From 5fff7ef5c64f4af0595b97a173d1c083b56de39c Mon Sep 17 00:00:00 2001
From: Brent Vatne <brentvatne@gmail.com>
Date: Thu, 26 Apr 2018 00:48:55 +0000
Subject: [PATCH] Give inactive routes in stack opportunity to handle action
 (#4064)

---
 examples/NavigationPlayground/js/App.js       |  8 ++
 .../NavigationPlayground/js/InactiveStack.js  | 96 +++++++++++++++++++
 src/StateUtils.js                             | 23 ++++-
 src/__tests__/NavigationStateUtils-test.js    |  4 +-
 .../__snapshots__/TabNavigator-test.js.snap   |  4 +-
 src/routers/StackRouter.js                    | 31 +++++-
 src/routers/__tests__/StackRouter-test.js     | 71 ++++++++++++--
 7 files changed, 219 insertions(+), 18 deletions(-)
 create mode 100644 examples/NavigationPlayground/js/InactiveStack.js

diff --git a/examples/NavigationPlayground/js/App.js b/examples/NavigationPlayground/js/App.js
index c091ca6..9db6a2c 100644
--- a/examples/NavigationPlayground/js/App.js
+++ b/examples/NavigationPlayground/js/App.js
@@ -27,6 +27,7 @@ import ModalStack from './ModalStack';
 import StacksInTabs from './StacksInTabs';
 import StacksOverTabs from './StacksOverTabs';
 import StacksWithKeys from './StacksWithKeys';
+import InactiveStack from './InactiveStack';
 import StackWithCustomHeaderBackImage from './StackWithCustomHeaderBackImage';
 import SimpleStack from './SimpleStack';
 import StackWithHeaderPreset from './StackWithHeaderPreset';
@@ -45,6 +46,11 @@ const ExampleInfo = {
     name: 'Switch between routes',
     description: 'Jump between routes',
   },
+  InactiveStack: {
+    name: 'Navigate idempotently to stacks in inactive routes',
+    description:
+      'An inactive route in a stack should be given the opportunity to handle actions',
+  },
   StackWithCustomHeaderBackImage: {
     name: 'Custom header back image',
     description: 'Stack with custom header back image',
@@ -150,6 +156,8 @@ const ExampleRoutes = {
   },
   TabsWithNavigationFocus,
   KeyboardHandlingExample,
+  // This is commented out because it's rarely useful
+  // InactiveStack,
 };
 
 type State = {
diff --git a/examples/NavigationPlayground/js/InactiveStack.js b/examples/NavigationPlayground/js/InactiveStack.js
new file mode 100644
index 0000000..17b28ea
--- /dev/null
+++ b/examples/NavigationPlayground/js/InactiveStack.js
@@ -0,0 +1,96 @@
+import React from 'react';
+import { Button, Text, StatusBar, View, StyleSheet } from 'react-native';
+import {
+  SafeAreaView,
+  createStackNavigator,
+  createSwitchNavigator,
+  NavigationActions,
+} from 'react-navigation';
+
+const runSubRoutes = navigation => {
+  navigation.dispatch(NavigationActions.navigate({ routeName: 'First2' }));
+  navigation.dispatch(NavigationActions.navigate({ routeName: 'Second2' }));
+  navigation.dispatch(NavigationActions.navigate({ routeName: 'First2' }));
+};
+
+const runSubRoutesWithIntermediate = navigation => {
+  navigation.dispatch(toFirst1);
+  navigation.dispatch(toSecond2);
+  navigation.dispatch(toFirst);
+  navigation.dispatch(toFirst2);
+};
+
+const runSubAction = navigation => {
+  navigation.dispatch(toFirst2);
+  navigation.dispatch(toSecond2);
+  navigation.dispatch(toFirstChild1);
+};
+
+const DummyScreen = ({ routeName, navigation, style }) => {
+  return (
+    <SafeAreaView
+      style={[
+        StyleSheet.absoluteFill,
+        {
+          alignItems: 'center',
+          justifyContent: 'center',
+          backgroundColor: 'white',
+        },
+        style,
+      ]}
+    >
+      <Text style={{ fontWeight: '800' }}>
+        {routeName}({navigation.state.key})
+      </Text>
+      <View>
+        <Button title="back" onPress={() => navigation.goBack()} />
+        <Button title="dismiss" onPress={() => navigation.dismiss()} />
+        <Button
+          title="between sub-routes"
+          onPress={() => runSubRoutes(navigation)}
+        />
+        <Button
+          title="between sub-routes (with intermediate)"
+          onPress={() => runSubRoutesWithIntermediate(navigation)}
+        />
+
+        <Button
+          title="with sub-action"
+          onPress={() => runSubAction(navigation)}
+        />
+      </View>
+      <StatusBar barStyle="default" />
+    </SafeAreaView>
+  );
+};
+
+const createDummyScreen = routeName => {
+  const BoundDummyScreen = props => DummyScreen({ ...props, routeName });
+  return BoundDummyScreen;
+};
+
+const toFirst = NavigationActions.navigate({ routeName: 'First' });
+const toFirst1 = NavigationActions.navigate({ routeName: 'First1' });
+const toFirst2 = NavigationActions.navigate({ routeName: 'First2' });
+const toSecond2 = NavigationActions.navigate({ routeName: 'Second2' });
+const toFirstChild1 = NavigationActions.navigate({
+  routeName: 'First',
+  action: NavigationActions.navigate({ routeName: 'First1' }),
+});
+
+export default createStackNavigator(
+  {
+    Other: createDummyScreen('Leaf'),
+    First: createStackNavigator({
+      First1: createDummyScreen('First1'),
+      First2: createDummyScreen('First2'),
+    }),
+    Second: createStackNavigator({
+      Second1: createDummyScreen('Second1'),
+      Second2: createDummyScreen('Second2'),
+    }),
+  },
+  {
+    headerMode: 'none',
+  }
+);
diff --git a/src/StateUtils.js b/src/StateUtils.js
index d2c8523..c743eac 100644
--- a/src/StateUtils.js
+++ b/src/StateUtils.js
@@ -116,8 +116,23 @@ const StateUtils = {
 
   /**
    * Replace a route by a key.
-   * Note that this moves the index to the positon to where the new route in the
-   * stack is at.
+   * Note that this moves the index to the position to where the new route in the
+   * stack is at and updates the routes array accordingly.
+   */
+  replaceAndPrune(state, key, route) {
+    const index = StateUtils.indexOf(state, key);
+    const replaced = StateUtils.replaceAtIndex(state, index, route);
+
+    return {
+      ...replaced,
+      routes: replaced.routes.slice(0, index + 1),
+    };
+  },
+
+  /**
+   * Replace a route by a key.
+   * Note that this moves the index to the position to where the new route in the
+   * stack is at. Does not prune the routes.
    */
   replaceAt(state, key, route) {
     const index = StateUtils.indexOf(state, key);
@@ -137,7 +152,7 @@ const StateUtils = {
       route.key
     );
 
-    if (state.routes[index] === route) {
+    if (state.routes[index] === route && index === state.index) {
       return state;
     }
 
@@ -153,7 +168,7 @@ const StateUtils = {
 
   /**
    * Resets all routes.
-   * Note that this moves the index to the positon to where the last route in the
+   * Note that this moves the index to the position to where the last route in the
    * stack is at if the param `index` isn't provided.
    */
   reset(state, routes, index) {
diff --git a/src/__tests__/NavigationStateUtils-test.js b/src/__tests__/NavigationStateUtils-test.js
index d5fec1f..8107076 100644
--- a/src/__tests__/NavigationStateUtils-test.js
+++ b/src/__tests__/NavigationStateUtils-test.js
@@ -202,7 +202,7 @@ describe('StateUtils', () => {
     ).toEqual(newState);
   });
 
-  it('Returns the state if index matches the route', () => {
+  it('Returns the state with updated index if route is unchanged but index changes', () => {
     const state = {
       index: 0,
       routes: [{ key: 'a', routeName }, { key: 'b', routeName }],
@@ -210,7 +210,7 @@ describe('StateUtils', () => {
     };
     expect(
       NavigationStateUtils.replaceAtIndex(state, 1, state.routes[1])
-    ).toEqual(state);
+    ).toEqual({ ...state, index: 1 });
   });
 
   // Reset
diff --git a/src/navigators/__tests__/__snapshots__/TabNavigator-test.js.snap b/src/navigators/__tests__/__snapshots__/TabNavigator-test.js.snap
index e120bf3..08abb05 100644
--- a/src/navigators/__tests__/__snapshots__/TabNavigator-test.js.snap
+++ b/src/navigators/__tests__/__snapshots__/TabNavigator-test.js.snap
@@ -143,7 +143,7 @@ exports[`TabNavigator renders successfully 1`] = `
                 },
                 false,
                 Object {
-                  "flexGrow": 1,
+                  "flex": 1,
                 },
               ]
             }
@@ -156,6 +156,7 @@ exports[`TabNavigator renders successfully 1`] = `
                   "alignSelf": "center",
                   "height": "100%",
                   "justifyContent": "center",
+                  "minWidth": 30,
                   "opacity": 1,
                   "position": "absolute",
                   "width": "100%",
@@ -170,6 +171,7 @@ exports[`TabNavigator renders successfully 1`] = `
                   "alignSelf": "center",
                   "height": "100%",
                   "justifyContent": "center",
+                  "minWidth": 30,
                   "opacity": 0,
                   "position": "absolute",
                   "width": "100%",
diff --git a/src/routers/StackRouter.js b/src/routers/StackRouter.js
index 45e1e16..00ba9b2 100644
--- a/src/routers/StackRouter.js
+++ b/src/routers/StackRouter.js
@@ -27,6 +27,10 @@ function behavesLikePushAction(action) {
 
 const defaultActionCreators = (route, navStateKey) => ({});
 
+function isResetToRootStack(action) {
+  return action.type === StackActions.RESET && action.key === null;
+}
+
 export default (routeConfigs, stackConfig = {}) => {
   // Fail fast on invalid route definitions
   validateRouteConfigMap(routeConfigs);
@@ -223,7 +227,10 @@ export default (routeConfigs, stackConfig = {}) => {
 
       // Check if the focused child scene wants to handle the action, as long as
       // it is not a reset to the root stack
-      if (action.type !== StackActions.RESET || action.key !== null) {
+      if (
+        !isResetToRootStack(action) &&
+        action.type !== NavigationActions.NAVIGATE
+      ) {
         const keyIndex = action.key
           ? StateUtils.indexOf(state, action.key)
           : -1;
@@ -243,6 +250,28 @@ export default (routeConfigs, stackConfig = {}) => {
             return StateUtils.replaceAt(state, childRoute.key, route);
           }
         }
+      } else if (action.type === NavigationActions.NAVIGATE) {
+        // Traverse routes from the top of the stack to the bottom, so the
+        // active route has the first opportunity, then the one before it, etc.
+        for (let childRoute of state.routes.slice().reverse()) {
+          let childRouter = childRouters[childRoute.routeName];
+          let debug = action.params && action.params.debug;
+
+          if (childRouter) {
+            const nextRouteState = childRouter.getStateForAction(
+              action,
+              childRoute
+            );
+
+            if (nextRouteState === null || nextRouteState !== childRoute) {
+              return StateUtils.replaceAndPrune(
+                state,
+                nextRouteState ? nextRouteState.key : childRoute.key,
+                nextRouteState ? nextRouteState : childRoute
+              );
+            }
+          }
+        }
       }
 
       // Handle explicit push navigation action. This must happen after the
diff --git a/src/routers/__tests__/StackRouter-test.js b/src/routers/__tests__/StackRouter-test.js
index a3c1983..295047b 100644
--- a/src/routers/__tests__/StackRouter-test.js
+++ b/src/routers/__tests__/StackRouter-test.js
@@ -679,23 +679,74 @@ describe('StackRouter', () => {
     expect(pushedState).toEqual(null);
   });
 
-  test('Navigate with key is idempotent', () => {
+  test('Navigate with key and without it is idempotent', () => {
     const TestRouter = StackRouter({
       foo: { screen: () => <div /> },
       bar: { screen: () => <div /> },
     });
     const initState = TestRouter.getStateForAction(NavigationActions.init());
-    const pushedState = TestRouter.getStateForAction(
-      NavigationActions.navigate({ routeName: 'bar', key: 'a' }),
-      initState
+    for (key of ['a', null]) {
+      const pushedState = TestRouter.getStateForAction(
+        NavigationActions.navigate({ routeName: 'bar', key: 'a' }),
+        initState
+      );
+      expect(pushedState.index).toEqual(1);
+      expect(pushedState.routes[1].routeName).toEqual('bar');
+      const pushedTwiceState = TestRouter.getStateForAction(
+        NavigationActions.navigate({ routeName: 'bar', key: 'a' }),
+        pushedState
+      );
+      expect(pushedTwiceState).toEqual(null);
+    }
+  });
+
+  // https://github.com/react-navigation/react-navigation/issues/4063
+  test('Navigate on inactive stackrouter is idempotent', () => {
+    const FirstChildNavigator = () => <div />;
+    FirstChildNavigator.router = StackRouter({
+      First1: () => <div />,
+      First2: () => <div />,
+    });
+
+    const SecondChildNavigator = () => <div />;
+    SecondChildNavigator.router = StackRouter({
+      Second1: () => <div />,
+      Second2: () => <div />,
+    });
+
+    const router = StackRouter({
+      Leaf: () => <div />,
+      First: FirstChildNavigator,
+      Second: SecondChildNavigator,
+    });
+
+    const state = router.getStateForAction({ type: NavigationActions.INIT });
+
+    const first = router.getStateForAction(
+      NavigationActions.navigate({ routeName: 'First2' }),
+      state
     );
-    expect(pushedState.index).toEqual(1);
-    expect(pushedState.routes[1].routeName).toEqual('bar');
-    const pushedTwiceState = TestRouter.getStateForAction(
-      NavigationActions.navigate({ routeName: 'bar', key: 'a' }),
-      pushedState
+
+    const second = router.getStateForAction(
+      NavigationActions.navigate({ routeName: 'Second2' }),
+      first
     );
-    expect(pushedTwiceState).toEqual(null);
+
+    const firstAgain = router.getStateForAction(
+      NavigationActions.navigate({
+        routeName: 'First2',
+        params: { debug: true },
+      }),
+      second
+    );
+
+    expect(first.routes.length).toEqual(2);
+    expect(first.index).toEqual(1);
+    expect(second.routes.length).toEqual(3);
+    expect(second.index).toEqual(2);
+
+    expect(firstAgain.index).toEqual(1);
+    expect(firstAgain.routes.length).toEqual(2);
   });
 
   test('Navigate to current routeName returns null to indicate handled action', () => {