImageFilter
        from PIL import ImageEnhance
    except ImportError:
        raise ImportError(_('Photologue was unable to import the Python Imaging Library. Please confirm it`s installed and available on your current Python path.'))

from utils import EXIF
from utils.image_entropy import image_entropy
from utils.reflection import add_reflection
from utils.watermark import apply_watermark

# Path to sample image
SAMPLE_IMAGE_PATH = getattr(settings, 'SAMPLE_IMAGE_PATH', os.path.join(os.path.dirname(__file__), 'res', 'sample.jpg')) # os.path.join(settings.PROJECT_PATH, 'darkroom', 'res', 'sample.jpg'

# Modify image file buffer size.
ImageFile.MAXBLOCK = getattr(settings, 'DARKROOM_MAXBLOCK', 256 * 2 ** 10)

# Photologue image path relative to media root
DARKROOM_DIR = getattr(settings, 'DARKROOM_DIR', 'darkroom/')

# Look for user function to define file paths
DARKROOM_PATH = getattr(settings, 'DARKROOM_PATH', None)
if DARKROOM_PATH is not None:
    if callable(DARKROOM_PATH):
        get_storage_path = DARKROOM_PATH
    else:
        parts = DARKROOM_PATH.split('.')
        module_name = '.'.join(parts[:-1])
        module = __import__(module_name)
        get_storage_path = getattr(module, parts[-1])
else:
    def get_storage_path(instance, filename):
        return os.path.join(DARKROOM_DIR, 'photos', filename)

# Quality options for JPEG images
JPEG_QUALITY_CHOICES = (
    (30, _('Very Low')),
    (40, _('Low')),
    (50, _('Medium-Low')),
    (60, _('Medium')),
    (70, _('Medium-High')),
    (80, _('High')),
    (90, _('Very High')),
    (100, _('Unchanged')),
)

# choices for new crop_anchor field in Photo
CROP_ANCHOR_CHOICES = (
    ('top', _('Top')),
    ('right', _('Right')),
    ('bottom', _('Bottom')),
    ('left', _('Left')),
    ('center', _('Center')),
    ('smart', _('Smart (Default)')),
)

IMAGE_TRANSPOSE_CHOICES = (
    ('FLIP_LEFT_RIGHT', _('Flip left to right')),
    ('FLIP_TOP_BOTTOM', _('Flip top to bottom')),
    ('ROTATE_90', _('Rotate 90 degrees counter-clockwise')),
    ('ROTATE_270', _('Rotate 90 degrees clockwise')),
    ('ROTATE_180', _('Rotate 180 degrees')),
)

WATERMARK_STYLE_CHOICES = (
    ('tile', _('Tile')),
    ('scale', _('Scale')),
)

IMAGE_ORIENTATION_CHOICES = (
    (0,_('no rotation')),
    (2,_('Rotate 90 degrees counter-clockwise')),
    (3,_('Rotate 180 degrees')),
    (4,_('Rotate 90 degrees clockwise')),
)

# see http://www.impulseadventure.com/photo/exif-orientation.html
IMAGE_EXIF_ORIENTATION_MAP = {
    1: 0,
    8: 2,
    3: 3,
    6: 4,
}

# Slideshow size choices, as dictated by the Soundslides application
# default ouputs.
SLIDESHOW_SIZE_CHOICES = (
    ('425x356', _('Small')),
    ('620x533', _('Standard')),
    ('800x596', _('Large')),
)

def _compare_entropy(start_slice, end_slice, slice, difference):
    """
    Calculate the entropy of two slices (from the start and end of an axis),
    returning a tuple containing the amount that should be added to the start
    and removed from the end of the axis.

    """
    start_entropy = image_entropy(start_slice)
    end_entropy = image_entropy(end_slice)
    if end_entropy and abs(start_entropy / end_entropy - 1) < 0.01:
        # Less than 1% difference, remove from both sides.
        if difference >= slice * 2:
            return slice, slice
        half_slice = slice // 2
        return half_slice, slice - half_slice
    if start_entropy > end_entropy:
        return 0, slice
    else:
        return slice, 0

# Prepare a list of image filters
filter_names = []
for n in dir(ImageFilter):
    klass = getattr(ImageFilter, n)
    if isclass(klass) and issubclass(klass, ImageFilter.BuiltinFilter) and \
        hasattr(klass, 'name'):
            filter_names.append(klass.__name__)
IMAGE_FILTERS_HELP_TEXT = _('Chain multiple filters using the following pattern "FILTER_ONE->FILTER_TWO->FILTER_THREE". Image filters will be applied in order. The following filters are available: %s.' % (', '.join(filter_names)))

# Next five functions streamline expanding zip files to folders
def path_name(name):
    return os.path.split(name)[0]

def file_name(name):
    return os.path.split(name)[1]

def path_names(names):
    return (name for name in names if path_name(name) and not file_name(name))

def file_names(names):
    return (name for name in names if file_name(name))

def extract(zipfile):
    SLIDE_PATH=settings.MEDIA_ROOT+DARKROOM_DIR+"slideshows/"
    names = zipfile.namelist()
    for name in path_names(names):
        if not os.path.exists(SLIDE_PATH+name): 
            if not name.find('__MACOSX'): # do not process meta or hidden files
                continue
            else:
                os.mkdir(SLIDE_PATH+name)
    for name in file_names(names):
        if name.startswith('__MACOSX'): # do not process meta or hidden files
            continue
        else:
            outfile = file(SLIDE_PATH+name, 'wb')
            outfile.write(zipfile.read(name))
        outfile.close()
    return names[0].split('/')[0] # Return the root folder for the model's sake

# End zip file to folder functions

class MediaMetadata(TimeStampedModel):
    title = models.CharField(_('title'), max_length=100)
    slug = AutoSlugField(_('slug'), populate_from='title', editable=True)
    description=models.TextField(_('description'), blank=True, null=True)
    published=models.BooleanField(_('published'), default=False, help_text=_('Published items will appear on all parts of the site.'))
    published_on = models.DateTimeField(_('date published'), blank=True)
    weight = models.IntegerField(_('Weight'), blank=True, null=True, max_length=2)
    towns = models.ManyToManyField(Town, blank=True, null=True)
    tags = TaggableManager(blank=True)
    auto_tag=models.BooleanField(_('auto-tag'), default=True)
    
    class Meta:
        unique_together=(("title", "slug"),)
        abstract=True

    def do_auto_tag(self):
        """
        Performs the auto-tagging work if necessary.
        
        Returns True if an additional save is required, False otherwise.
        """

        found = False
        if self.auto_tag:
            import re
            # don't clobber any existing tags!
            try:
                existing_ids = [t.id for t in self.tags.all()]
                unused = Tag.objects.all()
                unused = unused.exclude(id__in=existing_ids)
            except:
                unused = Tag.objects.all()

            for tag in unused:
                regex = re.compile(r'\b%s\b' % tag.name, re.I)
                if regex.search(self.description) or regex.search(self.title): 
                    self.tags.add(tag)
                    found = True

        return found

    def save(self, *args, **kwargs):
        
        super(TimeStampedModel, self).save(*args, **kwargs)
        
        requires_save = self.do_auto_tag()
        
        if requires_save:
            super(TimeStampedModel, self).save()

class Photographer(TimeStampedModel):
    name = models.CharField(_('name'), max_length=100)
    title = models.CharField(_('Title'), blank=True, null=True, max_length=100)
    slug = AutoSlugField(_('slug'), populate_from='name', editable=True)
    user = models.ForeignKey(User, blank=True, null=True)
    date_added = models.DateTimeField(_('date added'), default=datetime.now(), editable=False)
    
    class Meta:
        ordering = ('name',)
        get_latest_by = 'date_added'
    
    def __unicode__(self):
        return self.name
    
    def __str__(self):
        return self.__unicode__()
    
    def get_absolute_url(self):
        return reverse('dr-photographer', args=[self.slug])


class Slideshow(MediaMetadata):
    preview=models.ImageField(_('preview'), upload_to=get_storage_path, help_text="Slideshow previews are a standard 410 pixels wide by 276 pixels high")   
    folder=models.CharField(_('folder'), max_length=200, null=True, blank=True)
    size = models.CharField(_('size'), max_length=9, default='620x533', choices=SLIDESHOW_SIZE_CHOICES)
    
    class Meta:
        ordering =['created']
        get_latest_by='created'
        verbose_name=_('slideshow')
        verbose_name_plural=_('slideshows')
    
    def __unicode__(self):
        return self.title
    
    def __str__(self):
        return self.__unicode__()
    
    def get_absolute_url(self):
        return reverse('dr-slideshow-detail', args=[self.slug])
    
    def path(self):
            return 

    def delete(self):
        try:
            os.remove(self.folder)
        except:
            pass
        super(Slideshow, self).delete()

class SlideshowUpload(models.Model):
    zip_file = models.FileField(_('slideshow file (.zip)'), 
                                upload_to=DARKROOM_DIR+"/slideshows",
                                help_text=_('Select a .zip file with files to create a new Slideshow.'))
    slideshow=models.ForeignKey(Slideshow, null=True, blank=True)
    
    class Meta:
        verbose_name = _('slideshow upload')
        verbose_name_plural = _('slideshow uploads')
    
    def save(self, *args, **kwargs):
        super(SlideshowUpload, self).save(*args, **kwargs)
        self.process_zipfile()
        super(SlideshowUpload, self).delete()
    
    def process_zipfile(self):
        if os.path.isfile(self.zip_file.path):
            # TODO: implement try-except here
            zip = zipfile.ZipFile(self.zip_file.path)
            bad_file = zip.testzip()
            if bad_file:
                raise Exception('"%s" in the .zip archive is corrupt.' % bad_file)
            folder=extract(zip)
            slideshow = self.slideshow
            slideshow.folder = extract(zip) # Extract the zip contents, 
                                            # save the folder name to the model
            slideshow.save()
            zip.close()

class Webcam(models.Model):
    title = models.CharField(_('title'), max_length=80)
    slug = AutoSlugField(_('slug'), populate_from='title', editable=True)
    town = models.ForeignKey(Town, blank=True, null=True)
    image_file = models.CharField(_('webcam image location'), max_length=255)
    thumb_file = models.CharField(_('webcam thumbnail location'), max_length=255, blank=True, null=True)
    image_width = models.IntegerField(_('image width'), max_length=5, blank=True, null=True)
    image_height = models.IntegerField(_('image height'), max_length=5, blank=True, null=True)
    alt_text=models.CharField(_('alt text'), max_length=255, blank=True, null=True)
    description = models.TextField(_('description'), blank=True, null=True)
    ordering =models.IntegerField(_('order'), blank=True, null=True, max_length=3)
    
    class Meta:
        verbose_name=_('webcam')
        verbose_name_plural=_('webcams')
        ordering=['ordering']
    
    def __unicode__(self):
        return u'%s webcam' % self.title
    
    def get_absolute_url(self):
        return reverse('dr-webcam-detail', args=[self.slug])
        
class Gallery(MediaMetadata):
    preview = models.ImageField(_('graphic'), upload_to=DARKROOM_DIR+"/gallery-graphics", help_text="Gallery previews are a displayed at the top of the page if they exist.", null=True, blank=True)
    photos = models.ManyToManyField('Photo', related_name='gallery_photos', verbose_name=_('photos'), null=True, blank=True)
    slideshow=models.ForeignKey(Slideshow, null=True, blank=True)
    photographer=models.ForeignKey(Photographer, null=True, blank=True)
    sites=models.ManyToManyField(Site)

    objects = MediaManager()
    on_site = CurrentSiteManager('sites')

    class Meta:
        ordering = ['-created']
        get_latest_by = 'created'
        verbose_name = _('gallery')
        verbose_name_plural = _('galleries')
    
    def __unicode__(self):
        return self.title
    
    @models.permalink
    def get_absolute_url(self, site=''):
        return ('dr-gallery-detail', (), {
                'year': self.published_on.year,
                'month': self.published_on.strftime('%b').lower(),
                'day': self.published_on.day,
                'slug': self.slug})

    def last_photo(self):
        return self.photos.latest()
    
    def latest(self, limit=0, published=True):
        if limit == 0:
            limit = self.photo_count()
        if published:
            return self.published()[:limit]
        else:
            return self.photos.all()[:limit]
    
    def sample(self, count=0, published=True):
        if count == 0 or count > self.photo_count():
            count = self.photo_count()
        if published:
            photo_set = self.published()
        else:
            photo_set = self.photos.all()
        return random.sample(photo_set, count)
    
    def photo_count(self, published=True):
        if published:
            return self.published_photos().count()
        else:
            return self.photos.all().count()
    photo_count.short_description = _('count')
    
    def published_photos(self):
        return self.photos.filter(published=True).order_by('created')

    def save(self, *args, **kwargs):
        super(Gallery, self).save(*args, **kwargs)
        if self.photos:
            if self.published:
                for p in self.photos.all():
                    p.published=True
                    p.save()
            else: 
                for p in self.photos.all():
                    p.published=False
                    p.save()

class GalleryUpload(models.Model):
    zip_file = models.FileField(_('images file (.zip)'), upload_to=DARKROOM_DIR+"/temp",
                                help_text=_('Select a .zip file of images to upload into a new Gallery.'))
    gallery = models.ForeignKey(Gallery, null=True, blank=True, help_text=_('Select a gallery to add these images to. leave this empty to create a new gallery from the supplied title.'))
    title = models.CharField(_('title'), blank=True, null=True, help_text=_('Used to create a gallery if none is specified.'), max_length=140)
    description = models.TextField(_('description'), blank=True, help_text=_('Descrpition will be added to all photos.'))
    photographer=models.ForeignKey(Photographer, null=True, blank=True)
    
    class Meta:
        verbose_name = _('gallery upload')
        verbose_name_plural = _('gallery uploads')
    
    def save(self):
        super(GalleryUpload, self).save(*args, **kwargs)
        self.process_zipfile()
        super(GalleryUpload, self).delete()
    
    def process_zipfile(self):
        if os.path.isfile(self.zip_file.path):
            # TODO: implement try-except here
            zip = zipfile.ZipFile(self.zip_file.path)
            bad_file = zip.testzip()
            if bad_file:
                raise Exception('"%s" in the .zip archive is corrupt.' % bad_file)
            count = 1
            if self.gallery:
                gallery = self.gallery
            else:
                gallery = Gallery.objects.create(title=self.title,
                                                 slug=slugify(self.title),
                                                 description=self.description,
                                                 photographer=self.photographer)
            from cStringIO import StringIO
            for filename in zip.namelist():
                if filename.startswith('__'): # do not process meta files
                    continue
                data = zip.read(filename)
                if len(data):
                    try:
                        # the following is taken from django.newforms.fields.ImageField:
                        #  load() is the only method that can spot a truncated JPEG,
                        #  but it cannot be called sanely after verify()
                        trial_image = Image.open(StringIO(data))
                        trial_image.load()
                        # verify() is the only method that can spot a corrupt PNG,
                        #  but it must be called immediately after the constructor
                        trial_image = Image.open(StringIO(data))
                        trial_image.verify()
                    except Exception:
                        # if a "bad" file is found we just skip it.
                        continue
                    while 1:
                        title = ' '.join([gallery.title, str(count)])
                        slug = slugify(title)
                        try:
                            p = Photo.objects.get(slug=slug)
                        except Photo.DoesNotExist:
                            photo = Photo(title=title, slug=slug,
                                          published_on=gallery.published_on,
                                          description=self.description,
                                          published=gallery.published,
                                          photographer=self.photographer)
                            photo.image.save(filename, ContentFile(data))
                            # If EXIF data exists for comment and headline, set appropriate image info
                            #if photo.EXIF['Image ImageDescription']:
                            #    photo.description=unicode(photo.EXIF['Image ImageDescription'])
                            #else:
                            #    pass
                            #if photo.EXIF['Image DocumentName']:
                            #    photo.title=photo.EXIFunicode(['Image DocumentName'])
                            #    photo.slug=slugify(photo.EXIF['Image DocumentName'])
                            #else:
                            #    pass
                            photo.save()
                            gallery.photos.add(photo)
                            count = count + 1
                            break
                        count = count + 1
            zip.close()


class ImageModel(MediaMetadata):
    view_count = models.PositiveIntegerField(default=0, editable=False)
    crop_from = models.CharField(_('crop from'), blank=True, max_length=10, default='center', choices=CROP_ANCHOR_CHOICES)
    effect = models.ForeignKey('PhotoEffect', null=True, blank=True, related_name="%(class)s_related", verbose_name=_('effect'))
    orientation = models.IntegerField(_('Orientation'), choices=IMAGE_ORIENTATION_CHOICES, null=True, blank=True)
    
    class Meta:
        abstract = True
    
    @property
    def EXIF(self):
        try:
            return EXIF.process_file(open(self.image.path, 'rb'))
        except:
            try:
                return EXIF.process_file(open(self.image.path, 'rb'), details=False)
            except:
                return {}
    
    def admin_thumbnail(self):
        func = getattr(self, 'get_admin_thumbnail_url', None)
        if func is None:
            return _('An "admin_thumbnail" photo size has not been defined.')
        else:
            if hasattr(self, 'get_absolute_url'):
                return u'<a href="%s"><img src="%s"></a>' % \
                    (self.get_absolute_url(), func())
            else:
                return u'<a href="%s"><img src="%s"></a>' % \
                    (self.image.url, func())
    admin_thumbnail.short_description = _('Thumbnail')
    admin_thumbnail.allow_tags = True
    
    def cache_path(self):
        return os.path.join(os.path.dirname(self.image.path), "cache")
    
    def cache_url(self):
        return '/'.join([os.path.dirname(self.image.url), "cache"])
    
    def image_filename(self):
        return os.path.basename(self.image.path)
    
    def _get_filename_for_size(self, size):
        size = getattr(size, 'name', size)
        base, ext = os.path.splitext(self.image_filename())
        return ''.join([base, '_', size, ext])
    
    def _get_SIZE_photosize(self, size):
        return PhotoSizeCache().sizes.get(size)
    
    def _get_SIZE_size(self, size):
        photosize = PhotoSizeCache().sizes.get(size)
        if not self.size_exists(photosize):
            self.create_size(photosize)
        return Image.open(self._get_SIZE_filename(size)).size
    
    def _get_SIZE_url(self, size):
        photosize = PhotoSizeCache().sizes.get(size)
        if not self.size_exists(photosize):
            self.create_size(photosize)
        if photosize.increment_count:
            self.view_count += 1
            self.save(update=True)
        return '/'.join([self.cache_url(), self._get_filename_for_size(photosize.name)])
    
    def _get_SIZE_filename(self, size):
        photosize = PhotoSizeCache().sizes.get(size)
        return os.path.join(self.cache_path(),
                            self._get_filename_for_size(photosize.name))
    
    def add_accessor_methods(self, *args, **kwargs):
        for size in PhotoSizeCache().sizes.keys():
            setattr(self, 'get_%s_size' % size,
                    curry(self._get_SIZE_size, size=size))
            setattr(self, 'get_%s_photosize' % size,
                    curry(self._get_SIZE_photosize, size=size))
            setattr(self, 'get_%s_url' % size,
                    curry(self._get_SIZE_url, size=size))
            setattr(self, 'get_%s_filename' % size,
                    curry(self._get_SIZE_filename, size=size))
    
    def size_exists(self, photosize):
        func = getattr(self, "get_%s_filename" % photosize.name, None)
        if func is not None:
            if os.path.isfile(func()):
                return True
        return False
    
    def resize_image(self, im, photosize):
        cur_width, cur_height = im.size
        new_width, new_height = photosize.size
        if photosize.crop:
            ratio = max(float(new_width)/cur_width,float(new_height)/cur_height)
            x = (cur_width * ratio)
            y = (cur_height * ratio)
            xd = abs(new_width - x)
            yd = abs(new_height - y)
            x_diff = int(xd / 2)
            y_diff = int(yd / 2)
            if self.crop_from == 'top':
                box = (int(x_diff), 0, int(x_diff+new_width), new_height)
            elif self.crop_from == 'left':
                box = (0, int(y_diff), new_width, int(y_diff+new_height))
            elif self.crop_from == 'bottom':
                box = (int(x_diff), int(yd), int(x_diff+new_width), int(y)) # y - yd = new_height
            elif self.crop_from == 'right':
                box = (int(xd), int(y_diff), int(x), int(y_diff+new_height)) # x - xd = new_width
            elif self.crop_from == 'smart':
                left = top = 0
                right, bottom = x, y
                while xd:
                    slice = min(xd, max(xd // 5, 10))
                    start = im.crop((left, 0, left + slice, y))
                    end = im.crop((right - slice, 0, right, y))
                    add, remove = _compare_entropy(start, end, slice, xd)
                    left += add
                    right -= remove
                    xd = xd - add - remove
                while yd:
                    slice = min(yd, max(yd // 5, 10))
                    start = im.crop((0, top, x, top + slice))
                    end = im.crop((0, bottom - slice, x, bottom))
                    add, remove = _compare_entropy(start, end, slice, yd)
                    top += add
                    bottom -= remove
                    yd = yd - add - remove
                box = (left, top, right, bottom)
            else:
                box = (int(x_diff), int(y_diff), int(x_diff+new_width), int(y_diff+new_height))
            im = im.resize((int(x), int(y)), Image.ANTIALIAS).crop(box)
        else:
            if not new_width == 0 and not new_height == 0:
                ratio = min(float(new_width)/cur_width,
                            float(new_height)/cur_height)
            else:
                if new_width == 0:
                    ratio = float(new_height)/cur_height
                else:
                    ratio = float(new_width)/cur_width
            new_dimensions = (int(round(cur_width*ratio)),
                              int(round(cur_height*ratio)))
            if new_dimensions[0] > cur_width or \
               new_dimensions[1] > cur_height:
                if not photosize.upscale:
                    return im
            im = im.resize(new_dimensions, Image.ANTIALIAS)
        return im
    
    def create_size(self, photosize):
        if self.size_exists(photosize):
            return
        if not os.path.isdir(self.cache_path()):
            os.makedirs(self.cache_path())
        try:
            im = Image.open(self.image.path)
        except IOError:
            return
        # Apply effect if found
        if self.effect is not None:
            im = self.effect.pre_process(im)
        elif photosize.effect is not None:
            im = photosize.effect.pre_process(im)
        # Resize/crop image
        if im.size != photosize.size:
            im = self.resize_image(im, photosize)
        # Apply watermark if found
        if photosize.watermark is not None:
            im = photosize.watermark.post_process(im)
        # Apply effect if found
        if self.effect is not None:
            im = self.effect.post_process(im)
        elif photosize.effect is not None:
            im = photosize.effect.post_process(im)
        if self.orientation is not None and self.orientation > 0:
            im = im.transpose(self.orientation)
        # Save file
        im_filename = getattr(self, "get_%s_filename" % photosize.name)()
        try:
            if im.format == 'JPEG':
                im.save(im_filename, 'JPEG', quality=int(photosize.quality), optimize=True)
            else:
                im.save(im_filename)
        except IOError, e:
            if os.path.isfile(im_filename):
                os.unlink(im_filename)
            raise e
    
    def remove_size(self, photosize, remove_dirs=True):
        if not self.size_exists(photosize):
            return
        filename = getattr(self, "get_%s_filename" % photosize.name)()
        if os.path.isfile(filename):
            os.remove(filename)
        if remove_dirs:
            self.remove_cache_dirs()
    
    def clear_cache(self):
        cache = PhotoSizeCache()
        for photosize in cache.sizes.values():
            self.remove_size(photosize, False)
        self.remove_cache_dirs()
    
    def pre_cache(self):
        cache = PhotoSizeCache()
        for photosize in cache.sizes.values():
            if photosize.pre_cache:
                self.create_size(photosize)
    
    def remove_cache_dirs(self):
        try:
            os.removedirs(self.cache_path())
        except:
            pass
    
    def save(self, update=False, *args, **kwargs):
        if update:
            models.Model.save(self)
            return
        exif_title=self.EXIF.get('Image DocumentName', None)
        exif_description=self.EXIF.get('Image UserComment', None)
        if exif_title is not None:
            self.title=exif_title
            self.slug=slugify(exif_title)
        if exif_description is not None: 
            self.description=exif_description
        if self.date_taken:
            if self.date_taken is None:
                try:
                    exif_date = self.EXIF.get('EXIF DateTimeOriginal', None)

                    if exif_date is not None:
                        d, t = str.split(exif_date.values)
                        year, month, day = d.split(':')
                        hour, minute, second = t.split(':')
                        self.date_taken = datetime(int(year), int(month), int(day),
                                                   int(hour), int(minute), int(second))
                except:
                    self.date_taken = datetime.now()
        if self.orientation is None:
            try:
                exif_orientation = self.EXIF.get('Image Orientation', 1).values[0]
                self.orientation = IMAGE_EXIF_ORIENTATION_MAP[exif_orientation]
            except:
                self.orientation = 0
        if self._get_pk_val():
            self.clear_cache()
        super(ImageModel, self).save(*args, **kwargs)
        self.pre_cache()
    
    def delete(self):
        self.clear_cache()
        super(ImageModel, self).delete()

class Movie(MediaMetadata):
    flv_video = models.FileField(_('video file (.flv)'), upload_to=DARKROOM_DIR+"/movies")
    original_video = models.FileField(_('original file'), upload_to=DARKROOM_DIR+"/movies", blank=True, null=True, help_text=_('The original video preferably in a standard format like H.264.'))
    flash_skin = models.CharField(_('flash player skin'), blank=False, null=True, max_length=100, help_text=_("Do not include the .swf extension with the skin name."))    
    photographer = models.ForeignKey(Photographer, blank=True, null=True)
    preview=models.ImageField(_('preview'), upload_to=get_storage_path, help_text="Movie previews are a standard 70 pixels wide by 50 pixels high")   
    
    objects = MediaManager()

    class Meta:
        ordering=['-created']
        get_latest_by='created'
        verbose_name=_('movie')
        verbose_name_plural=_('movies')
        
    def __unicode__(self):
        return self.title
        
    def __str__(self):
        return self.__unicode__()
        
    def get_absolute_url(self):
        return reverse('dr-movie-detail', args=[self.slug])

class Photo(ImageModel):
    image = models.ImageField(_('Image'), upload_to=get_storage_path)
    cropped_image = models.ImageField(_('Cropped image'), blank=True, null=True, upload_to='darkroom/cropped/')
    date_taken = models.DateTimeField(_('Date taken'), null=True, blank=True, editable=False)
    photographer = models.ForeignKey(Photographer, blank=True, null=True)
    courtesy=models.CharField(_('Courtesy'), max_length=140, blank=True, null=True)
    file_photo=models.BooleanField(_('File photo?'), default=False)
    sites=models.ManyToManyField(Site)

    objects = MediaManager()
    on_site = CurrentSiteManager('sites')
    
    class Meta:
        ordering = ['-created']
        get_latest_by = 'published_on'
        verbose_name = _("photo")
        verbose_name_plural = _("photos")
    
    def __unicode__(self):
        return self.title
    
    def save(self, update=False):
        if self.slug is None:
            self.slug = slugify(self.title)
        super(Photo, self).save(update)
    
    @models.permalink
    def get_absolute_url(self, site=''):
        return ('dr-photo-detail', (), {
                'year': self.published_on.year,
                'month': self.published_on.strftime('%b').lower(),
                'day': self.published_on.day,
                'slug': self.slug})
    
    def get_lb_url(self):
        return reverse('dr-photo-lightbox', args=[self.slug])

    def published_galleries(self):
        """Return the published galleries to which this photo belongs."""
        return self.galleries.filter(published=True)
    
    def get_previous_in_gallery(self, gallery):
        try:
            return self.get_previous_by_published_on(galleries__exact=gallery)
        except Photo.DoesNotExist:
            return None
    
    def get_next_in_gallery(self, gallery):
        try:
            return self.get_next_by_published_on(galleries__exact=gallery)
        except Photo.DoesNotExist:
            return None

class Graphic(ImageModel):
    image = models.ImageField(_('image'), upload_to=DARKROOM_DIR+"/graphics")
    date_taken = models.DateTimeField(_('date created'), null=True, blank=True, editable=False)
    data_source=models.CharField(_('data source'), blank=True, null=True, max_length=150)
    source=models.ForeignKey(Place, blank=True, null=True)
    
    class Meta:
        ordering=['-created']
        get_latest_by='created'
        verbose_name=_("graphic")
        verbose_name_plural=_("graphics")
        
    def __unicode__(self):
        return self.title
        
    def __str__(self):
        return self.__unicode__()

    @models.permalink
    def get_absolute_url(self, site=''):
        return ('dr-graphic-detail', (), {
                'year': self.published_on.year,
                'month': self.published_on.strftime('%b').lower(),
                'day': self.published_on.day,
                'slug': self.slug})

class BaseEffect(models.Model):
    name = models.CharField(_('name'), max_length=30, unique=True)
    description = models.TextField(_('description'), blank=True)
    
    class Meta:
        abstract = True
    
    def sample_dir(self):
        return os.path.join(settings.MEDIA_ROOT, DARKROOM_DIR, 'samples')
    
    def sample_url(self):
        return settings.MEDIA_URL + '/'.join([DARKROOM_DIR, 'samples', '%s %s.jpg' % (self.name.lower(), 'sample')])
    
    def sample_filename(self):
        return os.path.join(self.sample_dir(), '%s %s.jpg' % (self.name.lower(), 'sample'))
    
    def create_sample(self):
        if not os.path.isdir(self.sample_dir()):
            os.makedirs(self.sample_dir())
        try:
            im = Image.open(SAMPLE_IMAGE_PATH)
        except IOError:
            raise IOError('Photologue was unable to open the sample image: %s.' % SAMPLE_IMAGE_PATH)
        im = self.process(im)
        im.save(self.sample_filename(), 'JPEG', quality=90, optimize=True)
    
    def admin_sample(self):
        return u'<img src="%s">' % self.sample_url()
    admin_sample.short_description = 'Sample'
    admin_sample.allow_tags = True
    
    def pre_process(self, im):
        return im
    
    def post_process(self, im):
        return im
    
    def process(self, im):
        im = self.pre_process(im)
        im = self.post_process(im)
        return im
    
    def __unicode__(self):
        return self.name
    
    def __str__(self):
        return self.__unicode__()
    
    def save(self):
        try:
            os.remove(self.sample_filename())
        except:
            pass
        models.Model.save(self)
        self.create_sample()
        for size in self.photo_sizes.all():
            size.clear_cache()
        # try to clear all related subclasses of ImageModel
        for prop in [prop for prop in dir(self) if prop[-8:] == '_related']:
            for obj in getattr(self, prop).all():
                obj.clear_cache()
                obj.pre_cache()
    
    def delete(self):
        try:
            os.remove(self.sample_filename())
        except:
            pass
        super(PhotoEffect, self).delete()

class PhotoEffect(BaseEffect):
    """ A pre-defined effect to apply to photos """
    transpose_method = models.CharField(_('rotate or flip'), max_length=15, blank=True, choices=IMAGE_TRANSPOSE_CHOICES)
    color = models.FloatField(_('color'), default=1.0, help_text=_("A factor of 0.0 gives a black and white image, a factor of 1.0 gives the original image."))
    brightness = models.FloatField(_('brightness'), default=1.0, help_text=_("A factor of 0.0 gives a black image, a factor of 1.0 gives the original image."))
    contrast = models.FloatField(_('contrast'), default=1.0, help_text=_("A factor of 0.0 gives a solid grey image, a factor of 1.0 gives the original image."))
    sharpness = models.FloatField(_('sharpness'), default=1.0, help_text=_("A factor of 0.0 gives a blurred image, a factor of 1.0 gives the original image."))
    filters = models.CharField(_('filters'), max_length=200, blank=True, help_text=_(IMAGE_FILTERS_HELP_TEXT))
    reflection_size = models.FloatField(_('size'), default=0, help_text=_("The height of the reflection as a percentage of the orignal image. A factor of 0.0 adds no reflection, a factor of 1.0 adds a reflection equal to the height of the orignal image."))
    reflection_strength = models.FloatField(_('strength'), default=0.6, help_text="The initial opacity of the reflection gradient.")
    background_color = models.CharField(_('color'), max_length=7, default="#FFFFFF", help_text="The background color of the reflection gradient. Set this to match the background color of your page.")
    
    class Meta:
        verbose_name = _("photo effect")
        verbose_name_plural = _("photo effects")
        
    def pre_process(self, im):
        if self.transpose_method != '':
            method = getattr(Image, self.transpose_method)
            im = im.transpose(method)
        if im.mode != 'RGB' and im.mode != 'RGBA':
            return im
        for name in ['Color', 'Brightness', 'Contrast', 'Sharpness']:
            factor = getattr(self, name.lower())
            if factor != 1.0:
                im = getattr(ImageEnhance, name)(im).enhance(factor)
        for name in self.filters.split('->'):
            image_filter = getattr(ImageFilter, name.upper(), None)
            if image_filter is not None:
                try:
                    im = im.filter(image_filter)
                except ValueError:
                    pass
        return im
        
    def post_process(self, im):
        if self.reflection_size != 0.0:
            im = add_reflection(im, bgcolor=self.background_color, amount=self.reflection_size, opacity=self.reflection_strength)
        return im
        

class Watermark(BaseEffect):
    image = models.ImageField(_('image'), upload_to=DARKROOM_DIR+"/watermarks")
    style = models.CharField(_('style'), max_length=5, choices=WATERMARK_STYLE_CHOICES, default='scale')
    opacity = models.FloatField(_('opacity'), default=1, help_text=_("The opacity of the overlay."))
    
    class Meta:
        verbose_name = _('watermark')
        verbose_name_plural = _('watermarks')
        
    def post_process(self, im):
        mark = Image.open(self.image.path)
        return apply_watermark(im, mark, self.style, self.opacity)
        

class PhotoSize(models.Model):
    name = models.CharField(_('name'), max_length=20, unique=True, help_text=_('Photo size name should contain only letters, numbers and underscores. Examples: "thumbnail", "display", "small", "main_page_widget".'))
    width = models.PositiveIntegerField(_('width'), default=0, help_text=_('If width is set to "0" the image will be scaled to the supplied height.'))
    height = models.PositiveIntegerField(_('height'), default=0, help_text=_('If height is set to "0" the image will be scaled to the supplied width'))
    quality = models.PositiveIntegerField(_('quality'), choices=JPEG_QUALITY_CHOICES, default=70, help_text=_('JPEG image quality.'))
    upscale = models.BooleanField(_('upscale images?'), default=False, help_text=_('If selected the image will be scaled up if necessary to fit the supplied dimensions. Cropped sizes will be upscaled regardless of this setting.'))
    crop = models.BooleanField(_('crop to fit?'), default=False, help_text=_('If selected the image will be scaled and cropped to fit the supplied dimensions.'))
    pre_cache = models.BooleanField(_('pre-cache?'), default=False, help_text=_('If selected this photo size will be pre-cached as photos are added.'))
    increment_count = models.BooleanField(_('increment view count?'), default=False, help_text=_('If selected the image\'s "view_count" will be incremented when this photo size is displayed.'))
    effect = models.ForeignKey('PhotoEffect', null=True, blank=True, related_name='photo_sizes', verbose_name=_('photo effect'))
    watermark = models.ForeignKey('Watermark', null=True, blank=True, related_name='photo_sizes', verbose_name=_('watermark image'))
    
    class Meta:
        ordering = ['width', 'height']
        verbose_name = _('photo size')
        verbose_name_plural = _('photo sizes')
        
    def __unicode__(self):
        return self.name
        
    def __str__(self):
        return self.__unicode__()
        
    def clear_cache(self):
        for cls in ImageModel.__subclasses__():
            for obj in cls.objects.all():
                obj.remove_size(self)
                if self.pre_cache:
                    obj.create_size(self)
        PhotoSizeCache().reset()
        
    def save(self, *args, **kwargs):
        if self.width + self.height <= 0:
            raise ValueError(_('A PhotoSize must have a positive height or width.'))
        super(PhotoSize, self).save(*args, **kwargs)
        PhotoSizeCache().reset()
        self.clear_cache()
        
    def delete(self):
        self.clear_cache()
        super(PhotoSize, self).delete()
        
    def _get_size(self):
        return (self.width, self.height)
    def _set_size(self, value):
        self.width, self.height = value
    size = property(_get_size, _set_size)

class PhotoSizeCache(object):
    __state = {"sizes": {}}
    
    def __init__(self):
        self.__dict__ = self.__state
        if not len(self.sizes):
            sizes = PhotoSize.objects.all()
            for size in sizes:
                self.sizes[size.name] = size
                
    def reset(self):
        self.sizes = {}


# Set up the accessor methods
def add_methods(sender, instance, signal, *args, **kwargs):
    """ Adds methods to access sized images (urls, paths)

    after the Photo model's __init__ function completes,
    this method calls "add_accessor_methods" on each instance.
    """
    if hasattr(instance, 'add_accessor_methods'):
        instance.add_accessor_methods()

# connect the add_accessor_methods function to the post_init signal
post_init.connect(add_methods)