from django.contrib import admin
from django.utils.html import format_html

from article.models import NoticeReceipt, Notice, Article, Carousel, Section
from users.models import User


# —————— 板块 ——————
@admin.register(Section)
class SectionAdmin(admin.ModelAdmin):
    list_display = ('display_name', 'code', 'parent', 'is_enabled', 'order')
    list_filter = ('parent', 'enabled')
    search_fields = ('name', 'code')
    ordering = ('order', 'name')
    list_editable = ('order',)
    fieldsets = (
        ('基本信息', {
            'fields': ('name', 'code', 'parent', 'enabled', 'order')
        }),
    )

    def display_name(self, obj):
        """在列表中显示层级缩进"""
        if obj.is_sub:
            return f"  └─ {obj.name}"  # 使用全角空格+符号模拟缩进
        return obj.name
    display_name.short_description = '板块名称'
    display_name.admin_order_field = 'name'

    def is_enabled(self, obj):
        return obj.enabled
    is_enabled.boolean = True
    is_enabled.short_description = '启用'

    def formfield_for_foreignkey(self, db_field, request, **kwargs):
        """限制 parent 只能选择主板块（无父级的板块）"""
        if db_field.name == "parent":
            kwargs["queryset"] = Section.objects.filter(parent__isnull=True)
        return super().formfield_for_foreignkey(db_field, request, **kwargs)

    def get_queryset(self, request):
        """优化查询，避免 N+1"""
        return super().get_queryset(request).select_related('parent')


# —————— 轮播图 ——————
@admin.register(Carousel)
class CarouselAdmin(admin.ModelAdmin):
    list_display = ('title', 'image_thumb', 'link_url', 'order', 'active')
    list_editable = ('order', 'active')
    ordering = ('order',)

    def image_thumb(self, obj):
        if obj.image:
            return format_html('<image src="{}" width="60" height="auto" />', obj.image.url)
        return "无图"
    image_thumb.short_description = "预览"


# —————— 文章 ——————
@admin.register(Article)
class ArticleAdmin(admin.ModelAdmin):
    list_display = ('title', 'section', 'author', 'is_published', 'created_at')
    list_filter = ('section', 'is_published', 'created_at')
    search_fields = ('title', 'content')
    date_hierarchy = 'created_at'
    autocomplete_fields = ('author',)  # 需要 UserAdmin 支持搜索

    fieldsets = (
        ('基本信息', {'fields': ('title', 'section', 'cover')}),
        ('内容', {'fields': ('content',)}),
        ('发布设置', {'fields': ('is_published',)}),
    )


# —————— 通知（带签收） ——————
@admin.register(Notice)
class NoticeAdmin(admin.ModelAdmin):
    list_display = (
        'title',
        'publisher',
        'require_sign',
        'is_published',
        'signed_count',
        'total_target_users',
        'created_at'
    )
    list_filter = ('require_sign', 'is_published', 'created_at', 'target_departments')
    search_fields = ('title', 'content')
    filter_horizontal = ('target_departments',)
    readonly_fields = ('created_at', 'updated_at', 'publisher')
    date_hierarchy = 'created_at'

    fieldsets = (
        ('基本信息', {
            'fields': ('title', 'content', 'is_published')
        }),
        ('签收设置', {
            'fields': ('require_sign', 'target_departments'),
            'description': '勾选“是否需要签收”后，可指定接收部门。未指定则默认全员可见但不可签收。'
        }),
        ('时间信息', {
            'fields': ('created_at', 'updated_at'),
            'classes': ('collapse',)
        }),
    )

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

    def signed_count(self, obj):
        return obj.receipts.count()
    signed_count.short_description = "已签收人数"

    def total_target_users(self, obj):
        if obj.target_departments.exists():
            count = User.objects.filter(
                dept__in=obj.target_departments.all(),
                is_active=True
            ).count()
        else:
            count = User.objects.filter(is_active=True).count()
        return count
    total_target_users.short_description = "应签收人数"


# —————— 签收记录 ——————
@admin.register(NoticeReceipt)
class NoticeReceiptAdmin(admin.ModelAdmin):
    list_display = ('notice', 'user', 'signed_at')
    list_filter = ('signed_at', 'notice__title')
    search_fields = ('user__cname', 'user__username', 'notice__title')
    readonly_fields = ('notice', 'user', 'signed_at')

    def has_add_permission(self, request):
        return False  # 禁止手动添加