lua-discordGameSDK.lua

local ffi = require "ffi"
local msg = require "mp.msg"
local libGameSDK = ffi.load("discord_game_sdk")

ffi.cdef[[
void free(void *ptr);
void *malloc(size_t size);
void *memset(void *s, int c, size_t n);

enum{DISCORD_VERSION = 2};
enum{DISCORD_APPLICATION_MANAGER_VERSION = 1};
enum{DISCORD_USER_MANAGER_VERSION = 1};
enum{DISCORD_IMAGE_MANAGER_VERSION = 1};
enum{DISCORD_ACTIVITY_MANAGER_VERSION = 1};
enum{DISCORD_RELATIONSHIP_MANAGER_VERSION = 1};
enum{DISCORD_LOBBY_MANAGER_VERSION = 1};
enum{DISCORD_NETWORK_MANAGER_VERSION = 1};
enum{DISCORD_OVERLAY_MANAGER_VERSION = 1};
enum{DISCORD_STORAGE_MANAGER_VERSION = 1};
enum{DISCORD_STORE_MANAGER_VERSION = 1};
enum{DISCORD_VOICE_MANAGER_VERSION = 1};
enum{DISCORD_ACHIEVEMENT_MANAGER_VERSION = 1};

enum EDiscordResult {
  DiscordResult_Ok = 0,
  DiscordResult_ServiceUnavailable = 1,
  DiscordResult_InvalidVersion = 2,
  DiscordResult_LockFailed = 3,
  DiscordResult_InternalError = 4,
  DiscordResult_InvalidPayload = 5,
  DiscordResult_InvalidCommand = 6,
  DiscordResult_InvalidPermissions = 7,
  DiscordResult_NotFetched = 8,
  DiscordResult_NotFound = 9,
  DiscordResult_Conflict = 10,
  DiscordResult_InvalidSecret = 11,
  DiscordResult_InvalidJoinSecret = 12,
  DiscordResult_NoEligibleActivity = 13,
  DiscordResult_InvalidInvite = 14,
  DiscordResult_NotAuthenticated = 15,
  DiscordResult_InvalidAccessToken = 16,
  DiscordResult_ApplicationMismatch = 17,
  DiscordResult_InvalidDataUrl = 18,
  DiscordResult_InvalidBase64 = 19,
  DiscordResult_NotFiltered = 20,
  DiscordResult_LobbyFull = 21,
  DiscordResult_InvalidLobbySecret = 22,
  DiscordResult_InvalidFilename = 23,
  DiscordResult_InvalidFileSize = 24,
  DiscordResult_InvalidEntitlement = 25,
  DiscordResult_NotInstalled = 26,
  DiscordResult_NotRunning = 27,
  DiscordResult_InsufficientBuffer = 28,
  DiscordResult_PurchaseCanceled = 29,
  DiscordResult_InvalidGuild = 30,
  DiscordResult_InvalidEvent = 31,
  DiscordResult_InvalidChannel = 32,
  DiscordResult_InvalidOrigin = 33,
  DiscordResult_RateLimited = 34,
  DiscordResult_OAuth2Error = 35,
  DiscordResult_SelectChannelTimeout = 36,
  DiscordResult_GetGuildTimeout = 37,
  DiscordResult_SelectVoiceForceRequired = 38,
  DiscordResult_CaptureShortcutAlreadyListening = 39,
  DiscordResult_UnauthorizedForAchievement = 40,
  DiscordResult_InvalidGiftCode = 41,
  DiscordResult_PurchaseError = 42,
  DiscordResult_TransactionAborted = 43,
};

enum EDiscordCreateFlags {
  DiscordCreateFlags_Default = 0,
  DiscordCreateFlags_NoRequireDiscord = 1,
};

enum EDiscordLogLevel {
  DiscordLogLevel_Error = 1,
  DiscordLogLevel_Warn,
  DiscordLogLevel_Info,
  DiscordLogLevel_Debug,
};

enum EDiscordUserFlag {
  DiscordUserFlag_Partner = 2,
  DiscordUserFlag_HypeSquadEvents = 4,
  DiscordUserFlag_HypeSquadHouse1 = 64,
  DiscordUserFlag_HypeSquadHouse2 = 128,
  DiscordUserFlag_HypeSquadHouse3 = 256,
};

enum EDiscordPremiumType {
  DiscordPremiumType_None = 0,
  DiscordPremiumType_Tier1 = 1,
  DiscordPremiumType_Tier2 = 2,
};

enum EDiscordImageType {
  DiscordImageType_User,
};

enum EDiscordActivityType {
  DiscordActivityType_Playing,
  DiscordActivityType_Streaming,
  DiscordActivityType_Listening,
  DiscordActivityType_Watching,
};

enum EDiscordActivityActionType {
  DiscordActivityActionType_Join = 1,
  DiscordActivityActionType_Spectate,
};

enum EDiscordActivityJoinRequestReply {
  DiscordActivityJoinRequestReply_No,
  DiscordActivityJoinRequestReply_Yes,
  DiscordActivityJoinRequestReply_Ignore,
};

enum EDiscordStatus {
  DiscordStatus_Offline = 0,
  DiscordStatus_Online = 1,
  DiscordStatus_Idle = 2,
  DiscordStatus_DoNotDisturb = 3,
};

enum EDiscordRelationshipType {
  DiscordRelationshipType_None,
  DiscordRelationshipType_Friend,
  DiscordRelationshipType_Blocked,
  DiscordRelationshipType_PendingIncoming,
  DiscordRelationshipType_PendingOutgoing,
  DiscordRelationshipType_Implicit,
};

enum EDiscordLobbyType {
  DiscordLobbyType_Private = 1,
  DiscordLobbyType_Public,
};

enum EDiscordLobbySearchComparison {
  DiscordLobbySearchComparison_LessThanOrEqual = -2,
  DiscordLobbySearchComparison_LessThan,
  DiscordLobbySearchComparison_Equal,
  DiscordLobbySearchComparison_GreaterThan,
  DiscordLobbySearchComparison_GreaterThanOrEqual,
  DiscordLobbySearchComparison_NotEqual,
};

enum EDiscordLobbySearchCast {
  DiscordLobbySearchCast_String = 1,
  DiscordLobbySearchCast_Number,
};

enum EDiscordLobbySearchDistance {
  DiscordLobbySearchDistance_Local,
  DiscordLobbySearchDistance_Default,
  DiscordLobbySearchDistance_Extended,
  DiscordLobbySearchDistance_Global,
};

enum EDiscordEntitlementType {
  DiscordEntitlementType_Purchase = 1,
  DiscordEntitlementType_PremiumSubscription,
  DiscordEntitlementType_DeveloperGift,
  DiscordEntitlementType_TestModePurchase,
  DiscordEntitlementType_FreePurchase,
  DiscordEntitlementType_UserGift,
  DiscordEntitlementType_PremiumPurchase,
};

enum EDiscordSkuType {
  DiscordSkuType_Application = 1,
  DiscordSkuType_DLC,
  DiscordSkuType_Consumable,
  DiscordSkuType_Bundle,
};

enum EDiscordInputModeType {
  DiscordInputModeType_VoiceActivity = 0,
  DiscordInputModeType_PushToTalk,
};

typedef int64_t DiscordClientId;
typedef int32_t DiscordVersion;
typedef int64_t DiscordSnowflake;
typedef int64_t DiscordTimestamp;
typedef DiscordSnowflake DiscordUserId;
typedef char DiscordLocale[128];
typedef char DiscordBranch[4096];
typedef DiscordSnowflake DiscordLobbyId;
typedef char DiscordLobbySecret[128];
typedef char DiscordMetadataKey[256];
typedef char DiscordMetadataValue[4096];
typedef uint64_t DiscordNetworkPeerId;
typedef uint8_t DiscordNetworkChannelId;
typedef char DiscordPath[4096];
typedef char DiscordDateTime[64];

struct DiscordUser {
  DiscordUserId id;
  char username[256];
  char discriminator[8];
  char avatar[128];
  bool bot;
};

struct DiscordOAuth2Token {
  char access_token[128];
  char scopes[1024];
  DiscordTimestamp expires;
};

struct DiscordImageHandle {
  enum EDiscordImageType type;
  int64_t id;
  uint32_t size;
};

struct DiscordImageDimensions {
  uint32_t width;
  uint32_t height;
};


struct DiscordActivityTimestamps {
  DiscordTimestamp start;
  DiscordTimestamp end;
};

struct DiscordActivityAssets {
  char large_image[128];
  char large_text[128];
  char small_image[128];
  char small_text[128];
};

struct DiscordPartySize {
  int32_t current_size;
  int32_t max_size;
};

struct DiscordActivityParty {
  char id[128];
  struct DiscordPartySize size;
};

struct DiscordActivitySecrets {
  char match[128];
  char join[128];
  char spectate[128];
};

struct DiscordActivity {
  enum EDiscordActivityType type;
  int64_t application_id;
  char name[128];
  char state[128];
  char details[128];
  struct DiscordActivityTimestamps timestamps;
  struct DiscordActivityAssets assets;
  struct DiscordActivityParty party;
  struct DiscordActivitySecrets secrets;
  bool instance;
};

struct DiscordPresence {
  enum EDiscordStatus status;
  struct DiscordActivity activity;
};

struct DiscordRelationship {
  enum EDiscordRelationshipType type;
  struct DiscordUser user;
  struct DiscordPresence presence;
};

struct DiscordLobby {
  DiscordLobbyId id;
  enum EDiscordLobbyType type;
  DiscordUserId owner_id;
  DiscordLobbySecret secret;
  uint32_t capacity;
  bool locked;
};

struct DiscordFileStat {
  const char filename[260];
  uint64_t size;
  uint64_t last_modified;
};

struct DiscordEntitlement {
  DiscordSnowflake id;
  enum EDiscordEntitlementType type;
  DiscordSnowflake sku_id;
};

struct DiscordSkuPrice {
  uint32_t amount;
  const char currency[16];
};

struct DiscordSku {
  DiscordSnowflake id;
  enum EDiscordSkuType type;
  const char name[256];
  struct DiscordSkuPrice price;
};

struct DiscordInputMode {
  enum EDiscordInputModeType type;
  const char shortcut[256];
};

struct DiscordUserAchievement {
  DiscordSnowflake user_id;
  DiscordSnowflake achievement_id;
  uint8_t percent_complete;
  DiscordDateTime unlocked_at;
};

struct IDiscordLobbyTransaction {
  enum EDiscordResult (*set_type)(struct IDiscordLobbyTransaction* lobby_transaction, enum EDiscordLobbyType type);
  enum EDiscordResult (*set_owner)(struct IDiscordLobbyTransaction* lobby_transaction, DiscordUserId owner_id);
  enum EDiscordResult (*set_capacity)(struct IDiscordLobbyTransaction* lobby_transaction, uint32_t capacity);
  enum EDiscordResult (*set_metadata)(struct IDiscordLobbyTransaction* lobby_transaction, DiscordMetadataKey key, DiscordMetadataValue value);
  enum EDiscordResult (*delete_metadata)(struct IDiscordLobbyTransaction* lobby_transaction, DiscordMetadataKey key);
  enum EDiscordResult (*set_locked)(struct IDiscordLobbyTransaction* lobby_transaction, bool locked);
};

struct IDiscordLobbyMemberTransaction {
  enum EDiscordResult (*set_metadata)(struct IDiscordLobbyMemberTransaction* lobby_member_transaction, DiscordMetadataKey key, DiscordMetadataValue value);
  enum EDiscordResult (*delete_metadata)(struct IDiscordLobbyMemberTransaction* lobby_member_transaction, DiscordMetadataKey key);
};

struct IDiscordLobbySearchQuery {
  enum EDiscordResult (*filter)(struct IDiscordLobbySearchQuery* lobby_search_query, DiscordMetadataKey key, enum EDiscordLobbySearchComparison comparison, enum EDiscordLobbySearchCast cast, DiscordMetadataValue value);
  enum EDiscordResult (*sort)(struct IDiscordLobbySearchQuery* lobby_search_query, DiscordMetadataKey key, enum EDiscordLobbySearchCast cast, DiscordMetadataValue value);
  enum EDiscordResult (*limit)(struct IDiscordLobbySearchQuery* lobby_search_query, uint32_t limit);
  enum EDiscordResult (*distance)(struct IDiscordLobbySearchQuery* lobby_search_query, enum EDiscordLobbySearchDistance distance);
};

typedef void* IDiscordApplicationEvents;

struct IDiscordApplicationManager {
  void (*validate_or_exit)(struct IDiscordApplicationManager* manager, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
  void (*get_current_locale)(struct IDiscordApplicationManager* manager, DiscordLocale* locale);
  void (*get_current_branch)(struct IDiscordApplicationManager* manager, DiscordBranch* branch);
  void (*get_oauth2_token)(struct IDiscordApplicationManager* manager, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result, struct DiscordOAuth2Token* oauth2_token));
  void (*get_ticket)(struct IDiscordApplicationManager* manager, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result, const char* data));
};

struct IDiscordUserEvents {
  void (*on_current_user_update)(void* event_data);
};

struct IDiscordUserManager {
  enum EDiscordResult (*get_current_user)(struct IDiscordUserManager* manager, struct DiscordUser* current_user);
  void (*get_user)(struct IDiscordUserManager* manager, DiscordUserId user_id, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result, struct DiscordUser* user));
  enum EDiscordResult (*get_current_user_premium_type)(struct IDiscordUserManager* manager, enum EDiscordPremiumType* premium_type);
  enum EDiscordResult (*current_user_has_flag)(struct IDiscordUserManager* manager, enum EDiscordUserFlag flag, bool* has_flag);
};

typedef void* IDiscordImageEvents;

struct IDiscordImageManager {
  void (*fetch)(struct IDiscordImageManager* manager, struct DiscordImageHandle handle, bool refresh, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result, struct DiscordImageHandle handle_result));
  enum EDiscordResult (*get_dimensions)(struct IDiscordImageManager* manager, struct DiscordImageHandle handle, struct DiscordImageDimensions* dimensions);
  enum EDiscordResult (*get_data)(struct IDiscordImageManager* manager, struct DiscordImageHandle handle, uint8_t* data, uint32_t data_length);
};

struct IDiscordActivityEvents {
  void (*on_activity_join)(void* event_data, const char* secret);
  void (*on_activity_spectate)(void* event_data, const char* secret);
  void (*on_activity_join_request)(void* event_data, struct DiscordUser* user);
  void (*on_activity_invite)(void* event_data, enum EDiscordActivityActionType type, struct DiscordUser* user, struct DiscordActivity* activity);
};

struct IDiscordActivityManager {
  enum EDiscordResult (*register_command)(struct IDiscordActivityManager* manager, const char* command);
  enum EDiscordResult (*register_steam)(struct IDiscordActivityManager* manager, uint32_t steam_id);
  void (*update_activity)(struct IDiscordActivityManager* manager, struct DiscordActivity* activity, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
  void (*clear_activity)(struct IDiscordActivityManager* manager, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
  void (*send_request_reply)(struct IDiscordActivityManager* manager, DiscordUserId user_id, enum EDiscordActivityJoinRequestReply reply, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
  void (*send_invite)(struct IDiscordActivityManager* manager, DiscordUserId user_id, enum EDiscordActivityActionType type, const char* content, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
  void (*accept_invite)(struct IDiscordActivityManager* manager, DiscordUserId user_id, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
};

struct IDiscordRelationshipEvents {
  void (*on_refresh)(void* event_data);
  void (*on_relationship_update)(void* event_data, struct DiscordRelationship* relationship);
};

struct IDiscordRelationshipManager {
  void (*filter)(struct IDiscordRelationshipManager* manager, void* filter_data, bool (*filter)(void* filter_data, struct DiscordRelationship* relationship));
  enum EDiscordResult (*count)(struct IDiscordRelationshipManager* manager, int32_t* count);
  enum EDiscordResult (*get)(struct IDiscordRelationshipManager* manager, DiscordUserId user_id, struct DiscordRelationship* relationship);
  enum EDiscordResult (*get_at)(struct IDiscordRelationshipManager* manager, uint32_t index, struct DiscordRelationship* relationship);
};

struct IDiscordLobbyEvents {
  void (*on_lobby_update)(void* event_data, int64_t lobby_id);
  void (*on_lobby_delete)(void* event_data, int64_t lobby_id, uint32_t reason);
  void (*on_member_connect)(void* event_data, int64_t lobby_id, int64_t user_id);
  void (*on_member_update)(void* event_data, int64_t lobby_id, int64_t user_id);
  void (*on_member_disconnect)(void* event_data, int64_t lobby_id, int64_t user_id);
  void (*on_lobby_message)(void* event_data, int64_t lobby_id, int64_t user_id, uint8_t* data, uint32_t data_length);
  void (*on_speaking)(void* event_data, int64_t lobby_id, int64_t user_id, bool speaking);
  void (*on_network_message)(void* event_data, int64_t lobby_id, int64_t user_id, uint8_t channel_id, uint8_t* data, uint32_t data_length);
};

struct IDiscordLobbyManager {
  enum EDiscordResult (*get_lobby_create_transaction)(struct IDiscordLobbyManager* manager, struct IDiscordLobbyTransaction** transaction);
  enum EDiscordResult (*get_lobby_update_transaction)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id, struct IDiscordLobbyTransaction** transaction);
  enum EDiscordResult (*get_member_update_transaction)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id, DiscordUserId user_id, struct IDiscordLobbyMemberTransaction** transaction);
  void (*create_lobby)(struct IDiscordLobbyManager* manager, struct IDiscordLobbyTransaction* transaction, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result, struct DiscordLobby* lobby));
  void (*update_lobby)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id, struct IDiscordLobbyTransaction* transaction, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
  void (*delete_lobby)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
  void (*connect_lobby)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id, DiscordLobbySecret secret, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result, struct DiscordLobby* lobby));
  void (*connect_lobby_with_activity_secret)(struct IDiscordLobbyManager* manager, DiscordLobbySecret activity_secret, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result, struct DiscordLobby* lobby));
  void (*disconnect_lobby)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
  enum EDiscordResult (*get_lobby)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id, struct DiscordLobby* lobby);
  enum EDiscordResult (*get_lobby_activity_secret)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id, DiscordLobbySecret* secret);
  enum EDiscordResult (*get_lobby_metadata_value)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id, DiscordMetadataKey key, DiscordMetadataValue* value);
  enum EDiscordResult (*get_lobby_metadata_key)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id, int32_t index, DiscordMetadataKey* key);
  enum EDiscordResult (*lobby_metadata_count)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id, int32_t* count);
  enum EDiscordResult (*member_count)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id, int32_t* count);
  enum EDiscordResult (*get_member_user_id)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id, int32_t index, DiscordUserId* user_id);
  enum EDiscordResult (*get_member_user)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id, DiscordUserId user_id, struct DiscordUser* user);
  enum EDiscordResult (*get_member_metadata_value)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id, DiscordUserId user_id, DiscordMetadataKey key, DiscordMetadataValue* value);
  enum EDiscordResult (*get_member_metadata_key)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id, DiscordUserId user_id, int32_t index, DiscordMetadataKey* key);
  enum EDiscordResult (*member_metadata_count)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id, DiscordUserId user_id, int32_t* count);
  void (*update_member)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id, DiscordUserId user_id, struct IDiscordLobbyMemberTransaction* transaction, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
  void (*send_lobby_message)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id, uint8_t* data, uint32_t data_length, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
  enum EDiscordResult (*get_search_query)(struct IDiscordLobbyManager* manager, struct IDiscordLobbySearchQuery** query);
  void (*search)(struct IDiscordLobbyManager* manager, struct IDiscordLobbySearchQuery* query, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
  void (*lobby_count)(struct IDiscordLobbyManager* manager, int32_t* count);
  enum EDiscordResult (*get_lobby_id)(struct IDiscordLobbyManager* manager, int32_t index, DiscordLobbyId* lobby_id);
  void (*connect_voice)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
  void (*disconnect_voice)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
  enum EDiscordResult (*connect_network)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id);
  enum EDiscordResult (*disconnect_network)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id);
  enum EDiscordResult (*flush_network)(struct IDiscordLobbyManager* manager);
  enum EDiscordResult (*open_network_channel)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id, uint8_t channel_id, bool reliable);
  enum EDiscordResult (*send_network_message)(struct IDiscordLobbyManager* manager, DiscordLobbyId lobby_id, DiscordUserId user_id, uint8_t channel_id, uint8_t* data, uint32_t data_length);
};

struct IDiscordNetworkEvents {
  void (*on_message)(void* event_data, DiscordNetworkPeerId peer_id, DiscordNetworkChannelId channel_id, uint8_t* data, uint32_t data_length);
  void (*on_route_update)(void* event_data, const char* route_data);
};

struct IDiscordNetworkManager {
  /**
   * Get the local peer ID for this process.
   */
  void (*get_peer_id)(struct IDiscordNetworkManager* manager, DiscordNetworkPeerId* peer_id);
  /**
   * Send pending network messages.
   */
  enum EDiscordResult (*flush)(struct IDiscordNetworkManager* manager);
  /**
   * Open a connection to a remote peer.
   */
  enum EDiscordResult (*open_peer)(struct IDiscordNetworkManager* manager, DiscordNetworkPeerId peer_id, const char* route_data);
  /**
   * Update the route data for a connected peer.
   */
  enum EDiscordResult (*update_peer)(struct IDiscordNetworkManager* manager, DiscordNetworkPeerId peer_id, const char* route_data);
  /**
   * Close the connection to a remote peer.
   */
  enum EDiscordResult (*close_peer)(struct IDiscordNetworkManager* manager, DiscordNetworkPeerId peer_id);
  /**
   * Open a message channel to a connected peer.
   */
  enum EDiscordResult (*open_channel)(struct IDiscordNetworkManager* manager, DiscordNetworkPeerId peer_id, DiscordNetworkChannelId channel_id, bool reliable);
  /**
   * Close a message channel to a connected peer.
   */
  enum EDiscordResult (*close_channel)(struct IDiscordNetworkManager* manager, DiscordNetworkPeerId peer_id, DiscordNetworkChannelId channel_id);
  /**
   * Send a message to a connected peer over an opened message channel.
   */
  enum EDiscordResult (*send_message)(struct IDiscordNetworkManager* manager, DiscordNetworkPeerId peer_id, DiscordNetworkChannelId channel_id, uint8_t* data, uint32_t data_length);
};

struct IDiscordOverlayEvents {
  void (*on_toggle)(void* event_data, bool locked);
};

struct IDiscordOverlayManager {
  void (*is_enabled)(struct IDiscordOverlayManager* manager, bool* enabled);
  void (*is_locked)(struct IDiscordOverlayManager* manager, bool* locked);
  void (*set_locked)(struct IDiscordOverlayManager* manager, bool locked, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
  void (*open_activity_invite)(struct IDiscordOverlayManager* manager, enum EDiscordActivityActionType type, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
  void (*open_guild_invite)(struct IDiscordOverlayManager* manager, const char* code, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
  void (*open_voice_settings)(struct IDiscordOverlayManager* manager, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
};

typedef void* IDiscordStorageEvents;

struct IDiscordStorageManager {
  enum EDiscordResult (*read)(struct IDiscordStorageManager* manager, const char* name, uint8_t* data, uint32_t data_length, uint32_t* read);
  void (*read_async)(struct IDiscordStorageManager* manager, const char* name, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result, uint8_t* data, uint32_t data_length));
  void (*read_async_partial)(struct IDiscordStorageManager* manager, const char* name, uint64_t offset, uint64_t length, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result, uint8_t* data, uint32_t data_length));
  enum EDiscordResult (*write)(struct IDiscordStorageManager* manager, const char* name, uint8_t* data, uint32_t data_length);
  void (*write_async)(struct IDiscordStorageManager* manager, const char* name, uint8_t* data, uint32_t data_length, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
  enum EDiscordResult (*delete_)(struct IDiscordStorageManager* manager, const char* name);
  enum EDiscordResult (*exists)(struct IDiscordStorageManager* manager, const char* name, bool* exists);
  void (*count)(struct IDiscordStorageManager* manager, int32_t* count);
  enum EDiscordResult (*stat)(struct IDiscordStorageManager* manager, const char* name, struct DiscordFileStat* stat);
  enum EDiscordResult (*stat_at)(struct IDiscordStorageManager* manager, int32_t index, struct DiscordFileStat* stat);
  enum EDiscordResult (*get_path)(struct IDiscordStorageManager* manager, DiscordPath* path);
};

struct IDiscordStoreEvents {
  void (*on_entitlement_create)(void* event_data, struct DiscordEntitlement* entitlement);
  void (*on_entitlement_delete)(void* event_data, struct DiscordEntitlement* entitlement);
};

struct IDiscordStoreManager {
  void (*fetch_skus)(struct IDiscordStoreManager* manager, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
  void (*count_skus)(struct IDiscordStoreManager* manager, int32_t* count);
  enum EDiscordResult (*get_sku)(struct IDiscordStoreManager* manager, DiscordSnowflake sku_id, struct DiscordSku* sku);
  enum EDiscordResult (*get_sku_at)(struct IDiscordStoreManager* manager, int32_t index, struct DiscordSku* sku);
  void (*fetch_entitlements)(struct IDiscordStoreManager* manager, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
  void (*count_entitlements)(struct IDiscordStoreManager* manager, int32_t* count);
  enum EDiscordResult (*get_entitlement)(struct IDiscordStoreManager* manager, DiscordSnowflake entitlement_id, struct DiscordEntitlement* entitlement);
  enum EDiscordResult (*get_entitlement_at)(struct IDiscordStoreManager* manager, int32_t index, struct DiscordEntitlement* entitlement);
  enum EDiscordResult (*has_sku_entitlement)(struct IDiscordStoreManager* manager, DiscordSnowflake sku_id, bool* has_entitlement);
  void (*start_purchase)(struct IDiscordStoreManager* manager, DiscordSnowflake sku_id, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
};

struct IDiscordVoiceEvents {
  void (*on_settings_update)(void* event_data);
};

struct IDiscordVoiceManager {
  enum EDiscordResult (*get_input_mode)(struct IDiscordVoiceManager* manager, struct DiscordInputMode* input_mode);
  void (*set_input_mode)(struct IDiscordVoiceManager* manager, struct DiscordInputMode input_mode, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
  enum EDiscordResult (*is_self_mute)(struct IDiscordVoiceManager* manager, bool* mute);
  enum EDiscordResult (*set_self_mute)(struct IDiscordVoiceManager* manager, bool mute);
  enum EDiscordResult (*is_self_deaf)(struct IDiscordVoiceManager* manager, bool* deaf);
  enum EDiscordResult (*set_self_deaf)(struct IDiscordVoiceManager* manager, bool deaf);
  enum EDiscordResult (*is_local_mute)(struct IDiscordVoiceManager* manager, DiscordSnowflake user_id, bool* mute);
  enum EDiscordResult (*set_local_mute)(struct IDiscordVoiceManager* manager, DiscordSnowflake user_id, bool mute);
  enum EDiscordResult (*get_local_volume)(struct IDiscordVoiceManager* manager, DiscordSnowflake user_id, uint8_t* volume);
  enum EDiscordResult (*set_local_volume)(struct IDiscordVoiceManager* manager, DiscordSnowflake user_id, uint8_t volume);
};

struct IDiscordAchievementEvents {
  void (*on_user_achievement_update)(void* event_data, struct DiscordUserAchievement* user_achievement);
};

struct IDiscordAchievementManager {
  void (*set_user_achievement)(struct IDiscordAchievementManager* manager, DiscordSnowflake achievement_id, uint8_t percent_complete, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
  void (*fetch_user_achievements)(struct IDiscordAchievementManager* manager, void* callback_data, void (*callback)(void* callback_data, enum EDiscordResult result));
  void (*count_user_achievements)(struct IDiscordAchievementManager* manager, int32_t* count);
  enum EDiscordResult (*get_user_achievement)(struct IDiscordAchievementManager* manager, DiscordSnowflake user_achievement_id, struct DiscordUserAchievement* user_achievement);
  enum EDiscordResult (*get_user_achievement_at)(struct IDiscordAchievementManager* manager, int32_t index, struct DiscordUserAchievement* user_achievement);
};

typedef void* IDiscordCoreEvents;

struct IDiscordCore {
  void (*destroy)(struct IDiscordCore* core);
  enum EDiscordResult (*run_callbacks)(struct IDiscordCore* core);
  void (*set_log_hook)(struct IDiscordCore* core, enum EDiscordLogLevel min_level, void* hook_data, void (*hook)(void* hook_data, enum EDiscordLogLevel level, const char* message));
  struct IDiscordApplicationManager* (*get_application_manager)(struct IDiscordCore* core);
  struct IDiscordUserManager* (*get_user_manager)(struct IDiscordCore* core);
  struct IDiscordImageManager* (*get_image_manager)(struct IDiscordCore* core);
  struct IDiscordActivityManager* (*get_activity_manager)(struct IDiscordCore* core);
  struct IDiscordRelationshipManager* (*get_relationship_manager)(struct IDiscordCore* core);
  struct IDiscordLobbyManager* (*get_lobby_manager)(struct IDiscordCore* core);
  struct IDiscordNetworkManager* (*get_network_manager)(struct IDiscordCore* core);
  struct IDiscordOverlayManager* (*get_overlay_manager)(struct IDiscordCore* core);
  struct IDiscordStorageManager* (*get_storage_manager)(struct IDiscordCore* core);
  struct IDiscordStoreManager* (*get_store_manager)(struct IDiscordCore* core);
  struct IDiscordVoiceManager* (*get_voice_manager)(struct IDiscordCore* core);
  struct IDiscordAchievementManager* (*get_achievement_manager)(struct IDiscordCore* core);
};

struct DiscordCreateParams {
  DiscordClientId client_id;
  uint64_t flags;
  IDiscordCoreEvents* events;
  void* event_data;
  IDiscordApplicationEvents* application_events;
  DiscordVersion application_version;
  struct IDiscordUserEvents* user_events;
  DiscordVersion user_version;
  IDiscordImageEvents* image_events;
  DiscordVersion image_version;
  struct IDiscordActivityEvents* activity_events;
  DiscordVersion activity_version;
  struct IDiscordRelationshipEvents* relationship_events;
  DiscordVersion relationship_version;
  struct IDiscordLobbyEvents* lobby_events;
  DiscordVersion lobby_version;
  struct IDiscordNetworkEvents* network_events;
  DiscordVersion network_version;
  struct IDiscordOverlayEvents* overlay_events;
  DiscordVersion overlay_version;
  IDiscordStorageEvents* storage_events;
  DiscordVersion storage_version;
  struct IDiscordStoreEvents* store_events;
  DiscordVersion store_version;
  struct IDiscordVoiceEvents* voice_events;
  DiscordVersion voice_version;
  struct IDiscordAchievementEvents* achievement_events;
  DiscordVersion achievement_version;
};

static void* DiscordCreateParamsSetDefault(struct DiscordCreateParams* params);

enum EDiscordResult DiscordCreate(DiscordVersion version, struct DiscordCreateParams* params, struct IDiscordCore** result);

typedef void (*callbackPtr)(void* callback_data, enum EDiscordResult result);

typedef void (*loggerPtr)(void* hook_data, enum EDiscordLogLevel level, const char* message);

typedef void (*onUserUpdatedPtr)(void* data);

typedef void (*onOAuth2Ptr)(void* data, enum EDiscordResult result, struct DiscordOAuth2Token* token);

struct Application {
  struct IDiscordCore* core;
  struct IDiscordUserManager* users;
  struct IDiscordAchievementManager* achievements;
  struct IDiscordActivityManager* activities;
  struct IDiscordRelationshipManager* relationships;
  struct IDiscordApplicationManager* application;
  struct IDiscordLobbyManager* lobbies;
  DiscordUserId user_id;
};
]]

-- Implement set default function in Lua because
-- somehow I couldn't get FFI to call the static method
-- DiscordCreateParamsSetDefault
local function create_params_set_default(paramsPtr)
  paramsPtr[0].application_version = libGameSDK.DISCORD_APPLICATION_MANAGER_VERSION
  paramsPtr[0].user_version = libGameSDK.DISCORD_USER_MANAGER_VERSION
  paramsPtr[0].image_version = libGameSDK.DISCORD_IMAGE_MANAGER_VERSION
  paramsPtr[0].activity_version = libGameSDK.DISCORD_ACTIVITY_MANAGER_VERSION
  paramsPtr[0].relationship_version = libGameSDK.DISCORD_RELATIONSHIP_MANAGER_VERSION
  paramsPtr[0].lobby_version = libGameSDK.DISCORD_LOBBY_MANAGER_VERSION
  paramsPtr[0].network_version = libGameSDK.DISCORD_NETWORK_MANAGER_VERSION
  paramsPtr[0].overlay_version = libGameSDK.DISCORD_OVERLAY_MANAGER_VERSION
  paramsPtr[0].storage_version = libGameSDK.DISCORD_STORAGE_MANAGER_VERSION
  paramsPtr[0].store_version = libGameSDK.DISCORD_STORE_MANAGER_VERSION
  paramsPtr[0].voice_version = libGameSDK.DISCORD_VOICE_MANAGER_VERSION
  paramsPtr[0].achievement_version = libGameSDK.DISCORD_ACHIEVEMENT_MANAGER_VERSION
  return params
end

local discordGameSDK = {} -- module table

-- proxy to detect garbage collection of the module
discordGameSDK.gcDummy = newproxy(true)

local on_user_updated = ffi.cast("onUserUpdatedPtr", function(data)
  local appPtr = ffi.cast("struct Application*", data)
  local app = appPtr[0]
  local user = ffi.new("struct DiscordUser")
  local userPtr = ffi.new("struct DiscordUser[1]", user)
  app.users.get_current_user(app.users, userPtr)
  user = userPtr[0]
  msg.verbose(string.format("Displaying Discord Status on user: %s#%s",
                            ffi.string(user.username),
                            ffi.string(user.discriminator)))
end)

local loggerCallback = ffi.cast("loggerPtr", function (data, level, message)
  msg.info(string.format("Discord reported an error of severity %s: %s",
                         tostring(level),
                         ffi.string(message)))
end)

-- Helper function to make sure the input is a given type
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

-- Helper function to make sure the input is a string within length
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

-- Helper function to make sure the input is within a max int value
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

-- This function is basically a complete line by line port
-- from examples/c/main.c in the Game SDK. with Lua quirks
-- here and there.

-- Pass by reference kinda works but kinda doesn't, and
-- so user_events != userEventsPtr[0], and app != appPtr[0].
-- The desired one is always [0], so we simply do not use
-- the original objects after a pointer to them have been made.
function discordGameSDK.initialize(clientId)
  local app = ffi.new("struct Application")
  local appPtr = ffi.new("struct Application[1]", app)
  ffi.C.memset(appPtr, 0, ffi.sizeof(app))

  local user_events = ffi.new("struct IDiscordUserEvents")
  local userEventsPtr = ffi.new("struct IDiscordUserEvents[1]", user_events)
  ffi.C.memset(userEventsPtr, 0, ffi.sizeof(user_events))
    
  userEventsPtr[0].on_current_user_update = on_user_updated
    
  local params = ffi.new("struct DiscordCreateParams")
  local paramsPtr = ffi.new("struct DiscordCreateParams[1]", params)
  ffi.C.memset(paramsPtr, 0, ffi.sizeof(params))
  create_params_set_default(paramsPtr)
  paramsPtr[0].client_id = clientId
  paramsPtr[0].flags = libGameSDK.DiscordCreateFlags_NoRequireDiscord
  paramsPtr[0].event_data = appPtr
  paramsPtr[0].user_events = userEventsPtr
    
  local corePtrPtr = ffi.new("struct IDiscordCore*[1]", app.core)
  ffi.C.memset(corePtrPtr, 0, ffi.sizeof(app.core))

  -- Attempt to create a Discord instance
  x = libGameSDK.DiscordCreate(libGameSDK.DISCORD_VERSION, paramsPtr, corePtrPtr)
  running = x == libGameSDK.DiscordResult_Ok

  if running then
    appPtr[0].core = corePtrPtr[0]

    appPtr[0].core:set_log_hook(libGameSDK.DiscordLogLevel_Debug, appPtr, loggerCallback)

    appPtr[0].activities = appPtr[0].core[0]:get_activity_manager()
    appPtr[0].application = appPtr[0].core[0]:get_application_manager()
    appPtr[0].users = appPtr[0].core[0]:get_user_manager()

    discordGameSDK.runCallbacks(appPtr[0].core)
  end

    -- By http://lua-users.org/lists/lua-l/2011-04/msg00516.html,
    -- The LuaJIT FFI Garbage Collector doesn't follow pointers when
    -- determining which references to keep. Therefore, "you must
    -- not store the only reference to an object allocated with
    -- ffi.new() as a pointer in a struct field."
    -- Hence, a referencesTable is passed around instead of just 
    -- the app, although none of the keys are used apart from app.
  local referencesTable = {
    running = running,
    clientId = clientId,
    app = appPtr[0],
    appPtr = appPtr,
    userEvents = userEvents,
    userEventsPtr = userEventsPtr,
    corePtr = appPtr[0].core,
    corePtrPtr = corePtrPtr,
    activities = appPtr[0].activities,
    application = appPtr[0].application,
    users = appPtr[0].users
  }

  -- Prevent memory leak when called multiple times by explicitly
  -- calling the garbage collector (twice, because some SO user said so)
  collectgarbage()
  collectgarbage()

  return referencesTable

end

function discordGameSDK.shutdown(app)
  app.core:destroy()
end

function discordGameSDK.runCallbacks(core)
  return core.run_callbacks(core)
end

local updateActivityCallback = ffi.cast("callbackPtr", function(callback_data, discord_result)
  if discord_result == libGameSDK.DiscordResult_Ok then
    msg.verbose("Successfully updated Discord activity")
  else 
    msg.verbose("Failed updating Discord activity: " .. tostring(discord_result))
  end
end)

local clearActivityCallback = ffi.cast("callbackPtr", function(callback_data, discord_result)
  if discord_result == libGameSDK.DiscordResult_Ok then
    msg.verbose("Successfully cleared Discord activity")
  else 
    msg.verbose("Failed clearing Discord activity: " .. tostring(discord_result))
  end
end)

function discordGameSDK.updatePresence(referencesTable, presence)
  -- If Discord isn't running, try initialising.
  -- If it still fails, then return early.
  if not referencesTable.running then
    referencesTable = discordGameSDK.initialize(referencesTable.clientId)
    if not referencesTable.running then
      return referencesTable
    end
  end

  local func = "discordGameSDK.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.start_time, 64, "presence.start_time", func, true)
  checkIntArg(presence.end_time, 64, "presence.end_time", func, true)

  checkStrArg(presence.large_image, 127, "presence.large_image", func, true)
  checkStrArg(presence.large_text, 127, "presence.large_text", func, true)
  checkStrArg(presence.small_image, 127, "presence.small_image", func, true)
  checkStrArg(presence.small_text, 127, "presence.small_text", func, true)

  checkStrArg(presence.party_id, 127, "presence.party_id", func, true)
  checkIntArg(presence.party_size, 32, "presence.party_size", func, true)
  checkIntArg(presence.party_max, 32, "presence.party_max", func, true)

  checkStrArg(presence.match_secret, 127, "presence.match_secret", func, true)
  checkStrArg(presence.join_secret, 127, "presence.join_secret", func, true)
  checkStrArg(presence.spectate_secret, 127, "presence.spectate_secret", func, true)

  local app = referencesTable.app
  app.activities = app.core[0]:get_activity_manager()
  app.application = app.core[0]:get_application_manager()
  app.users = app.core[0]:get_user_manager()

  local activity = ffi.new("struct DiscordActivity")
  local activityPtr = ffi.new("struct DiscordActivity[1]", activity)
  ffi.C.memset(activityPtr, 0, ffi.sizeof(activity))

  activityPtr[0].type = libGameSDK.DiscordActivityType_Playing
  activityPtr[0].state = presence.state or ""
  activityPtr[0].details = presence.details or ""
  activityPtr[0].timestamps.start = presence.start_time or 0
  activityPtr[0].timestamps["end"] = presence.end_time or 0
  activityPtr[0].assets.large_image = presence.large_image or ""
  activityPtr[0].assets.large_text = presence.large_text or ""
  activityPtr[0].assets.small_image = presence.small_image or ""
  activityPtr[0].assets.small_text = presence.small_text or ""
  activityPtr[0].party.id = presence.party_id or ""
  activityPtr[0].party.size.current_size = presence.party_size or 0
  activityPtr[0].party.size.max_size = presence.party_max or 0
  activityPtr[0].secrets.match = presence.match_secret or ""
  activityPtr[0].secrets.join = presence.join_secret or ""
  activityPtr[0].secrets.spectate = presence.spectate_secret or ""
  
  app.activities:update_activity(activityPtr, app.core, updateActivityCallback)
  x = discordGameSDK.runCallbacks(app.core)
  running = x == libGameSDK.DiscordResult_Ok

  -- Make sure garbage memory is collected, or otherwise
  -- this script will keep on increasming RAM usage by about 8KB
  -- everytime updateActivity or clearActivity is run.
  collectgarbage()
  collectgarbage()
  referencesTable.running = running
  return referencesTable
end

function discordGameSDK.clearPresence(referencesTable)
  -- If Discord isn't running, don't even try.
  if not referencesTable.running then
    return referencesTable
  end

  local app = referencesTable.app
  app.activities = app.core[0]:get_activity_manager()
  app.application = app.core[0]:get_application_manager()
  app.users = app.core[0]:get_user_manager()

  app.activities:clear_activity(app.core, clearActivityCallback)
  x = discordGameSDK.runCallbacks(app.core)
  running = x == libGameSDK.DiscordResult_Ok

  collectgarbage()
  collectgarbage()
  referencesTable.running = running
  return referencesTable
end

-- Attach a finaliser to run when discordGameSDK is garbage
-- collected. This happens when mpv quits.
getmetatable(discordGameSDK.gcDummy).__gc = function ()
  discordGameSDK.shutdown()
  updateActivityCallback:free()
  clearActivityCallback:free()
  loggerCallback:free()
end

-- http://luajit.org/ext_ffi_semantics.html#callback :
-- It is by default not allowed for C to callback into Lua, when
-- Lua had originally called into C. jit.off() allows it, so any
-- function that calls a callback needs to be wrapped in it.
jit.off(discordGameSDK.updatePresence)
jit.off(discordGameSDK.clearPresence)
jit.off(discordGameSDK.runCallbacks)
jit.off(discordGameSDK.initialize)

return discordGameSDK