from django import forms
from django.contrib import admin, messages
from django.contrib.admin.utils import quote, unquote
from django.contrib.auth.admin import UserAdmin as DjangoUserAdmin
from django.core.exceptions import PermissionDenied
from django.http import Http404, HttpResponseRedirect
from django.template.response import TemplateResponse
from django.urls import path, reverse
from django.utils.html import format_html

from apps.billing.services import WalletAdjustmentError, adjust_wallet_points

from .models import ApiKey, User, UserWallet


class WalletAdjustmentForm(forms.Form):
    points_delta = forms.IntegerField(
        label="点数变动",
        help_text="正数加点，负数扣点；不可为 0。",
    )
    reason = forms.CharField(
        label="调整原因",
        widget=forms.Textarea(attrs={"rows": 4}),
        help_text="必填，会写入点数流水用于审计。",
    )

    def clean_points_delta(self):
        points_delta = self.cleaned_data["points_delta"]
        if points_delta == 0:
            raise forms.ValidationError("点数变动不可为 0。")
        return points_delta

    def clean_reason(self):
        reason = self.cleaned_data["reason"].strip()
        if not reason:
            raise forms.ValidationError("必须填写调整原因。")
        return reason


@admin.register(User)
class UserAdmin(DjangoUserAdmin):
    fieldsets = DjangoUserAdmin.fieldsets + (
        ("Cmhub", {"fields": ("payment_user_id", "status", "created_at")}),
    )
    readonly_fields = ("created_at",)
    list_display = (
        "username",
        "email",
        "status",
        "wallet_points_balance",
        "is_staff",
        "is_active",
        "created_at",
    )
    list_filter = DjangoUserAdmin.list_filter + ("status",)
    search_fields = ("username", "email", "payment_user_id")

    def get_queryset(self, request):
        return super().get_queryset(request).select_related("wallet")

    @admin.display(description="points")
    def wallet_points_balance(self, obj):
        wallet = getattr(obj, "wallet", None)
        return wallet.points_balance if wallet else 0


@admin.register(UserWallet)
class UserWalletAdmin(admin.ModelAdmin):
    list_display = ("user", "points_balance", "updated_at", "adjust_points_link")
    search_fields = ("user__username", "user__email", "user__payment_user_id")
    readonly_fields = (
        "user",
        "points_balance",
        "created_at",
        "updated_at",
        "adjust_points_link",
    )
    fields = (
        "user",
        "points_balance",
        "created_at",
        "updated_at",
        "adjust_points_link",
    )
    ordering = ("user__username",)
    list_select_related = ("user",)

    def has_add_permission(self, request):
        return False

    def has_delete_permission(self, request, obj=None):
        return False

    def get_urls(self):
        urls = super().get_urls()
        custom_urls = [
            path(
                "<path:object_id>/adjust-points/",
                self.admin_site.admin_view(self.adjust_points_view),
                name="users_userwallet_adjust_points",
            ),
        ]
        return custom_urls + urls

    @admin.display(description="手工调点")
    def adjust_points_link(self, obj):
        if obj is None:
            return ""
        url = reverse(
            "admin:users_userwallet_adjust_points",
            args=(quote(obj.pk),),
            current_app=self.admin_site.name,
        )
        return format_html('<a class="button" href="{}">调点</a>', url)

    def adjust_points_view(self, request, object_id):
        wallet = self.get_object(request, unquote(object_id))
        if wallet is None:
            raise Http404("UserWallet does not exist.")
        if not self.has_change_permission(request, wallet):
            raise PermissionDenied

        if request.method == "POST":
            form = WalletAdjustmentForm(request.POST)
            if form.is_valid():
                try:
                    result = adjust_wallet_points(
                        user=wallet.user,
                        points_delta=form.cleaned_data["points_delta"],
                        reason=form.cleaned_data["reason"],
                        actor=request.user,
                    )
                except WalletAdjustmentError as exc:
                    form.add_error(None, str(exc))
                else:
                    messages.success(
                        request,
                        (
                            f"已调整 {wallet.user} 点数 {result.points_delta:+d}，"
                            f"当前余额 {result.balance_after}。"
                        ),
                    )
                    change_url = reverse(
                        "admin:users_userwallet_change",
                        args=(quote(wallet.pk),),
                        current_app=self.admin_site.name,
                    )
                    return HttpResponseRedirect(change_url)
        else:
            form = WalletAdjustmentForm()

        context = {
            **self.admin_site.each_context(request),
            "title": "手工调整点数",
            "opts": self.model._meta,
            "original": wallet,
            "form": form,
            "media": self.media + form.media,
            "has_change_permission": self.has_change_permission(request, wallet),
        }
        return TemplateResponse(
            request,
            "admin/users/userwallet/adjust_points.html",
            context,
        )


@admin.register(ApiKey)
class ApiKeyAdmin(admin.ModelAdmin):
    list_display = ("key_prefix", "user", "name", "status", "last_used_at", "created_at")
    list_filter = ("status", "created_at")
    search_fields = ("key_prefix", "user__username", "user__email", "name")
    list_select_related = ("user",)
    readonly_fields = (
        "user",
        "key_prefix",
        "key_hash_masked",
        "last_used_at",
        "created_at",
        "updated_at",
    )
    fields = (
        "user",
        "name",
        "status",
        "key_prefix",
        "key_hash_masked",
        "last_used_at",
        "created_at",
        "updated_at",
    )
    ordering = ("-created_at", "-id")

    @admin.display(description="key hash")
    def key_hash_masked(self, obj):
        if not obj.key_hash:
            return ""
        return f"{obj.key_hash[:8]}...{obj.key_hash[-6:]}"

    def has_add_permission(self, request):
        return False

    def has_delete_permission(self, request, obj=None):
        return False