Add local TBA file downloading

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Add `filter_boost_added` and `filter_reply_to_story` filters to `MessageFilterExt` trait
 - Add `filter_mention_command` filter to `HandlerExt` trait ([issue #494](https://github.com/teloxide/teloxide/issues/494))
 - Add `filter_business_connection`, `filter_business_message`, `filter_edited_business_message`, and `filter_deleted_business_messages` filters to update filters ([PR 1146](https://github.com/teloxide/teloxide/pull/1146))
+- Add local TBA file downloading support in `crate::net::download`
 
 ### Changed
 

crates/teloxide-core/src/bot/download.rs

@@ -1,6 +1,12 @@
+use std::path::Path;
+
 use bytes::Bytes;
 use futures::{future::BoxFuture, stream::BoxStream, FutureExt, StreamExt};
-use tokio::io::AsyncWrite;
+
+use tokio::{
+    fs::File,
+    io::{AsyncReadExt, AsyncWrite, AsyncWriteExt},
+};
 
 use crate::{
     bot::Bot,
@@ -17,9 +23,19 @@ impl Download for Bot {
 
     fn download_file<'dst>(
         &self,
-        path: &str,
+        path: &'dst str,
         destination: &'dst mut (dyn AsyncWrite + Unpin + Send),
     ) -> Self::Fut<'dst> {
+        let is_localhost = match &self.api_url.host_str() {
+            Some(host) => ["localhost", "127.0.0.1"].contains(host),
+            None => false,
+        };
+        // If path is absolute and api_url contains localhost, it is pretty clear there
+        // is a local TBA server with --local option, we can just copy the file
+        if is_localhost && Path::new(&path).is_absolute() {
+            return copy_file(path, destination).boxed();
+        }
+
         net::download_file(
             &self.client,
             reqwest::Url::clone(&*self.api_url),
@@ -45,3 +61,23 @@ impl Download for Bot {
         .boxed()
     }
 }
+
+async fn copy_file<'o, D>(path: &'o str, dst: &'o mut D) -> Result<(), DownloadError>
+where
+    D: ?Sized + AsyncWrite + Unpin,
+{
+    let mut src_file = File::open(path).await?;
+
+    let mut buffer = [0; 1024];
+    loop {
+        let n = src_file.read(&mut buffer).await?;
+        if n == 0 {
+            break;
+        }
+
+        dst.write_all(&buffer[..n]).await?;
+    }
+
+    dst.flush().await?;
+    Ok(())
+}

crates/teloxide-core/src/local_macros.rs

@@ -380,7 +380,7 @@ macro_rules! download_forward {
 
             fn download_file<'dst>(
                 &self,
-                path: &str,
+                path: &'dst str,
                 destination: &'dst mut (dyn tokio::io::AsyncWrite
                                + core::marker::Unpin
                                + core::marker::Send),

crates/teloxide-core/src/net/download.rs

@@ -28,6 +28,9 @@ pub trait Download {
     ///
     /// `path` can be obtained from [`GetFile`].
     ///
+    /// If the bot uses a [local bot api](https://github.com/tdlib/telegram-bot-api), this function
+    /// just copies the file into `destination`.
+    ///
     /// To download as a stream of chunks, see [`download_file_stream`].
     ///
     /// ## Examples
@@ -54,7 +57,7 @@ pub trait Download {
     /// [`download_file_stream`]: Self::download_file_stream
     fn download_file<'dst>(
         &self,
-        path: &str,
+        path: &'dst str,
         destination: &'dst mut (dyn AsyncWrite + Unpin + Send),
     ) -> Self::Fut<'dst>;