initial profile implementation!

src/lib/api.js

@@ -1,3 +1,7 @@
+const errors = {
+    AUTHENTICATION_FAILED: "AUTHENTICATION_FAILED",
+};
+
 /**
  * GET /api/v1/instance
  * @param {string} host - The domain of the target server.
@@ -421,3 +425,26 @@ export async function getUser(host, token, user_id) {
 
     return data;
 }
+
+/**
+ * GET /api/v1/accounts/lookup?acct={handle}
+ * @param {string} host - The domain of the target server.
+ * @param {string} token - The application token.
+ * @param {string} handle - The handle of the user to fetch.
+ */
+export async function lookupUser(host, token, handle) {
+    let url = `https://${host}/api/v1/accounts/lookup?acct=${handle}`;
+
+    const res = await fetch(url, {
+        method: 'GET',
+        headers: { "Authorization": token ? `Bearer ${token}` : null }
+    });
+    if (!res.ok) {
+        const json = await res.json();
+        if (json.error = errors.AUTHENTICATION_FAILED)
+            throw new Error("This method requires authentication");
+    }
+    const data = await res.json();
+
+    return data;
+}