add can_send_edit_request() api

deltachat-ffi/deltachat.h

@@ -1039,6 +1039,20 @@ uint32_t        dc_send_msg_sync                  (dc_context_t* context, uint32
 uint32_t        dc_send_text_msg             (dc_context_t* context, uint32_t chat_id, const char* text_to_send);
 
 
+/**
+ * Check if a message can be edited using dc_send_edit_request().
+ *
+ * Messages that cannot be edited are eg. info messages or messages not sent by self.
+ * UI will usually check this function whether to display an "Edit" option or not.
+ *
+ * @memberof dc_context_t
+ * @param context The context object.
+ * @param msg_id The message ID to check.
+ * @return 1=message can be edited, 0=message cannot be edited.
+ */
+ int             dc_can_send_edit_request    (dc_context_t* context, uint32_t msg_id);
+
+
 /**
  * Send chat members a request to edit the given message's text.
  *

deltachat-ffi/src/lib.rs

@@ -1041,6 +1041,23 @@ pub unsafe extern "C" fn dc_send_text_msg(
     })
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn dc_can_send_edit_request(
+    context: *mut dc_context_t,
+    msg_id: u32,
+    new_text: *const libc::c_char,
+) -> libc::c_int {
+    if context.is_null() || new_text.is_null() {
+        eprintln!("ignoring careless call to dc_can_send_edit_request()");
+        return 0;
+    }
+    let ctx = &*context;
+
+    block_on(message::can_send_edit_request(ctx, MsgId::new(msg_id)))
+        .log_err(ctx)
+        .unwrap_or_default() as libc::c_int
+}
+
 #[no_mangle]
 pub unsafe extern "C" fn dc_send_edit_request(
     context: *mut dc_context_t,

src/chat.rs

@@ -3133,22 +3133,13 @@ pub async fn send_text_msg(
 
 /// Sends chat members a request to edit the given message's text.
 pub async fn send_edit_request(context: &Context, msg_id: MsgId, new_text: String) -> Result<()> {
-    let mut original_msg = Message::load_from_db(context, msg_id).await?;
     ensure!(
-        original_msg.from_id == ContactId::SELF,
-        "Can edit only own messages"
-    );
-    ensure!(!original_msg.is_info(), "Cannot edit info messages");
-    ensure!(!original_msg.has_html(), "Cannot edit HTML messages");
-    ensure!(
-        original_msg.viewtype != Viewtype::VideochatInvitation,
-        "Cannot edit videochat invitations"
-    );
-    ensure!(
-        !original_msg.text.is_empty(), // avoid complexity in UI element changes. focus is typos and rewordings
-        "Cannot add text"
+        message::can_send_edit_request(context, msg_id).await?,
+        "Message cannot be edited"
     );
     ensure!(!new_text.trim().is_empty(), "Edited text cannot be empty");
+
+    let mut original_msg = Message::load_from_db(context, msg_id).await?;
     if original_msg.text == new_text {
         info!(context, "Text unchanged.");
         return Ok(());

src/message.rs

@@ -1500,6 +1500,22 @@ pub async fn get_msg_read_receipts(
         .await
 }
 
+/// Returns true if the message can be edited.
+pub async fn can_send_edit_request(context: &Context, msg_id: MsgId) -> Result<bool> {
+    let msg = Message::load_from_db(context, msg_id).await?;
+    if msg.from_id != ContactId::SELF
+        || msg.is_info()
+        || msg.viewtype == Viewtype::VideochatInvitation
+        || msg.has_html()
+        || msg.text.is_empty()
+    {
+        return Ok(false);
+    }
+    let chat = Chat::load_from_db(context, msg.get_chat_id()).await?;
+    let can_send = chat.can_send(context).await?;
+    Ok(can_send)
+}
+
 pub(crate) fn guess_msgtype_from_suffix(msg: &Message) -> Option<(Viewtype, &'static str)> {
     msg.param
         .get(Param::Filename)

src/message/message_tests.rs

@@ -783,3 +783,55 @@ async fn test_sanitize_filename_message() -> Result<()> {
 
     Ok(())
 }
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn text_can_send_edit_request() -> Result<()> {
+    let mut tcm = TestContextManager::new();
+    let alice = tcm.alice().await;
+    let bob = tcm.bob().await;
+    let chat_id = alice
+        .create_group_with_members(ProtectionStatus::Unprotected, "My Group", &[&bob])
+        .await;
+
+    // Alice can edit her message
+    let sent1 = alice.send_text(chat_id, "foo").await;
+    assert!(can_send_edit_request(&alice, sent1.sender_msg_id).await?);
+
+    // Bob cannot edit Alice's message
+    let msg = bob.recv_msg(&sent1).await;
+    assert!(!can_send_edit_request(&bob, msg.id).await?);
+
+    // HTML messages cannot be edited
+    let mut msg = Message::new_text("plain text".to_string());
+    msg.set_html(Some("<b>html</b> text".to_string()));
+    let sent2 = alice.send_msg(chat_id, &mut msg).await;
+    assert!(!can_send_edit_request(&alice, sent2.sender_msg_id).await?);
+
+    // Info messages cannot be edited
+    chat::set_chat_name(&alice, chat_id, "bar").await?;
+    let msg = alice.get_last_msg().await;
+    assert!(msg.is_info());
+    assert_eq!(msg.from_id, ContactId::SELF);
+    assert!(!can_send_edit_request(&alice, msg.id).await?);
+
+    // Videochat invitations cannot be edited
+    alice
+        .set_config(Config::WebrtcInstance, Some("https://foo.bar"))
+        .await?;
+    let msg_id = chat::send_videochat_invitation(&alice, chat_id).await?;
+    assert!(!can_send_edit_request(&alice, msg_id).await?);
+
+    // If not text was given initally, there is nothing to edit
+    // (this also avoids complexity in UI element changes; focus is typos and rewordings)
+    let mut msg = Message::new(Viewtype::File);
+    msg.make_vcard(&alice, &[ContactId::SELF]).await?;
+    let sent3 = alice.send_msg(chat_id, &mut msg).await;
+    assert!(msg.text.is_empty());
+    assert!(!can_send_edit_request(&alice, sent3.sender_msg_id).await?);
+
+    // Messages in left groups cannot be edited any longer (as one cannot send to that group)
+    chat::remove_contact_from_chat(&alice, chat_id, ContactId::SELF).await?;
+    assert!(!can_send_edit_request(&alice, sent1.sender_msg_id).await?);
+
+    Ok(())
+}