frontend-tools: Make instant replay script also save replay

With the "instant-replay.lua" script, it would only play the last replay
buffer saved, meaning the user would have to save a replay with the
replay buffer hotkey, and then press the "Play Last Replay" hotkey to
play the last replay buffer.

Instead, combine the two and make the script save the replay
automatically first, and then play it back as soon as it's available.
This makes it actually qualify as an "instant replay" script, as its
name implies.

UI/frontend-plugins/frontend-tools/data/scripts/instant-replay.lua

 obs         = obslua
 source_name = ""
 hotkey_id   = obs.OBS_INVALID_HOTKEY_ID
+attempts    = 0
 
 ----------------------------------------------------------
 
--- The "Play Last Replay Buffer" hotkey callback
-function play(pressed)
-	if not pressed then
-		return
-	end
-
+function try_play()
 	local replay_buffer = obs.obs_frontend_get_replay_buffer_output()
 	if replay_buffer == nil then
+		obs.remove_current_callback()
 		return
 	end
 
-	local ph = obs.obs_output_get_proc_handler(replay_buffer)
-
 	-- Call the procedure of the replay buffer named "get_last_replay" to
 	-- get the last replay created by the replay buffer
 	local cd = obs.calldata_create()
+	local ph = obs.obs_output_get_proc_handler(replay_buffer)
 	obs.proc_handler_call(ph, "get_last_replay", cd)
 	local path = obs.calldata_string(cd, "path")
 	obs.calldata_destroy(cd)
 
+	obs.obs_output_release(replay_buffer)
+
 	-- If the path is valid and the source exists, update it with the
-	-- replay file to play back the replay
-	if path ~= nil then
+	-- replay file to play back the replay.  Otherwise, stop attempting to
+	-- replay after 10 seconds
+	if path == nil then
+		attempts = attempts + 1
+		if attempts >= 10 then
+			obs.remove_current_callback()
+		end
+	else
 		local source = obs.obs_get_source_by_name(source_name)
 		if source ~= nil then
 			local settings = obs.obs_data_create()
@@ -43,9 +47,33 @@ function play(pressed)
 			obs.obs_data_release(settings)
 			obs.obs_source_release(source)
 		end
+
+		obs.remove_current_callback()
 	end
+end
 
-	obs.obs_output_release(replay_buffer)
+-- The "Instant Replay" hotkey callback
+function instant_replay(pressed)
+	if not pressed then
+		return
+	end
+
+	local replay_buffer = obs.obs_frontend_get_replay_buffer_output()
+	if replay_buffer ~= nil then
+		-- Call the procedure of the replay buffer named "get_last_replay" to
+		-- get the last replay created by the replay buffer
+		local ph = obs.obs_output_get_proc_handler(replay_buffer)
+		obs.proc_handler_call(ph, "save", nil)
+
+		-- Set a 1-second timer to attempt playback every 1 second
+		-- until the replay is available
+		if obs.obs_output_active(replay_buffer) then
+			attempts = 0
+			obs.timer_add(try_play, 1000)
+		end
+
+		obs.obs_output_release(replay_buffer)
+	end
 end
 
 ----------------------------------------------------------
@@ -58,7 +86,7 @@ end
 -- A function named script_description returns the description shown to
 -- the user
 function script_description()
-	return "Plays the last replay buffer in the specified media source when the user presses a hotkey.\n\nMade by Jim"
+	return "When the \"Instant Replay\" hotkey is triggered, saves a replay with the replay buffer, and then plays it in a media source as soon as the replay is ready.  Requires an active replay buffer.\n\nMade by Jim"
 end
 
 -- A function named script_properties defines the properties that the user
@@ -84,8 +112,8 @@ end
 
 -- A function named script_load will be called on startup
 function script_load(settings)
-	hotkey_id = obs.obs_hotkey_register_frontend("instant_replay.play", "Play Last Replay Buffer", play)
-	local hotkey_save_array = obs.obs_data_get_array(settings, "instant_replay.play")
+	hotkey_id = obs.obs_hotkey_register_frontend("instant_replay.trigger", "Instant Replay", instant_replay)
+	local hotkey_save_array = obs.obs_data_get_array(settings, "instant_replay.trigger")
 	obs.obs_hotkey_load(hotkey_id, hotkey_save_array)
 	obs.obs_data_array_release(hotkey_save_array)
 end
@@ -97,6 +125,6 @@ end
 -- automatically.
 function script_save(settings)
 	local hotkey_save_array = obs.obs_hotkey_save(hotkey_id)
-	obs.obs_data_set_array(settings, "instant_replay.play", hotkey_save_array)
+	obs.obs_data_set_array(settings, "instant_replay.trigger", hotkey_save_array)
 	obs.obs_data_array_release(hotkey_save_array)
 end