Break up the times into discrete shifts

[Tim Heap]

Have a distinct record for a person / day, register availability as PersonDay / shift:

class PersonDay(models.Model):
    person = models.ForeignKey(Person)
    day = models.DateField()

    class Meta:
        unique_together = [
            ('person', 'day'),
        ]

class Availablilty(models.Model):
    personday = models.ForeignKey(PersonDay)
    shift = models.ForeignKey(Shift)
    AVAILABILITY_CHOICES = [
        ('available', 'Available'),
        ('working', 'Working - Available'),
        ('rest', 'Rest day'),
    ]
    availability = models.CharField(choices=AVAILABILITY_CHOICES)

Show unavailable by a PersonDay with no Availability. Show shifts in the big ol' table, instead of blobs of time. Colour days that have been processed differently than days that have not.

[Tim Heap]

Done!