rich presence!!

discordRPC.lua

@@ -0,0 +1,252 @@
+local ffi = require "ffi"
+local discordRPClib = ffi.load("discord-rpc")
+
+ffi.cdef[[
+typedef struct DiscordRichPresence {
+    const char* state;   /* max 128 bytes */
+    const char* details; /* max 128 bytes */
+    int64_t startTimestamp;
+    int64_t endTimestamp;
+    const char* largeImageKey;  /* max 32 bytes */
+    const char* largeImageText; /* max 128 bytes */
+    const char* smallImageKey;  /* max 32 bytes */
+    const char* smallImageText; /* max 128 bytes */
+    const char* partyId;        /* max 128 bytes */
+    int partySize;
+    int partyMax;
+    const char* matchSecret;    /* max 128 bytes */
+    const char* joinSecret;     /* max 128 bytes */
+    const char* spectateSecret; /* max 128 bytes */
+    int8_t instance;
+} DiscordRichPresence;
+
+typedef struct DiscordUser {
+    const char* userId;
+    const char* username;
+    const char* discriminator;
+    const char* avatar;
+} DiscordUser;
+
+typedef void (*readyPtr)(const DiscordUser* request);
+typedef void (*disconnectedPtr)(int errorCode, const char* message);
+typedef void (*erroredPtr)(int errorCode, const char* message);
+typedef void (*joinGamePtr)(const char* joinSecret);
+typedef void (*spectateGamePtr)(const char* spectateSecret);
+typedef void (*joinRequestPtr)(const DiscordUser* request);
+
+typedef struct DiscordEventHandlers {
+    readyPtr ready;
+    disconnectedPtr disconnected;
+    erroredPtr errored;
+    joinGamePtr joinGame;
+    spectateGamePtr spectateGame;
+    joinRequestPtr joinRequest;
+} DiscordEventHandlers;
+
+void Discord_Initialize(const char* applicationId,
+                        DiscordEventHandlers* handlers,
+                        int autoRegister,
+                        const char* optionalSteamId);
+
+void Discord_Shutdown(void);
+
+void Discord_RunCallbacks(void);
+
+void Discord_UpdatePresence(const DiscordRichPresence* presence);
+
+void Discord_ClearPresence(void);
+
+void Discord_Respond(const char* userid, int reply);
+
+void Discord_UpdateHandlers(DiscordEventHandlers* handlers);
+]]
+
+local discordRPC = {} -- module table
+
+-- proxy to detect garbage collection of the module
+discordRPC.gcDummy = newproxy(true)
+
+local function unpackDiscordUser(request)
+    return ffi.string(request.userId), ffi.string(request.username),
+        ffi.string(request.discriminator), ffi.string(request.avatar)
+end
+
+-- callback proxies
+-- note: callbacks are not JIT compiled (= SLOW), try to avoid doing performance critical tasks in them
+-- luajit.org/ext_ffi_semantics.html
+local ready_proxy = ffi.cast("readyPtr", function(request)
+    if discordRPC.ready then
+        discordRPC.ready(unpackDiscordUser(request))
+    end
+end)
+
+local disconnected_proxy = ffi.cast("disconnectedPtr", function(errorCode, message)
+    if discordRPC.disconnected then
+        discordRPC.disconnected(errorCode, ffi.string(message))
+    end
+end)
+
+local errored_proxy = ffi.cast("erroredPtr", function(errorCode, message)
+    if discordRPC.errored then
+        discordRPC.errored(errorCode, ffi.string(message))
+    end
+end)
+
+local joinGame_proxy = ffi.cast("joinGamePtr", function(joinSecret)
+    if discordRPC.joinGame then
+        discordRPC.joinGame(ffi.string(joinSecret))
+    end
+end)
+
+local spectateGame_proxy = ffi.cast("spectateGamePtr", function(spectateSecret)
+    if discordRPC.spectateGame then
+        discordRPC.spectateGame(ffi.string(spectateSecret))
+    end
+end)
+
+local joinRequest_proxy = ffi.cast("joinRequestPtr", function(request)
+    if discordRPC.joinRequest then
+        discordRPC.joinRequest(unpackDiscordUser(request))
+    end
+end)
+
+-- helpers
+local function checkArg(arg, argType, argName, func, maybeNil)
+    assert(type(arg) == argType or (maybeNil and arg == nil),
+        string.format("Argument \"%s\" to function \"%s\" has to be of type \"%s\"",
+            argName, func, argType))
+end
+
+local function checkStrArg(arg, maxLen, argName, func, maybeNil)
+    if maxLen then
+        assert(type(arg) == "string" and arg:len() <= maxLen or (maybeNil and arg == nil),
+            string.format("Argument \"%s\" of function \"%s\" has to be of type string with maximum length %d",
+                argName, func, maxLen))
+    else
+        checkArg(arg, "string", argName, func, true)
+    end
+end
+
+local function checkIntArg(arg, maxBits, argName, func, maybeNil)
+    maxBits = math.min(maxBits or 32, 52) -- lua number (double) can only store integers < 2^53
+    local maxVal = 2^(maxBits-1) -- assuming signed integers, which, for now, are the only ones in use
+    assert(type(arg) == "number" and math.floor(arg) == arg
+        and arg < maxVal and arg >= -maxVal
+        or (maybeNil and arg == nil),
+        string.format("Argument \"%s\" of function \"%s\" has to be a whole number <= %d",
+            argName, func, maxVal))
+end
+
+-- function wrappers
+function discordRPC.initialize(applicationId, autoRegister, optionalSteamId)
+    local func = "discordRPC.Initialize"
+    checkStrArg(applicationId, nil, "applicationId", func)
+    checkArg(autoRegister, "boolean", "autoRegister", func)
+    if optionalSteamId ~= nil then
+        checkStrArg(optionalSteamId, nil, "optionalSteamId", func)
+    end
+
+    local eventHandlers = ffi.new("struct DiscordEventHandlers")
+    eventHandlers.ready = ready_proxy
+    eventHandlers.disconnected = disconnected_proxy
+    eventHandlers.errored = errored_proxy
+    eventHandlers.joinGame = joinGame_proxy
+    eventHandlers.spectateGame = spectateGame_proxy
+    eventHandlers.joinRequest = joinRequest_proxy
+
+    discordRPClib.Discord_Initialize(applicationId, eventHandlers,
+        autoRegister and 1 or 0, optionalSteamId)
+end
+
+function discordRPC.shutdown()
+    discordRPClib.Discord_Shutdown()
+end
+
+function discordRPC.runCallbacks()
+    discordRPClib.Discord_RunCallbacks()
+end
+-- http://luajit.org/ext_ffi_semantics.html#callback :
+-- It is not allowed, to let an FFI call into a C function (runCallbacks)
+-- get JIT-compiled, which in turn calls a callback, calling into Lua again (e.g. discordRPC.ready).
+-- Usually this attempt is caught by the interpreter first and the C function
+-- is blacklisted for compilation.
+-- solution:
+-- "Then you'll need to manually turn off JIT-compilation with jit.off() for
+-- the surrounding Lua function that invokes such a message polling function."
+jit.off(discordRPC.runCallbacks)
+
+function discordRPC.updatePresence(presence)
+    local func = "discordRPC.updatePresence"
+    checkArg(presence, "table", "presence", func)
+
+    -- -1 for string length because of 0-termination
+    checkStrArg(presence.state, 127, "presence.state", func, true)
+    checkStrArg(presence.details, 127, "presence.details", func, true)
+
+    checkIntArg(presence.startTimestamp, 64, "presence.startTimestamp", func, true)
+    checkIntArg(presence.endTimestamp, 64, "presence.endTimestamp", func, true)
+
+    checkStrArg(presence.largeImageKey, 31, "presence.largeImageKey", func, true)
+    checkStrArg(presence.largeImageText, 127, "presence.largeImageText", func, true)
+    checkStrArg(presence.smallImageKey, 31, "presence.smallImageKey", func, true)
+    checkStrArg(presence.smallImageText, 127, "presence.smallImageText", func, true)
+    checkStrArg(presence.partyId, 127, "presence.partyId", func, true)
+
+    checkIntArg(presence.partySize, 32, "presence.partySize", func, true)
+    checkIntArg(presence.partyMax, 32, "presence.partyMax", func, true)
+
+    checkStrArg(presence.matchSecret, 127, "presence.matchSecret", func, true)
+    checkStrArg(presence.joinSecret, 127, "presence.joinSecret", func, true)
+    checkStrArg(presence.spectateSecret, 127, "presence.spectateSecret", func, true)
+
+    checkIntArg(presence.instance, 8, "presence.instance", func, true)
+
+    local cpresence = ffi.new("struct DiscordRichPresence")
+    cpresence.state = presence.state
+    cpresence.details = presence.details
+    cpresence.startTimestamp = presence.startTimestamp or 0
+    cpresence.endTimestamp = presence.endTimestamp or 0
+    cpresence.largeImageKey = presence.largeImageKey
+    cpresence.largeImageText = presence.largeImageText
+    cpresence.smallImageKey = presence.smallImageKey
+    cpresence.smallImageText = presence.smallImageText
+    cpresence.partyId = presence.partyId
+    cpresence.partySize = presence.partySize or 0
+    cpresence.partyMax = presence.partyMax or 0
+    cpresence.matchSecret = presence.matchSecret
+    cpresence.joinSecret = presence.joinSecret
+    cpresence.spectateSecret = presence.spectateSecret
+    cpresence.instance = presence.instance or 0
+
+    discordRPClib.Discord_UpdatePresence(cpresence)
+end
+
+function discordRPC.clearPresence()
+    discordRPClib.Discord_ClearPresence()
+end
+
+local replyMap = {
+    no = 0,
+    yes = 1,
+    ignore = 2
+}
+
+-- maybe let reply take ints too (0, 1, 2) and add constants to the module
+function discordRPC.respond(userId, reply)
+    checkStrArg(userId, nil, "userId", "discordRPC.respond")
+    assert(replyMap[reply], "Argument 'reply' to discordRPC.respond has to be one of \"yes\", \"no\" or \"ignore\"")
+    discordRPClib.Discord_Respond(userId, replyMap[reply])
+end
+
+-- garbage collection callback
+getmetatable(discordRPC.gcDummy).__gc = function()
+    discordRPC.shutdown()
+    ready_proxy:free()
+    disconnected_proxy:free()
+    errored_proxy:free()
+    joinGame_proxy:free()
+    spectateGame_proxy:free()
+    joinRequest_proxy:free()
+end
+
+return discordRPC

main.lua

@@ -1,4 +1,45 @@
+discordRPC = require("discordRPC")
+appId = "599778517789573120"
+
+function discordRPC.ready(userId, username, discriminator, avatar)
+    print(string.format("Discord: ready (%s, %s, %s, %s)", userId, username, discriminator, avatar))
+end
+
+function discordRPC.disconnected(errorCode, message)
+    print(string.format("Discord: disconnected (%d: %s)", errorCode, message))
+end
+
+function discordRPC.errored(errorCode, message)
+    print(string.format("Discord: error (%d: %s)", errorCode, message))
+end
+
+function discordRPC.joinGame(joinSecret)
+    print(string.format("Discord: join (%s)", joinSecret))
+end
+
+function discordRPC.spectateGame(spectateSecret)
+    print(string.format("Discord: spectate (%s)", spectateSecret))
+end
+
+function discordRPC.joinRequest(userId, username, discriminator, avatar)
+    print(string.format("Discord: join request (%s, %s, %s, %s)", userId, username, discriminator, avatar))
+    discordRPC.respond(userId, "yes")
+end
+
 function love.load()
+
+	discordRPC.initialize(appId, true)
+	local now = os.time(os.date("*t"))
+	presence = {
+			startTimestamp = now,
+			details = "Loading game...",
+			state = "",
+			largeImageKey = "",
+			largeImageText = "",
+			smallImageKey = "",
+			smallImageText = ""
+	}
+
 	math.randomseed(os.time())
 	highscores = {}
 	require "load.graphics"

scene/game.lua

@@ -5,6 +5,9 @@ function GameScene:new(game_mode, ruleset)
 	self.game = game_mode()
 	self.ruleset = ruleset()
 	self.game:initialize(self.ruleset)
+	presence.details = "In game"
+	presence.state = game_mode.name
+	discordRPC.updatePresence(presence)
 end
 
 function GameScene:update()

scene/input_config.lua

@@ -22,6 +22,10 @@ function ConfigScene:new()
 	-- load current config
 	self.config = config.input
 	self.input_state = 1
+
+	presence.details = "In menus"
+	presence.state = "Changing input config"
+	discordRPC.updatePresence(presence)
 end
 
 function ConfigScene:update()

scene/mode_select.lua

@@ -47,6 +47,9 @@ function ModeSelectScene:new()
 		ruleset = current_ruleset,
 		select = "mode",
 	}
+	presence.details = "In menus"
+	presence.state = "Choosing a mode"
+	discordRPC.updatePresence(presence)
 end
 
 function ModeSelectScene:update()

scene/title.lua

@@ -6,8 +6,13 @@ local main_menu_screens = {
     ExitScene,
 }
 
+local mainmenuidle = {"Idle", "Twiddling their thumbs", "Admiring the main menu's BG", "Waiting for spring to come"}
+
 function TitleScene:new()
 	self.main_menu_state = 1
+	presence.details = "In menus"
+	presence.state =  mainmenuidle[math.random(#mainmenuidle)]
+	discordRPC.updatePresence(presence)
 end
 
 function TitleScene:update()