from typing import Any, Dict, List
from decimal import Decimal

from django.contrib.auth import get_user_model
from django.test import TestCase
from django.utils import timezone
from unittest.mock import patch

from stock import models as stock_models
from business import models as business_models, services

from .fixtures import create_basic_fixtures


class PurchaseOrderServiceTestCase(TestCase):
    def setUp(self):
        (
            self.merchant,
            self.supplier,
            self.warehouse_strict,
            self.warehouse_relaxed,
            self.product,
            self.operator,
        ) = create_basic_fixtures()
        User = get_user_model()
        self.user = User.objects.create_user(username='creator', password='pass123')
        self.strict_items: List[Dict[str, Any]] = [
            {'product_id': self.product.id, 'numbers': [10, 5], 'price': '12.5', 'unit': '米'}
        ]
        self.relaxed_items: List[Dict[str, Any]] = [
            {'product_id': self.product.id, 'quantity': 120, 'num_of_rolls': 3, 'price': '10.0', 'unit': '米'}
        ]

    def test_create_purchase_order_does_not_trigger_task_immediately(self):
        with patch('business.services.create_purchase_order_stock_entries.delay') as mock_delay:
            purchase_order = services.create_purchase_order(
                merchant=self.merchant,
                supplier=self.supplier,
                order_date=timezone.now().date(),
                warehouse=self.warehouse_strict,
                operator=self.operator,
                items=self.strict_items,
                remarks='自动化测试',
                created_by=self.user,
            )

        self.assertIsInstance(purchase_order, business_models.PurchaseOrder)
        self.assertEqual(purchase_order.status, business_models.PurchaseOrderStatusEnum.PENDING)
        self.assertEqual(purchase_order.items.count(), 1)
        item = purchase_order.items.first()
        self.assertEqual(item.quantity_of_rolls, '10,5')
        self.assertEqual(item.split_quantity_of_rolls(), [10, 5])
        mock_delay.assert_not_called()

    def test_purchase_order_human_id_generation(self):
        purchase_order = services.create_purchase_order(
            merchant=self.merchant,
            supplier=self.supplier,
            order_date=timezone.now().date(),
            warehouse=self.warehouse_strict,
            operator=self.operator,
            items=self.strict_items,
            created_by=self.user,
        )
        self.assertIsNotNone(purchase_order.human_id)
        self.assertEqual(
            purchase_order.human_id,
            f"CG{purchase_order.created_at.strftime('%Y%m%d')}{purchase_order.id:06d}",
        )

    def test_review_purchase_order_approval_triggers_task(self):
        purchase_order = services.create_purchase_order(
            merchant=self.merchant,
            supplier=self.supplier,
            order_date=timezone.now().date(),
            warehouse=self.warehouse_strict,
            operator=self.operator,
            items=self.strict_items,
            created_by=self.user,
        )

        with patch('business.services.create_purchase_order_stock_entries.delay') as mock_delay:
            reviewed = services.review_purchase_order(
                purchase_order=purchase_order,
                target_status=business_models.PurchaseOrderStatusEnum.APPROVED,
                reviewed_by=self.user,
            )

        self.assertEqual(reviewed.status, business_models.PurchaseOrderStatusEnum.APPROVED)
        mock_delay.assert_called_once_with(
            purchase_order_id=purchase_order.id,
            warehouse_id=self.warehouse_strict.id,
            items=[{'product_id': self.product.id, 'quantities': ['10', '5']}],
            created_by_id=self.user.id,
        )
        balance = business_models.SupplierBalance.objects.get(
            merchant=self.merchant,
            supplier=self.supplier,
        )
        self.assertEqual(balance.balance, purchase_order.get_total_amount())
        record = business_models.BalanceChangeRecord.objects.get(
            merchant=self.merchant,
            source_type=business_models.BalanceChangeSourceEnum.PURCHASE_ORDER,
            source_id=purchase_order.id,
        )
        self.assertEqual(record.target_type, business_models.BalanceChangeTargetEnum.SUPPLIER)
        self.assertEqual(record.delta, purchase_order.get_total_amount())
        self.assertEqual(record.balance_after, balance.balance)
        self.assertEqual(record.direction, business_models.BalanceChangeDirectionEnum.INCREASE)

    def test_create_purchase_order_without_items_raises(self):
        with self.assertRaises(ValueError):
            services.create_purchase_order(
                merchant=self.merchant,
                supplier=self.supplier,
                order_date=timezone.now().date(),
                warehouse=self.warehouse_strict,
                operator=self.operator,
                items=[],
            )

    def test_review_purchase_order_cancel_without_stock(self):
        purchase_order = services.create_purchase_order(
            merchant=self.merchant,
            supplier=self.supplier,
            order_date=timezone.now().date(),
            warehouse=self.warehouse_relaxed,
            operator=self.operator,
            items=self.relaxed_items,
            created_by=self.user,
        )
        item = purchase_order.items.first()
        self.assertIsNone(item.quantity_of_rolls)
        self.assertEqual(item.split_quantity_of_rolls(), [])

        cancelled = services.review_purchase_order(
            purchase_order=purchase_order,
            target_status=business_models.PurchaseOrderStatusEnum.CANCELLED,
            reviewed_by=self.user,
        )
        self.assertEqual(cancelled.status, business_models.PurchaseOrderStatusEnum.CANCELLED)
        self.assertFalse(
            business_models.BalanceChangeRecord.objects.filter(
                merchant=self.merchant,
                source_type=business_models.BalanceChangeSourceEnum.PURCHASE_ORDER,
                source_id=purchase_order.id,
            ).exists()
        )

    def test_review_purchase_order_cancel_blocked_after_stock_created(self):
        purchase_order = services.create_purchase_order(
            merchant=self.merchant,
            supplier=self.supplier,
            order_date=timezone.now().date(),
            warehouse=self.warehouse_relaxed,
            operator=self.operator,
            items=self.relaxed_items,
            created_by=self.user,
        )
        stock_models.StockChangeRecord.objects.create(
            merchant=self.merchant,
            type=stock_models.StockChangeTypeEnum.ADD,
            warehouse=self.warehouse_relaxed,
            source_type=stock_models.StockChangeSourceEnum.PURCHASE,
            source_id=purchase_order.id,
        )

        with self.assertRaises(ValueError):
            services.review_purchase_order(
                purchase_order=purchase_order,
                target_status=business_models.PurchaseOrderStatusEnum.CANCELLED,
                reviewed_by=self.user,
            )

    def test_review_purchase_order_relaxed_mode_approval_payload(self):
        purchase_order = services.create_purchase_order(
            merchant=self.merchant,
            supplier=self.supplier,
            order_date=timezone.now().date(),
            warehouse=self.warehouse_relaxed,
            operator=self.operator,
            items=self.relaxed_items,
            created_by=self.user,
        )

        with patch('business.services.create_purchase_order_stock_entries.delay') as mock_delay:
            services.review_purchase_order(
                purchase_order=purchase_order,
                target_status=business_models.PurchaseOrderStatusEnum.APPROVED,
                reviewed_by=self.user,
            )

        mock_delay.assert_called_once_with(
            purchase_order_id=purchase_order.id,
            warehouse_id=self.warehouse_relaxed.id,
            items=[{'product_id': self.product.id, 'value': '120.00', 'num_of_rolls': 3}],
            created_by_id=self.user.id,
        )

    def test_update_purchase_order_success(self):
        purchase_order = services.create_purchase_order(
            merchant=self.merchant,
            supplier=self.supplier,
            order_date=timezone.now().date(),
            warehouse=self.warehouse_relaxed,
            operator=self.operator,
            items=self.relaxed_items,
            created_by=self.user,
        )
        updated = services.update_purchase_order(
            purchase_order=purchase_order,
            warehouse=self.warehouse_strict,
            items=self.strict_items,
            remarks='updated',
        )
        self.assertEqual(updated.remarks, 'updated')
        self.assertEqual(updated.items.count(), 1)
        self.assertEqual(updated.items.first().split_quantity_of_rolls(), [10, 5])

    def test_update_purchase_order_rejects_non_pending(self):
        purchase_order = services.create_purchase_order(
            merchant=self.merchant,
            supplier=self.supplier,
            order_date=timezone.now().date(),
            warehouse=self.warehouse_relaxed,
            operator=self.operator,
            items=self.relaxed_items,
            created_by=self.user,
        )
        purchase_order.status = business_models.PurchaseOrderStatusEnum.APPROVED
        purchase_order.save(update_fields=['status'])
        with self.assertRaises(ValueError):
            services.update_purchase_order(
                purchase_order=purchase_order,
                items=self.relaxed_items,
            )

    def test_purchase_order_relaxed_mode_even_split(self):
        purchase_order = services.create_purchase_order(
            merchant=self.merchant,
            supplier=self.supplier,
            order_date=timezone.now().date(),
            warehouse=self.warehouse_relaxed,
            operator=self.operator,
            items=[
                {
                    'product_id': self.product.id,
                    'quantity': 99,
                    'num_of_rolls': 2,
                    'price': '10.0',
                    'unit': '米',
                }
            ],
            created_by=self.user,
        )
        stock_flow_items = services._build_stock_flow_items_from_order(purchase_order)
        payload = services.create_purchase_order_stock_entries_sync(
            purchase_order_id=purchase_order.id,
            warehouse_id=self.warehouse_relaxed.id,
            items=stock_flow_items,
            created_by_id=self.user.id,
        )
        record = stock_models.StockChangeRecord.objects.get(id=payload['stock_change_record_id'])
        quantities = sorted([detail.quantity for detail in record.details.order_by('id')], reverse=True)
        self.assertEqual(quantities, [Decimal('49.50'), Decimal('49.50')])