From a7aadafc8d6842fb960786d4840dc29c490d3071 Mon Sep 17 00:00:00 2001
From: Felix Morgner <felix.morgner@gmail.com>
Date: Thu, 18 Jun 2026 16:42:03 +0200
Subject: lib: add simple echo router

---
 ttwhy/routers/echo.cppm | 84 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)
 create mode 100644 ttwhy/routers/echo.cppm

(limited to 'ttwhy/routers')

diff --git a/ttwhy/routers/echo.cppm b/ttwhy/routers/echo.cppm
new file mode 100644
index 0000000..41b7b51
--- /dev/null
+++ b/ttwhy/routers/echo.cppm
@@ -0,0 +1,84 @@
+module;
+
+#include <asio.hpp>
+
+#include <format>
+#include <string_view>
+
+export module ttwhy.routers:echo;
+
+import ttwhy;
+
+namespace ttwhy::routers
+{
+
+  using namespace std::string_view_literals;
+
+  constexpr auto vte_backspace_sequence = "\b \b"sv;
+
+  export template<typename StreamType>
+  struct echo
+  {
+    explicit echo(StreamType & stream)
+        : m_output_stream{stream}
+    {}
+
+    auto process(ttwhy::input_event event) -> asio::awaitable<void>
+    {
+      co_await std::visit(
+          [&](auto && event) -> asio::awaitable<void> {
+            using event_type = std::decay_t<decltype(event)>;
+
+            if constexpr (std::same_as<character_event, event_type>)
+            {
+              co_await process_character(event.value);
+            }
+            else if constexpr (std::same_as<control_event, event_type>)
+            {
+              co_await process_control_key(event.key);
+            }
+            else if constexpr (std::same_as<navigation_event, event_type>)
+            {
+              co_await process_navigation_key(event.key);
+            }
+          },
+          event);
+    }
+
+  private:
+    auto process_character(char character) -> asio::awaitable<void>
+    {
+      co_await asio::async_write(m_output_stream, asio::buffer(&character, 1), asio::as_tuple(asio::use_awaitable));
+    }
+
+    auto process_control_key(control_key key) -> asio::awaitable<void>
+    {
+      switch (key)
+      {
+        case control_key::backspace:
+          co_await asio::async_write(m_output_stream, asio::buffer(vte_backspace_sequence),
+                                     asio::as_tuple(asio::use_awaitable));
+          break;
+        default:
+          co_await asio::async_write(m_output_stream, asio::buffer(std::format("{{CTRL:{}}}", std::to_underlying(key))),
+                                     asio::as_tuple(asio::use_awaitable));
+      };
+    }
+
+    auto process_navigation_key(navigation_key key) -> asio::awaitable<void>
+    {
+      switch (key)
+      {
+        case navigation_key::delete_key:
+          co_await asio::async_write(m_output_stream, asio::buffer("{DEL}"), asio::as_tuple(asio::use_awaitable));
+          break;
+        default:
+          co_await asio::async_write(m_output_stream, asio::buffer(std::format("{{NAV:{}}}", std::to_underlying(key))),
+                                     asio::as_tuple(asio::use_awaitable));
+      }
+    }
+
+    StreamType & m_output_stream;
+  };
+
+}  // namespace ttwhy::routers
-- 
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