Added concept of OfferStatus to domain model

refs https://github.com/TryGhost/Team/issues/1131

This allows us to model the behaviour of archived & active offers, as
well as allowing us to set their status on the model.

ghost/offers/lib/domain/errors/index.js

@@ -22,6 +22,7 @@ class InvalidOfferTierName extends InvalidPropError {}
 class InvalidOfferCadence extends InvalidPropError {}
 class InvalidOfferDuration extends InvalidPropError {}
 class InvalidOfferCoupon extends InvalidPropError {}
+class InvalidOfferStatus extends InvalidPropError {}
 
 module.exports = {
     InvalidOfferName,
@@ -34,5 +35,6 @@ module.exports = {
     InvalidOfferCadence,
     InvalidOfferDuration,
     InvalidOfferTierName,
-    InvalidOfferCoupon
+    InvalidOfferCoupon,
+    InvalidOfferStatus
 };

ghost/offers/lib/domain/models/Offer.js

@@ -10,6 +10,7 @@ const OfferCadence = require('./OfferCadence');
 const OfferType = require('./OfferType');
 const OfferDuration = require('./OfferDuration');
 const OfferCurrency = require('./OfferCurrency');
+const OfferStatus = require('./OfferStatus');
 
 /**
  * @typedef {object} OfferProps
@@ -24,6 +25,7 @@ const OfferCurrency = require('./OfferCurrency');
  * @prop {OfferDuration} duration
  * @prop {OfferCurrency} [currency]
  * @prop {string} [stripe_coupon_id]
+ * @prop {OfferStatus} status
  * @prop {OfferTier} tier
  */
 
@@ -41,6 +43,7 @@ const OfferCurrency = require('./OfferCurrency');
  * @prop {number} duration_in_months
  * @prop {string} currency
  * @prop {string} [stripe_coupon_id]
+ * @prop {string} status
  * @prop {TierProps|OfferTier} tier
  */
 
@@ -117,6 +120,14 @@ class Offer {
         return this.props.duration;
     }
 
+    get status() {
+        return this.props.status;
+    }
+
+    set status(value) {
+        this.props.status = value;
+    }
+
     get oldCode() {
         return this.changed.code;
     }
@@ -248,6 +259,7 @@ class Offer {
         const type = OfferType.create(data.type);
         const cadence = OfferCadence.create(data.cadence);
         const duration = OfferDuration.create(data.duration, data.duration_in_months);
+        const status = OfferStatus.create(data.status);
 
         if (cadence.value === 'year' && duration.value.type === 'repeating') {
             throw new errors.InvalidOfferDuration({
@@ -306,7 +318,8 @@ class Offer {
             duration,
             currency,
             tier,
-            stripe_coupon_id: couponId
+            stripe_coupon_id: couponId,
+            status
         }, {isNew});
     }
 }

ghost/offers/lib/domain/models/OfferStatus.js

@@ -0,0 +1,23 @@
+const ValueObject = require('./shared/ValueObject');
+const InvalidOfferStatus = require('../errors').InvalidOfferStatus;
+
+/** @extends ValueObject<'active'|'archived'> */
+class OfferStatus extends ValueObject {
+    /** @param {unknown} status */
+    static create(status) {
+        if (typeof status !== 'string') {
+            throw new InvalidOfferStatus({
+                message: 'Offer `status` must be a string.'
+            });
+        }
+
+        if (status !== 'active' && status !== 'archived') {
+            throw new InvalidOfferStatus({
+                message: 'Offer `status` must be either "active" or "archived".'
+            });
+        }
+        return new OfferStatus(status);
+    }
+}
+
+module.exports = OfferStatus;