import logging
from decimal import Decimal, InvalidOperation

from django.conf import settings
from django.contrib import messages
from django.contrib.auth.decorators import login_required
from django.db.models import Avg, Count
from django.http import HttpResponse, HttpResponseBadRequest
from django.shortcuts import get_object_or_404, redirect, render
from django.urls import reverse
from django.utils.text import slugify
from django.views.decorators.csrf import csrf_exempt
from django.views.decorators.http import require_http_methods, require_POST

from contacts.models import Contact
from shop.models import Order, Product, ProductReview
from shop.services import (
    ShopError,
    add_to_cart,
    adjust_stock,
    available_qty,
    cart_lines,
    cart_total,
    create_checkout_session,
    create_order_from_cart,
    mark_paid,
    qualifying_order_for_review,
    save_cart,
    set_cart_qty,
    user_has_reviewed,
)
from shop.stats import sales_dashboard

logger = logging.getLogger(__name__)


def _site_base(request) -> str:
    base = (settings.PUBLIC_SITE_URL or "").rstrip("/")
    if base:
        return base
    return request.build_absolute_uri("/").rstrip("/")


def product_list(request):
    products = Product.objects.filter(is_published=True)
    return render(request, "shop/list.html", {"products": products})


def product_detail(request, slug):
    product = get_object_or_404(Product, slug=slug, is_published=True)
    reviews = list(product.reviews.select_related("user").all()[:50])
    stats = product.reviews.aggregate(avg=Avg("rating"), n=Count("id"))
    can_review = False
    already_reviewed = False
    if request.user.is_authenticated:
        already_reviewed = user_has_reviewed(request.user, product)
        can_review = (
            not already_reviewed
            and qualifying_order_for_review(request.user, product) is not None
        )
    return render(
        request,
        "shop/detail.html",
        {
            "product": product,
            "available": available_qty(product),
            "reviews": reviews,
            "review_avg": stats["avg"],
            "review_count": stats["n"] or 0,
            "can_review": can_review,
            "already_reviewed": already_reviewed,
        },
    )


@login_required(login_url="account:login")
@require_POST
def product_review(request, slug):
    product = get_object_or_404(Product, slug=slug, is_published=True)
    if user_has_reviewed(request.user, product):
        messages.info(request, "You already reviewed this product.")
        return redirect("shop:detail", slug=product.slug)
    order = qualifying_order_for_review(request.user, product)
    if order is None:
        messages.error(request, "Only customers who purchased this product can review it.")
        return redirect("shop:detail", slug=product.slug)
    try:
        rating = int(request.POST.get("rating") or "0")
    except ValueError:
        rating = 0
    if rating < 1 or rating > 5:
        messages.error(request, "Choose a rating from 1 to 5.")
        return redirect("shop:detail", slug=product.slug)
    title = (request.POST.get("title") or "").strip()[:120]
    body = (request.POST.get("body") or "").strip()
    ProductReview.objects.create(
        product=product,
        user=request.user,
        order=order,
        rating=rating,
        title=title,
        body=body,
    )
    messages.success(request, "Thanks for the review.")
    return redirect("shop:detail", slug=product.slug)


def cart_view(request):
    lines = cart_lines(request.session)
    return render(
        request,
        "shop/cart.html",
        {"lines": lines, "total": cart_total(lines)},
    )


@require_POST
def cart_add(request, slug):
    product = get_object_or_404(Product, slug=slug, is_published=True)
    try:
        qty = int(request.POST.get("quantity") or "1")
    except ValueError:
        qty = 1
    try:
        add_to_cart(request.session, product, qty)
    except ShopError as exc:
        messages.error(request, str(exc))
        return redirect("shop:detail", slug=product.slug)
    messages.success(request, f"Added {product.name} to cart.")
    return redirect("shop:cart")


@require_POST
def cart_update(request, slug):
    product = get_object_or_404(Product, slug=slug)
    try:
        qty = int(request.POST.get("quantity") or "0")
    except ValueError:
        qty = 0
    set_cart_qty(request.session, product, qty)
    return redirect("shop:cart")


@require_http_methods(["GET", "POST"])
def checkout(request):
    lines = cart_lines(request.session)
    if not lines:
        messages.error(request, "Cart is empty.")
        return redirect("shop:cart")
    if request.method == "POST":
        email = (request.POST.get("email") or "").strip()
        name = (request.POST.get("customer_name") or "").strip()
        address = Contact.make_postal_address(
            line1=request.POST.get("address_line1") or "",
            line2=request.POST.get("address_line2") or "",
            city=request.POST.get("address_city") or "",
            state=request.POST.get("address_state") or "",
            zip_code=request.POST.get("address_zip") or "",
        )
        buyer = request.user if request.user.is_authenticated else None
        if buyer:
            email = (buyer.email or buyer.username or email).strip()
            if not name:
                name = buyer.get_full_name()
        try:
            order = create_order_from_cart(
                request.session,
                email=email,
                customer_name=name,
                shipping_address=address,
                user=buyer,
            )
            base = _site_base(request)
            success = base + reverse("shop:checkout_success", kwargs={"pk": order.pk})
            cancel = base + reverse("shop:checkout_cancel", kwargs={"pk": order.pk})
            url = create_checkout_session(
                order,
                success_url=success + "?session_id={CHECKOUT_SESSION_ID}",
                cancel_url=cancel,
            )
        except ShopError as exc:
            messages.error(request, str(exc))
        except Exception as exc:  # noqa: BLE001
            logger.exception("shop checkout failed")
            messages.error(request, f"Could not start checkout: {exc}")
        else:
            save_cart(request.session, {})
            return redirect(url)
    checkout_initial = {
        "email": "",
        "customer_name": "",
        "address": {},
    }
    if request.user.is_authenticated:
        from accounts.services import get_customer_profile

        profile = get_customer_profile(request.user)
        checkout_initial = {
            "email": request.user.email or request.user.username,
            "customer_name": request.user.get_full_name(),
            "address": profile.shipping_address or {},
        }
    return render(
        request,
        "shop/checkout.html",
        {
            "lines": lines,
            "total": cart_total(lines),
            "checkout_initial": checkout_initial,
        },
    )


def checkout_success(request, pk):
    order = get_object_or_404(Order, pk=pk)
    return render(request, "shop/success.html", {"order": order})


def checkout_cancel(request, pk):
    order = get_object_or_404(Order, pk=pk)
    return render(request, "shop/cancel.html", {"order": order})


@login_required
def portal_product_list(request):
    products = Product.objects.all()
    return render(request, "shop/portal/products.html", {"products": products})


@login_required
@require_http_methods(["GET", "POST"])
def portal_product_edit(request, pk=None):
    product = get_object_or_404(Product, pk=pk) if pk else None
    if request.method == "POST":
        name = (request.POST.get("name") or "").strip()
        sku = (request.POST.get("sku") or "").strip()
        description = (request.POST.get("description") or "").strip()
        slug = (request.POST.get("slug") or "").strip()
        fulfillment = request.POST.get("fulfillment") or Product.Fulfillment.STOCKED
        errors = []
        if not name:
            errors.append("Name is required.")
        try:
            price = Decimal(request.POST.get("price") or "")
            if price < 0:
                raise InvalidOperation
        except Exception:
            price = None
            errors.append("Enter a valid price.")
        try:
            stock_qty = int(request.POST.get("stock_qty") or "0")
        except ValueError:
            stock_qty = 0
            errors.append("Stock must be a number.")
        try:
            print_minutes = int(request.POST.get("print_minutes") or "0")
            filament_grams = int(request.POST.get("filament_grams") or "0")
        except ValueError:
            print_minutes = 0
            filament_grams = 0
        if errors:
            for err in errors:
                messages.error(request, err)
        else:
            if product is None:
                product = Product()
            product.name = name
            product.sku = sku
            product.description = description
            product.slug = slugify(slug)[:220] if slug else ""
            product.price = price
            product.currency = (settings.STRIPE_CURRENCY or "usd").lower()
            product.fulfillment = fulfillment
            product.stock_qty = stock_qty
            product.print_minutes = max(print_minutes, 0)
            product.filament_grams = max(filament_grams, 0)
            product.is_published = request.POST.get("is_published") == "on"
            product.track_inventory = request.POST.get("track_inventory") == "on"
            product.save()
            messages.success(request, f"Saved {product.name}.")
            return redirect("shop_portal:product_list")
    return render(request, "shop/portal/product_edit.html", {"product": product})


@login_required
@require_POST
def portal_stock_adjust(request, pk):
    product = get_object_or_404(Product, pk=pk)
    try:
        delta = int(request.POST.get("delta") or "0")
    except ValueError:
        messages.error(request, "Enter a whole-number adjustment.")
        return redirect("shop_portal:product_edit", pk=product.pk)
    try:
        adjust_stock(product, delta)
    except ShopError as exc:
        messages.error(request, str(exc))
    else:
        messages.success(request, f"{product.sku} stock is now {product.stock_qty}.")
    return redirect("shop_portal:product_edit", pk=product.pk)


@login_required
def portal_sales(request):
    return render(request, "shop/portal/sales.html", sales_dashboard())


@login_required
def portal_order_list(request):
    orders = Order.objects.all()[:200]
    return render(request, "shop/portal/orders.html", {"orders": orders})


@login_required
def portal_order_detail(request, pk):
    qs = Order.objects.prefetch_related("items")
    from django.apps import apps as django_apps

    if django_apps.is_installed("shipping"):
        qs = qs.prefetch_related("shipments")
    order = get_object_or_404(qs, pk=pk)
    return render(request, "shop/portal/order_detail.html", {"order": order})


@login_required(login_url="account:login")
def account_order_list(request):
    from accounts.services import claim_orders_for_user
    from django.apps import apps as django_apps

    claim_orders_for_user(request.user)
    qs = Order.objects.filter(user=request.user).prefetch_related("items")
    if django_apps.is_installed("shipping"):
        qs = qs.prefetch_related("shipments")
    orders = qs.exclude(status=Order.Status.DRAFT)
    return render(request, "shop/account/orders.html", {"orders": orders})


@login_required(login_url="account:login")
def account_order_detail(request, pk):
    from django.apps import apps as django_apps

    qs = Order.objects.prefetch_related("items")
    if django_apps.is_installed("shipping"):
        qs = qs.prefetch_related("shipments")
    order = get_object_or_404(qs, pk=pk, user=request.user)

    if django_apps.is_installed("shipping"):
        from datetime import timedelta

        from django.utils import timezone
        from shipping.models import Shipment
        from shipping.services import refresh_tracking

        stale_after = timezone.now() - timedelta(minutes=15)
        for shipment in order.shipments.all():
            if (
                shipment.status == Shipment.Status.LABELED
                and shipment.tracking_number
                and shipment.tracking_status != Shipment.TrackingStatus.DELIVERED
                and (
                    shipment.last_tracked_at is None
                    or shipment.last_tracked_at < stale_after
                )
            ):
                try:
                    refresh_tracking(shipment)
                except Exception:
                    logger.exception("order tracking refresh failed for %s", order.number)
    return render(request, "shop/account/order_detail.html", {"order": order})


@csrf_exempt
@require_http_methods(["POST"])
def stripe_webhook(request):
    secret = (settings.STRIPE_WEBHOOK_SECRET or "").strip()
    if not secret:
        logger.error("STRIPE_WEBHOOK_SECRET unset")
        return HttpResponseBadRequest("webhook not configured")
    try:
        import stripe
    except ImportError:
        return HttpResponseBadRequest("stripe not installed")
    sig = request.headers.get("Stripe-Signature", "")
    try:
        event = stripe.Webhook.construct_event(request.body, sig, secret)
    except Exception:
        logger.exception("shop stripe webhook signature failed")
        return HttpResponseBadRequest("invalid signature")

    obj = event.get("data", {}).get("object", {}) or {}
    if event.get("type") != "checkout.session.completed":
        return HttpResponse("ok")
    order_id = (obj.get("metadata") or {}).get("shop_order_id") or ""
    order = None
    if order_id:
        order = Order.objects.filter(pk=order_id).first()
    if order is None:
        session_id = obj.get("id") or ""
        order = Order.objects.filter(stripe_checkout_session_id=session_id).first()
    if order and order.status != Order.Status.PAID:
        mark_paid(
            order,
            stripe_id=obj.get("id") or "",
            stripe_customer_id=obj.get("customer") or "",
        )
        logger.info("shop order %s marked paid", order.number)
    return HttpResponse("ok")