from django.db import transaction

from rest_framework import serializers

from core.apps.finance.models import Expence
from core.apps.notifications.utils.notify_user import notify_user


class ExpenceCreateSerializer(serializers.ModelSerializer):
    class Meta:
        model = Expence
        fields = [
            'cash_transaction', 'payment_type', 'project_folder', 'project', 'expence_type',
            'counterparty', 'price', 'exchange_rate', 'currency', 'date', 'comment', 'audit', 'file'
        ]
    
    def validate(self, data):
        cash_transaction = data.get('cash_transaction')
        payment_type = data.get('payment_type')
        price = data.get('price')
        exchange_rate = data.get('exchange_rate', 1)
        currency = data.get('currency', 'uzs')
        
        final_price = price
        
        if currency == 'uzs' and payment_type.total_uzs < final_price:
            raise serializers.ValidationError(f"Yetarli UZS balansi yo'q. Mavjud: {payment_type.total_uzs}")
        elif currency == 'usd' and payment_type.total_usd < final_price:
            raise serializers.ValidationError(f"Yetarli USD balansi yo'q. Mavjud: {payment_type.total_usd}")
        
        return data
    
    def create(self, validated_data):
        with transaction.atomic():
            exchange_rate = validated_data.get('exchange_rate') or 1
            final_price = validated_data.get('price')
            
            expence = Expence.objects.create(
                user=self.context.get('user'),
                cash_transaction=validated_data.get('cash_transaction'),
                payment_type=validated_data.get('payment_type'),
                project_folder=validated_data.get('project_folder'),
                project=validated_data.get('project'),
                expence_type=validated_data.get('expence_type'),
                counterparty=validated_data.get('counterparty'),
                price=final_price,
                exchange_rate=exchange_rate,
                currency=validated_data.get('currency'),
                date=validated_data.get('date'),
                comment=validated_data.get('comment'),
                audit=validated_data.get('audit'),
                file=validated_data.get('file'),
            )
            
            cash_transaction = expence.cash_transaction
            payment_type = expence.payment_type
            currency = validated_data.get('currency', 'uzs').lower()
            user = self.context.get('user')
            
            if currency == 'uzs':
                cash_transaction.expence_balance_uzs += expence.price
                cash_transaction.total_balance_uzs = cash_transaction.income_balance_uzs - cash_transaction.expence_balance_uzs
                
                payment_type.total_uzs -= expence.price
                
                if expence.counterparty:
                    if expence.counterparty.kredit_uzs > 0:
                        expence.counterparty.kredit_uzs -= expence.price
                        expence.counterparty.total_kredit -= expence.price
                        
                        expence.counterparty.debit_uzs += expence.price
                        expence.counterparty.total_debit += expence.price
                    else:
                        expence.counterparty.debit_uzs += expence.price
                        expence.counterparty.total_debit += expence.price
                    
                    expence.counterparty.save()
            
            elif currency == 'usd':
                cash_transaction.expence_balance_usd += expence.price
                cash_transaction.total_balance_usd = cash_transaction.income_balance_usd - cash_transaction.expence_balance_usd
                
                payment_type.total_usd -= expence.price
                
                if expence.counterparty:
                    if expence.counterparty.kredit_usd > 0:
                        expence.counterparty.kredit_usd -= expence.price  
                        expence.counterparty.total_kredit -= expence.price
                        
                        expence.counterparty.debit_usd += expence.price  
                        expence.counterparty.total_debit += expence.price
                    else:
                        expence.counterparty.debit_usd += expence.price  
                        expence.counterparty.total_debit += expence.price
                    
                    expence.counterparty.save()
            
            body = f"""{user.full_name} {expence.price} {expence.currency.upper()}... \n screen: /monitoring"""
            data = {
                "screen": "/monitoring",
                "type": "expence",
            }
            notify_user(user=user, title="Tasdiqlang yoki rad eting", body=body, data=data)
            
            cash_transaction.save()
            payment_type.save()
            
            return expence

        
    
class ExpenceListSerializer(serializers.ModelSerializer):
    cash_transaction = serializers.SerializerMethodField(method_name='get_cash_transaction')
    payment_type = serializers.SerializerMethodField(method_name='get_payment_type')
    project_folder = serializers.SerializerMethodField(method_name='get_project_folder')
    project = serializers.SerializerMethodField(method_name='get_project')
    counterparty = serializers.SerializerMethodField(method_name='get_counterparty')
    expence_type = serializers.SerializerMethodField(method_name='get_expence_type')
    user = serializers.SerializerMethodField(method_name='get_user')

    class Meta:
        model = Expence
        fields = [
            'id', 'cash_transaction', 'payment_type', 'project_folder', 'project', 'expence_type',
            'counterparty', 'price', 'exchange_rate', 'currency', 'date', 'comment', 'audit', 'file',
            'user', 'expence_chats', 'created_at'
        ]
    
    def get_user(self, obj):
        return {
            'id': obj.user.id,
            'full_name': obj.user.full_name,
        } if obj.user else None
    
    def get_cash_transaction(self, obj):
        return {
            'id': obj.cash_transaction.id,
            'name': obj.cash_transaction.name
        }
    
    def get_payment_type(self, obj):
        return {
            'id': obj.payment_type.id,
            'name': obj.payment_type.name
        }
    
    def get_project_folder(self, obj):
        return {
            'id': obj.project_folder.id,
            'name': obj.project_folder.name
        } if obj.project_folder else None
    
    def get_project(self, obj):
        return {
            'id': obj.project.id,
            'name': obj.project.name
        } if obj.project else None
    
    def get_counterparty(self, obj):
        return {
            'id': obj.counterparty.id,
            'name': obj.counterparty.name
        } if obj.counterparty else None
    
    def get_expence_type(self, obj):
        return {
            'id': obj.expence_type.id,
            'name': obj.expence_type.name
        } if obj.expence_type else None


class ExpenceDeleteSerializer(serializers.Serializer):
    comment = serializers.CharField()


class ExpenceUpdateSerializer(serializers.ModelSerializer):
    class Meta:
        model = Expence
        fields = [
            'project_folder', 'project', 'price', 'expence_type', 'counterparty',
            'date', 'comment', 'audit', 'file', 
        ]
        extra_kwargs = {
            'price': {'required': False},
        }
    
    def validate_price(self, value):
        if value and value < 0:
            raise serializers.ValidationError("Narxi manfiy bo'lishi mumkin emas")
        return value
    
    def update(self, instance, validated_data):
        with transaction.atomic():
            old_price = instance.price
            old_counterparty = instance.counterparty
            new_price = validated_data.get('price', instance.price)
            new_counterparty = validated_data.get('counterparty', instance.counterparty)
            currency = instance.currency.lower()
            
            instance.project_folder = validated_data.get('project_folder', instance.project_folder)
            instance.project = validated_data.get('project', instance.project)
            instance.price = new_price
            instance.expence_type = validated_data.get('expence_type', instance.expence_type)
            instance.counterparty = new_counterparty
            instance.date = validated_data.get('date', instance.date)
            instance.comment = validated_data.get('comment', instance.comment)
            instance.audit = validated_data.get('audit', instance.audit)
            instance.file = validated_data.get('file', instance.file)
            
            if validated_data.get('price') and old_price != new_price:
                price_difference = new_price - old_price  
                cash_transaction = instance.cash_transaction
                payment_type = instance.payment_type
                
                if currency == 'uzs':
                    cash_transaction.expence_balance_uzs += price_difference
                    cash_transaction.total_balance_uzs = (
                        cash_transaction.income_balance_uzs - cash_transaction.expence_balance_uzs
                    )
                    
                    payment_type.total_uzs -= price_difference 
                    
                elif currency == 'usd':
                    cash_transaction.expence_balance_usd += price_difference
                    cash_transaction.total_balance_usd = (
                        cash_transaction.income_balance_usd - cash_transaction.expence_balance_usd
                    )
                    
                    payment_type.total_usd -= price_difference
                
                cash_transaction.save()
                payment_type.save()
            
            if new_counterparty != old_counterparty:
                if old_counterparty:
                    if currency == 'uzs':
                        if old_counterparty.debit_uzs > 0:
                            old_counterparty.debit_uzs -= old_price
                            old_counterparty.total_debit -= old_price
                        else:
                            old_counterparty.kredit_uzs += old_price
                            old_counterparty.total_kredit += old_price
                    else:
                        if old_counterparty.debit_usd > 0:
                            old_counterparty.debit_usd -= old_price
                            old_counterparty.total_debit -= old_price
                        else:
                            old_counterparty.kredit_usd += old_price
                            old_counterparty.total_kredit += old_price
                    
                    old_counterparty.save()
                
                if new_counterparty:
                    if currency == 'uzs':
                        if new_counterparty.kredit_uzs > 0:
                            new_counterparty.kredit_uzs -= new_price
                            new_counterparty.total_kredit -= new_price
                            new_counterparty.debit_uzs += new_price
                            new_counterparty.total_debit += new_price
                        else:
                            new_counterparty.debit_uzs += new_price
                            new_counterparty.total_debit += new_price
                    else:
                        if new_counterparty.kredit_usd > 0:
                            new_counterparty.kredit_usd -= new_price
                            new_counterparty.total_kredit -= new_price
                            new_counterparty.debit_usd += new_price
                            new_counterparty.total_debit += new_price
                        else:
                            new_counterparty.debit_usd += new_price
                            new_counterparty.total_debit += new_price
                    
                    new_counterparty.save()
            
            instance.save()
            return instance