From 0bfc4bcdd90876d13ba5a904f52ff955c62f043d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=BCrgen=20Wenzel?= <jurgen@jwenzel.se>
Date: Mon, 16 Oct 2017 00:20:54 +0200
Subject: [PATCH] feat(router): viewport defaults Adds viewPortDefaults to
 RouterConfiguration so that optional viewports in route configurations can
 have a default module.

Depending on aurelia/templating-router/optional-viewports.
Closes aurelia/router#482.
---
 src/navigation-plan.js      | 33 ++++++++++++++++++++++++---------
 src/router-configuration.js |  5 +++++
 src/router.js               |  5 +++++
 3 files changed, 34 insertions(+), 9 deletions(-)

diff --git a/src/navigation-plan.js b/src/navigation-plan.js
index f29ca19b..c8f27c74 100644
--- a/src/navigation-plan.js
+++ b/src/navigation-plan.js
@@ -1,5 +1,5 @@
-import {Redirect} from './navigation-commands';
-import {_resolveUrl} from './util';
+import { Redirect } from './navigation-commands';
+import { _resolveUrl } from './util';
 
 /**
 * The strategy to use when activating modules during navigation.
@@ -38,9 +38,13 @@ export function _buildNavigationPlan(instruction: NavigationInstruction, forceLi
 
   let newParams = prev ? hasDifferentParameterValues(prev, instruction) : true;
 
+  let viewPortDefaults = Object.assign({}, instruction.router.viewPortDefaults);
+
   if (prev && !config.explicitViewPorts) {
     for (let viewPortName in prev.viewPortInstructions) {
-      let viewPortPlan = buildViewPortPlan(instruction, forceLifecycleMinimum, newParams, viewPortName, true);
+      delete viewPortDefaults[viewPortName.split('.')[0]];
+
+      let viewPortPlan = buildViewPortPlan(instruction, instruction.config.viewPorts, forceLifecycleMinimum, newParams, viewPortName, true);
       plan[viewPortPlan.name] = viewPortPlan.plan;
       if (viewPortPlan.task) {
         pending.push(viewPortPlan.task);
@@ -48,15 +52,26 @@ export function _buildNavigationPlan(instruction: NavigationInstruction, forceLi
     }
   }
 
-  let viewPortNames = {};
+  let viewPorts = {};
+
+  if (viewPortDefaults) {
+    for (let viewPortName in viewPortDefaults) {
+      if (config.viewPorts[viewPortName] === undefined) {
+        viewPorts[viewPortName] = viewPortDefaults[viewPortName];
+      }
+    }
+  }
+
   if (config.viewPorts) {
     for (let viewPortName in config.viewPorts) {
-      viewPortNames[viewPortName] = config.viewPorts[viewPortName];
+      if (config.viewPorts[viewPortName] !== undefined || !viewPorts[viewPortName]) {
+        viewPorts[viewPortName] = config.viewPorts[viewPortName];
+      }
     }
   }
 
-  for (let viewPortName in viewPortNames) {
-    let viewPortPlan = buildViewPortPlan(instruction, forceLifecycleMinimum, newParams, viewPortName, false);
+  for (let viewPortName in viewPorts) {
+    let viewPortPlan = buildViewPortPlan(instruction, viewPorts, forceLifecycleMinimum, newParams, viewPortName, false);
     plan[viewPortPlan.name] = viewPortPlan.plan;
     if (viewPortPlan.task) {
       pending.push(viewPortPlan.task);
@@ -66,13 +81,13 @@ export function _buildNavigationPlan(instruction: NavigationInstruction, forceLi
   return Promise.all(pending).then(() => plan);
 }
 
-function buildViewPortPlan(instruction: NavigationInstruction, forceLifecycleMinimum, newParams: boolean, viewPortName: string, previous: boolean) {
+function buildViewPortPlan(instruction: NavigationInstruction, viewPorts: any, forceLifecycleMinimum, newParams: boolean, viewPortName: string, previous: boolean) {
   let plan = {};
   let prev = instruction.previousInstruction;
   let config = instruction.config;
   let configViewPortName = viewPortName;
   let prevViewPortInstruction = prev ? prev.viewPortInstructions[viewPortName] : undefined;
-  let nextViewPortConfig = !previous ? config.viewPorts[configViewPortName] : undefined;
+  let nextViewPortConfig = !previous ? viewPorts[configViewPortName] : undefined;
 
   if (config.explicitViewPorts && nextViewPortConfig === undefined) {
     nextViewPortConfig = null;
diff --git a/src/router-configuration.js b/src/router-configuration.js
index 79ba9a34..4e9d6157 100644
--- a/src/router-configuration.js
+++ b/src/router-configuration.js
@@ -11,6 +11,7 @@ export class RouterConfiguration {
   pipelineSteps: Array<Function|PipelineStep> = [];
   title: string;
   unknownRouteConfig: any;
+  viewPortDefaults: any;
 
   /**
   * Adds a step to be run during the [[Router]]'s navigation pipeline.
@@ -174,5 +175,9 @@ export class RouterConfiguration {
         pipelineProvider.addStep(name, step);
       }
     }
+
+    if (this.viewPortDefaults) {
+      router.viewPortDefaults = this.viewPortDefaults;
+    }
   }
 }
diff --git a/src/router.js b/src/router.js
index c96ead0f..c7fa11c8 100644
--- a/src/router.js
+++ b/src/router.js
@@ -64,6 +64,11 @@ export class Router {
 
   options: any = {};
 
+  /**
+  * The defaults used when a viewport lacks specified content
+  */
+  viewPortDefaults: any;
+
   /**
   * Extension point to transform the document title before it is built and displayed.
   * By default, child routers delegate to the parent router, and the app router