adapt to new webxdc-api (#1525)

* adapt to new webxdc-api

we track lastKnownSerial in the swift part and remove the need of
JavaScript calling to Swift and get a return back from getWebxdcStatusUpdates()
(which is complicated, see removed code).

* update maxSerial on sending updates

* do not send webxdc updates if lastSerial is unset

that speeds up webxdc starts as the updates are not fired "for nothing"
if the handler ist not set yet.

moreover, that removes a theoretical race
if an update happens between `update_listener = cb`
and `webkit.messageHandlers.setUpdateListener.postMessage`.

(in practise, both, dcNotificationWebxdcUpdate() and userContentController()
are called on the main thread so there should have been not races in practise,
however, for the future, this may change)

* another msg_id is no error

DcCore/DcCore/DC/Wrapper.swift

@@ -155,8 +155,8 @@ public class DcContext {
         return dc_send_webxdc_status_update(contextPointer, UInt32(msgId), payload, description) == 1
     }
 
-    public func getWebxdcStatusUpdates(msgId: Int, statusUpdateId: Int) -> String {
-        guard let cString = dc_get_webxdc_status_updates(contextPointer, UInt32(msgId), UInt32(statusUpdateId)) else { return "" }
+    public func getWebxdcStatusUpdates(msgId: Int, lastKnownSerial: Int) -> String {
+        guard let cString = dc_get_webxdc_status_updates(contextPointer, UInt32(msgId), UInt32(lastKnownSerial)) else { return "" }
         let swiftString = String(cString: cString)
         dc_str_unref(cString)
         return swiftString

DcCore/DcCore/DC/events.swift

@@ -235,7 +235,6 @@ public class DcEventHandler {
                     object: nil,
                     userInfo: [
                         "message_id": Int(data1),
-                        "status_id": Int(data2),
                     ]
                 )
             }

deltachat-ios/Controller/WebxdcViewController.swift

@@ -6,7 +6,7 @@ class WebxdcViewController: WebViewViewController {
     
     enum WebxdcHandler: String {
         case log  = "log"
-        case getStatusUpdates = "getStatusUpdatesHandler"
+        case setUpdateListener = "setUpdateListener"
         case sendStatusUpdate = "sendStatusUpdateHandler"
     }
     let INTERNALSCHEMA = "webxdc"
@@ -44,46 +44,31 @@ class WebxdcViewController: WebViewViewController {
           var log = (s)=>webkit.messageHandlers.log.postMessage(s);
         
           var update_listener = () => {};
-        
-          // instead of calling .getStatusUpdatesHandler (-> async),
-          // we're passing the updates directly to this js function
+
           window.__webxdcUpdate = (updateString) => {
             try {
                 var updates = JSON.parse(updateString);
-                if (updates.length === 1) {
-                  update_listener(updates[0]);
-                }
-            } catch (e) {
-                log("json error: "+ e.message)
-            }
-          };
-        
-          
-          var async_calls = {};
-          var async_call_id = 0;
-          window.__resolve_async_call = (id, rawPayload) => {
-            try {
-                const payload = JSON.parse(rawPayload);
-                if (async_calls[id]) {
-                  async_calls[id](payload);
-                  delete async_calls[id];
-                }
+                updates.forEach((update) => {
+                  update_listener(update);
+                });
             } catch (e) {
                 log("json error: "+ e.message)
             }
-          };
-        
+          }
+
           return {
             selfAddr: atob("\((dcContext.addr ?? "unknown").toBase64())"),
         
             selfName: atob("\((dcContext.displayname ?? dcContext.addr ?? "unknown").toBase64())"),
         
-            setUpdateListener: (cb) => (update_listener = cb),
-        
+            setUpdateListener: (cb, serial) => {
+                update_listener = cb
+                webkit.messageHandlers.setUpdateListener.postMessage(typeof serial === "undefined" ? 0 : parseInt(serial));
+            },
+
             getAllUpdates: () => {
-              const invocation_id = async_call_id++;
-              webkit.messageHandlers.getStatusUpdatesHandler.postMessage(invocation_id);
-              return new Promise((resolve, reject) => {async_calls[invocation_id] = resolve;});
+              console.error("deprecated 2022-02-20 all updates are returned through the callback set by setUpdateListener");
+              return Promise.resolve([]);
             },
         
             sendUpdate: (payload, descr) => {
@@ -106,7 +91,7 @@ class WebxdcViewController: WebViewViewController {
         let contentController = WKUserContentController()
         
         contentController.add(self, name: WebxdcHandler.sendStatusUpdate.rawValue)
-        contentController.add(self, name: WebxdcHandler.getStatusUpdates.rawValue)
+        contentController.add(self, name: WebxdcHandler.setUpdateListener.rawValue)
         contentController.add(self, name: WebxdcHandler.log.rawValue)
         
         config.userContentController = contentController
@@ -167,13 +152,13 @@ class WebxdcViewController: WebViewViewController {
         ) { [weak self] notification in
             guard let self = self else { return }
             guard let ui = notification.userInfo,
-                  let messageId = ui["message_id"] as? Int,
-                  let statusId = ui["status_id"] as? Int,
-                  messageId == self.messageId else {
+                  let messageId = ui["message_id"] as? Int else {
                       logger.error("failed to handle dcNotificationWebxdcUpdate")
                       return
                   }
-            self.updateWebxdc(statusId: statusId)
+            if messageId == self.messageId {
+                self.updateWebxdc()
+            }
         }
     }
     
@@ -227,11 +212,19 @@ class WebxdcViewController: WebViewViewController {
             }
         }
     }
-    
-    private func updateWebxdc(statusId: Int) {
-        let statusUpdates = self.dcContext.getWebxdcStatusUpdates(msgId: messageId, statusUpdateId: statusId)
-        logger.debug("status updates: \(statusUpdates)")
-        webView.evaluateJavaScript("window.__webxdcUpdate(atob(\"\(statusUpdates.toBase64())\"))", completionHandler: nil)
+
+    var lastSerial: Int?
+    private func updateWebxdc() {
+        if let lastSerial = lastSerial {
+            let statusUpdates = dcContext.getWebxdcStatusUpdates(msgId: messageId, lastKnownSerial: lastSerial)
+            if let data: Data = statusUpdates.data(using: .utf8),
+               let array = (try? JSONSerialization.jsonObject(with: data, options: [])) as? [Any],
+               let first = array.first as? [String: Any],
+               let maxSerial = first["max_serial"] as? Int {
+                self.lastSerial = maxSerial
+            }
+            webView.evaluateJavaScript("window.__webxdcUpdate(atob(\"\(statusUpdates.toBase64())\"))", completionHandler: nil)
+        }
     }
 }
 
@@ -239,14 +232,13 @@ extension WebxdcViewController: WKScriptMessageHandler {
     func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
         let handler = WebxdcHandler(rawValue: message.name)
         switch handler {
-        case .getStatusUpdates:
-            guard let invocationId = message.body as? Int else {
+        case .setUpdateListener:
+            guard let lastKnownSerial = message.body as? Int else {
                 logger.error("could not convert param \(message.body) to int")
                 return
             }
-            let statusUpdates = dcContext.getWebxdcStatusUpdates(msgId: messageId, statusUpdateId: 0)
-            logger.debug("status updates for message \(messageId): \(statusUpdates)")
-            webView.evaluateJavaScript("window.__resolve_async_call(\(invocationId), (atob(\"\(statusUpdates.toBase64())\")))", completionHandler: nil)
+            lastSerial = lastKnownSerial
+            updateWebxdc()
             
         case .log:
             guard let msg = message.body as? String else {
@@ -264,8 +256,8 @@ extension WebxdcViewController: WKScriptMessageHandler {
                       logger.error("Failed to parse status update parameters \(message.body)")
                       return
                   }
-            
             _ = dcContext.sendWebxdcStatusUpdate(msgId: messageId, payload: payloadString, description: description)
+
         default:
             logger.debug("another method was called")
         }