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 import transaction
from django.db.models import Prefetch
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, ProductColor, ProductImage
from shop.services import (
    ShopError,
    add_to_cart,
    adjust_stock,
    append_product_images,
    available_qty,
    cart_lines,
    cart_total,
    create_checkout_session,
    create_order_from_cart,
    mark_paid,
    product_media_payload,
    refresh_listing_image,
    remove_product_images,
    save_cart,
    set_cart_qty,
    store_product_stl,
    sync_product_colors,
)
from shop.stats import sales_dashboard

logger = logging.getLogger(__name__)


def _delete_replaced_file(previous, current_id, kind):
    if previous and previous.pk != current_id and previous.kind == kind:
        previous.delete()


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


def _gallery_prefetch():
    def images():
        return ProductImage.objects.select_related("file").order_by(
            "sort_order", "created_at"
        )

    return (
        Prefetch("images", queryset=images()),
        Prefetch(
            "colors",
            queryset=ProductColor.objects.prefetch_related(
                Prefetch("images", queryset=images())
            ),
        ),
    )


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


def product_detail(request, slug):
    product = get_object_or_404(
        Product.objects.select_related("image", "stl").prefetch_related(
            *_gallery_prefetch()
        ),
        slug=slug,
        is_published=True,
    )
    colors = list(product.colors.all())
    selected = colors[0] if colors else None
    return render(
        request,
        "shop/detail.html",
        {
            "product": product,
            "colors": colors,
            "selected_color": selected,
            "available": available_qty(product, selected),
            "gallery_items": product.gallery_items(selected),
            "gallery_photos": product.photos_for(selected),
            "gallery_data": product_media_payload(product, colors),
        },
    )


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.objects.prefetch_related("colors"),
        slug=slug,
        is_published=True,
    )
    try:
        qty = int(request.POST.get("quantity") or "1")
    except ValueError:
        qty = 1
    color = None
    colors = list(product.colors.all())
    if colors:
        color_id = (request.POST.get("color") or "").strip()
        color = next((item for item in colors if str(item.pk) == color_id), None)
        if color is None:
            messages.error(request, "Choose a color.")
            return redirect("shop:detail", slug=product.slug)
    try:
        add_to_cart(request.session, product, qty, color=color)
    except ShopError as exc:
        messages.error(request, str(exc))
        return redirect("shop:detail", slug=product.slug)
    label = f"{product.name} ({color.name})" if color else product.name
    messages.success(request, f"Added {label} 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
    color = None
    color_id = (request.POST.get("color") or "").strip()
    if color_id:
        color = get_object_or_404(ProductColor, pk=color_id, product=product)
    set_cart_qty(request.session, product, qty, color=color)
    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 "",
        )
        try:
            order = create_order_from_cart(
                request.session,
                email=email,
                customer_name=name,
                shipping_address=address,
            )
            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)
    return render(
        request,
        "shop/checkout.html",
        {"lines": lines, "total": cart_total(lines)},
    )


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.select_related("image").prefetch_related("colors")
    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.objects.select_related("image", "stl").prefetch_related(
                *_gallery_prefetch()
            ),
            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
        stl_upload = request.FILES.get("stl")
        if errors:
            for err in errors:
                messages.error(request, err)
        else:
            try:
                with transaction.atomic():
                    stored_stl = None
                    if stl_upload:
                        stored_stl = store_product_stl(
                            upload=stl_upload, user=request.user
                        )
                    if product is None:
                        product = Product()
                    previous_stl = product.stl
                    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"
                    if stored_stl is not None:
                        product.stl = stored_stl
                    elif request.POST.get("clear_stl") == "on":
                        product.stl = None
                    product.save()
                    colors = sync_product_colors(
                        product,
                        ids=request.POST.getlist("color_id"),
                        names=request.POST.getlist("color_name"),
                        hexes=request.POST.getlist("color_hex"),
                        keys=request.POST.getlist("color_key"),
                        stocks=request.POST.getlist("color_stock"),
                    )
                    remove_product_images(
                        product, request.POST.getlist("remove_image")
                    )
                    append_product_images(
                        product,
                        uploads=request.FILES.getlist("images"),
                        user=request.user,
                    )
                    for key, color in colors.items():
                        uploads = request.FILES.getlist(f"color_images_{key}")
                        if not uploads:
                            continue
                        append_product_images(
                            product,
                            uploads=uploads,
                            user=request.user,
                            color=color,
                        )
                    refresh_listing_image(product)
                    _delete_replaced_file(
                        previous_stl,
                        product.stl_id,
                        previous_stl.Kind.PRODUCT_STL if previous_stl else None,
                    )
            except ShopError as exc:
                messages.error(request, str(exc))
            else:
                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):
    order = get_object_or_404(Order.objects.prefetch_related("items"), pk=pk)
    return render(request, "shop/portal/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 "")
        logger.info("shop order %s marked paid", order.number)
    return HttpResponse("ok")