handle parent for webxdc info-messages (#2984)

* set parent for webxdc info-messages

* test parent() for info-messages

* add dc_msg_get_parent() ffi

deltachat-ffi/deltachat.h

@@ -3965,8 +3965,11 @@ int             dc_msg_is_forwarded           (const dc_msg_t* msg);
  * These messages are typically shown in the center of the chat view,
  * dc_msg_get_text() returns a descriptive text about what is going on.
  *
+ * For informational messages created by Webxdc apps,
+ * dc_msg_get_parent() usually returns the Webxdc instance;
+ * UIs can use that to scroll to the Webxdc app when the info is tapped.
+ *
  * There is no need to perform any action when seeing such a message - this is already done by the core.
- * Typically, these messages are displayed in the center of the chat.
  *
  * @memberof dc_msg_t
  * @param msg The message object.
@@ -4367,6 +4370,23 @@ char*           dc_msg_get_quoted_text        (const dc_msg_t* msg);
  */
 dc_msg_t*       dc_msg_get_quoted_msg         (const dc_msg_t* msg);
 
+/**
+ * Get parent message, if available.
+ *
+ * Used for Webxdc-info-messages
+ * to jump to the corresponding instance that created the info message.
+ *
+ * For quotes, please use the more specialized
+ * dc_msg_get_quoted_text() and dc_msg_get_quoted_msg().
+ *
+ * @memberof dc_msg_t
+ * @param msg The message object.
+ * @return The parent message or NULL.
+ *     Must be freed using dc_msg_unref() after usage.
+ */
+dc_msg_t*       dc_msg_get_parent             (const dc_msg_t* msg);
+
+
 /**
  * Force the message to be sent in plain text.
  *

deltachat-ffi/src/lib.rs

@@ -3594,6 +3594,29 @@ pub unsafe extern "C" fn dc_msg_get_quoted_msg(msg: *const dc_msg_t) -> *mut dc_
     }
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn dc_msg_get_parent(msg: *const dc_msg_t) -> *mut dc_msg_t {
+    if msg.is_null() {
+        eprintln!("ignoring careless call to dc_msg_get_parent()");
+        return ptr::null_mut();
+    }
+    let ffi_msg: &MessageWrapper = &*msg;
+    let context = &*ffi_msg.context;
+    let res = block_on(async move {
+        ffi_msg
+            .message
+            .parent(context)
+            .await
+            .log_err(context, "failed to get parent message")
+            .unwrap_or(None)
+    });
+
+    match res {
+        Some(message) => Box::into_raw(Box::new(MessageWrapper { context, message })),
+        None => ptr::null_mut(),
+    }
+}
+
 #[no_mangle]
 pub unsafe extern "C" fn dc_msg_force_plaintext(msg: *mut dc_msg_t) {
     if msg.is_null() {