refactor: internationalise pagination and clean up related code

src/Utility/Utility.c

@@ -1,5 +1,6 @@
 #include "Utility.h"
 #include <beaker.h>
+#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -32,3 +33,101 @@ char *get_locale(const char *default_locale) {
   free(cookie);
   return strdup(default_locale);
 }
+
+int add_link_to_collection(const char *href, const char *label,
+                           const char *class_name, char ****collection,
+                           int **inner_counts, int current_count) {
+  char ***old_collection = *collection;
+  int *old_inner_counts = *inner_counts;
+  char ***new_collection =
+      (char ***)malloc(sizeof(char **) * (current_count + 1));
+  int *new_inner_counts =
+      (int *)malloc(sizeof(int) * (current_count + 1));
+
+  if (!new_collection || !new_inner_counts) {
+    free(new_collection);
+    free(new_inner_counts);
+    return current_count;
+  }
+
+  if (*collection && current_count > 0) {
+    memcpy(new_collection, *collection, sizeof(char **) * current_count);
+  }
+  if (*inner_counts && current_count > 0) {
+    memcpy(new_inner_counts, *inner_counts, sizeof(int) * current_count);
+  }
+
+  *collection = new_collection;
+  *inner_counts = new_inner_counts;
+
+  (*collection)[current_count] =
+      (char **)malloc(sizeof(char *) * LINK_FIELD_COUNT);
+  if (!(*collection)[current_count]) {
+    *collection = old_collection;
+    *inner_counts = old_inner_counts;
+    free(new_collection);
+    free(new_inner_counts);
+    return current_count;
+  }
+
+  (*collection)[current_count][0] = strdup(href ? href : "");
+  (*collection)[current_count][1] = strdup(label ? label : "");
+  (*collection)[current_count][2] = strdup(class_name ? class_name : "");
+
+  if (!(*collection)[current_count][0] || !(*collection)[current_count][1] ||
+      !(*collection)[current_count][2]) {
+    free((*collection)[current_count][0]);
+    free((*collection)[current_count][1]);
+    free((*collection)[current_count][2]);
+    free((*collection)[current_count]);
+    *collection = old_collection;
+    *inner_counts = old_inner_counts;
+    free(new_collection);
+    free(new_inner_counts);
+    return current_count;
+  }
+
+  (*inner_counts)[current_count] = LINK_FIELD_COUNT;
+
+  free(old_collection);
+  free(old_inner_counts);
+  return current_count + 1;
+}
+
+int build_pagination(int page, const char *locale,
+                     char *(*href_builder)(int page, void *data), void *data,
+                     char ****out_matrix, int **out_inner_counts) {
+  enum { PAGER_WINDOW_SIZE = 5 };
+
+  *out_matrix = NULL;
+  *out_inner_counts = NULL;
+  int count = 0;
+
+  int pager_start = page <= 3 ? 1 : page - 2;
+  int pager_end = pager_start + PAGER_WINDOW_SIZE - 1;
+
+  if (page > 1) {
+    char *href = href_builder(page - 1, data);
+    count = add_link_to_collection(href, "<", "pagination-btn prev",
+                                   out_matrix, out_inner_counts, count);
+    free(href);
+  }
+
+  for (int i = pager_start; i <= pager_end; i++) {
+    char label[16];
+    snprintf(label, sizeof(label), "%d", i);
+    char *href = href_builder(i, data);
+    count = add_link_to_collection(
+        href, label,
+        i == page ? "pagination-btn pagination-current" : "pagination-btn",
+        out_matrix, out_inner_counts, count);
+    free(href);
+  }
+
+  char *href = href_builder(page + 1, data);
+  count = add_link_to_collection(href, ">", "pagination-btn next",
+                                 out_matrix, out_inner_counts, count);
+  free(href);
+
+  return count;
+}