{-# LANGUAGE OverloadedStrings #-}

-- | Data structures pertaining to gateway dispatch 'Event's
module Discord.Types.Events where

import Prelude hiding (id)

import Data.Time.ISO8601 (parseISO8601)
import Data.Time (UTCTime)
import Data.Time.Clock.POSIX (posixSecondsToUTCTime)

import Data.Aeson
import Data.Aeson.Types
import qualified Data.Text as T

import Discord.Types.Prelude
import Discord.Types.Channel
import Discord.Types.Guild (Guild, GuildUnavailable, GuildInfo,
                            GuildMember, Role, Emoji)


-- | Represents possible events sent by discord. Detailed information can be found at https://discordapp.com/developers/docs/topics/gateway.
data Event =
    Ready                   Int User [Channel] [GuildUnavailable] String
  | Resumed                 [T.Text]
  | ChannelCreate           Channel
  | ChannelUpdate           Channel
  | ChannelDelete           Channel
  | ChannelPinsUpdate       ChannelId (Maybe UTCTime)
  | GuildCreate             Guild GuildInfo
  | GuildUpdate             Guild
  | GuildDelete             GuildUnavailable
  | GuildBanAdd             GuildId User
  | GuildBanRemove          GuildId User
  | GuildEmojiUpdate        GuildId [Emoji]
  | GuildIntegrationsUpdate GuildId
  | GuildMemberAdd          GuildId GuildMember
  | GuildMemberRemove       GuildId User
  | GuildMemberUpdate       GuildId [RoleId] User (Maybe String)
  | GuildMemberChunk        GuildId [GuildMember]
  | GuildRoleCreate         GuildId Role
  | GuildRoleUpdate         GuildId Role
  | GuildRoleDelete         GuildId RoleId
  | MessageCreate           Message
  | MessageUpdate           ChannelId MessageId
  | MessageDelete           ChannelId MessageId
  | MessageDeleteBulk       ChannelId [MessageId]
  | MessageReactionAdd      ReactionInfo
  | MessageReactionRemove   ReactionInfo
  | MessageReactionRemoveAll ChannelId MessageId
  | PresenceUpdate          PresenceInfo
  | TypingStart             TypingInfo
  | UserUpdate              User
  -- | VoiceStateUpdate
  -- | VoiceServerUpdate
  | UnknownEvent     String Object
  deriving Show

data ReactionInfo = ReactionInfo
  { reactionUserId    :: UserId
  , reactionChannelId :: ChannelId
  , reactionMessageId :: MessageId
  , reactionEmoji     :: Emoji
  } deriving Show

instance FromJSON ReactionInfo where
  parseJSON = withObject "ReactionInfo" $ \o ->
    ReactionInfo <$> o .: "user_id"
                 <*> o .: "channel_id"
                 <*> o .: "message_id"
                 <*> o .: "emoji"

data PresenceInfo = PresenceInfo
  { presenceUserId  :: UserId
  , presenceRoles   :: [RoleId]
  -- , presenceGame :: Maybe Activity
  , presenceGuildId :: GuildId
  , presenceStatus  :: String
  } deriving Show

instance FromJSON PresenceInfo where
  parseJSON = withObject "PresenceInfo" $ \o ->
    PresenceInfo <$> (o .: "user" >>= (.: "id"))
                 <*> o .: "roles"
              -- <*> o .: "game"
                 <*> o .: "guild_id"
                 <*> o .: "status"

data TypingInfo = TypingInfo
  { typingUserId    :: UserId
  , typingChannelId :: ChannelId
  , typingTimestamp :: UTCTime
  } deriving Show

instance FromJSON TypingInfo where
  parseJSON = withObject "TypingInfo" $ \o ->
    do cid <- o .: "channel_id"
       uid <- o .: "user_id"
       posix <- o .: "timestamp"
       let utc = posixSecondsToUTCTime posix
       pure (TypingInfo uid cid utc)



-- | Convert ToJSON value to FromJSON value
reparse :: (ToJSON a, FromJSON b) => a -> Parser b
reparse val = case parseEither parseJSON $ toJSON val of
                Left r -> fail r
                Right b -> pure b

eventParse :: T.Text -> Object -> Parser Event
eventParse t o = case t of
    "READY"                     -> Ready <$> o .: "v"
                                         <*> o .: "user"
                                         <*> o .: "private_channels"
                                         <*> o .: "guilds"
                                         <*> o .: "session_id"
    "RESUMED"                   -> Resumed <$> o .: "_trace"
    "CHANNEL_CREATE"            -> ChannelCreate             <$> reparse o
    "CHANNEL_UPDATE"            -> ChannelUpdate             <$> reparse o
    "CHANNEL_DELETE"            -> ChannelDelete             <$> reparse o
    "CHANNEL_PINS_UPDATE"       -> do id <- o .: "channel_id"
                                      stamp <- o .:? "last_pin_timestamp"
                                      let utc = stamp >>= parseISO8601
                                      pure (ChannelPinsUpdate id utc)
    "GUILD_CREATE"              -> GuildCreate               <$> reparse o <*> reparse o
    "GUILD_UPDATE"              -> GuildUpdate               <$> reparse o
    "GUILD_DELETE"              -> GuildDelete               <$> reparse o
    "GUILD_BAN_ADD"             -> GuildBanAdd    <$> o .: "guild_id" <*> reparse o
    "GUILD_BAN_REMOVE"          -> GuildBanRemove <$> o .: "guild_id" <*> reparse o
    "GUILD_EMOJI_UPDATE"        -> GuildEmojiUpdate <$> o .: "guild_id" <*> o .: "emojis"
    "GUILD_INTEGRATIONS_UPDATE" -> GuildIntegrationsUpdate   <$> o .: "guild_id"
    "GUILD_MEMBER_ADD"          -> GuildMemberAdd <$> o .: "guild_id" <*> reparse o
    "GUILD_MEMBER_REMOVE"       -> GuildMemberRemove <$> o .: "guild_id" <*> o .: "user"
    "GUILD_MEMBER_UPDATE"       -> GuildMemberUpdate <$> o .: "guild_id"
                                                     <*> o .: "roles"
                                                     <*> o .: "user"
                                                     <*> o .:? "nick"
    "GUILD_MEMBER_CHUNK"        -> GuildMemberChunk <$> o .: "guild_id" <*> o .: "members"
    "GUILD_ROLE_CREATE"         -> GuildRoleCreate  <$> o .: "guild_id" <*> o .: "role"
    "GUILD_ROLE_UPDATE"         -> GuildRoleUpdate  <$> o .: "guild_id" <*> o .: "role"
    "GUILD_ROLE_DELETE"         -> GuildRoleDelete  <$> o .: "guild_id" <*> o .: "role"
    "MESSAGE_CREATE"            -> MessageCreate     <$> reparse o
    "MESSAGE_UPDATE"            -> MessageUpdate     <$> o .: "channel_id" <*> o .: "id"
    "MESSAGE_DELETE"            -> MessageDelete     <$> o .: "channel_id" <*> o .: "id"
    "MESSAGE_DELETE_BULK"       -> MessageDeleteBulk <$> o .: "channel_id" <*> o .: "ids"
    "MESSAGE_REACTION_ADD"      -> MessageReactionAdd <$> reparse o
    "MESSAGE_REACTION_REMOVE"   -> MessageReactionRemove <$> reparse o
    "MESSAGE_REACTION_REMOVE_ALL" -> MessageReactionRemoveAll <$> o .: "channel_id"
                                                              <*> o .: "message_id"
    "PRESENCE_UPDATE"           -> PresenceUpdate            <$> reparse o
    "TYPING_START"              -> TypingStart               <$> reparse o
    "USER_UPDATE"               -> UserUpdate                <$> reparse o
 -- "VOICE_STATE_UPDATE"        -> VoiceStateUpdate          <$> reparse o
 -- "VOICE_SERVER_UPDATE"       -> VoiceServerUpdate         <$> reparse o
    _other_event                -> UnknownEvent (T.unpack t) <$> reparse o