Fix: Correctly resolving shipping methods

src/Shipping/Support/PlaceShippingRateResolver.php

@@ -0,0 +1,208 @@
+<?php
+
+namespace Modules\Core\Shipping\Support;
+
+use Illuminate\Database\Eloquent\Builder;
+use Illuminate\Support\Collection;
+use Lunar\Models\State;
+use Lunar\Shipping\DataTransferObjects\PostcodeLookup;
+use Lunar\Shipping\Facades\Shipping;
+use Lunar\Shipping\Models\ShippingMethod;
+use Lunar\Shipping\Models\ShippingRate;
+use Lunar\Shipping\Models\ShippingZone;
+use Lunar\Shipping\Resolvers\ShippingRateResolver;
+
+/**
+ * Resolves shipping by place, from the innermost place outwards: postcode →
+ * state → country → unrestricted. The first place that has shipping
+ * zones with usable rates is the whole answer — outer places are not
+ * consulted at all, so a cheaper Athens postcode rule replaces the
+ * Greece-wide one for those postcodes instead of competing with it.
+ *
+ * Lunar's own resolver gathers every matching zone of every type at once
+ * and keeps the first rate per shipping method, so which price a customer
+ * saw depended on the order the zones were inserted.
+ *
+ * Postcode zones are tried from the most specific match to the least, in
+ * the order Lunar's postcode resolver lists the parts ("12345", then
+ * shorter prefixes and their "*" wildcards), so an exact postcode beats a
+ * prefix. Several zones matching at the same place are combined; if two of
+ * them carry the same shipping method, the older zone's rate is used.
+ *
+ * "Usable" means passing the same checks as Lunar's resolver (rate
+ * enabled, method in the customer's group and in schedule, stock, weight
+ * limits) plus one of ours: the method's driver is still registered —
+ * otherwise Lunar calls a missing driver to price it and the checkout
+ * fails with "Driver [x] not supported". So a place whose rates all fail
+ * those checks (e.g. the cart is too heavy for its only method) falls
+ * through to the next place out.
+ *
+ * Exclusion lists deliberately do NOT make a place fall through. An
+ * exclusion list on a zone means "these products can't be shipped there",
+ * so the place is still the answer; each driver then drops that zone's
+ * options for a cart holding an excluded product
+ * (ExcludesRestrictedProducts). If nothing is left, the customer gets no
+ * shipping options for that address rather than an outer place's rule.
+ *
+ * Queries stay fixed whatever the number of places or zones: every zone
+ * containing the address comes back in one query (with its matching
+ * postcodes, rates and methods eager-loaded), the customer-group check is
+ * one query over all their methods, and the layering happens in PHP.
+ */
+class PlaceShippingRateResolver extends ShippingRateResolver
+{
+    public function get(): Collection
+    {
+        if (! $this->postcode || ! $this->country) {
+            return collect();
+        }
+
+        $parts = (new PostcodeLookup(country: $this->country, postcode: $this->postcode))->getParts()->values();
+        $state = $this->state ? State::whereName($this->state)->first() : null;
+
+        $zones = $this->candidateZones($parts, $state);
+        $visibleMethodIds = $this->methodsVisibleToCustomer($zones);
+
+        foreach ($this->placesInsideOut($zones, $parts) as $placeZones) {
+            $rates = $this->usableRates($placeZones, $visibleMethodIds);
+
+            if ($rates->isNotEmpty()) {
+                return $rates;
+            }
+        }
+
+        return collect();
+    }
+
+    /**
+     * Every zone containing the address, of every place, oldest first.
+     *
+     * @param  Collection<int, string>  $parts
+     * @return Collection<int, ShippingZone>
+     */
+    private function candidateZones(Collection $parts, ?State $state): Collection
+    {
+        $inCountry = fn (Builder $countries) => $countries->where('country_id', $this->country->id);
+
+        return ShippingZone::query()
+            ->where(function (Builder $query) use ($parts, $state, $inCountry) {
+                $query
+                    ->where(fn (Builder $zone) => $zone->where('type', 'postcodes')
+                        ->whereHas('postcodes', fn (Builder $postcodes) => $postcodes->whereIn('postcode', $parts))
+                        ->whereHas('countries', $inCountry))
+                    ->when($state, fn (Builder $q) => $q->orWhere(fn (Builder $zone) => $zone->where('type', 'states')
+                        ->whereHas('states', fn (Builder $states) => $states->where('state_id', $state->id))))
+                    ->orWhere(fn (Builder $zone) => $zone->where('type', 'countries')
+                        ->whereHas('countries', $inCountry))
+                    ->orWhere('type', 'unrestricted');
+            })
+            ->with([
+                'postcodes' => fn ($postcodes) => $postcodes->whereIn('postcode', $parts),
+                'rates' => fn ($rates) => $rates->orderBy('id'),
+                'rates.shippingMethod',
+            ])
+            ->orderBy('id')
+            ->get();
+    }
+
+    /**
+     * The candidate zones grouped by place, innermost first. A postcode
+     * zone belongs to the most specific part it matches.
+     *
+     * @param  Collection<int, ShippingZone>  $zones
+     * @param  Collection<int, string>  $parts
+     * @return iterable<int, Collection<int, ShippingZone>>
+     */
+    private function placesInsideOut(Collection $zones, Collection $parts): iterable
+    {
+        $specificity = $parts->flip();
+
+        $postcodeZones = $zones
+            ->where('type', 'postcodes')
+            ->groupBy(fn (ShippingZone $zone) => $zone->postcodes
+                ->map(fn ($postcode) => $specificity[$postcode->postcode] ?? PHP_INT_MAX)
+                ->min());
+
+        foreach ($postcodeZones->sortKeys() as $placeZones) {
+            yield $placeZones;
+        }
+
+        foreach (['states', 'countries', 'unrestricted'] as $type) {
+            yield $zones->where('type', $type);
+        }
+    }
+
+    /**
+     * Ids of the candidate zones' shipping methods that the customer's
+     * group may use — Lunar's own customerGroup() check, once for all of
+     * them instead of once per rate.
+     *
+     * @param  Collection<int, ShippingZone>  $zones
+     * @return Collection<int, bool>  keyed by method id
+     */
+    private function methodsVisibleToCustomer(Collection $zones): Collection
+    {
+        $methodIds = $zones->flatMap->rates->pluck('shipping_method_id')->filter()->unique()->values();
+
+        if ($methodIds->isEmpty()) {
+            return collect();
+        }
+
+        return ShippingMethod::query()
+            ->whereIn('id', $methodIds)
+            ->customerGroup($this->customerGroups)
+            ->pluck('id')
+            ->flip()
+            ->map(fn () => true);
+    }
+
+    /**
+     * The zones' rates that pass Lunar's own checks and whose driver is
+     * registered — one per shipping method.
+     *
+     * @param  Collection<int, ShippingZone>  $zones
+     * @param  Collection<int, bool>  $visibleMethodIds
+     * @return Collection<int, ShippingRate>
+     */
+    private function usableRates(Collection $zones, Collection $visibleMethodIds): Collection
+    {
+        $registered = Shipping::getSupportedDrivers();
+
+        return $zones
+            ->flatMap(fn (ShippingZone $zone) => $zone->rates)
+            ->filter(function (ShippingRate $rate) use ($registered, $visibleMethodIds) {
+                $method = $rate->shippingMethod;
+
+                if (! $rate->enabled || ! $method || ! $visibleMethodIds->has($method->id)) {
+                    return false;
+                }
+
+                if (! $method->isAvailable() || ! $registered->has($method->driver)) {
+                    return false;
+                }
+
+                if (! $this->allCartItemsAreInStock && ($method->stock_available ?? false)) {
+                    return false;
+                }
+
+                return $this->withinWeightLimits($method);
+            })
+            ->unique(fn (ShippingRate $rate) => $rate->shippingMethod->code)
+            ->values();
+    }
+
+    private function withinWeightLimits(ShippingMethod $method): bool
+    {
+        $minWeight = $method->min_weight;
+        $maxWeight = $method->max_weight;
+
+        if ($minWeight === null && $maxWeight === null) {
+            return true;
+        }
+
+        $cartWeight = $this->cartWeightIn($method->weight_unit ?? 'kg');
+
+        return ! ($minWeight !== null && $cartWeight < (float) $minWeight)
+            && ! ($maxWeight !== null && $cartWeight > (float) $maxWeight);
+    }
+}

src/Shipping/Support/RegisteredDriverRateResolver.php

@@ -1,27 +0,0 @@
-<?php
-
-namespace Modules\Core\Shipping\Support;
-
-use Illuminate\Support\Collection;
-use Lunar\Shipping\Facades\Shipping;
-use Lunar\Shipping\Resolvers\ShippingRateResolver;
-
-/**
- * Lunar's rate resolver, minus rates whose shipping method points at a
- * driver that isn't registered anymore (e.g. a carrier commented out of
- * ShippingServiceProvider while its shipping method still exists). Lunar
- * would go on to call that driver to price the option and throw "Driver
- * [x] not supported", taking the whole checkout down; here the method is
- * simply not offered. It stays in the admin as it was.
- */
-class RegisteredDriverRateResolver extends ShippingRateResolver
-{
-    public function get(): Collection
-    {
-        $registered = Shipping::getSupportedDrivers();
-
-        return parent::get()
-            ->filter(fn ($rate) => $registered->has($rate->shippingMethod?->driver))
-            ->values();
-    }
-}

src/Shipping/Support/ShippingManager.php

@@ -31,12 +31,12 @@ use Lunar\Shipping\Resolvers\ShippingRateResolver;
 class ShippingManager extends VendorShippingManager
 {
     /**
-     * Rates for a cart, leaving out shipping methods whose driver is no
+     * Rates for a cart, resolved by place from the inside out (see
-     * longer registered (see RegisteredDriverRateResolver).
+     * PlaceShippingRateResolver).
      */
     public function shippingRates(?CartContract $cart = null): ShippingRateResolver
     {
-        return new RegisteredDriverRateResolver($cart);
+        return new PlaceShippingRateResolver($cart);
     }
 
     public function getSupportedDrivers(): \Illuminate\Support\Collection