from django.db.models import Sum, Case, F, DecimalField, When

from core.apps.finance.models import Expence
from core.apps.finance.models import Income


def update_counterparty_balance(counterparty):
    if not counterparty:
        return
    
    expences = Expence.objects.filter(
        counterparty=counterparty,
        is_deleted=False,
    )
    
    debit_usd = expences.filter(currency='usd').aggregate(
        total=Sum('price')
    )['total'] or 0
    
    debit_uzs_direct = expences.filter(currency='uzs').aggregate(
        total=Sum('price')
    )['total'] or 0
    
    debit_uzs_from_usd = expences.filter(currency='usd').aggregate(
        total=Sum(
            Case(
                When(exchange_rate__gt=0, then=F('price') * F('exchange_rate') / 100),
                default=0,
                output_field=DecimalField()
            )
        )
    )['total'] or 0
    
    debit_uzs = debit_uzs_direct + debit_uzs_from_usd
    
    
    incomes = Income.objects.filter(
        counterparty=counterparty,
        is_deleted=False
    )
    
    kredit_usd = incomes.filter(currency='usd').aggregate(
        total=Sum('price')
    )['total'] or 0
    
    kredit_uzs_direct = incomes.filter(currency='uzs').aggregate(
        total=Sum('price')
    )['total'] or 0
    
    kredit_uzs_from_usd = incomes.filter(currency='usd').aggregate(
        total=Sum(
            Case(
                When(exchange_rate__gt=0, then=F('price') * F('exchange_rate') / 100),
                default=0,
                output_field=DecimalField()
            )
        )
    )['total'] or 0
    
    kredit_uzs = kredit_uzs_direct + kredit_uzs_from_usd
    
    
    total_debit = debit_usd + debit_uzs
    total_kredit = kredit_usd + kredit_uzs
    
    counterparty.debit_usd = debit_usd
    counterparty.debit_uzs = int(debit_uzs)
    counterparty.total_debit = int(total_debit)
    counterparty.kredit_usd = kredit_usd
    counterparty.kredit_uzs = int(kredit_uzs)
    counterparty.total_kredit = int(total_kredit)
    counterparty.save(update_fields=[
        'debit_usd', 'debit_uzs', 'total_debit',
        'kredit_usd', 'kredit_uzs', 'total_kredit'
    ])