From c4d289956275677b24459237d13ed8c23a606079 Mon Sep 17 00:00:00 2001
From: Florian Dold <florian.dold@gmail.com>
Date: Mon, 23 Mar 2020 17:47:35 +0530
Subject: [PATCH] implement time travelling

---
 src/headless/taler-wallet-cli.ts | 9 +++++++++
 src/util/time.ts                 | 8 +++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/headless/taler-wallet-cli.ts b/src/headless/taler-wallet-cli.ts
index c4d8664d9..9a21d2a1d 100644
--- a/src/headless/taler-wallet-cli.ts
+++ b/src/headless/taler-wallet-cli.ts
@@ -31,6 +31,7 @@ import { Bank } from "./bank";
 import { classifyTalerUri, TalerUriType } from "../util/taleruri";
 import util = require("util");
 import { Configuration } from "../util/talerconfig";
+import { setDangerousTimetravel } from "../util/time";
 
 // Backwards compatibility with nodejs<0.11, where TextEncoder and TextDecoder
 // are not globals yet.
@@ -119,6 +120,14 @@ const walletCli = clk
   .maybeOption("walletDbFile", ["--wallet-db"], clk.STRING, {
     help: "location of the wallet database file"
   })
+  .maybeOption("timetravel", ["--timetravel"], clk.INT, {
+    help: "modify system time by given offset in microseconds",
+    onPresentHandler: (x) => {
+      // Convert microseconds to milliseconds and do timetravel
+      logger.info(`timetravelling ${x} microseconds`);
+      setDangerousTimetravel(x / 1000);
+    },
+  })
   .maybeOption("inhibit", ["--inhibit"], clk.STRING, {
     help:
       "Inhibit running certain operations, useful for debugging and testing.",
diff --git a/src/util/time.ts b/src/util/time.ts
index 88297f9a9..2740c361f 100644
--- a/src/util/time.ts
+++ b/src/util/time.ts
@@ -34,9 +34,15 @@ export interface Duration {
   readonly d_ms: number | "forever";
 }
 
+let timeshift: number = 0;
+
+export function setDangerousTimetravel(dt: number) {
+  timeshift = dt;
+}
+
 export function getTimestampNow(): Timestamp {
   return {
-    t_ms: new Date().getTime(),
+    t_ms: new Date().getTime() + timeshift,
   };
 }