feat: Donation request device message (#6913)

A donation request device message is added if >= 100 messages have been sent and delivered. The
condition is checked every 30 days since the first message is sent. The message is added only once.

deltachat-ffi/deltachat.h

@@ -7667,6 +7667,9 @@ void dc_event_unref(dc_event_t* event);
 /// @deprecated 2025-06-05
 #define DC_STR_SECUREJOIN_TAKES_LONGER 192
 
+/// "❤️ Seems you're enjoying Delta Chat!"… (donation request device message)
+#define DC_STR_DONATION_REQUEST 193
+
 /// "Contact". Deprecated, currently unused.
 #define DC_STR_CONTACT 200
 

src/chat.rs

@@ -2967,6 +2967,9 @@ async fn prepare_send_msg(
     let row_ids = create_send_msg_jobs(context, msg)
         .await
         .context("Failed to create send jobs")?;
+    if !row_ids.is_empty() {
+        donation_request_maybe(context).await.log_err(context).ok();
+    }
     Ok(row_ids)
 }
 
@@ -3211,6 +3214,31 @@ pub async fn send_videochat_invitation(context: &Context, chat_id: ChatId) -> Re
     send_msg(context, chat_id, &mut msg).await
 }
 
+async fn donation_request_maybe(context: &Context) -> Result<()> {
+    let secs_between_checks = 30 * 24 * 60 * 60;
+    let now = time();
+    let ts = context
+        .get_config_i64(Config::DonationRequestNextCheck)
+        .await?;
+    if ts > now {
+        return Ok(());
+    }
+    let msg_cnt = context.sql.count(
+        "SELECT COUNT(*) FROM msgs WHERE state>=? AND hidden=0",
+        (MessageState::OutDelivered,),
+    );
+    let ts = if ts == 0 || msg_cnt.await? < 100 {
+        now.saturating_add(secs_between_checks)
+    } else {
+        let mut msg = Message::new_text(stock_str::donation_request(context).await);
+        add_device_msg(context, None, Some(&mut msg)).await?;
+        i64::MAX
+    };
+    context
+        .set_config_internal(Config::DonationRequestNextCheck, Some(&ts.to_string()))
+        .await
+}
+
 /// Chat message list request options.
 #[derive(Debug)]
 pub struct MessageListOptions {

src/config.rs

@@ -369,6 +369,9 @@ pub enum Config {
     #[strum(props(default = "0"))]
     DisableIdle,
 
+    /// Timestamp of the next check for donation request need.
+    DonationRequestNextCheck,
+
     /// Defines the max. size (in bytes) of messages downloaded automatically.
     /// 0 = no limit.
     #[strum(props(default = "0"))]

src/context.rs

@@ -1054,6 +1054,12 @@ impl Context {
                 .await?
                 .to_string(),
         );
+        res.insert(
+            "donation_request_next_check",
+            self.get_config_i64(Config::DonationRequestNextCheck)
+                .await?
+                .to_string(),
+        );
         res.insert(
             "first_key_contacts_msg_id",
             self.sql

src/stock_str.rs

@@ -413,6 +413,16 @@ pub enum StockMessage {
 
     #[strum(props(fallback = "Establishing guaranteed end-to-end encryption, please wait…"))]
     SecurejoinWait = 190,
+
+    #[strum(props(fallback = "❤️ Seems you're enjoying Delta Chat!
+
+Please consider donating to help that Delta Chat stays free for everyone.
+
+While Delta Chat is free to use and open source, development costs money.
+Help keeping us to keep Delta Chat independent and make it more awesome in the future.
+
+https://delta.chat/donate"))]
+    DonationRequest = 193,
 }
 
 impl StockMessage {
@@ -785,6 +795,11 @@ pub(crate) async fn securejoin_wait(context: &Context) -> String {
     translated(context, StockMessage::SecurejoinWait).await
 }
 
+/// Stock string: `❤️ Seems you're enjoying Delta Chat!`…
+pub(crate) async fn donation_request(context: &Context) -> String {
+    translated(context, StockMessage::DonationRequest).await
+}
+
 /// Stock string: `Scan to chat with %1$s`.
 pub(crate) async fn setup_contact_qr_description(
     context: &Context,