# -*- coding: utf-8 -*-
from __future__ import print_function, unicode_literals
from __future__ import absolute_import
import os.path

from django.db import models
from django.utils.translation import ugettext_lazy as _
from django.utils.encoding import python_2_unicode_compatible
from django.conf import settings as django_settings

from . import settings

from wiki import managers
from wiki.models.pluginbase import ReusablePlugin
from wiki.models.article import BaseRevisionMixin
from django.db.models import signals
from six.moves import map
from six.moves import zip
from six.moves import range


class IllegalFileExtension(Exception):
    """File extension on upload is not allowed"""
    pass

@python_2_unicode_compatible
class Attachment(ReusablePlugin):

    objects = managers.ArticleFkManager()

    current_revision = models.OneToOneField(
        'AttachmentRevision', 
        verbose_name=_('current revision'),
        blank=True, null=True, related_name='current_set',
        help_text=_('The revision of this attachment currently in use (on all articles using the attachment)'),
    )
    
    original_filename = models.CharField(max_length=256, verbose_name=_('original filename'), blank=True, null=True)

    def can_write(self, user):
        if not settings.ANONYMOUS and (not user or user.is_anonymous()):
            return False
        return ReusablePlugin.can_write(self, user)
    
    def can_delete(self, user):
        return self.can_write(user)
    
    class Meta:
        verbose_name = _('attachment')
        verbose_name_plural = _('attachments')
        if settings.APP_LABEL:
            app_label = settings.APP_LABEL
    
    def __str__(self):
        return "%s: %s" % (self.article.current_revision.title, self.original_filename)    

def extension_allowed(filename):
    try:
        extension = filename.split(".")[-1]
    except IndexError:
        # No extension
        raise IllegalFileExtension(_("No file extension found in filename. That's not okay!"))
    if not extension.lower() in map(lambda x: x.lower(), settings.FILE_EXTENSIONS):
        raise IllegalFileExtension(_("The following filename is illegal: %s. Extension has to be one of %s") % 
                                   (filename, ", ".join(settings.FILE_EXTENSIONS)))
    
    return extension
    
def upload_path(instance, filename):
    from os import path
    
    extension = extension_allowed(filename)
    
    # Has to match original extension filename
    if instance.id and instance.attachment and instance.attachment.original_filename:
        original_extension = instance.attachment.original_filename.split(".")[-1]
        if not extension.lower() == original_extension:
            raise IllegalFileExtension("File extension has to be '%s', not '%s'." %
                                       (original_extension, extension.lower()))
    elif instance.attachment:
        instance.attachment.original_filename = filename
        
    upload_path = settings.UPLOAD_PATH
    upload_path = upload_path.replace('%aid', str(instance.attachment.article.id))
    if settings.UPLOAD_PATH_OBSCURIFY:
        import random, hashlib
        m=hashlib.md5(str(random.randint(0,100000000000000)).encode('ascii'))
        upload_path = path.join(upload_path, m.hexdigest())
        
    if settings.APPEND_EXTENSION:
        filename += '.upload'
    return path.join(upload_path, filename)


@python_2_unicode_compatible
class AttachmentRevision(BaseRevisionMixin, models.Model):
    
    attachment = models.ForeignKey('Attachment')

    file = models.FileField(upload_to=upload_path, #@ReservedAssignment
                            max_length=255,
                            verbose_name=_('file'),
                            storage=settings.STORAGE_BACKEND)
        
    description = models.TextField(blank=True)
    
    class Meta:
        verbose_name = _('attachment revision')
        verbose_name_plural = _('attachment revisions')
        ordering = ('created',)
        get_latest_by = 'revision_number'
        if settings.APP_LABEL:
            app_label = settings.APP_LABEL
        
    def get_filename(self):
        """Used to retrieve the filename of a revision.
        But attachment.original_filename should always be used in the frontend
        such that filenames stay consistent."""
        # TODO: Perhaps we can let file names change when files are replaced?
        if not self.file:
            return None
        filename = self.file.name.split("/")[-1]
        return ".".join(filename.split(".")[:-1])
    
    def get_size(self):
        """Used to retrieve the file size and not cause exceptions."""
        try:
            return self.file.size
        except OSError:
            return None
        except ValueError:
            return None
    
    def save(self, *args, **kwargs):
        if (not self.id and
            not self.previous_revision and 
            self.attachment and
            self.attachment.current_revision and 
            self.attachment.current_revision != self):
            
            self.previous_revision = self.attachment.current_revision

        if not self.revision_number:
            try:
                previous_revision = self.attachment.attachmentrevision_set.latest()
                self.revision_number = previous_revision.revision_number + 1
            # NB! The above should not raise the below exception, but somehow it does.
            except AttachmentRevision.DoesNotExist as noattach: 
                Attachment.DoesNotExist = noattach
                self.revision_number = 1
        
        super(AttachmentRevision, self).save(*args, **kwargs)
        
        if not self.attachment.current_revision:
            # If I'm saved from Django admin, then article.current_revision is me!
            self.attachment.current_revision = self
            self.attachment.save()

    def __str__(self):
        return "%s: %s (r%d)" % (self.attachment.article.current_revision.title, 
                                 self.attachment.original_filename,
                                 self.revision_number)    


def on_revision_delete(instance, *args, **kwargs):
    if not instance.file:
        return
    
    # Remove file
    path = instance.file.path.split("/")[:-1]
    instance.file.delete(save=False)
    
    # Clean up empty directories
    
    # Check for empty folders in the path. Delete the first two.
    if len(path[-1]) == 32:
        # Path was (most likely) obscurified so we should look 2 levels down
        max_depth = 2
    else:
        max_depth = 1
    for depth in range(0, max_depth):
        delete_path = "/".join(path[:-depth] if depth > 0 else path)
        try:
            if len(os.listdir(os.path.join(django_settings.MEDIA_ROOT, delete_path))) == 0:
                os.rmdir(delete_path)
        except OSError:
            # Raised by os.listdir if directory is missing
            pass

signals.pre_delete.connect(on_revision_delete, AttachmentRevision)
