from django.contrib import admin
from django.utils.html import format_html
from django.urls import reverse
from django.db.models import Sum
from decimal import Decimal

from inventory.models import (
    Warehouse, StockBatch, Incoming, IncomingBatch, Sale, WriteOff, Transfer,
    Inventory, InventoryLine, Reservation, Stock, StockMovement,
    SaleBatchAllocation, Showcase, WriteOffDocument, WriteOffDocumentItem
)


# ===== SHOWCASE =====
@admin.register(Showcase)
class ShowcaseAdmin(admin.ModelAdmin):
    list_display = ('name', 'warehouse', 'is_default', 'is_active', 'created_at')
    list_filter = ('is_active', 'is_default', 'warehouse', 'created_at')
    search_fields = ('name', 'warehouse__name')
    date_hierarchy = 'created_at'
    fieldsets = (
        ('Основная информация', {
            'fields': ('name', 'warehouse', 'description', 'is_active', 'is_default')
        }),
        ('Даты', {
            'fields': ('created_at', 'updated_at'),
            'classes': ('collapse',)
        }),
    )
    readonly_fields = ('created_at', 'updated_at')


# ===== WAREHOUSE =====
@admin.register(Warehouse)
class WarehouseAdmin(admin.ModelAdmin):
    list_display = ('name', 'is_default_display', 'is_active', 'created_at')
    list_filter = ('is_active', 'is_default', 'created_at')
    search_fields = ('name',)
    fieldsets = (
        ('Основная информация', {
            'fields': ('name', 'description', 'is_active', 'is_default')
        }),
        ('Даты', {
            'fields': ('created_at', 'updated_at'),
            'classes': ('collapse',)
        }),
    )
    readonly_fields = ('created_at', 'updated_at')

    def is_default_display(self, obj):
        if obj.is_default:
            return format_html('<span style="color: #ff9900; font-weight: bold;">★ По умолчанию</span>')
        return '-'
    is_default_display.short_description = 'По умолчанию'


# ===== STOCK BATCH =====
@admin.register(StockBatch)
class StockBatchAdmin(admin.ModelAdmin):
    list_display = ('product', 'warehouse', 'quantity_display', 'cost_price', 'created_at', 'is_active')
    list_filter = ('warehouse', 'is_active', 'created_at')
    search_fields = ('product__name', 'product__sku', 'warehouse__name')
    date_hierarchy = 'created_at'
    fieldsets = (
        ('Партия', {
            'fields': ('product', 'warehouse', 'quantity', 'is_active')
        }),
        ('Финансы', {
            'fields': ('cost_price',)
        }),
        ('Даты', {
            'fields': ('created_at', 'updated_at'),
            'classes': ('collapse',)
        }),
    )
    readonly_fields = ('created_at', 'updated_at')

    def quantity_display(self, obj):
        if obj.quantity <= 0:
            color = '#ff0000'  # красный
        elif obj.quantity < 10:
            color = '#ff9900'  # оранжевый
        else:
            color = '#008000'  # зелёный

        return format_html(
            '<span style="color: {}; font-weight: bold;">{}</span>',
            color,
            f'{obj.quantity} шт'
        )
    quantity_display.short_description = 'Количество'


# ===== INCOMING BATCH =====
@admin.register(IncomingBatch)
class IncomingBatchAdmin(admin.ModelAdmin):
    list_display = ('document_number', 'warehouse', 'supplier_name', 'items_count', 'created_at')
    list_filter = ('warehouse', 'created_at')
    search_fields = ('document_number', 'supplier_name')
    date_hierarchy = 'created_at'
    fieldsets = (
        ('Партия поступления', {
            'fields': ('document_number', 'warehouse', 'supplier_name', 'notes')
        }),
        ('Даты', {
            'fields': ('created_at', 'updated_at'),
            'classes': ('collapse',)
        }),
    )
    readonly_fields = ('created_at', 'updated_at')

    def items_count(self, obj):
        return obj.items.count()
    items_count.short_description = 'Товаров'


# ===== INCOMING =====
@admin.register(Incoming)
class IncomingAdmin(admin.ModelAdmin):
    list_display = ('product', 'batch', 'quantity', 'cost_price', 'created_at')
    list_filter = ('batch__warehouse', 'created_at', 'product')
    search_fields = ('product__name', 'batch__document_number')
    date_hierarchy = 'created_at'
    fieldsets = (
        ('Товар в партии', {
            'fields': ('batch', 'product', 'quantity', 'cost_price', 'stock_batch')
        }),
        ('Дата', {
            'fields': ('created_at',),
            'classes': ('collapse',)
        }),
    )
    readonly_fields = ('created_at', 'stock_batch')


# ===== SALE BATCH ALLOCATION (INLINE) =====
class SaleBatchAllocationInline(admin.TabularInline):
    model = SaleBatchAllocation
    extra = 0
    readonly_fields = ('batch', 'quantity', 'cost_price')
    can_delete = False
    fields = ('batch', 'quantity', 'cost_price')


# ===== SALE =====
@admin.register(Sale)
class SaleAdmin(admin.ModelAdmin):
    list_display = ('product', 'warehouse', 'quantity', 'sale_price', 'order_display', 'processed_display', 'date')
    list_filter = ('warehouse', 'processed', 'date')
    search_fields = ('product__name', 'order__order_number')
    date_hierarchy = 'date'
    fieldsets = (
        ('Продажа', {
            'fields': ('product', 'warehouse', 'quantity', 'sale_price', 'order')
        }),
        ('Статус', {
            'fields': ('processed',)
        }),
        ('Документ', {
            'fields': ('document_number',)
        }),
        ('Дата', {
            'fields': ('date',),
            'classes': ('collapse',)
        }),
    )
    readonly_fields = ('date',)
    inlines = [SaleBatchAllocationInline]

    def order_display(self, obj):
        if obj.order:
            return f"ORD-{obj.order.order_number}"
        return "-"
    order_display.short_description = 'Заказ'

    def processed_display(self, obj):
        if obj.processed:
            return format_html('<span style="color: green;">✓ Обработана</span>')
        return format_html('<span style="color: red;">✗ Ожидает</span>')
    processed_display.short_description = 'Статус'


# ===== WRITE OFF =====
@admin.register(WriteOff)
class WriteOffAdmin(admin.ModelAdmin):
    list_display = ('batch', 'quantity', 'reason_display', 'cost_price', 'date')
    list_filter = ('reason', 'date', 'batch__warehouse')
    search_fields = ('batch__product__name', 'document_number')
    date_hierarchy = 'date'
    fieldsets = (
        ('Списание', {
            'fields': ('batch', 'quantity', 'reason', 'cost_price')
        }),
        ('Документ', {
            'fields': ('document_number', 'notes')
        }),
        ('Дата', {
            'fields': ('date',),
            'classes': ('collapse',)
        }),
    )
    readonly_fields = ('date', 'cost_price')

    def reason_display(self, obj):
        return obj.get_reason_display()
    reason_display.short_description = 'Причина'


# ===== TRANSFER =====
@admin.register(Transfer)
class TransferAdmin(admin.ModelAdmin):
    list_display = ('batch', 'from_warehouse', 'to_warehouse', 'quantity', 'date')
    list_filter = ('date', 'from_warehouse', 'to_warehouse')
    search_fields = ('batch__product__name', 'document_number')
    date_hierarchy = 'date'
    fieldsets = (
        ('Перемещение', {
            'fields': ('batch', 'from_warehouse', 'to_warehouse', 'quantity', 'new_batch')
        }),
        ('Документ', {
            'fields': ('document_number',)
        }),
        ('Дата', {
            'fields': ('date',),
            'classes': ('collapse',)
        }),
    )
    readonly_fields = ('date', 'new_batch')


# ===== INVENTORY LINE (INLINE) =====
class InventoryLineInline(admin.TabularInline):
    model = InventoryLine
    extra = 1
    fields = ('product', 'quantity_system', 'quantity_fact', 'difference', 'processed')
    readonly_fields = ('difference', 'processed')


# ===== INVENTORY =====
@admin.register(Inventory)
class InventoryAdmin(admin.ModelAdmin):
    list_display = ('warehouse', 'status_display', 'date', 'conducted_by')
    list_filter = ('status', 'date', 'warehouse')
    search_fields = ('warehouse__name', 'conducted_by')
    date_hierarchy = 'date'
    fieldsets = (
        ('Инвентаризация', {
            'fields': ('warehouse', 'status', 'conducted_by', 'notes')
        }),
        ('Дата', {
            'fields': ('date',),
            'classes': ('collapse',)
        }),
    )
    readonly_fields = ('date',)
    inlines = [InventoryLineInline]
    actions = ['process_inventory']

    def status_display(self, obj):
        colors = {
            'draft': '#ff9900',      # оранжевый
            'processing': '#0099ff', # синий
            'completed': '#008000'   # зелёный
        }
        return format_html(
            '<span style="color: {}; font-weight: bold;">{}</span>',
            colors.get(obj.status, '#000000'),
            obj.get_status_display()
        )
    status_display.short_description = 'Статус'

    def process_inventory(self, request, queryset):
        from inventory.services import InventoryProcessor

        for inventory in queryset:
            result = InventoryProcessor.process_inventory(inventory.id)
            self.message_user(
                request,
                f"Инвентаризация {inventory.warehouse.name}: "
                f"обработано {result['processed_lines']} строк, "
                f"создано {result['writeoffs_created']} списаний и "
                f"{result['incomings_created']} приходов"
            )

    process_inventory.short_description = 'Обработать инвентаризацию'


# ===== RESERVATION =====
@admin.register(Reservation)
class ReservationAdmin(admin.ModelAdmin):
    list_display = ('product', 'warehouse', 'quantity', 'status_display', 'context_info', 'reserved_at')
    list_filter = ('status', 'reserved_at', 'warehouse', 'showcase')
    search_fields = ('product__name', 'order_item__order__order_number', 'showcase__name')
    date_hierarchy = 'reserved_at'
    fieldsets = (
        ('Резерв', {
            'fields': ('product', 'warehouse', 'quantity', 'status', 'order_item', 'showcase')
        }),
        ('Даты', {
            'fields': ('reserved_at', 'released_at', 'converted_at')
        }),
    )
    readonly_fields = ('reserved_at', 'released_at', 'converted_at')

    def status_display(self, obj):
        colors = {
            'reserved': '#0099ff',         # синий
            'released': '#ff0000',         # красный
            'converted_to_sale': '#008000' # зелёный
        }
        return format_html(
            '<span style="color: {}; font-weight: bold;">{}</span>',
            colors.get(obj.status, '#000000'),
            obj.get_status_display()
        )
    status_display.short_description = 'Статус'

    def context_info(self, obj):
        if obj.order_item:
            return format_html(
                '<span style="color: #0066cc;">📎 Заказ ORD-{}</span>',
                obj.order_item.order.order_number
            )
        elif obj.showcase:
            return format_html(
                '<span style="color: #ff9900;">🌺 Витрина: {}</span>',
                obj.showcase.name
            )
        return "-"
    context_info.short_description = 'Контекст'


# ===== STOCK =====
@admin.register(Stock)
class StockAdmin(admin.ModelAdmin):
    list_display = ('product', 'warehouse', 'quantity_available', 'quantity_reserved', 'quantity_free', 'updated_at')
    list_filter = ('warehouse', 'updated_at')
    search_fields = ('product__name', 'product__sku', 'warehouse__name')
    fieldsets = (
        ('Остаток', {
            'fields': ('product', 'warehouse', 'quantity_available', 'quantity_reserved')
        }),
        ('Дата', {
            'fields': ('updated_at',),
            'classes': ('collapse',)
        }),
    )
    readonly_fields = ('quantity_available', 'quantity_reserved', 'updated_at')


# ===== STOCK MOVEMENT (для аудита) =====
@admin.register(StockMovement)
class StockMovementAdmin(admin.ModelAdmin):
    list_display = ('product', 'change', 'reason', 'order', 'created_at')
    list_filter = ('reason', 'created_at')
    search_fields = ('product__name', 'order__order_number')
    date_hierarchy = 'created_at'
    readonly_fields = ('created_at',)


# ===== WRITEOFF DOCUMENT (документы списания) =====
class WriteOffDocumentItemInline(admin.TabularInline):
    model = WriteOffDocumentItem
    extra = 0
    fields = ('product', 'quantity', 'reason', 'notes', 'reservation')
    readonly_fields = ('reservation',)
    raw_id_fields = ('product',)


@admin.register(WriteOffDocument)
class WriteOffDocumentAdmin(admin.ModelAdmin):
    list_display = ('document_number', 'warehouse', 'status_display', 'date', 'items_count', 'total_quantity_display', 'created_by', 'created_at')
    list_filter = ('status', 'warehouse', 'date', 'created_at')
    search_fields = ('document_number', 'warehouse__name')
    date_hierarchy = 'date'
    readonly_fields = ('document_number', 'created_at', 'updated_at', 'confirmed_at', 'confirmed_by')
    inlines = [WriteOffDocumentItemInline]

    fieldsets = (
        ('Документ', {
            'fields': ('document_number', 'warehouse', 'status', 'date', 'notes')
        }),
        ('Аудит', {
            'fields': ('created_by', 'created_at', 'confirmed_by', 'confirmed_at', 'updated_at'),
            'classes': ('collapse',)
        }),
    )

    def status_display(self, obj):
        colors = {
            'draft': '#ff9900',
            'confirmed': '#008000',
            'cancelled': '#ff0000',
        }
        return format_html(
            '<span style="color: {}; font-weight: bold;">{}</span>',
            colors.get(obj.status, '#000000'),
            obj.get_status_display()
        )
    status_display.short_description = 'Статус'

    def items_count(self, obj):
        return obj.items.count()
    items_count.short_description = 'Позиций'

    def total_quantity_display(self, obj):
        return f"{obj.total_quantity} шт"
    total_quantity_display.short_description = 'Всего'


@admin.register(WriteOffDocumentItem)
class WriteOffDocumentItemAdmin(admin.ModelAdmin):
    list_display = ('document', 'product', 'quantity', 'reason', 'created_at')
    list_filter = ('reason', 'document__status', 'created_at')
    search_fields = ('product__name', 'document__document_number')
    raw_id_fields = ('product', 'document', 'reservation')