from django.contrib import admin
from django.utils.html import format_html
from polymorphic.admin import (
    PolymorphicChildModelAdmin, 
    PolymorphicParentModelAdmin, 
    PolymorphicChildModelFilter
)
from .models import Gost, MaterialGrade, BaseMaterial, SheetMaterial, ProfileMaterial, StockItem

@admin.register(Gost)
class GostAdmin(admin.ModelAdmin):
    list_display = ('name', 'description', 'get_pdf_link')
    search_fields = ('name',)

    def get_pdf_link(self, obj):
        if obj.pdf_file:
            return format_html('<a href="{}" target="_blank">📄 PDF</a>', obj.pdf_file.url)
        return "—"
    get_pdf_link.short_description = "Файл"

@admin.register(MaterialGrade)
class MaterialGradeAdmin(admin.ModelAdmin):
    list_display = ('name', 'gost', 'density')
    search_fields = ('name', 'gost__name')

class BaseChildAdmin(PolymorphicChildModelAdmin):
    base_model = BaseMaterial

@admin.register(SheetMaterial)
class SheetMaterialAdmin(BaseChildAdmin):
    list_display = ('title', 'thickness', 'grade', 'gost')

@admin.register(ProfileMaterial)
class ProfileMaterialAdmin(BaseChildAdmin):
    list_display = ('title', 'profile_type', 'weight_per_meter', 'grade', 'gost')

@admin.register(BaseMaterial)
class BaseMaterialParentAdmin(PolymorphicParentModelAdmin):
    base_model = BaseMaterial
    child_models = (SheetMaterial, ProfileMaterial)
    list_display = ('get_icon', 'title', 'grade', 'gost', 'get_specs')
    list_filter = (PolymorphicChildModelFilter, 'grade', 'gost')
    search_fields = ('title',)

    def get_icon(self, obj):
        if isinstance(obj, SheetMaterial):
            return format_html('<span title="Лист" style="font-size: 1.2rem;">📄</span>')
        if isinstance(obj, ProfileMaterial):
            return format_html('<span title="Профиль" style="font-size: 1.2rem;">🏗️</span>')
        return "❓"
    get_icon.short_description = ""

    def get_specs(self, obj):
        real_obj = obj.get_real_instance()
        if isinstance(real_obj, SheetMaterial):
            return f"t = {real_obj.thickness} мм"
        if isinstance(real_obj, ProfileMaterial):
            return f"{real_obj.weight_per_meter} кг/м"
        return "-"
    get_specs.short_description = "Характеристики"

@admin.register(StockItem)
class StockItemAdmin(admin.ModelAdmin):
    list_display = (
        'get_material_name', 
        'display_dimensions', 
        'quantity', 
        'colored_status', 
        'order_reference', 
        'location'
    )
    list_filter = ('is_scrap', 'material__grade', 'material')
    search_fields = ('order_reference', 'material__title', 'location')
    
    def get_material_name(self, obj):
        return obj.material.title
    get_material_name.short_description = "Заготовка"

    def display_dimensions(self, obj):
        if obj.width:
            return format_html(f"<b>{obj.length} × {obj.width}</b>")
        return format_html(f"L = <b>{obj.length}</b>")
    display_dimensions.short_description = "Размеры (мм)"

    def colored_status(self, obj):
        if obj.is_scrap:
            return format_html('<b style="color: #ca8a04;">ОБРЕЗОК</b>')
        return format_html('<b style="color: #16a34a;">ЦЕЛЫЙ</b>')
    colored_status.short_description = "Статус"

    fieldsets = (
        (None, {
            'fields': ('material', 'quantity')
        }),
        ('Габариты (мм)', {
            'fields': (('length', 'width'),)
        }),
        ('Учет и хранение', {
            'fields': ('is_scrap', 'order_reference', 'location')
        }),
    )