From 44d6a1d2368157f03bbc0620504ed25a6cf68a92 Mon Sep 17 00:00:00 2001
From: mazmazz <mar.marcoz@outlook.com>
Date: Fri, 14 Dec 2018 00:22:25 -0500
Subject: [PATCH] Attempt to handle unstable device IDs

---
 src/sdl/i_system.c | 22 ++++++++++++----------
 src/sdl/i_video.c  | 29 ++++++++++++++++++++++++++++-
 2 files changed, 40 insertions(+), 11 deletions(-)

diff --git a/src/sdl/i_system.c b/src/sdl/i_system.c
index d1ce041a5..6ac41de16 100644
--- a/src/sdl/i_system.c
+++ b/src/sdl/i_system.c
@@ -1019,10 +1019,9 @@ void I_GetJoystickEvents(void)
 
 
 */
-static int joy_open(const char *fname)
+static int joy_open(int joyindex)
 {
 	SDL_Joystick *newdev = NULL;
-	int joyindex = atoi(fname);
 	int num_joy = 0;
 
 	if (SDL_WasInit(SDL_INIT_JOYSTICK) == 0)
@@ -1292,10 +1291,9 @@ void I_GetJoystick2Events(void)
 
 
 */
-static int joy_open2(const char *fname)
+static int joy_open2(int joyindex)
 {
 	SDL_Joystick *newdev = NULL;
-	int joyindex = atoi(fname);
 	int num_joy = 0;
 
 	if (SDL_WasInit(SDL_INIT_JOYSTICK) == 0)
@@ -1392,16 +1390,18 @@ void I_InitJoystick(void)
 		}
 	}
 
-	if (strcmp(cv_usejoystick.string, "0") && joy_open(cv_usejoystick.string) != -1)
+	if (cv_usejoystick.value && joy_open(cv_usejoystick.value) != -1)
 	{
-		JoyInfo.oldjoy = atoi(cv_usejoystick.string);
+		// SDL's device indexes are unstable, so cv_usejoystick may not match
+		// the actual device index. So let's cheat a bit and use the instance ID.
+		// oldjoy's exact value doesn't matter, because we use it like a boolean
+		JoyInfo.oldjoy = SDL_JoystickInstanceID(JoyInfo.dev) + 1;
 		joystick_started = 1;
 	}
 	else
 	{
 		if (JoyInfo.oldjoy)
 			I_ShutdownJoystick();
-		cv_usejoystick.value = 0;
 		joystick_started = 0;
 	}
 }
@@ -1423,16 +1423,18 @@ void I_InitJoystick2(void)
 		}
 	}
 
-	if (strcmp(cv_usejoystick2.string, "0") && joy_open2(cv_usejoystick2.string) != -1)
+	if (cv_usejoystick2.value && joy_open2(cv_usejoystick2.value) != -1)
 	{
-		JoyInfo2.oldjoy = atoi(cv_usejoystick2.string);
+		// SDL's device indexes are unstable, so cv_usejoystick2 may not match
+		// the actual device index. So let's cheat a bit and use the instance ID.
+		// oldjoy's exact value doesn't matter, because we use it like a boolean
+		JoyInfo2.oldjoy = SDL_JoystickInstanceID(JoyInfo2.dev) + 1;
 		joystick2_started = 1;
 	}
 	else
 	{
 		if (JoyInfo2.oldjoy)
 			I_ShutdownJoystick2();
-		cv_usejoystick2.value = 0;
 		joystick2_started = 0;
 	}
 
diff --git a/src/sdl/i_video.c b/src/sdl/i_video.c
index 51da55cb2..6fc8f5779 100644
--- a/src/sdl/i_video.c
+++ b/src/sdl/i_video.c
@@ -885,7 +885,27 @@ void I_GetEvent(void)
 			case SDL_JOYDEVICEADDED:
 				CONS_Debug(DBG_GAMELOGIC, "Joystick device index %d added\n", evt.jdevice.which + 1);
 
-				// recount hotplugged joysticks
+				// Because SDL's device index is unstable, we're going to cheat here a bit:
+				// For the first joystick setting that is NOT active:
+				// Set cv_usejoystickX.value to the new device index (this does not change what is written to config.cfg)
+				// Set OTHERS' cv_usejoystickX.value to THEIR new device index, because it likely changed
+				if (!JoyInfo.dev || !SDL_JoystickGetAttached(JoyInfo.dev))
+				{
+					cv_usejoystick.value = evt.jdevice.which + 1;
+
+					if (JoyInfo2.dev)
+						cv_usejoystick2.value = SDL_JoystickInstanceID(JoyInfo2.dev) + 1;
+				}
+				else if (!JoyInfo2.dev || !SDL_JoystickGetAttached(JoyInfo2.dev))
+				{
+					cv_usejoystick2.value = evt.jdevice.which + 1;
+
+					if (JoyInfo.dev)
+						cv_usejoystick.value = SDL_JoystickInstanceID(JoyInfo.dev) + 1;
+				}
+
+				// If an active joystick's index has changed, these will just
+				// change the corresponding JoyInfo.oldjoy
 				I_InitJoystick();
 				I_InitJoystick2();
 
@@ -909,6 +929,13 @@ void I_GetEvent(void)
 					I_ShutdownJoystick2();
 				}
 
+				// Update the device indexes, because they likely changed
+				if (JoyInfo.dev)
+					JoyInfo.oldjoy = SDL_JoystickInstanceID(JoyInfo.dev) + 1;
+
+				if (JoyInfo2.dev)
+					JoyInfo2.oldjoy = SDL_JoystickInstanceID(JoyInfo2.dev) + 1;
+
 				CONS_Debug(DBG_GAMELOGIC, "Joystick1 device index: %d\n", JoyInfo.oldjoy);
 				CONS_Debug(DBG_GAMELOGIC, "Joystick2 device index: %d\n", JoyInfo2.oldjoy);