From 530196af81f9981d18888e1326ff37d0bd249d7e Mon Sep 17 00:00:00 2001
From: Martin Ridgers <martin.ridgers+clink@gmail.com>
Date: Thu, 18 May 2023 22:37:13 +0200
Subject: [PATCH] Use Windows 10's virtual terminal if available

---
 clink/terminal/include/terminal/terminal.h |  1 +
 clink/terminal/src/terminal.cpp            | 60 +++++++++++++++++++---
 2 files changed, 55 insertions(+), 6 deletions(-)

diff --git a/clink/terminal/include/terminal/terminal.h b/clink/terminal/include/terminal/terminal.h
index ee9a90ff..324e521c 100644
--- a/clink/terminal/include/terminal/terminal.h
+++ b/clink/terminal/include/terminal/terminal.h
@@ -12,6 +12,7 @@ struct Terminal
 {
     TerminalIn*     in;
     TerminalOut*    out;
+    uintptr_t       impl;
 };
 
 //------------------------------------------------------------------------------
diff --git a/clink/terminal/src/terminal.cpp b/clink/terminal/src/terminal.cpp
index a0599ca3..97cf0ff4 100644
--- a/clink/terminal/src/terminal.cpp
+++ b/clink/terminal/src/terminal.cpp
@@ -6,20 +6,55 @@
 #include "ecma48_terminal_out.h"
 #include "win_screen_buffer.h"
 #include "win_terminal_in.h"
+#include "win_terminal_out.h"
 
 #include <core/base.h>
 
+//------------------------------------------------------------------------------
+#if defined(PLATFORM_WINDOWS)
+struct WinVirtualTerminal
+{
+    DWORD           prev_mode = ~0u;
+    ScreenBuffer*   screen = nullptr;
+};
+#endif
+
 //------------------------------------------------------------------------------
 Terminal terminal_create(ScreenBuffer* screen)
 {
 #if defined(PLATFORM_WINDOWS)
-    if (screen == nullptr)
-        screen = new WinScreenBuffer(); // TODO: this leaks.
+    auto* impl = new WinVirtualTerminal();
+
+    Terminal terminal;
+    terminal.in = new WinTerminalIn();
+    terminal.out = nullptr;
+    terminal.impl = uintptr_t(impl);
+
+    // Try and use Win10's VT100 support
+    DWORD prev_mode;
+    HANDLE handle = GetStdHandle(STD_OUTPUT_HANDLE);
+    if (GetConsoleMode(handle, &prev_mode))
+    {
+        if (SetConsoleMode(handle, prev_mode|ENABLE_VIRTUAL_TERMINAL_PROCESSING))
+        {
+            impl->prev_mode = prev_mode;
+            terminal.out = new WinTerminalOut();
+        }
+    }
 
-    return {
-        new WinTerminalIn(),
-        new Ecma48TerminalOut(*screen),
-    };
+    // If it wasn't possible to enable VT100 support we'll fallback to Clink's
+    if (terminal.out == nullptr)
+    {
+        if (screen == nullptr)
+        {
+            screen = new WinScreenBuffer();
+            impl->screen = screen;
+        }
+
+        terminal.out = new Ecma48TerminalOut(*screen);
+    }
+
+    return terminal;
 #else
     return {};
 #endif
@@ -30,4 +65,17 @@ void terminal_destroy(const Terminal& terminal)
 {
     delete terminal.out;
     delete terminal.in;
+
+    auto* impl = (WinVirtualTerminal*)(terminal.impl);
+
+    if (impl->prev_mode != ~0u)
+    {
+        HANDLE handle = GetStdHandle(STD_OUTPUT_HANDLE);
+        SetConsoleMode(handle, impl->prev_mode);
+    }
+
+    if (impl->screen != nullptr)
+        delete impl->screen;
+
+    delete impl;
 }