FIX: groundcontrol notifications for internal invoices

class/Invo.js

@@ -1,3 +1,4 @@
+var crypto = require('crypto');
 var lightningPayReq = require('bolt11');
 
 export class Invo {
@@ -65,6 +66,31 @@ export class Invo {
     return await this._redis.get('ispaid_' + paymentHash);
   }
 
+  async getPreimage() {
+    if (!this._bolt11) throw new Error('bolt11 is not provided');
+    const decoded = lightningPayReq.decode(this._bolt11);
+    let paymentHash = false;
+    for (const tag of decoded.tags) {
+      if (tag.tagName === 'payment_hash') {
+        paymentHash = tag.data;
+      }
+    }
+    if (!paymentHash) throw new Error('Could not find payment hash in invoice tags');
+    return await this._redis.get('preimage_for_' + paymentHash);
+  }
+
+  async savePreimage(preimageHex) {
+    const paymentHashHex = require('crypto').createHash('sha256').update(Buffer.from(preimageHex, 'hex')).digest('hex');
+    const key = 'preimage_for_' + paymentHashHex;
+    await this._redis.set(key, preimageHex);
+    await this._redis.expire(key, 3600 * 24 * 30); // 1 month
+  }
+
+  makePreimageHex() {
+    let buffer = crypto.randomBytes(32);
+    return buffer.toString('hex');
+  }
+
   /**
    * Queries LND ofr all user invoices
    *