feat(orders): добавлено отображение скидок в админке заказов

- Добавлен DiscountApplicationInline для просмотра истории скидок на странице заказа
- OrderAdmin: добавлены колонки subtotal_display и discount_display
- OrderAdmin: добавлен фильтр по applied_discount
- OrderAdmin: добавлена секция "Скидки" в fieldsets
- OrderItemInline: добавлено отображение скидки в inline
- OrderItemAdmin: добавлена колонка и фильтр по скидкам

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

myproject/orders/admin.py

@@ -6,6 +6,7 @@
 """
 from django.contrib import admin
 from django.utils.html import format_html
+from django.urls import reverse
 from .models import Order, OrderItem, Transaction, PaymentMethod, Address, OrderStatus, Recipient, Delivery
 from tenants.admin_mixins import TenantAdminOnlyMixin
 
@@ -27,14 +28,21 @@ class OrderItemInline(admin.TabularInline):
     """
     model = OrderItem
     extra = 1
-    fields = ['product', 'product_kit', 'quantity', 'price']
+    fields = ['product', 'product_kit', 'quantity', 'price', 'item_discount_inline']
     readonly_fields = []
 
     def get_readonly_fields(self, request, obj=None):
         """Делаем цену readonly для существующих позиций"""
         if obj and obj.pk:
-            return ['price']
+            return ['price', 'item_discount_inline']
-        return []
+        return ['item_discount_inline']
+
+    def item_discount_inline(self, obj):
+        """Отображение скидки в inline"""
+        if obj.discount_amount and obj.discount_amount > 0:
+            return f'-{obj.discount_amount:.2f} руб.'
+        return '-'
+    item_discount_inline.short_description = 'Скидка'
 
 
 class DeliveryInline(admin.StackedInline):
@@ -49,6 +57,46 @@ class DeliveryInline(admin.StackedInline):
     verbose_name_plural = 'Доставка'
 
 
+class DiscountApplicationInline(admin.TabularInline):
+    """
+    Inline для просмотра истории применённых скидок.
+    """
+    from discounts.models import DiscountApplication
+    model = DiscountApplication
+    extra = 0
+    can_delete = False
+    verbose_name = 'Применённая скидка'
+    verbose_name_plural = 'Скидки'
+
+    fields = [
+        'discount_link',
+        'promo_code_display',
+        'target',
+        'discount_amount',
+        'applied_at',
+    ]
+    readonly_fields = fields
+
+    def discount_link(self, obj):
+        if obj.discount:
+            return format_html(
+                '<a href="/admin/discounts/discount/{}/">{}</a>',
+                obj.discount.id, obj.discount.name
+            )
+        return '-'
+    discount_link.short_description = 'Скидка'
+
+    def promo_code_display(self, obj):
+        return obj.promo_code.code if obj.promo_code else '-'
+    promo_code_display.short_description = 'Промокод'
+
+    def has_add_permission(self, request, obj=None):
+        return False
+
+    def has_change_permission(self, request, obj=None):
+        return False
+
+
 @admin.register(Order)
 class OrderAdmin(TenantAdminOnlyMixin, admin.ModelAdmin):
     """Админ-панель для управления заказами."""
@@ -56,6 +104,8 @@ class OrderAdmin(TenantAdminOnlyMixin, admin.ModelAdmin):
         'order_number',
         'customer',
         'status',
+        'subtotal_display',
+        'discount_display',
         'total_amount',
         'payment_status',
         'amount_paid',
@@ -66,6 +116,7 @@ class OrderAdmin(TenantAdminOnlyMixin, admin.ModelAdmin):
         'status',
         'payment_status',
         'created_at',
+        'applied_discount',
     ]
 
     search_fields = [
@@ -80,6 +131,8 @@ class OrderAdmin(TenantAdminOnlyMixin, admin.ModelAdmin):
         'order_number',
         'created_at',
         'updated_at',
+        'subtotal_display',
+        'discount_display',
         'amount_due',
         'payment_status',
     ]
@@ -94,8 +147,18 @@ class OrderAdmin(TenantAdminOnlyMixin, admin.ModelAdmin):
             ),
             'description': 'Если получатель не указан, получателем является покупатель'
         }),
+        ('Скидки', {
+            'fields': (
+                'applied_discount',
+                'applied_promo_code',
+                'discount_amount',
+            ),
+            'classes': ('collapse',)
+        }),
         ('Оплата', {
             'fields': (
+                'subtotal_display',
+                'discount_display',
                 'total_amount',
                 'amount_paid',
                 'amount_due',
@@ -112,7 +175,7 @@ class OrderAdmin(TenantAdminOnlyMixin, admin.ModelAdmin):
         }),
     )
 
-    inlines = [OrderItemInline, DeliveryInline, TransactionInline]
+    inlines = [OrderItemInline, DeliveryInline, TransactionInline, DiscountApplicationInline]
 
     actions = [
         'mark_as_confirmed',
@@ -152,6 +215,23 @@ class OrderAdmin(TenantAdminOnlyMixin, admin.ModelAdmin):
         self.message_user(request, f'{updated} заказ(ов) отмечено как оплаченные')
     mark_as_paid.short_description = 'Отметить как оплаченные'
 
+    def subtotal_display(self, obj):
+        """Отображение subtotal (сумма товаров)"""
+        return f'{obj.subtotal:.2f} руб.' if obj.subtotal else '0.00 руб.'
+    subtotal_display.short_description = 'Подытог'
+
+    def discount_display(self, obj):
+        """Отображение информации о скидке"""
+        if not obj.discount_amount or obj.discount_amount == 0:
+            return '-'
+        discount_info = f'-{obj.discount_amount:.2f} руб.'
+        if obj.applied_discount:
+            from django.utils.safestring import mark_safe
+            discount_link = f'<a href="/admin/discounts/discount/{obj.applied_discount.id}/">{obj.applied_discount.name}</a>'
+            return format_html('{}<br><small class="text-muted">{}</small>', discount_info, discount_link)
+        return discount_info
+    discount_display.short_description = 'Скидка'
+
 
 @admin.register(Transaction)
 class TransactionAdmin(TenantAdminOnlyMixin, admin.ModelAdmin):
@@ -202,12 +282,14 @@ class OrderItemAdmin(TenantAdminOnlyMixin, admin.ModelAdmin):
         'item_name',
         'quantity',
         'price',
+        'item_discount_display',
         'get_total_price',
     ]
 
     list_filter = [
         'order__status',
         'order__created_at',
+        'applied_discount',
     ]
 
     search_fields = [
@@ -216,7 +298,7 @@ class OrderItemAdmin(TenantAdminOnlyMixin, admin.ModelAdmin):
         'product_kit__name',
     ]
 
-    readonly_fields = ['created_at', 'get_total_price']
+    readonly_fields = ['created_at', 'get_total_price', 'item_discount_display']
 
     fieldsets = (
         ('Заказ', {
@@ -226,7 +308,11 @@ class OrderItemAdmin(TenantAdminOnlyMixin, admin.ModelAdmin):
             'fields': ('product', 'product_kit')
         }),
         ('Информация', {
-            'fields': ('quantity', 'price', 'get_total_price')
+            'fields': ('quantity', 'price', 'item_discount_display', 'get_total_price')
+        }),
+        ('Скидка', {
+            'fields': ('applied_discount', 'discount_amount'),
+            'classes': ('collapse',)
         }),
         ('Системная информация', {
             'fields': ('created_at',),
@@ -234,6 +320,16 @@ class OrderItemAdmin(TenantAdminOnlyMixin, admin.ModelAdmin):
         }),
     )
 
+    def item_discount_display(self, obj):
+        """Отображение скидки на позицию"""
+        if not obj.discount_amount or obj.discount_amount == 0:
+            return '-'
+        result = f'-{obj.discount_amount:.2f} руб.'
+        if obj.applied_discount:
+            result += format_html('<br><small class="text-muted">{}</small>', obj.applied_discount.name)
+        return result
+    item_discount_display.short_description = 'Скидка'
+
 
 @admin.register(Address)
 class AddressAdmin(TenantAdminOnlyMixin, admin.ModelAdmin):