bgneal@515: """
bgneal@515: Tools for the Photo of the Day (potd) application.
bgneal@515: 
bgneal@515: """
bgneal@515: import random
bgneal@515: import logging
bgneal@515: 
bgneal@515: from potd.models import Current, Sequence, Photo
bgneal@515: 
bgneal@515: 
bgneal@515: logger = logging.getLogger(__name__)
bgneal@515: 
bgneal@515: 
bgneal@515: def get_sequence():
bgneal@515:     """
bgneal@515:     Reads the photo sequence object from the database and converts it into a
bgneal@515:     list of photo IDs. If the sequence object is not found, and empty list is
bgneal@515:     returned.
bgneal@515: 
bgneal@515:     """
bgneal@515:     try:
bgneal@515:         s = Sequence.objects.get(pk=1)
bgneal@515:     except Sequence.DoesNotExist:
bgneal@515:         return []
bgneal@515: 
bgneal@515:     return [int(x) for x in s.seq.split(',')]
bgneal@515: 
bgneal@515: 
bgneal@515: def new_sequence():
bgneal@515:     """
bgneal@515:     Generates a new random sequence of photos and saves it to the database.
bgneal@515:     The sequence is returned as a list of photo IDs.
bgneal@515: 
bgneal@515:     """
bgneal@515:     ids = list(Photo.objects.values_list('id', flat=True))
bgneal@515:     random.shuffle(ids)
bgneal@515: 
bgneal@515:     try:
bgneal@515:         s = Sequence.objects.get(pk=1)
bgneal@515:     except Sequence.DoesNotExist:
bgneal@515:         s = Sequence()
bgneal@515: 
bgneal@515:     s.seq = ','.join([str(n) for n in ids])
bgneal@515:     s.save()
bgneal@515:     return ids
bgneal@515: 
bgneal@515: 
bgneal@515: def pick_potd():
bgneal@515:     """
bgneal@515:     Chooses the next POTD. Run this command at midnight to update the POTD.
bgneal@515: 
bgneal@515:     """
bgneal@515:     # Get the "current" record for the now old POTD:
bgneal@515:     try:
bgneal@515:         c = Current.objects.get(pk=1)
bgneal@515:         current = c.potd.pk
bgneal@515:     except Current.DoesNotExist:
bgneal@515:         c = Current()
bgneal@515:         current = None
bgneal@515: 
bgneal@515:     # Get the sequence of photo ID's:
bgneal@515:     seq = get_sequence()
bgneal@515: 
bgneal@515:     # If there is no current object, sequence, or if this was the last POTD in
bgneal@515:     # the sequence, generate a new random sequence:
bgneal@515: 
bgneal@515:     if current is None or not seq or current == seq[-1]:
bgneal@515:         # time to generate a new random sequence
bgneal@515:         seq = new_sequence()
bgneal@515:         # set current to the first one in the sequence
bgneal@515:         if seq:
bgneal@515:             try:
bgneal@515:                 c.potd = Photo.objects.get(pk=seq[0])
bgneal@515:             except Photo.DoesNotExist:
bgneal@515:                 logger.error("POTD: missing photo %d", seq[0])
bgneal@515:             else:
bgneal@515:                 c.potd.potd_count += 1
bgneal@515:                 c.potd.save()
bgneal@515:                 c.save()
bgneal@515:     else:
bgneal@515:         # find current in the sequence, pick the next one
bgneal@515:         try:
bgneal@515:             i = seq.index(current)
bgneal@515:         except ValueError:
bgneal@515:             logger.error("POTD: current photo (%d) not in sequence", current)
bgneal@515:             return
bgneal@515: 
bgneal@515:         n = i + 1
bgneal@515:         try:
bgneal@515:             c.potd = Photo.objects.get(pk=seq[n])
bgneal@515:         except Photo.DoesNotExist:
bgneal@515:             logger.error("POTD: missing next photo %d", n)
bgneal@515:         else:
bgneal@515:             c.potd.potd_count += 1
bgneal@515:             c.potd.save()
bgneal@515:             c.save()