From d4226ab83f665f51de08150e07320deacfaa1239 Mon Sep 17 00:00:00 2001
From: Tobe O <thosakwe@gmail.com>
Date: Sun, 1 Apr 2018 21:05:35 -0400
Subject: [PATCH] Skeleton for ResponseCache

---
 README.md                  |  6 +++-
 lib/angel_cache.dart       | 23 ++------------
 lib/src/cache.dart         | 61 ++++++++++++++++++++++++++++++++++++++
 lib/src/cache_service.dart | 21 +++++++++++++
 pubspec.yaml               |  2 ++
 5 files changed, 91 insertions(+), 22 deletions(-)
 create mode 100644 lib/src/cache.dart
 create mode 100644 lib/src/cache_service.dart

diff --git a/README.md b/README.md
index 3cd87af0..dfacc4a8 100644
--- a/README.md
+++ b/README.md
@@ -8,4 +8,8 @@ Support for server-side caching in [Angel](https://angel-dart.github.io).
 *TODO: Documentation*
 
 A `Service` class that caches data from one service, storing it in another.
-An imaginable use case is storing results from MongoDB or another database in Redis.
\ No newline at end of file
+An imaginable use case is storing results from MongoDB or another database in
+MemcacheD/Redis.
+
+## `Cache`
+*TODO: Documentation*
\ No newline at end of file
diff --git a/lib/angel_cache.dart b/lib/angel_cache.dart
index 3a8ef9cf..faba4152 100644
--- a/lib/angel_cache.dart
+++ b/lib/angel_cache.dart
@@ -1,21 +1,2 @@
-import 'package:angel_framework/angel_framework.dart';
-import 'package:meta/meta.dart';
-
-/// An Angel [Service] that caches data from another service.
-///
-/// This is useful for applications of scale, where network latency
-/// can have real implications on application performance.
-class CacheService extends Service {
-  /// The underlying [Service] that represents the original data store.
-  final Service database;
-
-  /// The [Service] used to interface with a caching layer.
-  ///
-  /// If not provided, this defaults to a [MapService].
-  final Service cache;
-
-  CacheService({@required this.database, Service cache})
-      : this.cache = cache ?? new MapService() {
-    assert(database != null);
-  }
-}
+export 'src/cache.dart';
+export 'src/cache_service.dart';
\ No newline at end of file
diff --git a/lib/src/cache.dart b/lib/src/cache.dart
new file mode 100644
index 00000000..fe4622fb
--- /dev/null
+++ b/lib/src/cache.dart
@@ -0,0 +1,61 @@
+import 'dart:async';
+import 'package:angel_framework/angel_framework.dart';
+import 'package:intl/intl.dart';
+
+final DateFormat _fmt = new DateFormat('EEE, d MMM yyyy HH:mm:ss');
+
+/// Formats a date (converted to UTC), ex: `Sun, 03 May 2015 23:02:37 GMT`.
+String _formatDateForHttp(DateTime dt) => _fmt.format(dt.toUtc()) + ' GMT';
+
+class ResponseCache {
+  final List<Pattern> patterns = [];
+  final Duration timeout;
+  final Map<String, _CachedResponse> _cache = {};
+
+  ResponseCache({this.timeout});
+
+  Future<bool> handleRequest(RequestContext req, ResponseContext res) async {
+    var now = new DateTime.now().toUtc();
+
+    // Check if there is a cache entry.
+    for (var pattern in patterns) {
+      if (pattern.allMatches(req.uri.path).isNotEmpty && _cache.containsKey(req.uri.path)) {
+        var response = _cache[req.uri.path];
+
+        // Only send a cached response if it is valid.
+        if (timeout == null || now.difference(response.timestamp) >= timeout) {
+          // TODO: If-Last-Modified
+          break;
+        }
+      }
+    }
+
+    return true;
+  }
+
+  Future<bool> responseFinalizer(RequestContext req, ResponseContext res) async {
+    var now = new DateTime.now().toUtc();
+  }
+
+  void setCachedHeaders(
+      DateTime modified, RequestContext req, ResponseContext res) {
+    var privacy = 'public';
+
+    res.headers
+      ..['cache-control'] = '$privacy, max-age=${timeout?.inSeconds ?? 0}'
+      ..['last-modified'] = _formatDateForHttp(modified);
+
+    if (timeout != null) {
+      var expiry = new DateTime.now().add(timeout);
+      res.headers['expires'] = _formatDateForHttp(expiry);
+    }
+  }
+}
+
+class _CachedResponse {
+  final Map<String, String> headers;
+  final List<int> body;
+  final DateTime timestamp;
+
+  _CachedResponse({this.headers, this.body, this.timestamp});
+}
\ No newline at end of file
diff --git a/lib/src/cache_service.dart b/lib/src/cache_service.dart
new file mode 100644
index 00000000..3a8ef9cf
--- /dev/null
+++ b/lib/src/cache_service.dart
@@ -0,0 +1,21 @@
+import 'package:angel_framework/angel_framework.dart';
+import 'package:meta/meta.dart';
+
+/// An Angel [Service] that caches data from another service.
+///
+/// This is useful for applications of scale, where network latency
+/// can have real implications on application performance.
+class CacheService extends Service {
+  /// The underlying [Service] that represents the original data store.
+  final Service database;
+
+  /// The [Service] used to interface with a caching layer.
+  ///
+  /// If not provided, this defaults to a [MapService].
+  final Service cache;
+
+  CacheService({@required this.database, Service cache})
+      : this.cache = cache ?? new MapService() {
+    assert(database != null);
+  }
+}
diff --git a/pubspec.yaml b/pubspec.yaml
index c3e683ee..091d738c 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,7 +1,9 @@
 name: angel_cache
 dependencies:
   angel_framework: ">=1.0.0-dev <2.0.0"
+  intl: ^0.15.0
   meta: ^1.0.0
 dev_dependencies:
   angel_test: ^1.1.0
+  glob: ^1.0.0
   test: ^0.12.0
\ No newline at end of file