# workflows.py
from rest_framework.decorators import api_view
from rest_framework.response import Response
from rest_framework import status
from django.db import transaction
from django.db.models import F
from decimal import Decimal
from app.models import (
    Transaction,User, Transaction_Detail, Product, Product_Status, Payment_Schedule, 
    Transaction_Phase, Transaction_Status, Payment_Status, Entry_Category,
    Payment_Plan,Product_Booked
)
from app.payment import account_entry_api
from datetime import datetime, timedelta # Corrected: Import timedelta

@api_view(['POST'])
@transaction.atomic
def create_reservation(request):
    """
    Tạo một giao dịch giữ chỗ (24h hoặc giữ chỗ thường).
    """
    data = request.data
    try:
        phase_code = data.get('phase_code')
        deposit_received = data.get('deposit_received')
        customer_id = data.get('customer_id')
        product_id = data.get('product_id')
        policy_id = data.get('policy_id')
        user_id = data.get('user_id')
        origin_price = data.get('origin_price')
        discount_amount = data.get('discount_amount', 0)
        sale_price = data.get('sale_price')
        deposit_amount = data.get('deposit_amount')
        installments = data.get('installments', [])
        payment_plan = data.get('payment_plan', None)

        reservation_phase = Transaction_Phase.objects.get(code=phase_code) 
        initial_detail_status = Transaction_Status.objects.get(code='new')
        # Correction: Use 'unpaid' for unconfirmed payment status
        unconfirmed_payment_status = Payment_Status.objects.get(code='unpaid')

        if phase_code == 'reserved24H':
            product_status_code = 'resvered24H'
        elif phase_code == 'deposit':
            product_status_code = 'deposit'
        elif phase_code == 'fulfillwish':
            product_status_code = 'deposit'
        else:
            product_status_code = 'resvered'
        product_status_reserved = Product_Status.objects.get(code=product_status_code)

        transaction_obj = Transaction.objects.create(
            customer_id=customer_id, product_id=product_id, policy_id=policy_id,
            phase=reservation_phase, date=datetime.now().strftime('%Y-%m-%d'),
            origin_price=origin_price, discount_amount=discount_amount, sale_price=sale_price,
            deposit_amount=deposit_amount, deposit_received=0,
            deposit_remaining=deposit_amount, amount_received=0,
            payment_plan=payment_plan
        )

        amount_recived = installments[0].get('amount') if installments else 0
        transaction_detail_obj = Transaction_Detail.objects.create(
            transaction=transaction_obj, phase=reservation_phase, status=initial_detail_status,
            date=datetime.now().strftime('%Y-%m-%d'),amount=deposit_amount,amount_recived=amount_recived,
            due_date=datetime.now().replace(hour=0, minute=0, second=0, microsecond=0) + timedelta(days=2),
            creator_id=user_id
        )

        product_obj = Product.objects.get(id=product_id)
        product_obj.status = product_status_reserved
        product_obj.save()
        
        product_booked_obj = Product_Booked.objects.create(
            transaction=transaction_obj, 
            product=product_obj
        )
            
        schedules = []
        for i, installment in enumerate(installments):
            schedule = Payment_Schedule.objects.create(
                txn_detail=transaction_detail_obj,
                from_date=datetime.now().strftime('%Y-%m-%d'),
                to_date=datetime.now().replace(hour=0, minute=0, second=0, microsecond=0) + timedelta(days=installment.get('due_days', 0)),
                amount=installment.get('amount'), cycle=i + 1,
                cycle_days=installment.get('due_days', 0), type_id=1,
                status=unconfirmed_payment_status, updater_id=user_id,
                detail={'note': f"Thanh toán cọc đợt {i+1}"}
            )
            schedules.append(schedule.id)

        return Response({
            'message': f'Giao dịch "{reservation_phase.name}" đã được tạo thành công.',
            'transaction_id': transaction_obj.id,
            'transaction_code': transaction_obj.code,
            'transaction_detail_id': transaction_detail_obj.id,
            'product_status': product_obj.status.name,
            'payment_schedule_ids': schedules
        }, status=status.HTTP_201_CREATED)

    except Exception as e:
        return Response({'error': str(e)}, status=status.HTTP_400_BAD_REQUEST)

@api_view(['POST'])
@transaction.atomic
def confirm_payment_schedule(request):
    """
    Kế toán xác nhận một công nợ (Payment_Schedule).
    Job chạy ngầm sẽ lo việc chuyển trạng thái detail.
    """
    data = request.data
    try:
        payment_schedule_id = data.get('payment_schedule_id')
        accountant_id = data.get('user_id')
        internal_account_code = data.get('internal_account_code', 'HOAC02VND')

        # Correction: Use 'paid' for confirmed payment status
        confirmed_payment_status = Payment_Status.objects.get(code='paid')
        
        schedule_obj = Payment_Schedule.objects.select_related('txn_detail', 'txn_detail__transaction__customer', 'status').get(id=payment_schedule_id)
        
        if schedule_obj.status.code == 'paid':
            return Response({'message': 'Công nợ này đã được xác nhận trước đó.'}, status=status.HTTP_200_OK)

        schedule_obj.status = confirmed_payment_status
        schedule_obj.updater_id = accountant_id
        
        entry_content = f"Xác nhận thanh toán đợt {schedule_obj.cycle} cho GD {schedule_obj.txn_detail.code} của KH {schedule_obj.txn_detail.transaction.customer.code}"
        deposit_category = Entry_Category.objects.get(code='THU_COC')

        entry_data = account_entry_api(
            code=internal_account_code, amount=schedule_obj.amount, content=entry_content,
            type='CR', category=deposit_category.id, userid=accountant_id,
            ref=schedule_obj.txn_detail.code
        )

        if 'error' in entry_data:
            raise Exception(entry_data['error'])
        
        schedule_obj.entry_id = entry_data['id']
        schedule_obj.save()

        transaction_obj = schedule_obj.txn_detail.transaction
        
        schedule_amount = Decimal(str(schedule_obj.amount))

        transaction_obj.amount_received = (transaction_obj.amount_received or Decimal('0')) + schedule_amount
        transaction_obj.deposit_received = (transaction_obj.deposit_received or Decimal('0')) + schedule_amount
        transaction_obj.deposit_remaining = (transaction_obj.deposit_remaining or Decimal('0')) - schedule_amount
        transaction_obj.save()
        
        return Response({
            'message': 'Công nợ đã được xác nhận thành công.'
        }, status=status.HTTP_200_OK)

    except Exception as e:
        return Response({'error': str(e)}, status=status.HTTP_400_BAD_REQUEST)


@api_view(['POST'])
@transaction.atomic
def approve_transaction_detail(request):
    """
    Duyệt một Transaction_Detail.
    Nếu phase là 'reserved24H', sẽ tự động chuyển Transaction sang phase 'reserved'.
    """
    data = request.data
    try:
        transaction_detail_id = data.get('transaction_detail_id')
        approver_id = data.get('user_id')

        detail_obj = Transaction_Detail.objects.select_related('status', 'phase', 'transaction').get(id=transaction_detail_id)
        
        user_obj = User.objects.get(id=approver_id)
        
        if detail_obj.status.code != 'pending':
            return Response(
                {'error': f'Giao dịch không ở trạng thái "Chờ duyệt". Trạng thái hiện tại: {detail_obj.status.name}'},
                status=status.HTTP_400_BAD_REQUEST
            )

        # Correction: Use 'approved' for approved status
        approved_status = Transaction_Status.objects.get(code='approved')
        detail_obj.status = approved_status
        detail_obj.approver = user_obj
        detail_obj.approve_time = datetime.now().strftime('%Y-%m-%d %H:%M:%S')
        detail_obj.save()

        if detail_obj.phase.code == 'reserved24H':
            transaction_obj = detail_obj.transaction
            
            next_phase_obj = Transaction_Phase.objects.get(code='reserved')
            transaction_obj.phase = next_phase_obj
            transaction_obj.save()

            productId = transaction_obj.product_id
            product_obj = Product.objects.get(id=productId)
            product_obj.status = Product_Status.objects.get(code='resvered')
            product_obj.save()

            new_detail_obj = Transaction_Detail.objects.create(
                transaction=transaction_obj, phase=next_phase_obj,
                status=Transaction_Status.objects.get(code='new'), 
                date=datetime.now().strftime('%Y-%m-%d'),
                amount=0, creator_id=approver_id
            )
            
            return Response({
                'message': 'Giao dịch đã được duyệt và tự động chuyển sang giai đoạn "Giữ chỗ".',
                'transaction_id': transaction_obj.id,
                'new_transaction_phase': next_phase_obj.name,
                'new_transaction_detail_id': new_detail_obj.id
            }, status=status.HTTP_200_OK)
        else:
            return Response({
                'message': 'Giao dịch đã được duyệt thành công.',
                'transaction_detail_id': detail_obj.id,
                'new_status': approved_status.name
            }, status=status.HTTP_200_OK)

    except Exception as e:
        return Response({'error ': str(e)}, status=status.HTTP_400_BAD_REQUEST)

@api_view(['POST'])
@transaction.atomic
def advance_transaction_phase(request):
    """
    Chuyển một Transaction sang một giai đoạn mới và tự động tạo công nợ nếu cần.
    """
    data = request.data
    try:
        transaction_id = data.get('transaction_id')
        next_phase_code = data.get('next_phase_code')
        user_id = data.get('user_id')
        product_status = data.get('product_status')


        if not all([transaction_id, next_phase_code, user_id]):
            return Response({'error': 'transaction_id, next_phase_code, và user_id là bắt buộc.'}, status=status.HTTP_400_BAD_REQUEST)

        transaction_obj = Transaction.objects.select_related('phase', 'product', 'policy').get(id=transaction_id)

        next_phase_obj = Transaction_Phase.objects.get(code=next_phase_code)
        initial_detail_status = Transaction_Status.objects.get(code='new')
        
        next_product_status = Product_Status.objects.get(code=product_status)

        transaction_obj.phase = next_phase_obj
        transaction_obj.save()

        productId = transaction_obj.product_id
        product_obj = Product.objects.get(id=productId)
        product_obj.status = next_product_status
        product_obj.save()

        new_detail_obj = Transaction_Detail.objects.create(
            transaction=transaction_obj, phase=next_phase_obj, status=initial_detail_status,
            date=datetime.now().strftime('%Y-%m-%d'),
            amount=0, creator_id=user_id
        )

        if next_phase_code == 'pertrade':
            unconfirmed_payment_status = Payment_Status.objects.get(code='unpaid')
            total_plan_amount = 0

            # Ưu tiên kế hoạch thanh toán riêng trong giao dịch
            if transaction_obj.payment_plan and isinstance(transaction_obj.payment_plan, list):
                for i, plan_item in enumerate(transaction_obj.payment_plan):
                    plan_amount = Decimal(str(plan_item.get('amount', 0)))
                    due_days = plan_item.get('due_days', 0)
                    total_plan_amount += plan_amount
                    Payment_Schedule.objects.create(
                        txn_detail=new_detail_obj,
                        from_date=datetime.now().strftime('%Y-%m-%d'),
                        to_date=datetime.now().replace(hour=0, minute=0, second=0, microsecond=0) + timedelta(days=due_days),
                        amount=plan_amount,
                        cycle=i + 1,
                        cycle_days=due_days,
                        type_id=2,  # Giả sử type_id=2 cho thanh toán mua bán
                        status=unconfirmed_payment_status,
                        updater_id=user_id,
                        detail={'note': f"Thanh toán đợt {i + 1} theo kế hoạch riêng"}
                    )
                new_detail_obj.amount = total_plan_amount
                new_detail_obj.save()
            
            # Nếu không có kế hoạch riêng, dùng chính sách bán hàng
            elif transaction_obj.policy:
                payment_plans_from_policy = Payment_Plan.objects.filter(policy=transaction_obj.policy).select_related('type').order_by('cycle')
                if payment_plans_from_policy.exists():
                    for plan in payment_plans_from_policy:
                        plan_amount = 0
                        if plan.type.code == 'percentage':
                            plan_amount = (transaction_obj.sale_price * plan.value) / 100
                        elif plan.type.code == 'money':
                            plan_amount = plan.value
                        
                        total_plan_amount += Decimal(str(plan_amount))
                        Payment_Schedule.objects.create(
                            txn_detail=new_detail_obj, from_date=datetime.now().strftime('%Y-%m-%d'),
                            to_date=datetime.now().replace(hour=0, minute=0, second=0, microsecond=0) + timedelta(days=plan.days),
                            amount=plan_amount, cycle=plan.cycle, cycle_days=plan.days,
                            type_id=2, status=unconfirmed_payment_status, updater_id=user_id,
                            detail={'note': f"Thanh toán đợt {plan.cycle} theo chính sách {transaction_obj.policy.name}"}
                        )
                    new_detail_obj.amount = total_plan_amount
                    new_detail_obj.save()
            else:
                raise Exception("Giao dịch không có chính sách bán hàng hoặc kế hoạch thanh toán riêng để tạo công nợ.")

        return Response({
            'message': f'Giao dịch đã được chuyển thành công sang giai đoạn "{next_phase_obj.name}".',
            'transaction_id': transaction_obj.id,
            'new_transaction_detail_id': new_detail_obj.id,
            'new_transaction_detail_code': new_detail_obj.code,
            'product_id': productId,
            'customer':transaction_obj.customer.id,
            'new_product_status': next_product_status.name
        }, status=status.HTTP_200_OK)

    except Transaction.DoesNotExist:
        return Response({'error': 'Giao dịch không tồn tại.'}, status=status.HTTP_404_NOT_FOUND)
    except Transaction_Phase.DoesNotExist:
        return Response({'error': f'Giai đoạn mới "{next_phase_code}" không hợp lệ.'}, status=status.HTTP_400_BAD_REQUEST)
    except Exception as e:
        return Response({'error': str(e)}, status=status.HTTP_400_BAD_REQUEST)