[core] use Min() and Max() to track next timer fire time (#8808)

src/core/coap/coap.cpp

@@ -490,10 +490,7 @@ void CoapBase::HandleRetransmissionTimer(void)
             }
         }
 
-        if (nextTime > metadata.mNextTimerShot)
-        {
-            nextTime = metadata.mNextTimerShot;
-        }
+        nextTime = Min(nextTime, metadata.mNextTimerShot);
     }
 
     if (nextTime < now.GetDistantFuture())
@@ -1586,10 +1583,7 @@ void ResponsesQueue::HandleTimer(void)
             continue;
         }
 
-        if (metadata.mDequeueTime < nextDequeueTime)
-        {
-            nextDequeueTime = metadata.mDequeueTime;
-        }
+        nextDequeueTime = Min(nextDequeueTime, metadata.mDequeueTime);
     }
 
     if (nextDequeueTime < now.GetDistantFuture())

src/core/meshcop/commissioner.cpp

@@ -660,14 +660,7 @@ void Commissioner::UpdateJoinerExpirationTimer(void)
             continue;
         }
 
-        if (joiner.mExpirationTime <= now)
-        {
-            next = now;
-        }
-        else if (joiner.mExpirationTime < next)
-        {
-            next = joiner.mExpirationTime;
-        }
+        next = Min(next, Max(now, joiner.mExpirationTime));
     }
 
     if (next < now.GetDistantFuture())

src/core/net/dns_client.cpp

@@ -1080,10 +1080,7 @@ void Client::HandleTimer(void)
             SendQuery(query, info, /* aUpdateTimer */ false);
         }
 
-        if (nextTime > info.mRetransmissionTime)
-        {
-            nextTime = info.mRetransmissionTime;
-        }
+        nextTime = Min(nextTime, info.mRetransmissionTime);
     }
 
     if (nextTime < now.GetDistantFuture())

src/core/net/dnssd_server.cpp

@@ -1285,43 +1285,23 @@ void Server::ResetTimer(void)
 
     for (QueryTransaction &query : mQueryTransactions)
     {
-        TimeMilli expire;
-
         if (!query.IsValid())
         {
             continue;
         }
 
-        expire = query.GetStartTime() + kQueryTimeout;
-        if (expire <= now)
-        {
-            nextExpire = now;
-        }
-        else if (expire < nextExpire)
-        {
-            nextExpire = expire;
-        }
+        nextExpire = Min(nextExpire, Max(now, query.GetStartTime() + kQueryTimeout));
     }
 
 #if OPENTHREAD_CONFIG_DNS_UPSTREAM_QUERY_ENABLE
     for (UpstreamQueryTransaction &query : mUpstreamQueryTransactions)
     {
-        TimeMilli expire;
-
         if (!query.IsValid())
         {
             continue;
         }
 
-        expire = query.GetExpireTime();
-        if (expire <= now)
-        {
-            nextExpire = now;
-        }
-        else if (expire < nextExpire)
-        {
-            nextExpire = expire;
-        }
+        nextExpire = Min(nextExpire, Max(now, query.GetExpireTime()));
     }
 #endif
 

src/core/net/sntp_client.cpp

@@ -302,10 +302,7 @@ void Client::HandleRetransmissionTimer(void)
             SendCopy(message, messageInfo);
         }
 
-        if (nextTime > queryMetadata.mTransmissionTime)
-        {
-            nextTime = queryMetadata.mTransmissionTime;
-        }
+        nextTime = Min(nextTime, queryMetadata.mTransmissionTime);
     }
 
     if (nextTime < now.GetDistantFuture())

src/core/net/srp_client.cpp

@@ -1763,9 +1763,9 @@ void Client::UpdateState(void)
                     service.SetState(kToRefresh);
                     shouldUpdate = true;
                 }
-                else if (service.GetLeaseRenewTime() < earliestRenewTime)
+                else
                 {
-                    earliestRenewTime = service.GetLeaseRenewTime();
+                    earliestRenewTime = Min(earliestRenewTime, service.GetLeaseRenewTime());
                 }
 
                 break;

src/core/thread/mle.cpp

@@ -1625,10 +1625,7 @@ void Mle::HandleDelayedResponseTimer(void)
 
         if (now < metadata.mSendTime)
         {
-            if (nextSendTime > metadata.mSendTime)
-            {
-                nextSendTime = metadata.mSendTime;
-            }
+            nextSendTime = Min(nextSendTime, metadata.mSendTime);
         }
         else
         {