from django.db import models
from django.core.exceptions import ValidationError

def nonzero_validator(value):
	if value == 0:
		raise ValidationError("Must be non-zero value!")

ACCOUNT_OBJECT_CHOICES= (
	(0, "Optional"),
	(1, "Required"),
	(2, "Forbidden"),
)

class AccountClass(models.Model):
	name = models.CharField(max_length=100)
	inbalance = models.BooleanField(null=False, blank=False, default=False)
	balancenegative = models.BooleanField(null=False, blank=False, default=False)

	def __unicode__(self):
		return self.name

	class Meta:
		verbose_name = 'Account classes'
		ordering = ('name', )

class AccountGroup(models.Model):
	name = models.CharField(max_length=100)
	accountclass = models.ForeignKey(AccountClass, blank=False, default=False)
	foldable = models.BooleanField(null=False, blank=False, default=False)

	def __unicode__(self):
		return self.name

	class Meta:
		ordering = ('name', )

class Account(models.Model):
	num = models.IntegerField(verbose_name="Account number", unique=True)
	group = models.ForeignKey(AccountGroup, null=False, blank=False)
	name = models.CharField(max_length=100)
	availableforinvoicing = models.BooleanField(null=False, blank=False, default=False)
	objectrequirement = models.IntegerField(null=False, default=0, choices=ACCOUNT_OBJECT_CHOICES, verbose_name="Object requirements")

	def __unicode__(self):
		return "%s - %s" % (self.num, self.name)

	class Meta:
		ordering = ('num', )

class Year(models.Model):
	year = models.IntegerField(primary_key=True)
	isopen = models.BooleanField(null=False, blank=False)

	def __unicode__(self):
		if self.isopen:
			return "%s *" % self.year
		return "%s" % self.year

	class Meta:
		ordering = ('-year',)

class IncomingBalance(models.Model):
	year = models.ForeignKey(Year, null=False, blank=False)
	account = models.ForeignKey(Account, to_field='num', null=False, blank=False)
	amount = models.DecimalField(max_digits=10, decimal_places=2, null=False, blank=False, validators=[nonzero_validator,])

	def __unicode__(self):
		return "%s / %s" % (self.year_id, self.account)

	class Meta:
		ordering = ('year__pk', 'account')
		unique_together = (('year', 'account'),)


class Object(models.Model):
	name = models.CharField(max_length=30, null=False, blank=False)
	active = models.BooleanField(null=False, blank=False, default=True)

	def __unicode__(self):
		return self.name

	class Meta:
		ordering = ('name', )

class JournalEntry(models.Model):
	year = models.ForeignKey(Year, null=False, blank=False)
	seq = models.IntegerField(null=False, blank=False)
	date = models.DateField(null=False, blank=False)
	closed = models.BooleanField(blank=False, null=False, default=False)

	def __unicode__(self):
		return "%s-%04d (%s)" % (self.year.year, self.seq, self.date)

	class Meta:
		unique_together = (('year', 'seq'), )


class JournalItem(models.Model):
	journal = models.ForeignKey(JournalEntry, null=False, blank=False)
	account = models.ForeignKey(Account, to_field='num', null=False, blank=False)
	amount = models.DecimalField(max_digits=10, decimal_places=2, null=False, blank=False, validators=[nonzero_validator,])
	object = models.ForeignKey(Object, null=True, blank=True)
	description = models.CharField(max_length=200, null=False, blank=False)

	@property
	def debit(self):
		if self.amount > 0:
			return self.amount
		return ""

	@property
	def credit(self):
		if self.amount < 0:
			return -self.amount
		return ""

class JournalUrl(models.Model):
	journal = models.ForeignKey(JournalEntry, null=False, blank=False)
	url = models.URLField(null=False, blank=False)

	def __unicode__(self):
		return self.url