miduo/224_perf: Optimize login latency and reduce redundant I/O in so…

lib/solid_auth_issuer.dart

@@ -32,26 +32,100 @@ import 'dart:async';
 
 import 'package:http/http.dart' as http;
 
-/// Get POD issuer URI
+/// In-memory cache: maps a server URL / WebID to its resolved OIDC issuer URI.
+/// The issuer URI for a given Solid server never changes at runtime, so a
+/// simple process-lifetime cache is safe and avoids repeated HTTP round-trips.
+
+final Map<String, String> _issuerCache = {};
+
+/// Profile-body cache: maps the plain profile card URL (fragment stripped) to
+/// the Turtle body fetched during [getIssuer].
+///
+/// When the user enters a WebID URL such as `https://example.org/profile/card#me`,
+/// [getIssuer] must fetch the profile document to extract the OIDC issuer URI.
+/// The same document is needed again after authentication to populate profile
+/// data. Caching it here avoids a redundant (second) HTTP round-trip.
+
+final Map<String, String> _profileBodyCache = {};
+
+/// Strips any URI fragment (e.g. `#me`) from [profUrl] so that cache keys are
+/// canonical regardless of whether the caller includes a fragment.
+
+String _normalizeProfileUrl(String profUrl) {
+  final int hashIndex = profUrl.indexOf('#');
+  return hashIndex == -1 ? profUrl : profUrl.substring(0, hashIndex);
+}
+
+/// Returns the profile card body that was fetched during [getIssuer], or `null`
+/// if the profile has not been fetched yet (e.g. the server URL is a plain
+/// issuer URI rather than a WebID URL).
+///
+/// The [profUrl] fragment (if any) is stripped before the look-up so callers
+/// may pass either the bare document URL or a full WebID URL.
+
+String? getCachedIssuerProfileBody(String profUrl) =>
+    _profileBodyCache[_normalizeProfileUrl(profUrl)];
+
+/// Clears both in-memory caches.
+/// Useful in tests or whenever server configuration may have changed.
+
+void clearIssuerCaches() {
+  _issuerCache.clear();
+  _profileBodyCache.clear();
+}
+
+/// Get POD issuer URI.
+///
+/// Results are cached in memory so that repeated calls for the same [textUrl]
+/// (e.g. when the user logs out and back in) skip the network look-up.
+
 Future<String> getIssuer(String textUrl) async {
+  // Trim leading/trailing whitespace defensively so that solid_auth behaves
+  // correctly regardless of whether the caller has already sanitised the input.
+  final String trimmed = textUrl.trim();
+
+  // Normalize the key so that trivially different representations of the same
+  // URL (e.g. percent-encoding variants) share a single cache entry.
+  // Uri.tryParse is used instead of Uri.parse to avoid a FormatException for
+  // malformed inputs; fall back to the trimmed string if parsing fails.
+  final String cacheKey = Uri.tryParse(trimmed)?.toString() ?? trimmed;
+
+  // Return cached result immediately when available.
+
+  if (_issuerCache.containsKey(cacheKey)) {
+    return _issuerCache[cacheKey]!;
+  }
+
   String issuerUri = '';
-  if (textUrl.contains('profile/card#me')) {
-    String pubProf = await fetchProfileData(textUrl);
+  if (trimmed.contains('profile/card#me')) {
+    String pubProf = await fetchProfileData(trimmed);
+
+    // Cache the profile body under the plain profile document URL (fragment
+    // stripped). solidpod/authenticate.dart can reuse this to skip a second
+    // HTTP GET.
+
+    _profileBodyCache[_normalizeProfileUrl(trimmed)] = pubProf;
     issuerUri = getIssuerUri(pubProf);
   }
 
   if (issuerUri == '') {
-    /// This reg expression works with localhost and other urls
+    /// This reg expression works with localhost and other urls.
     RegExp exp = RegExp(r'(?:(?:https?|ftp):\/\/)?[\w/\-?=%.]+(\.|\:)[\w\.]+');
-    Iterable<RegExpMatch> matches = exp.allMatches(textUrl);
+    Iterable<RegExpMatch> matches = exp.allMatches(trimmed);
     for (var match in matches) {
-      issuerUri = textUrl.substring(match.start, match.end);
+      issuerUri = trimmed.substring(match.start, match.end);
     }
   }
+
+  if (issuerUri.isNotEmpty) {
+    _issuerCache[cacheKey] = issuerUri;
+  }
+
   return issuerUri;
 }
 
-/// Get public profile information from webId
+/// Get public profile information from webId.
+
 Future<String> fetchProfileData(String profUrl) async {
   final response = await http.get(
     Uri.parse(profUrl),
@@ -71,7 +145,8 @@ Future<String> fetchProfileData(String profUrl) async {
   }
 }
 
-/// Read public profile RDF file and get the issuer URI
+/// Read public profile RDF file and get the issuer URI.
+
 String getIssuerUri(String profileRdfStr) {
   String issuerUri = '';
   var profileDataList = profileRdfStr.split('\n');