Add initial API interaction functions and database schema

app/API/API.js

@@ -0,0 +1,48 @@
+// This file contains functions to interact with the API or local database.
+
+const API_BASE_URL = 'http://localhost:3000'; // Change this to the actual API endpoint when needed
+
+// Generic fetch function
+const APIFetch = async (endpoint, options = {}) => {
+  try {
+    const response = await fetch(`${API_BASE_URL}/${endpoint}`, {
+      ...options,
+      headers: {
+        'Content-Type': 'application/json',
+        ...options.headers,
+      },
+    });
+
+    if (!response.ok) {
+      throw new Error(`API error: ${response.statusText}`);
+    }
+
+    return await response.json();
+  } catch (error) {
+    console.error('Fetch error:', error);
+    throw error;
+  }
+};
+
+// Example function to fetch a user by username
+const fetchUserByUsername = async (username) => {
+  return await APIFetch(`users?username=${username}`);
+};
+
+// Example function to fetch all groups
+const fetchGroups = async () => {
+  return await APIFetch('groups');
+};
+
+// Example function to fetch subgroups by group ID
+const fetchSubgroupsByGroupId = async (groupId) => {
+  return await APIFetch(`groups/${groupId}/subgroups`);
+};
+
+// RESTful API functions
+const fetchItems = async (endpoint) => await APIFetch(endpoint);
+const createItem = async (endpoint, data) => await APIFetch(endpoint, { method: 'POST', body: JSON.stringify(data) });
+const updateItem = async (endpoint, data) => await APIFetch(endpoint, { method: 'PUT', body: JSON.stringify(data) });
+const deleteItem = async (endpoint) => await APIFetch(endpoint, { method: 'DELETE' });
+
+export { APIFetch, fetchUserByUsername, fetchGroups, fetchSubgroupsByGroupId, fetchItems, createItem, updateItem, deleteItem };