djadhere/stocking/admin.py

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

from mptt.admin import MPTTModelAdmin

from .models import Equipment, Category, Location


### Inlines

class EquipmentInline(admin.TabularInline):
    model = Equipment

class ExistingEquipmentInline(EquipmentInline):
    max_num = 0
    fields = ('location', 'category', 'quantity',)
    readonly_fields = ('location', 'category',)

    def get_queryset(self, request):
        qs = super().get_queryset(request)
        qs = qs.select_related('location', 'category',)
        return qs

class NewEquipmentInline(admin.TabularInline):
    model = Equipment
    extra = 0
    verbose_name_plural = 'Nouveaux équipements'

    def get_queryset(self, request):
        return Equipment.objects.none()


### Filters

class CategoryFilter(admin.SimpleListFilter):
    title = 'Catégorie'
    parameter_name = 'category'

    def lookups(self, request, model_admin):
        return [ (c.pk, '    ' * c.get_level() + c.name) for c in Category.objects.all() ]
    
    def queryset(self, request, queryset):
        try:
            category = Category.objects.get(pk=int(self.value()))
        except (TypeError, ValueError, Category.DoesNotExist):
            pass
        else:
            categories = category.get_descendants(include_self=True)
            queryset = queryset.filter(category__in=categories)
        return queryset


### Mixins

class StockMixin:
    search_fields = ('name',)
    list_display = ('__str__', 'quantity',)
    inlines = (ExistingEquipmentInline, NewEquipmentInline,)

    def get_queryset(self, request):
        qs = super().get_queryset(request)
        qs = qs.annotate(quantity=models.Sum('equipments__quantity'))
        return qs

    def quantity(self, category):
        return category.quantity
    quantity.short_description = 'Quantité'
    quantity.admin_order_field = 'quantity'

    def get_actions(self, request):
        actions = super().get_actions(request)
        if 'delete_selected' in actions:
            del actions['delete_selected']
        return actions


### Admins

class CategoryAdmin(StockMixin, MPTTModelAdmin):
    def has_delete_permission(self, request, obj=None):
        # Interdiction de supprimer la catégorie si elle contient des équipements
        return obj \
            and not obj.get_descendants().exists \
            and not Equipment.objects.filter(category__in=obj.get_descendants(include_self=True)).exists()


class LocationAdmin(StockMixin, admin.ModelAdmin):
    def has_delete_permission(self, request, obj=None):
        # Interdiction de supprimer l’emplacement si il contient des équipements
        return obj and not obj.equipments.exists()


#class EquipmentAdmin(admin.ModelAdmin):
#    list_display = ('location', 'category', 'quantity',)
#    list_display_links = ('location', 'category',)
#    list_editable = ('quantity',)
#    list_filter = (
#        ('location', admin.RelatedOnlyFieldListFilter),
#        CategoryFilter,
#    )
#
#    def get_actions(self, request):
#        actions = super().get_actions(request)
#        if 'delete_selected' in actions:
#            del actions['delete_selected']
#        return actions
#
#    def has_delete_permission(self, request, obj=None):
#        # Interdiction de supprimer le stock d’équipements s’il n’est pas vide
#        return obj and obj.quantity == 0


admin.site.register(Category, CategoryAdmin)
admin.site.register(Location, LocationAdmin)
#admin.site.register(Equipment, EquipmentAdmin)