feat: Implement server-side category and product search via WebSockets, replacing client-side filtering with debounced input and dynamic tree expansion based on server results.

src/server/utils/search-helper.js

@@ -0,0 +1,73 @@
+import fs from 'fs/promises';
+import path from 'path';
+
+export async function findMatches(query, cacheDir) {
+    if (!query || !query.trim()) return [];
+    const terms = query.toLowerCase().split(/\s+/).filter(t => t);
+
+    // Load category tree
+    const treePath = path.join(cacheDir, 'category_tree.json');
+    let tree = [];
+    try {
+        const treeData = await fs.readFile(treePath, 'utf-8');
+        tree = JSON.parse(treeData);
+    } catch (e) {
+        console.error("Failed to load category tree for search", e);
+        return [];
+    }
+
+    const matchingCategoryIds = new Set();
+
+    // Helper to check text match
+    const isMatch = (text) => {
+        if (!text) return false;
+        const lower = text.toLowerCase();
+        return terms.every(t => lower.includes(t));
+    };
+
+    // Flatten tree to linear list for easier iteration
+    const queue = [...tree];
+    const nodes = [];
+    while (queue.length > 0) {
+        const node = queue.shift();
+        nodes.push(node);
+        if (node.children) {
+            queue.push(...node.children);
+        }
+    }
+
+    // Process in chunks to avoid too many open files
+    const CHUNK_SIZE = 50;
+    for (let i = 0; i < nodes.length; i += CHUNK_SIZE) {
+        const chunk = nodes.slice(i, i + CHUNK_SIZE);
+        await Promise.all(chunk.map(async (node) => {
+            let nodeMatches = false;
+
+            // Check category name
+            if (isMatch(node.cName)) {
+                nodeMatches = true;
+            } else {
+                // Check products
+                try {
+                    const prodPath = path.join(cacheDir, 'products', `category_${node.kKategorie}.json`);
+                    // Check if file exists before reading to avoid throwing too many errors
+                    // Actually readFile throws ENOENT which is fine
+                    const prodData = await fs.readFile(prodPath, 'utf-8');
+                    const products = JSON.parse(prodData);
+
+                    if (products.some(p => isMatch(p.cName))) {
+                        nodeMatches = true;
+                    }
+                } catch (e) {
+                    // Ignore missing files
+                }
+            }
+
+            if (nodeMatches) {
+                matchingCategoryIds.add(node.kKategorie);
+            }
+        }));
+    }
+
+    return Array.from(matchingCategoryIds);
+}