Implement user favorites feature for recipes

- Add UserFavorites MongoDB model with ObjectId references
- Create authenticated API endpoints for favorites management
- Add Heart icon and FavoriteButton components with toggle functionality
- Display favorite button below recipe tags for logged-in users
- Add Favoriten navigation link (visible only when authenticated)
- Create favorites page with grid layout and search functionality
- Store favorites by MongoDB ObjectId for data integrity

🤖 Generated with [Claude Code](https://claude.ai/code)

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

src/lib/assets/icons/Heart.svelte

@@ -0,0 +1,33 @@
+<script>
+</script>
+<style>
+@keyframes shake{
+    0%{
+      transform: rotate(0)
+		scale(1,1);
+    }
+    25%{
+    	box-shadow: 0em 0em 1em 0.2em rgba(0, 0, 0, 0.6);
+      	transform: rotate(30deg)
+      		scale(1.2,1.2)
+      ;
+    }
+    50%{
+
+    	box-shadow: 0em 0em 1em 0.2em rgba(0, 0, 0, 0.6);
+      	transform: rotate(-30deg)
+      		scale(1.2,1.2);
+    }
+    74%{
+
+    	box-shadow: 0em 0em 1em 0.2em rgba(0, 0, 0, 0.6);
+  	transform: rotate(30deg)
+  		scale(1.2, 1.2);
+	}
+	100%{
+      transform: rotate(0)
+      	scale(1,1);
+    }
+  }
+</style>
+<svg xmlns="http://www.w3.org/2000/svg" height="1em" viewBox="0 0 512 512" {...$$restProps}><!--! Font Awesome Free 6.4.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license (Commercial License) Copyright 2023 Fonticons, Inc. --><path d="m47.6 300.4 180.7 168.7c7.5 7 17.4 10.9 27.7 10.9s20.2-3.9 27.7-10.9L464.4 300.4c30.4-28.3 47.6-68 47.6-109.5v-5.8c0-69.9-50.5-129.5-119.4-141C347 36.5 300.6 51.4 268 84L256 96 244 84c-32.6-32.6-79-47.5-124.6-39.9C50.5 55.6 0 115.2 0 185.1v5.8c0 41.5 17.2 81.2 47.6 109.5z"/></svg>

src/lib/components/FavoriteButton.svelte

@@ -0,0 +1,102 @@
+<script lang="ts">
+  import Heart from '$lib/assets/icons/Heart.svelte';
+  
+  export let recipeId: string;
+  export let isFavorite: boolean = false;
+  export let isLoggedIn: boolean = false;
+  
+  let isLoading = false;
+
+  async function toggleFavorite() {
+    if (!isLoggedIn || isLoading) return;
+    
+    isLoading = true;
+    
+    try {
+      const method = isFavorite ? 'DELETE' : 'POST';
+      const response = await fetch('/api/rezepte/favorites', {
+        method,
+        headers: {
+          'Content-Type': 'application/json',
+        },
+        body: JSON.stringify({ recipeId }),
+      });
+      
+      if (response.ok) {
+        isFavorite = !isFavorite;
+      }
+    } catch (error) {
+      console.error('Failed to toggle favorite:', error);
+    } finally {
+      isLoading = false;
+    }
+  }
+</script>
+
+<style>
+  .favorite-button {
+    all: unset;
+    color: var(--nord0);
+    font-size: 1.1rem;
+    background-color: var(--nord5);
+    border-radius: 10000px;
+    padding: 0.5em 1em;
+    transition: 100ms;
+    box-shadow: 0em 0em 0.5em 0.05em rgba(0,0,0,0.3);
+    display: flex;
+    align-items: center;
+    gap: 0.5em;
+    cursor: pointer;
+  }
+  
+  .favorite-button:disabled {
+    opacity: 0.6;
+    cursor: not-allowed;
+  }
+  
+  .favorite-button.favorited {
+    background-color: var(--nord11);
+    color: white;
+  }
+  
+  .favorite-button:not(.favorited):hover,
+  .favorite-button:not(.favorited):focus-visible {
+    transform: scale(1.1);
+    background-color: var(--nord11);
+    color: white;
+    box-shadow: 0.1em 0.1em 0.5em 0.1em rgba(0,0,0,0.3);
+  }
+  
+  .favorite-button.favorited:hover,
+  .favorite-button.favorited:focus-visible {
+    transform: scale(1.1);
+    background-color: var(--nord5);
+    color: var(--nord0);
+    box-shadow: 0.1em 0.1em 0.5em 0.1em rgba(0,0,0,0.3);
+  }
+  
+  @media (prefers-color-scheme: dark) {
+    .favorite-button {
+      background-color: var(--nord0);
+      color: white;
+    }
+    
+    .favorite-button.favorited:hover,
+    .favorite-button.favorited:focus-visible {
+      background-color: var(--nord6);
+      color: var(--nord0);
+    }
+  }
+</style>
+
+{#if isLoggedIn}
+  <button 
+    class="favorite-button" 
+    class:favorited={isFavorite}
+    disabled={isLoading}
+    on:click={toggleFavorite}
+  >
+    <Heart />
+    {isFavorite ? 'Favorit entfernen' : 'Als Favorit speichern'}
+  </button>
+{/if}

src/models/UserFavorites.ts

@@ -0,0 +1,11 @@
+import mongoose from 'mongoose';
+
+const UserFavoritesSchema = new mongoose.Schema(
+  {
+    username: { type: String, required: true, unique: true },
+    favorites: [{ type: mongoose.Schema.Types.ObjectId, ref: 'Recipe' }] // Recipe MongoDB ObjectIds
+  },
+  { timestamps: true }
+);
+
+export const UserFavorites = mongoose.model("UserFavorites", UserFavoritesSchema);

src/routes/api/rezepte/favorites/+server.ts

@@ -0,0 +1,112 @@
+import { json, type RequestHandler } from '@sveltejs/kit';
+import { UserFavorites } from '../../../../models/UserFavorites';
+import { Recipe } from '../../../../models/Recipe';
+import { dbConnect, dbDisconnect } from '../../../../utils/db';
+import { error } from '@sveltejs/kit';
+import mongoose from 'mongoose';
+
+export const GET: RequestHandler = async ({ locals }) => {
+  const session = await locals.auth();
+  
+  if (!session?.user?.nickname) {
+    throw error(401, 'Authentication required');
+  }
+  
+  await dbConnect();
+  
+  try {
+    const userFavorites = await UserFavorites.findOne({ 
+      username: session.user.nickname 
+    }).lean();
+    
+    await dbDisconnect();
+    
+    return json({
+      favorites: userFavorites?.favorites || []
+    });
+  } catch (e) {
+    await dbDisconnect();
+    throw error(500, 'Failed to fetch favorites');
+  }
+};
+
+export const POST: RequestHandler = async ({ request, locals }) => {
+  const session = await locals.auth();
+  
+  if (!session?.user?.nickname) {
+    throw error(401, 'Authentication required');
+  }
+  
+  const { recipeId } = await request.json();
+  
+  if (!recipeId) {
+    throw error(400, 'Recipe ID required');
+  }
+  
+  await dbConnect();
+  
+  try {
+    // Validate that the recipe exists and get its ObjectId
+    const recipe = await Recipe.findOne({ short_name: recipeId });
+    if (!recipe) {
+      await dbDisconnect();
+      throw error(404, 'Recipe not found');
+    }
+    
+    await UserFavorites.findOneAndUpdate(
+      { username: session.user.nickname },
+      { $addToSet: { favorites: recipe._id } },
+      { upsert: true, new: true }
+    );
+    
+    await dbDisconnect();
+    
+    return json({ success: true });
+  } catch (e) {
+    await dbDisconnect();
+    if (e instanceof Error && e.message.includes('404')) {
+      throw e;
+    }
+    throw error(500, 'Failed to add favorite');
+  }
+};
+
+export const DELETE: RequestHandler = async ({ request, locals }) => {
+  const session = await locals.auth();
+  
+  if (!session?.user?.nickname) {
+    throw error(401, 'Authentication required');
+  }
+  
+  const { recipeId } = await request.json();
+  
+  if (!recipeId) {
+    throw error(400, 'Recipe ID required');
+  }
+  
+  await dbConnect();
+  
+  try {
+    // Find the recipe's ObjectId
+    const recipe = await Recipe.findOne({ short_name: recipeId });
+    if (!recipe) {
+      await dbDisconnect();
+      throw error(404, 'Recipe not found');
+    }
+    
+    await UserFavorites.findOneAndUpdate(
+      { username: session.user.nickname },
+      { $pull: { favorites: recipe._id } }
+    );
+    
+    await dbDisconnect();
+    
+    return json({ success: true });
+  } catch (e) {
+    await dbDisconnect();
+    if (e instanceof Error && e.message.includes('404')) {
+      throw e;
+    }
+    throw error(500, 'Failed to remove favorite');
+  }
+};

src/routes/api/rezepte/favorites/check/[shortName]/+server.ts

@@ -0,0 +1,42 @@
+import { json, type RequestHandler } from '@sveltejs/kit';
+import { UserFavorites } from '../../../../../../models/UserFavorites';
+import { Recipe } from '../../../../../../models/Recipe';
+import { dbConnect, dbDisconnect } from '../../../../../../utils/db';
+import { error } from '@sveltejs/kit';
+
+export const GET: RequestHandler = async ({ locals, params }) => {
+  const session = await locals.auth();
+  
+  if (!session?.user?.nickname) {
+    return json({ isFavorite: false });
+  }
+  
+  await dbConnect();
+  
+  try {
+    // Find the recipe by short_name to get its ObjectId
+    const recipe = await Recipe.findOne({ short_name: params.shortName });
+    if (!recipe) {
+      await dbDisconnect();
+      throw error(404, 'Recipe not found');
+    }
+    
+    // Check if this recipe is in the user's favorites
+    const userFavorites = await UserFavorites.findOne({ 
+      username: session.user.nickname,
+      favorites: recipe._id
+    }).lean();
+    
+    await dbDisconnect();
+    
+    return json({
+      isFavorite: !!userFavorites
+    });
+  } catch (e) {
+    await dbDisconnect();
+    if (e instanceof Error && e.message.includes('404')) {
+      throw e;
+    }
+    throw error(500, 'Failed to check favorite status');
+  }
+};

src/routes/api/rezepte/favorites/recipes/+server.ts

@@ -0,0 +1,40 @@
+import { json, type RequestHandler } from '@sveltejs/kit';
+import { UserFavorites } from '../../../../../models/UserFavorites';
+import { Recipe } from '../../../../../models/Recipe';
+import { dbConnect, dbDisconnect } from '../../../../../utils/db';
+import type { RecipeModelType } from '../../../../../types/types';
+import { error } from '@sveltejs/kit';
+
+export const GET: RequestHandler = async ({ locals }) => {
+  const session = await locals.auth();
+  
+  if (!session?.user?.nickname) {
+    throw error(401, 'Authentication required');
+  }
+  
+  await dbConnect();
+  
+  try {
+    const userFavorites = await UserFavorites.findOne({ 
+      username: session.user.nickname 
+    }).lean();
+    
+    if (!userFavorites?.favorites?.length) {
+      await dbDisconnect();
+      return json([]);
+    }
+    
+    let recipes = await Recipe.find({ 
+      _id: { $in: userFavorites.favorites }
+    }).lean() as RecipeModelType[];
+    
+    await dbDisconnect();
+    
+    recipes = JSON.parse(JSON.stringify(recipes));
+    
+    return json(recipes);
+  } catch (e) {
+    await dbDisconnect();
+    throw error(500, 'Failed to fetch favorite recipes');
+  }
+};

src/routes/rezepte/+layout.svelte

@@ -11,6 +11,9 @@ if(data.session){
 <Header>
 	<ul class=site_header slot=links>
 	<li><a href="/rezepte">Alle Rezepte</a></li>
+	{#if user}
+		<li><a href="/rezepte/favorites">Favoriten</a></li>
+	{/if}
 	<li><a href="/rezepte/season">In Saison</a></li>
 	<li><a href="/rezepte/category">Kategorie</a></li>
 	<li><a href="/rezepte/icon">Icon</a></li>

src/routes/rezepte/[name]/+page.svelte

@@ -12,6 +12,7 @@
     	import {season} from '$lib/js/season_store';
 	import RecipeNote from '$lib/components/RecipeNote.svelte';
 	import {stripHtmlTags} from '$lib/js/stripHtmlTags';
+	import FavoriteButton from '$lib/components/FavoriteButton.svelte';
 
     	export let data: PageData;
 
@@ -308,6 +309,15 @@ h4{
 				<a class=tag href="/rezepte/tag/{tag}">{tag}</a>
 			{/each}
 		</div>
+		
+		<div class="tags center">
+			<FavoriteButton 
+				recipeId={data.short_name} 
+				isFavorite={data.isFavorite || false} 
+				isLoggedIn={!!data.session?.user} 
+			/>
+		</div>
+		
 		{#if data.note}
 			<RecipeNote note={data.note}></RecipeNote>
 		{/if}

src/routes/rezepte/[name]/+page.ts

@@ -6,5 +6,21 @@ export async function load({ fetch, params}) {
     if(!res.ok){
 	    throw error(res.status, item.message)
     }
-    return item;
+    
+    // Check if this recipe is favorited by the user
+    let isFavorite = false;
+    try {
+        const favRes = await fetch(`/api/rezepte/favorites/check/${params.name}`);
+        if (favRes.ok) {
+            const favData = await favRes.json();
+            isFavorite = favData.isFavorite;
+        }
+    } catch (e) {
+        // Silently fail if not authenticated or other error
+    }
+    
+    return {
+        ...item,
+        isFavorite
+    };
 }

src/routes/rezepte/favorites/+page.server.ts

@@ -0,0 +1,32 @@
+import type { PageServerLoad } from "./$types";
+import { redirect } from '@sveltejs/kit';
+
+export const load: PageServerLoad = async ({ fetch, locals }) => {
+    const session = await locals.auth();
+    
+    if (!session?.user?.nickname) {
+        throw redirect(302, '/rezepte');
+    }
+
+    try {
+        const res = await fetch('/api/rezepte/favorites/recipes');
+        if (!res.ok) {
+            return {
+                favorites: [],
+                error: 'Failed to load favorites'
+            };
+        }
+        
+        const favorites = await res.json();
+        
+        return {
+            favorites,
+            session
+        };
+    } catch (e) {
+        return {
+            favorites: [],
+            error: 'Failed to load favorites'
+        };
+    }
+};

src/routes/rezepte/favorites/+page.svelte

@@ -0,0 +1,58 @@
+<script lang="ts">
+    import type { PageData } from './$types';
+    import '$lib/css/nordtheme.css';
+    import Recipes from '$lib/components/Recipes.svelte';
+    import Card from '$lib/components/Card.svelte';
+    import Search from '$lib/components/Search.svelte';
+    export let data: PageData;
+    export let current_month = new Date().getMonth() + 1;
+</script>
+
+<style>
+h1{
+    text-align: center;
+    margin-bottom: 0;
+    font-size: 4rem;
+}
+.subheading{
+    text-align: center;
+    margin-top: 0;
+    font-size: 1.5rem;
+}
+.empty-state{
+    text-align: center;
+    margin-top: 3rem;
+    color: var(--nord3);
+}
+</style>
+
+<svelte:head>
+    <title>Meine Favoriten - Bocken Rezepte</title>
+    <meta name="description" content="Meine favorisierten Rezepte aus der Bockenschen Küche." />
+</svelte:head>
+
+<h1>Favoriten</h1>
+<p class=subheading>
+    {#if data.favorites.length > 0}
+        {data.favorites.length} favorisierte Rezepte
+    {:else}
+        Noch keine Favoriten gespeichert
+    {/if}
+</p>
+
+<Search></Search>
+
+{#if data.error}
+    <p class="empty-state">Fehler beim Laden der Favoriten: {data.error}</p>
+{:else if data.favorites.length > 0}
+    <Recipes>
+        {#each data.favorites as recipe}
+            <Card {recipe} {current_month}></Card>
+        {/each}
+    </Recipes>
+{:else}
+    <div class="empty-state">
+        <p>Du hast noch keine Rezepte als Favoriten gespeichert.</p>
+        <p>Besuche ein <a href="/rezepte">Rezept</a> und klicke auf das Herz-Symbol, um es zu deinen Favoriten hinzuzufügen.</p>
+    </div>
+{/if}