refactor: issuer discovery (#637)

Author: big-kahuna-burger

lib/issuer.js

@@ -138,35 +138,8 @@ class Issuer {
   }
 
   static async discover(uri) {
-    const parsed = url.parse(uri);
-
-    if (parsed.pathname.includes('/.well-known/')) {
-      const response = await request.call(this, {
-        method: 'GET',
-        responseType: 'json',
-        url: uri,
-        headers: {
-          Accept: 'application/json',
-        },
-      });
-      const body = processResponse(response);
-      return new Issuer({
-        ...ISSUER_DEFAULTS,
-        ...body,
-        [AAD_MULTITENANT]: !!AAD_MULTITENANT_DISCOVERY.find((discoveryURL) =>
-          uri.startsWith(discoveryURL),
-        ),
-      });
-    }
-
-    let pathname;
-    if (parsed.pathname.endsWith('/')) {
-      pathname = `${parsed.pathname}.well-known/openid-configuration`;
-    } else {
-      pathname = `${parsed.pathname}/.well-known/openid-configuration`;
-    }
 
-    const wellKnownUri = url.format({ ...parsed, pathname });
+    const wellKnownUri = resolveWellKnownUri(uri);
 
     const response = await request.call(this, {
       method: 'GET',
@@ -201,4 +174,19 @@ class Issuer {
   }
 }
 
+function resolveWellKnownUri(uri) {
+  const parsed = url.parse(uri);
+  if (parsed.pathname.includes('/.well-known/')) {
+    return uri;
+  } else {
+    let pathname;
+    if (parsed.pathname.endsWith('/')) {
+      pathname = `${parsed.pathname}.well-known/openid-configuration`;
+    } else {
+      pathname = `${parsed.pathname}/.well-known/openid-configuration`;
+    }
+    return url.format({ ...parsed, pathname });
+  }
+}
+
 module.exports = Issuer;