From 7b3cfd2724d2c0bb178712278976d836f9277ded Mon Sep 17 00:00:00 2001
From: Marius Greuel <greuelm@mgtek.com>
Date: Wed, 4 Jan 2023 08:02:48 +0100
Subject: [PATCH] Add readline library replacement for MSVC

---
 CMakeLists.txt               |  2 +
 src/CMakeLists.txt           |  1 +
 src/msvc/readline.cpp        | 99 ++++++++++++++++++++++++++++++++++++
 src/msvc/readline/history.h  | 17 +++++++
 src/msvc/readline/readline.h | 24 +++++++++
 src/term.c                   |  4 +-
 6 files changed, 146 insertions(+), 1 deletion(-)
 create mode 100644 src/msvc/readline.cpp
 create mode 100644 src/msvc/readline/history.h
 create mode 100644 src/msvc/readline/readline.h

diff --git a/CMakeLists.txt b/CMakeLists.txt
index eed335f7..224f626b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -223,6 +223,8 @@ endif()
 find_library(HAVE_LIBREADLINE NAMES ${PREFERRED_LIBREADLINE})
 if(HAVE_LIBREADLINE)
     set(LIB_LIBREADLINE ${HAVE_LIBREADLINE})
+elseif(MSVC)
+    set(HAVE_LIBREADLINE 1)
 endif()
 
 # =====================================
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 462d9eae..c51214e6 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -70,6 +70,7 @@ if(MSVC)
         "msvc/getopt.c"
         "msvc/gettimeofday.c"
         "msvc/usleep.cpp"
+        "msvc/readline.cpp"
         )
     set(EXTRA_WINDOWS_INCLUDES ${EXTRA_WINDOWS_INCLUDES}
         "msvc"
diff --git a/src/msvc/readline.cpp b/src/msvc/readline.cpp
new file mode 100644
index 00000000..786bf247
--- /dev/null
+++ b/src/msvc/readline.cpp
@@ -0,0 +1,99 @@
+//
+// readline.cpp
+// Copyright (C) 2022 Marius Greuel
+// SPDX-License-Identifier: GPL-2.0-or-later
+//
+
+#include <string.h>
+#include <iostream>
+#include <memory>
+#include <mutex>
+#include <string>
+#include <thread>
+#include "readline/readline.h"
+#include "readline/history.h"
+
+int rl_readline_version = 0x0500;
+
+static char* rl_prompt;
+static rl_vcpfunc_t* rl_handler;
+static std::unique_ptr<std::thread> rl_thread;
+static std::mutex rl_mutex;
+static std::string rl_line;
+static bool rl_has_line = false;
+
+static void get_line_thread()
+{
+    std::string line;
+    std::getline(std::cin, line);
+
+    const std::lock_guard<std::mutex> lock(rl_mutex);
+    rl_line = line;
+    rl_has_line = true;
+}
+
+static void call_handler(const char* string)
+{
+    rl_thread->join();
+    rl_thread = nullptr;
+
+    if (rl_handler != nullptr)
+    {
+        if (string == nullptr)
+        {
+            rl_handler(nullptr);
+        }
+        else
+        {
+            rl_handler(_strdup(string));
+        }
+    }
+}
+
+int rl_input_available(void)
+{
+    return 1;
+}
+
+void rl_callback_read_char(void)
+{
+    if (std::cin.eof())
+    {
+        call_handler(nullptr);
+    }
+    else if (!rl_thread)
+    {
+        rl_thread = std::make_unique<std::thread>(get_line_thread);
+    }
+    else
+    {
+        const std::lock_guard<std::mutex> lock(rl_mutex);
+        if (rl_has_line)
+        {
+            rl_has_line = false;
+            call_handler(rl_line.c_str());
+        }
+    }
+}
+
+void rl_callback_handler_install(char* prompt, rl_vcpfunc_t* handler)
+{
+    rl_prompt = _strdup(prompt);
+    rl_handler = handler;
+
+    std::cout << rl_prompt;
+}
+
+void rl_callback_handler_remove(void)
+{
+    if (rl_prompt != nullptr)
+    {
+        free(rl_prompt);
+    }
+
+    rl_handler = nullptr;
+}
+
+void add_history(const char*)
+{
+}
diff --git a/src/msvc/readline/history.h b/src/msvc/readline/history.h
new file mode 100644
index 00000000..86a7b0a8
--- /dev/null
+++ b/src/msvc/readline/history.h
@@ -0,0 +1,17 @@
+//
+// history.h
+// Copyright (C) 2022 Marius Greuel
+// SPDX-License-Identifier: GPL-2.0-or-later
+//
+
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+    
+void add_history(const char* string);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/src/msvc/readline/readline.h b/src/msvc/readline/readline.h
new file mode 100644
index 00000000..6a7d7a55
--- /dev/null
+++ b/src/msvc/readline/readline.h
@@ -0,0 +1,24 @@
+//
+// readline.h
+// Copyright (C) 2022 Marius Greuel
+// SPDX-License-Identifier: GPL-2.0-or-later
+//
+
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef void (rl_vcpfunc_t)(char* line);
+
+extern int rl_readline_version;
+
+int rl_input_available(void);
+void rl_callback_read_char(void);
+void rl_callback_handler_install(char* prompt, rl_vcpfunc_t* handler);
+void rl_callback_handler_remove(void);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/src/term.c b/src/term.c
index d53d2df3..0828e17e 100644
--- a/src/term.c
+++ b/src/term.c
@@ -1314,7 +1314,9 @@ static int term_running;
 
 // Any character in standard input available (without sleeping)?
 static int readytoread() {
-#ifdef WIN32
+#ifdef _MSC_VER
+    return rl_input_available();
+#elif defined(WIN32)
   HANDLE hStdin = GetStdHandle(STD_INPUT_HANDLE);
 
   while(1) {