refactor: extract signals filter builder, add ESLint 10 config, fix low-hanging issues

web/lib/apiHelpers.ts

@@ -1,5 +1,8 @@
-import { NextRequest, NextResponse } from 'next/server';
+import { type NextRequest, NextResponse } from 'next/server';
+
 import { isAuthorized, unauthorized } from './auth';
+import { getServerLocaleMap } from './localeServer';
+import { matchKeys } from './localization';
 
 type RouteContext = { params: Promise<Record<string, string>> };
 type Handler = (req: NextRequest, ctx: RouteContext) => Promise<NextResponse>;
@@ -24,3 +27,53 @@ export function withAuth(handler: Handler): Handler {
     }
   };
 }
+
+/**
+ * Builds a SQL WHERE clause fragment for item whitelist/blacklist filtering.
+ *
+ * - `isWhitelist=true`:  `item_key ~* $N OR item_key = ANY($N+1)`  (regex),  `item_key = ANY($N)`  (exact)
+ * - `isWhitelist=false`: `item_key !~* $N AND item_key != ALL($N+1)` (regex), `item_key != ALL($N)` (exact)
+ *
+ * Mutates `values` and `param.current` to track parameter bindings.
+ */
+export function buildItemFilter(
+  items: string[],
+  useRegex: boolean,
+  isWhitelist: boolean,
+  values: unknown[],
+  param: { current: number },
+): string | null {
+  if (items.length === 0) return null;
+
+  if (useRegex) {
+    const localeMap = getServerLocaleMap();
+    const localeKeys = [...new Set(items.flatMap((p) => matchKeys(p, localeMap)))];
+    const sqlPattern = items.map((p) => `(${p})`).join('|');
+
+    if (isWhitelist) {
+      const orConds: string[] = [`item_key ~* $${param.current++}`];
+      values.push(sqlPattern);
+      if (localeKeys.length > 0) {
+        orConds.push(`item_key = ANY($${param.current++})`);
+        values.push(localeKeys);
+      }
+      return `(${orConds.join(' OR ')})`;
+    } else {
+      const andConds: string[] = [`item_key !~* $${param.current++}`];
+      values.push(sqlPattern);
+      if (localeKeys.length > 0) {
+        andConds.push(`item_key != ALL($${param.current++})`);
+        values.push(localeKeys);
+      }
+      return `(${andConds.join(' AND ')})`;
+    }
+  }
+
+  if (isWhitelist) {
+    values.push(items);
+    return `item_key = ANY($${param.current++})`;
+  } else {
+    values.push(items);
+    return `item_key != ALL($${param.current++})`;
+  }
+}