Wired up welcome_page_url to Tier modal

refs https://github.com/TryGhost/Team/issues/1168

This allows users to set the welcome page url on a tier by tier basis
rather than globally for all paid tiers or all free tiers.

ghost/admin/app/components/modal-product.hbs

@@ -137,10 +137,16 @@
                 <h4 class="gh-main-section-header small bn">Advanced</h4>
                 <div class="gh-main-section-content grey gh-product-priceform-block">
                     <GhFormGroup>
-                        <label for="" class="fw6">Welcome page</label>
-                        <GhTextInput
-                            @class="gh-input" />
-                            <p>Redirect to this URL after signup for premium membership</p>
+                        <label for="welcomePage" class="fw6">Welcome page</label>
+                        <GhUrlInput
+                            @id="welcomePage"
+                            @value={{readonly this.model.product.welcomePageURL}}
+                            @baseUrl={{readonly this.siteUrl}}
+                            @setResult={{this.setWelcomePageURL}}
+                            @validateUrl={{this.validateWelcomePageURL}}
+                            @placeholder={{readonly this.siteUrl}}
+                        />
+                        <p>Redirect to this URL after signup for premium membership</p>
                     </GhFormGroup>
                 </div>
             </div>

ghost/admin/app/components/modal-product.js

@@ -21,6 +21,7 @@ const CURRENCIES = currencies.map((currency) => {
 @classic
 export default class ModalProductPrice extends ModalBase {
     @service settings;
+    @service config;
     @tracked model;
     @tracked product;
     @tracked periodVal;
@@ -31,6 +32,7 @@ export default class ModalProductPrice extends ModalBase {
     @tracked stripePlanError = '';
     @tracked benefits = emberA([]);
     @tracked newBenefit = null;
+    @tracked welcomePageURL
 
     confirm() {}
 
@@ -76,6 +78,31 @@ export default class ModalProductPrice extends ModalBase {
         });
     }
 
+    @action
+    validateWelcomePageURL() {
+        const siteUrl = this.siteUrl;
+
+        if (this.welcomePageURL === undefined) {
+            // Not initialised
+            return;
+        }
+
+        if (this.welcomePageURL.href.startsWith(siteUrl)) {
+            const path = this.welcomePageURL.href.replace(siteUrl, '');
+            this.model.product.welcomePageURL = path;
+        } else {
+            this.model.product.welcomePageURL = this.welcomePageURL.href;
+        }
+    }
+
+    get siteUrl() {
+        return this.config.get('blogUrl');
+    }
+
+    get welcomePageURL() {
+        return this.model.product.welcomePageURL;
+    }
+
     get title() {
         if (this.isExistingProduct) {
             if (this.isFreeProduct) {
@@ -101,6 +128,10 @@ export default class ModalProductPrice extends ModalBase {
         const newCurrency = event.value;
         this.currency = newCurrency;
     }
+    @action
+    setWelcomePageURL(url) {
+        this.welcomePageURL = url;
+    }
 
     reset() {
         this.newBenefit = ProductBenefitItem.create({isNew: true, name: ''});

ghost/admin/app/models/product.js

@@ -8,6 +8,7 @@ export default Model.extend(ValidationEngine, {
     description: attr('string'),
     active: attr('boolean'),
     slug: attr('string'),
+    welcomePageURL: attr('string'),
     type: attr('string', {defaultValue: 'paid'}),
     monthlyPrice: attr('stripe-price'),
     yearlyPrice: attr('stripe-price'),