Add Page Middleware

@@ -9,6 +9,7 @@ export 'src/routes/custom_transition.dart';
 export 'src/routes/default_route.dart';
 export 'src/routes/get_route.dart';
 export 'src/routes/observers/route_observer.dart';
+export 'src/routes/route_middleware.dart';
 export 'src/routes/transitions_type.dart';
 export 'src/snackbar/snack.dart';
 export 'src/snackbar/snack_route.dart';

@@ -188,7 +188,14 @@ class GetCupertinoApp extends StatelessWidget {
         super(key: key);
 
   Route<dynamic> generator(RouteSettings settings) {
-    final match = Get.routeTree.matchRoute(settings.name);
+    var match = Get.routeTree.matchRoute(settings.name);
+
+    final redirect =
+        MiddlewareRunner(match.route.middlewares).runOnPageCalled();
+    if (!redirect.isNullOrBlank) {
+      match = Get.routeTree.matchRoute(redirect);
+    }
+
     Get.parameters = match?.parameters;
 
     if (match?.route == null) {
@@ -207,6 +214,7 @@ class GetCupertinoApp extends StatelessWidget {
         transition: unknownRoute.transition,
         popGesture: unknownRoute.popGesture,
         fullscreenDialog: unknownRoute.fullscreenDialog,
+        middlewares: unknownRoute.middlewares,
       );
     }
 
@@ -225,6 +233,7 @@ class GetCupertinoApp extends StatelessWidget {
       transition: match.route.transition,
       popGesture: match.route.popGesture,
       fullscreenDialog: match.route.fullscreenDialog,
+      middlewares: match.route.middlewares,
     );
   }
 

@@ -199,7 +199,14 @@ class GetMaterialApp extends StatelessWidget {
         super(key: key);
 
   Route<dynamic> generator(RouteSettings settings) {
-    final match = Get.routeTree.matchRoute(settings.name);
+    var match = Get.routeTree.matchRoute(settings.name);
+
+    final redirect =
+        MiddlewareRunner(match.route.middlewares).runOnPageCalled();
+    if (!redirect.isNullOrBlank) {
+      match = Get.routeTree.matchRoute(redirect);
+    }
+
     Get.parameters = match?.parameters;
 
     if (match?.route == null) {
@@ -218,6 +225,7 @@ class GetMaterialApp extends StatelessWidget {
         transition: unknownRoute.transition,
         popGesture: unknownRoute.popGesture,
         fullscreenDialog: unknownRoute.fullscreenDialog,
+        middlewares: unknownRoute.middlewares,
       );
     }
 
@@ -236,6 +244,7 @@ class GetMaterialApp extends StatelessWidget {
       transition: match.route.transition,
       popGesture: match.route.popGesture,
       fullscreenDialog: match.route.fullscreenDialog,
+      middlewares: match.route.middlewares
     );
   }
 

@@ -70,23 +70,24 @@ class ParseRouteTree {
   }
 
   /// Change the Path for a [GetPage]
-  GetPage _changePath(GetPage orgin, String routePath) => GetPage(
-        name: routePath + orgin.name,
-        page: orgin.page,
-        title: orgin.title,
-        alignment: orgin.alignment,
-        transition: orgin.transition,
-        binding: orgin.binding,
-        bindings: orgin.bindings,
-        curve: orgin.curve,
-        customTransition: orgin.customTransition,
-        fullscreenDialog: orgin.fullscreenDialog,
-        maintainState: orgin.maintainState,
-        opaque: orgin.opaque,
-        parameter: orgin.parameter,
-        popGesture: orgin.popGesture,
-        settings: orgin.settings,
-        transitionDuration: orgin.transitionDuration,
+  GetPage _changePath(GetPage origin, String routePath) => GetPage(
+        name: routePath + origin.name,
+        page: origin.page,
+        title: origin.title,
+        alignment: origin.alignment,
+        transition: origin.transition,
+        binding: origin.binding,
+        bindings: origin.bindings,
+        curve: origin.curve,
+        customTransition: origin.customTransition,
+        fullscreenDialog: origin.fullscreenDialog,
+        maintainState: origin.maintainState,
+        opaque: origin.opaque,
+        parameter: origin.parameter,
+        popGesture: origin.popGesture,
+        settings: origin.settings,
+        transitionDuration: origin.transitionDuration,
+        middlewares: origin.middlewares,
       );
 
   _GetPageMatch matchRoute(String path) {

@@ -30,6 +30,7 @@ class GetPageRoute<T> extends PageRoute<T> {
     this.barrierLabel,
     this.maintainState = true,
     bool fullscreenDialog = false,
+    this.middlewares
   })  : assert(opaque != null),
         assert(barrierDismissible != null),
         assert(maintainState != null),
@@ -64,6 +65,8 @@ class GetPageRoute<T> extends PageRoute<T> {
   final Curve curve;
 
   final Alignment alignment;
+  
+  final List<GetPageMiddleware> middlewares;
 
   @override
   final Color barrierColor;
@@ -111,14 +114,18 @@ class GetPageRoute<T> extends PageRoute<T> {
     Animation<double> secondaryAnimation,
   ) {
     Get.reference = settings.name ?? routeName;
+
+    final middlewareRunner = MiddlewareRunner(middlewares);
+    final bindingsToBind = middlewareRunner.runOnBindingsStart(bindings);
     binding?.dependencies();
-    if (bindings != null) {
-      for (final binding in bindings) {
+    if (bindingsToBind != null) {
+      for (final binding in bindingsToBind) {
         binding.dependencies();
       }
     }
-    // final pageWidget = page();
-    return page();
+    
+    final pageToBuild =  middlewareRunner.runOnPageBuildStart(page);    
+    return middlewareRunner.runOnPageBuilt(pageToBuild());
   }
 
   static bool isPopGestureInProgress(PageRoute<dynamic> route) {

 import 'package:flutter/widgets.dart';
+
 import '../../../get_instance/get_instance.dart';
+import '../../get_navigation.dart';
 import 'custom_transition.dart';
 import 'transitions_type.dart';
 
@@ -21,6 +23,7 @@ class GetPage {
   final bool fullscreenDialog;
   final RouteSettings settings;
   final List<GetPage> children;
+  final List<GetPageMiddleware> middlewares;
 
   const GetPage({
     @required this.name,
@@ -40,6 +43,7 @@ class GetPage {
     this.customTransition,
     this.fullscreenDialog = false,
     this.children,
+    this.middlewares,
   })  : assert(page != null),
         assert(name != null),
         assert(maintainState != null),

+import 'package:flutter/cupertino.dart';
+import '../../../get.dart';
+
+/// The Page Middlewares
+/// The Functions will be called in this order
+/// (( [onPageCalled] -> [onBindingsStart] -> [onPageBuildStart] ->
+/// [onPageBuilt] -> [onPageDispose] ))
+abstract class GetPageMiddleware {
+  /// The Order of the Middlewares to run.
+  int priority;
+
+  /// This function will be the first thing to call when this Page is called
+  /// you can use it to redirect befor anything in this page happend.
+  /// {@tool snippet}
+  /// ```dart
+  /// GetPage onPageCalled( ) {
+  ///   final authService = Get.find<AuthService>();
+  ///   return authService.isAuthed ? null : '/login';
+  /// }
+  /// ```
+  /// {@end-tool}
+  String redirect();
+
+  ///This function will be called right before the [Bindings] are initialize.
+  /// Here you can change [Bindings] for this page
+  List<Bindings> onBindingsStart(List<Bindings> bindings);
+
+  /// This function will be called right after the [Bindings] are initialize.
+  GetPageBuilder onPageBuildStart(GetPageBuilder page);
+
+  // Get the built page
+  Widget onPageBuilt(Widget page);
+
+  void onPageDispose();
+}
+
+class MiddlewareRunner {
+  MiddlewareRunner(this._middlewares);
+
+  final List<GetPageMiddleware> _middlewares;
+
+  List<GetPageMiddleware> _getMiddlewares() {
+    if (_middlewares != null) {
+      _middlewares.sort((a, b) => a.priority.compareTo(b.priority));
+      return _middlewares;
+    }
+    return <GetPageMiddleware>[];
+  }
+
+  String runOnPageCalled() {
+    var to = '';
+    _getMiddlewares().forEach((element) {
+      to = element.redirect();
+    });
+    if (!to.isNullOrBlank) {
+      Get.log('Redirect to $to');
+    }
+    return to;
+  }
+
+  List<Bindings> runOnBindingsStart(List<Bindings> bindings) {
+    _getMiddlewares().forEach((element) {
+      bindings = element.onBindingsStart(bindings);
+    });
+    return bindings;
+  }
+
+  GetPageBuilder runOnPageBuildStart(GetPageBuilder page) {
+    _getMiddlewares().forEach((element) {
+      page = element.onPageBuildStart(page);
+    });
+    return page;
+  }
+
+  Widget runOnPageBuilt(Widget page) {
+    _getMiddlewares().forEach((element) {
+      page = element.onPageBuilt(page);
+    });
+    return page;
+  }
+
+  void runOnPageDispose() =>
+      _getMiddlewares().forEach((element) => element.onPageDispose());
+}