Mitigate Apple Mail re-sync (both bodies and meta info)

pkg/pmapi/clientmanager.go

@@ -31,7 +31,7 @@ import (
 const maxLogoutRetries = 5
 
 // ClientManager is a manager of clients.
-type ClientManager struct {
+type ClientManager struct { //nolint[maligned]
 	// newClient is used to create new Clients. By default this creates pmapi clients but it can be overridden to
 	// create other types of clients (e.g. for integration tests).
 	newClient func(userID string) Client
@@ -61,6 +61,8 @@ type ClientManager struct {
 
 	idGen idGen
 
+	connectionOff bool
+
 	log *logrus.Entry
 }
 
@@ -108,6 +110,8 @@ func NewClientManager(config *ClientConfig) (cm *ClientManager) {
 		proxyProvider:    newProxyProvider(dohProviders, proxyQuery),
 		proxyUseDuration: proxyUseDuration,
 
+		connectionOff: false,
+
 		log: logrus.WithField("pkg", "pmapi-manager"),
 	}
 
@@ -121,6 +125,30 @@ func NewClientManager(config *ClientConfig) (cm *ClientManager) {
 	return cm
 }
 
+func (cm *ClientManager) noConnection() {
+	cm.log.Trace("No connection available")
+	if cm.connectionOff {
+		return
+	}
+
+	cm.log.Warn("Connection lost")
+	cm.config.ConnectionOffHandler()
+	cm.connectionOff = true
+
+	go func() {
+		for {
+			time.Sleep(30 * time.Second)
+
+			if err := cm.CheckConnection(); err == nil {
+				cm.log.Info("Connection re-established")
+				cm.config.ConnectionOnHandler()
+				cm.connectionOff = false
+				return
+			}
+		}
+	}()
+}
+
 // SetClientConstructor sets the method used to construct clients.
 // By default this is `pmapi.newClient` but can be overridden with this method.
 func (cm *ClientManager) SetClientConstructor(f func(userID string) Client) {