refactor: extract user authentication logic into dedicated service class with dependency injection

inplace_url.h

@@ -10,6 +10,8 @@
 #include <regex.h>
 #include "http.h"
 #include "url.h"
+#include <stdlib.h>
+#include <string.h>
 
 void extract_urls(const char *input, char **urls, int *url_count) {
     const char *pattern = "https?://[^ ]+";
@@ -29,18 +31,18 @@ void extract_urls(const char *input, char **urls, int *url_count) {
     regfree(&regex);
 }
 
-void inplace_urls_markdown_style(char *input, char **urls, char **contents, int url_count) {
+void inplace_urls_markdown_style(char **input, char **urls, char **contents, int url_count) {
     for (int i = 0; i < url_count; i++) {
-        char *found = strstr(input, urls[i]);
+        char *found = strstr(*input, urls[i]);
         if (found) {
-            char *new_text = (char *)malloc(strlen(input) + strlen(contents[i]) - strlen(urls[i]) + 1);
-            strncpy(new_text, input, found - input);
-            new_text[found - input] = '\0';
+            char *new_text = (char *)malloc(strlen(*input) + strlen(contents[i]) - strlen(urls[i]) + 1);
+            strncpy(new_text, *input, found - *input);
+            new_text[found - *input] = '\0';
             strcat(new_text, contents[i]);
             strcat(new_text, found + strlen(urls[i]));
 
-            free(input);
-            input = new_text;
+            free(*input);
+            *input = new_text;
         }
     }
 }