feat: tag-based product alternatives

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

app/Models/Product.php

@@ -3,6 +3,7 @@
 namespace App\Models;
 
 use Illuminate\Database\Eloquent\Builder;
+use Illuminate\Database\Eloquent\Collection;
 use Illuminate\Database\Eloquent\Factories\HasFactory;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
@@ -173,6 +174,31 @@ class Product extends Model
         return $this->belongsToMany(Tag::class);
     }
 
+    /**
+     * Get approved products sharing tags with this one, best matches first.
+     * Single query; each result has a shared_tags_count attribute.
+     */
+    public function alternatives(int $limit = 3): Collection
+    {
+        return static::query()
+            ->approved()
+            ->where('products.id', '!=', $this->id)
+            ->join('product_tag', 'product_tag.product_id', '=', 'products.id')
+            ->whereIn('product_tag.tag_id', function ($query) {
+                $query->select('tag_id')->from('product_tag')->where('product_id', $this->id);
+            })
+            ->select('products.*')
+            ->selectRaw('COUNT(product_tag.tag_id) as shared_tags_count')
+            ->withCount('upvotes')
+            ->groupBy('products.id')
+            ->orderByDesc('shared_tags_count')
+            ->orderByDesc('upvotes_count')
+            ->orderByDesc('products.created_at')
+            ->orderByDesc('products.id')
+            ->limit($limit)
+            ->get();
+    }
+
     /**
      * Scope a query to only include approved products.
      */

resources/views/components/product/alternatives.blade.php

@@ -0,0 +1,34 @@
+@props(['product'])
+
+@php
+    $alternatives = $product->alternatives();
+@endphp
+
+@if($alternatives->isNotEmpty())
+    <div data-alternatives {{ $attributes->class('bg-white dark:bg-gray-800 rounded-lg shadow-sm border border-gray-200 dark:border-gray-700 p-6 mb-6') }}>
+        <h2 class="text-lg font-semibold text-gray-900 dark:text-white mb-4">Alternatives</h2>
+        <div class="grid grid-cols-1 sm:grid-cols-3 gap-4">
+            @foreach($alternatives as $alt)
+                <div class="rounded-lg border border-gray-200 dark:border-gray-700 overflow-hidden">
+                    <a href="{{ route('products.show', $alt) }}" class="block aspect-video bg-gradient-to-br from-gray-100 to-gray-200 dark:from-gray-700 dark:to-gray-600">
+                        @if($alt->thumbnail_url)
+                            <img src="{{ $alt->thumbnail_url }}" alt="{{ $alt->title }}" class="w-full h-full object-cover" loading="lazy">
+                        @else
+                            <div class="w-full h-full flex items-center justify-center">
+                                <svg class="h-10 w-10 text-gray-400 dark:text-gray-500" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                                    <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M4 16l4.586-4.586a2 2 0 012.828 0L16 16m-2-2l1.586-1.586a2 2 0 012.828 0L20 14m-6-6h.01M6 20h12a2 2 0 002-2V6a2 2 0 00-2-2H6a2 2 0 00-2 2v12a2 2 0 002 2z"></path>
+                                </svg>
+                            </div>
+                        @endif
+                    </a>
+                    <div class="p-3">
+                        <a href="{{ route('products.show', $alt) }}" class="font-semibold text-gray-900 dark:text-white hover:text-primary-600">{{ $alt->title }}</a>
+                        <p class="mt-1 text-sm text-gray-600 dark:text-gray-400">{{ \Illuminate\Support\Str::limit($alt->description, 80) }}</p>
+                        <x-product.badges :product="$alt" class="mt-2" />
+                        <p class="mt-2 text-xs text-gray-500 dark:text-gray-400">{{ $alt->shared_tags_count }} shared {{ \Illuminate\Support\Str::plural('tag', $alt->shared_tags_count) }}</p>
+                    </div>
+                </div>
+            @endforeach
+        </div>
+    </div>
+@endif

resources/views/products/show.blade.php

@@ -183,7 +183,7 @@
 
             <x-product.pricing :product="$product" />
 
-            <!-- slot:alternatives -->
+            <x-product.alternatives :product="$product" />
 
     <!-- Comments Section -->
     <div class="bg-white dark:bg-gray-800 rounded-lg shadow-sm border border-gray-200 dark:border-gray-700">

tests/Feature/ProductAlternativesTest.php

@@ -0,0 +1,99 @@
+<?php
+
+use App\Models\Product;
+use App\Models\Tag;
+use App\Models\Upvote;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Illuminate\Support\Facades\DB;
+
+uses(RefreshDatabase::class);
+
+function altTags(int $n): array
+{
+    return collect(range(1, $n))->map(fn ($i) => Tag::create([
+        'name' => "Alt Tag $i",
+        'slug' => "alt-tag-$i",
+    ]))->all();
+}
+
+function altProduct(array $tags, string $state = 'approved', array $attrs = []): Product
+{
+    $product = Product::factory()->{$state}()->create($attrs);
+    $product->tags()->sync(collect($tags)->pluck('id')->all());
+
+    return $product;
+}
+
+test('orders by shared tags', function () {
+    [$a, $b, $c, $d] = altTags(4);
+    $self = altProduct([$a, $b, $c]);
+    $two = altProduct([$a, $b]);
+    $three = altProduct([$a, $b, $c, $d]);
+    $one = altProduct([$a]);
+
+    $result = $self->alternatives();
+
+    expect($result->pluck('id')->all())->toBe([$three->id, $two->id, $one->id]);
+    expect($result->pluck('shared_tags_count')->map(fn ($v) => (int) $v)->all())->toBe([3, 2, 1]);
+});
+
+test('excludes self, pending, rejected and zero-shared-tag products', function () {
+    [$a, $b] = altTags(2);
+    $self = altProduct([$a]);
+    $good = altProduct([$a]);
+    altProduct([$a], 'pending');
+    altProduct([$a], 'rejected');
+    altProduct([$b]);
+
+    expect($self->alternatives()->pluck('id')->all())->toBe([$good->id]);
+});
+
+test('ties are ordered by upvotes then newest', function () {
+    [$a] = altTags(1);
+    $self = altProduct([$a]);
+    $old = altProduct([$a], 'approved', ['created_at' => now()->subDays(3)]);
+    $new = altProduct([$a], 'approved', ['created_at' => now()->subDay()]);
+    $voted = altProduct([$a], 'approved', ['created_at' => now()->subDays(5)]);
+    Upvote::create(['product_id' => $voted->id, 'user_id' => userWithRole('user')->id]);
+
+    expect($self->alternatives()->pluck('id')->all())->toBe([$voted->id, $new->id, $old->id]);
+});
+
+test('limits to 3', function () {
+    [$a] = altTags(1);
+    $self = altProduct([$a]);
+    foreach (range(1, 5) as $i) {
+        altProduct([$a]);
+    }
+
+    expect($self->alternatives())->toHaveCount(3);
+    expect($self->alternatives(2))->toHaveCount(2);
+});
+
+test('alternatives is a single query', function () {
+    [$a, $b] = altTags(2);
+    $self = altProduct([$a, $b]);
+    altProduct([$a]);
+    altProduct([$b]);
+
+    DB::enableQueryLog();
+    $self->alternatives();
+    expect(DB::getQueryLog())->toHaveCount(1);
+});
+
+test('show page renders alternative cards and hides the section when none', function () {
+    [$a] = altTags(1);
+    $self = altProduct([$a]);
+
+    $this->get(route('products.show', $self))->assertOk()->assertDontSee('data-alternatives', false);
+
+    $alt = altProduct([$a], 'approved', ['title' => 'Cool Alternative', 'eu_made' => true]);
+
+    $this->get(route('products.show', $self))
+        ->assertOk()
+        ->assertSee('data-alternatives', false)
+        ->assertSee('Cool Alternative')
+        ->assertSee(route('products.show', $alt), false)
+        ->assertSee('1 shared tag')
+        ->assertSee('EU made');
+});