[WIP, help wanted] implement better second device setup

deltachat-ffi/deltachat.h

@@ -349,6 +349,8 @@ char*           dc_get_blobdir               (const dc_context_t* context);
  *                    https://github.com/cracker0dks/basicwebrtc which some UIs have native support for.
  *                    The type `jitsi:` may be handled by external apps.
  *                    If no type is prefixed, the videochat is handled completely in a browser.
+ * - `dc_was_used_before` = Set during the configure process. If true, DC was used with this email account before
+ *                    and the user re-installed DC or is setting up a second device.
  *
  * If you want to retrieve a value, use dc_get_config().
  *

src/config.rs

@@ -128,6 +128,8 @@ pub enum Config {
 
     /// address to webrtc instance to use for videochats
     WebrtcInstance,
+
+    DcWasUsedBefore,
 }
 
 impl Context {

src/configure/mod.rs

@@ -335,15 +335,20 @@ async fn configure(ctx: &Context, param: &mut LoginParam) -> Result<()> {
         .await
         .context("could not read INBOX status")?;
 
-    drop(imap);
-
+    let was_configured_before = ctx.sql.get_raw_config_bool(ctx, "configured").await;
     progress!(ctx, 910);
     // configuration success - write back the configured parameters with the
     // "configured_" prefix; also write the "configured"-flag */
     // the trailing underscore is correct
     param.save_to_database(ctx, "configured_").await?;
     ctx.sql.set_raw_config_bool(ctx, "configured", true).await?;
 
+    if !was_configured_before && imap.was_dc_used_before(ctx).await? {
+        ctx.set_config(Config::DcWasUsedBefore, Some("1")).await?;
+    }
+
+    drop(imap);
+
     progress!(ctx, 920);
 
     e2ee::ensure_secret_key_exists(ctx).await?;

src/imap/mod.rs

@@ -5,6 +5,7 @@
 
 use std::collections::BTreeMap;
 
+use anyhow::Context as _;
 use async_imap::{
     error::Result as ImapResult,
     types::{Capability, Fetch, Flag, Mailbox, Name, NameAttribute},
@@ -1319,6 +1320,27 @@ impl Imap {
         info!(context, "FINISHED configuring IMAP-folders.");
         Ok(())
     }
+
+    pub(crate) async fn was_dc_used_before(&mut self, context: &Context) -> Result<bool> {
+        let self_addr = context
+            .get_config(Config::ConfiguredAddr)
+            .await
+            .context("was_dc_used_before: not configured")?;
+        for config in &[Config::ConfiguredInboxFolder, Config::ConfiguredMvboxFolder] {
+            if let Some(mailbox) = context.get_config(*config).await {
+                self.select_folder(context, Some(&mailbox)).await?;
+                if let Some(ref mut session) = self.session {
+                    let query = format!(r#"HEADER Chat-Version "" FROM {}"#, self_addr);
+                    if !session.search(query).await?.is_empty() {
+                        info!(context, "Found outgoing chat msgs in {}.", &mailbox);
+                        return Ok(true);
+                    }
+                }
+            }
+        }
+        info!(context, "Did not find any outgoing chat msgs.");
+        Ok(false)
+    }
 }
 
 /// Try to get the folder meaning by the name of the folder only used if the server does not support XLIST.