From e41bdbcd96a567cac025174cdfcc1b5222e6644b Mon Sep 17 00:00:00 2001
From: Iz P <pehisaac@gmail.com>
Date: Wed, 10 Apr 2019 15:02:40 -0600
Subject: [PATCH 1/2] Created Reset Functionality for useTimer.

---
 src/App.js      |  4 +++-
 src/useTimer.js | 19 ++++++++++++++++---
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/src/App.js b/src/App.js
index fc26383..7269ce2 100644
--- a/src/App.js
+++ b/src/App.js
@@ -9,7 +9,8 @@ function MyTimer({ expiryTimestamp }) {
     days,
     start,
     pause,
-    resume
+    resume,
+    restart
   } = useTimer({ expiryTimestamp, onExpire: () => console.warn('onExpire called') });
 
 
@@ -23,6 +24,7 @@ function MyTimer({ expiryTimestamp }) {
       <button onClick={start}>Start</button>
       <button onClick={pause}>Pause</button>
       <button onClick={resume}>Resume</button>
+      <button onClick={() => restart(500) /* resets to 50 seconds */}>restart</button>
     </div>
   );
 }
diff --git a/src/useTimer.js b/src/useTimer.js
index 9bf5106..e3e6215 100644
--- a/src/useTimer.js
+++ b/src/useTimer.js
@@ -105,7 +105,7 @@ export function useStopwatch(settings) {
 /* ---------------------- useTimer --------------------- */
 
 export function useTimer(settings) {
-  const { expiryTimestamp, onExpire } = settings || {};
+  let { expiryTimestamp, onExpire } = settings || {};
 
   const [seconds, setSeconds] = useState(0);
   function subtractSecond() {
@@ -164,7 +164,7 @@ export function useTimer(settings) {
   function start() {
     if(isValidExpiryTimestamp(expiryTimestamp) && !intervalRef.current) {
       calculateExpiryDate();
-      intervalRef.current = setInterval(() => calculateExpiryDate(), 1000);
+      intervalRef.current = setInterval(() => subtractSecond(), 1000);
     }
   }
 
@@ -192,6 +192,19 @@ export function useTimer(settings) {
     }
   }
 
+  function restart(offset) {
+    reset();
+    // Calculate fresh expiry and start timer again with new expiry ammount
+    calcNewExpiry(offset);
+    start();
+  }
+
+  function calcNewExpiry(offset) {
+    let t = new Date();
+    t.setSeconds(t.getSeconds() + offset);
+    expiryTimestamp = t;
+  }
+
   // Timer expiry date calculation
   function calculateExpiryDate() {
     var now = new Date().getTime();
@@ -236,7 +249,7 @@ export function useTimer(settings) {
     return isValid;
   }
 
-  return { seconds, minutes, hours, days, start, pause, resume };
+  return { seconds, minutes, hours, days, start, pause, resume, restart };
 }
 
 

From 91e8b7d2710be662221ca57b9ea56d2df2d61700 Mon Sep 17 00:00:00 2001
From: Iz P <pehisaac@gmail.com>
Date: Sat, 13 Apr 2019 16:30:28 -0600
Subject: [PATCH 2/2] Updates to implementation of Restart function

---
 src/App.js      |  7 ++++++-
 src/useTimer.js | 16 +++++-----------
 2 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/src/App.js b/src/App.js
index 7269ce2..e6f5903 100644
--- a/src/App.js
+++ b/src/App.js
@@ -24,7 +24,12 @@ function MyTimer({ expiryTimestamp }) {
       <button onClick={start}>Start</button>
       <button onClick={pause}>Pause</button>
       <button onClick={resume}>Resume</button>
-      <button onClick={() => restart(500) /* resets to 50 seconds */}>restart</button>
+      <button onClick={() => {
+        // Resets to 10 minutes timer 
+        var t = new Date();
+        t.setSeconds(t.getSeconds() + 600);
+        restart(t)
+      }}>restart</button>
     </div>
   );
 }
diff --git a/src/useTimer.js b/src/useTimer.js
index e3e6215..264e343 100644
--- a/src/useTimer.js
+++ b/src/useTimer.js
@@ -105,7 +105,8 @@ export function useStopwatch(settings) {
 /* ---------------------- useTimer --------------------- */
 
 export function useTimer(settings) {
-  let { expiryTimestamp, onExpire } = settings || {};
+  const { expiryTimestamp: expiry, onExpire } = settings || {};
+  const [expiryTimestamp, setExpiryTimestamp] = useState(expiry);
 
   const [seconds, setSeconds] = useState(0);
   function subtractSecond() {
@@ -192,18 +193,11 @@ export function useTimer(settings) {
     }
   }
 
-  function restart(offset) {
+  function restart(newExpiryTimestamp) {
     reset();
-    // Calculate fresh expiry and start timer again with new expiry ammount
-    calcNewExpiry(offset);
-    start();
+    setExpiryTimestamp(newExpiryTimestamp);
   }
 
-  function calcNewExpiry(offset) {
-    let t = new Date();
-    t.setSeconds(t.getSeconds() + offset);
-    expiryTimestamp = t;
-  }
 
   // Timer expiry date calculation
   function calculateExpiryDate() {
@@ -228,7 +222,7 @@ export function useTimer(settings) {
   useEffect(() => {
     start();
     return reset;
-  },[]);
+  },[expiryTimestamp]);
 
 
   // Validate expiryTimestamp