from django.contrib import admin, messages
from django.utils import timezone

from warehouse.services.transfers import receive_transfer

from .models import Location, Material, MaterialCategory, SteelGrade, StockItem, TransferLine, TransferRecord

@admin.register(MaterialCategory)
class MaterialCategoryAdmin(admin.ModelAdmin):
    list_display = ('name', 'form_factor', 'gost_standard')
    list_filter = ('form_factor',)
    search_fields = ('name', 'gost_standard')

@admin.register(SteelGrade)
class SteelGradeAdmin(admin.ModelAdmin):
    list_display = ('name', 'gost_standard')
    search_fields = ('name', 'gost_standard')

@admin.register(Material)
class MaterialAdmin(admin.ModelAdmin):
    list_display = ('full_name', 'category', 'steel_grade', 'name')
    list_filter = ('category', 'steel_grade')
    search_fields = ('name', 'full_name')
    readonly_fields = ('full_name',)


@admin.register(Location)
class LocationAdmin(admin.ModelAdmin):
    list_display = ('name', 'is_production_area')
    list_filter = ('is_production_area',)
    search_fields = ('name',)


@admin.register(StockItem)
class StockItemAdmin(admin.ModelAdmin):
    list_display = ('location', 'material', 'entity', 'quantity', 'is_remnant', 'unique_id')
    list_filter = ('location', 'is_remnant', 'material__category')
    search_fields = ('material__name', 'material__full_name', 'entity__name', 'entity__drawing_number', 'unique_id')
    autocomplete_fields = ('location', 'material', 'entity')


class TransferLineInline(admin.TabularInline):
    model = TransferLine
    fk_name = 'transfer'
    fields = ('stock_item', 'quantity')
    autocomplete_fields = ('stock_item',)
    extra = 5

    def formfield_for_foreignkey(self, db_field, request, **kwargs):
        if db_field.name == 'stock_item':
            from_location_id = None

            tr = getattr(request, '_transfer_obj', None)
            if tr and getattr(tr, 'from_location_id', None):
                from_location_id = tr.from_location_id

            if not from_location_id and request.method == 'POST':
                raw = (request.POST.get('from_location') or '').strip()
                if raw.isdigit():
                    from_location_id = int(raw)

            if from_location_id:
                kwargs['queryset'] = StockItem.objects.filter(location_id=from_location_id)
            else:
                kwargs['queryset'] = StockItem.objects.all()

        return super().formfield_for_foreignkey(db_field, request, **kwargs)


@admin.register(TransferRecord)
class TransferRecordAdmin(admin.ModelAdmin):
    list_display = ('from_location', 'to_location', 'id', 'occurred_at', 'sender', 'receiver', 'status', 'is_applied')
    list_display_links = ('from_location',)
    list_filter = ('status', 'from_location', 'to_location')
    search_fields = ('sender__username', 'receiver__username')
    autocomplete_fields = ('from_location', 'to_location', 'sender', 'receiver')
    inlines = (TransferLineInline,)
    actions = ('action_receive',)

    def get_changeform_initial_data(self, request):
        initial = super().get_changeform_initial_data(request)
        initial.setdefault('sender', request.user.id)
        initial.setdefault('occurred_at', timezone.now())
        return initial

    def get_form(self, request, obj=None, **kwargs):
        request._transfer_obj = obj
        return super().get_form(request, obj, **kwargs)

    def save_model(self, request, obj, form, change):
        if not obj.sender_id:
            obj.sender = request.user
        super().save_model(request, obj, form, change)

    def save_related(self, request, form, formsets, change):
        super().save_related(request, form, formsets, change)

        obj = form.instance

        # Применяем перемещение автоматически после сохранения строк.
        # Если строк нет — receive_transfer выбросит понятную ошибку.
        if not getattr(obj, 'is_applied', False):
            try:
                receive_transfer(obj.id, request.user.id)
            except Exception as e:
                self.message_user(request, f'Перемещение id={obj.id}: {e}', level=messages.ERROR)

    @admin.action(description='Принять перемещение')
    def action_receive(self, request, queryset):
        ok = 0
        failed = 0

        for tr in queryset:
            try:
                receive_transfer(tr.id, request.user.id)
                ok += 1
            except Exception as e:
                failed += 1
                self.message_user(request, f'Перемещение id={tr.id}: {e}', level=messages.ERROR)

        if ok:
            self.message_user(request, f'Применено: {ok}.', level=messages.SUCCESS)
        if failed:
            self.message_user(request, f'Ошибок: {failed}.', level=messages.ERROR)