From 615421bb99d10db2a0e0860f2bfe8063271e986a Mon Sep 17 00:00:00 2001
From: Aleksandr Razumov <ernado@go-faster.org>
Date: Mon, 29 Jan 2024 19:20:28 +0300
Subject: [PATCH] refactor(client): add AuthTransferHandler type

---
 telegram/client.go   |  4 ++--
 telegram/options.go  | 10 +++-------
 telegram/transfer.go |  8 ++++++++
 3 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/telegram/client.go b/telegram/client.go
index 564264b30a..7476c001b3 100644
--- a/telegram/client.go
+++ b/telegram/client.go
@@ -129,8 +129,8 @@ type Client struct {
 	// Tracing.
 	tracer trace.Tracer
 
-	// onTransfer is called on authorization transfer.
-	onTransfer func(ctx context.Context, client *Client, tx func(ctx context.Context) error) error
+	// onTransfer is called in transfer.
+	onTransfer AuthTransferHandler
 }
 
 // NewClient creates new unstarted client.
diff --git a/telegram/options.go b/telegram/options.go
index 724a581ed7..af80cb06dd 100644
--- a/telegram/options.go
+++ b/telegram/options.go
@@ -95,13 +95,9 @@ type Options struct {
 	// OpenTelemetry.
 	TracerProvider trace.TracerProvider
 
-	// OnTransfer is called on authorization transfer to acquire external lock.
-	//
-	// The function should call tx function to perform transfer, serializing it
-	// with external lock.
-	//
-	// The function must return error if tx function returned error.
-	OnTransfer func(ctx context.Context, c *Client, tx func(context.Context) error) error
+	// OnTransfer is called during authorization transfer.
+	// See [AuthTransferHandler] for details.
+	OnTransfer AuthTransferHandler
 }
 
 func (opt *Options) setDefaults() {
diff --git a/telegram/transfer.go b/telegram/transfer.go
index f33a25cd63..ec77228348 100644
--- a/telegram/transfer.go
+++ b/telegram/transfer.go
@@ -17,6 +17,14 @@ func (c *Client) exportAuth(ctx context.Context, dcID int) (*tg.AuthExportedAuth
 	return export, nil
 }
 
+// AuthTransferHandler is a function that is called during authorization transfer.
+//
+// The fn callback should be serialized by user id via external locking.
+// You can call [Client.Self] to acquire current user id.
+//
+// The fn callback must return fn error if any.
+type AuthTransferHandler func(ctx context.Context, client *Client, fn func(context.Context) error) error
+
 func noopOnTransfer(ctx context.Context, _ *Client, fn func(context.Context) error) error {
 	return fn(ctx)
 }