feat: configure search engines in user settings

src/Utility/Utility.c

@@ -1,4 +1,5 @@
 #include "Utility.h"
+#include "../Scraping/Scraping.h"
 #include <beaker.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -34,6 +35,89 @@ char *get_locale(const char *default_locale) {
   return strdup(default_locale);
 }
 
+static int engine_id_casecmp(const char *a, const char *b) {
+  while (*a && *b) {
+    char la = *a;
+    char lb = *b;
+    if (la >= 'A' && la <= 'Z') la = la - 'A' + 'a';
+    if (lb >= 'A' && lb <= 'Z') lb = lb - 'A' + 'a';
+    if (la != lb) return 0;
+    a++;
+    b++;
+  }
+  return *a == *b;
+}
+
+int is_engine_id_enabled(const char *engine_id) {
+  if (!engine_id) return 0;
+  for (int i = 0; i < ENGINE_COUNT; i++) {
+    if (ENGINE_REGISTRY[i].enabled &&
+        engine_id_casecmp(ENGINE_REGISTRY[i].id, engine_id)) {
+      return 1;
+    }
+  }
+  return 0;
+}
+
+int get_user_engines(char ***out_ids, int *out_count) {
+  *out_ids = NULL;
+  *out_count = 0;
+
+  char *cookie = get_cookie("engines");
+  if (!cookie || cookie[0] == '\0') {
+    free(cookie);
+    return -1;
+  }
+
+  char **ids = NULL;
+  int count = 0;
+
+  char *copy = strdup(cookie);
+  if (!copy) {
+    free(cookie);
+    return -1;
+  }
+
+  char *saveptr;
+  char *token = strtok_r(copy, ",", &saveptr);
+  while (token) {
+    while (*token == ' ' || *token == '\t')
+      token++;
+
+    if (token[0] != '\0' && is_engine_id_enabled(token)) {
+      char **new_ids = realloc(ids, sizeof(char *) * (count + 1));
+      if (new_ids) {
+        ids = new_ids;
+        ids[count] = strdup(token);
+        count++;
+      }
+    }
+
+    token = strtok_r(NULL, ",", &saveptr);
+  }
+
+  free(copy);
+  free(cookie);
+
+  if (count == 0) {
+    free(ids);
+    return -1;
+  }
+
+  *out_ids = ids;
+  *out_count = count;
+  return 0;
+}
+
+int user_engines_contains(const char *engine_id, char **ids, int count) {
+  if (!engine_id || !ids) return 0;
+  for (int i = 0; i < count; i++) {
+    if (engine_id_casecmp(ids[i], engine_id))
+      return 1;
+  }
+  return 0;
+}
+
 int add_link_to_collection(const char *href, const char *label,
                            const char *class_name, char ****collection,
                            int **inner_counts, int current_count) {