module CQRSExample.Json
       ( qProjectListJson
       , qTaskListJson
       , qTimesheetJson
       ) where

import           Control.Monad (liftM)
import           Data.Aeson (ToJSON, Value, toJSON)
import           Data.CQRS.GUID (GUID, hexEncode)
import           Data.List (groupBy)
import           Data.Map (Map)
import qualified Data.Map as M
import           Data.Text (Text)
import qualified Data.Text as T
import qualified Data.Text.Encoding as TE
import           Data.Time.Calendar (Day)
import           Database.HDBC (IConnection)

import           CQRSExample.Aggregates (UserId)
import qualified CQRSExample.Duration as D
import           CQRSExample.Query

-- Instances.
instance ToJSON Day where
  toJSON d = toJSON $ show d

-- Generate a list of JSONable values.
qListToJson :: (IConnection c, ToJSON b) => (c -> IO [a]) -> (a -> b) -> c -> IO [b]
qListToJson lister f conn = liftM (map f) $ lister conn

-- JSON queries.
qProjectListJson :: (IConnection c) => c -> IO [Map Text Text]
qProjectListJson =
  (qListToJson qProjectList
   (\(g,pn,psd) ->
     M.fromList [ (T.pack "id"        , TE.decodeUtf8 $ hexEncode g)
                , (T.pack "name"      , pn)
                , (T.pack "short_desc", psd)
                ]))

qTaskListJson :: (IConnection c) => UserId -> Maybe GUID -> c -> IO [Map Text Value]
qTaskListJson userId mProjectId =
  (qListToJson (qTaskList userId mProjectId)
   (\(g,tsd,starred) ->
     M.fromList [ (T.pack "id"               , toJSON $ TE.decodeUtf8 $ hexEncode g)
                , (T.pack "short_description", toJSON $ tsd)
                , (T.pack "starred"          , toJSON $ starred)
                ]))

qTimesheetJson :: (IConnection c) => Day -> Day -> UserId -> c -> IO [Map Text Value]
qTimesheetJson fromDate toDate userId connection = do
  -- Generate the time sheet data.
  timeSheet <- fmap g $ qTimeSheet fromDate toDate userId connection
  -- Generate the JSON data.
  return $ map
    (\entries ->
      case entries of
        [] -> M.fromList []
        ((tid,tsd,_,_):_) ->
          M.fromList [ (T.pack "task_id", toJSON $ hexEncode tid)
                     , (T.pack "task_short_description", toJSON tsd)
                     , (T.pack "timeSheet",
                        toJSON $ map (\(_,_,day,total) ->
                                       M.fromList [ (T.pack "date", toJSON $ day)
                                                  , (T.pack "total", toJSON $ D.toMinutes total) ] ) entries) ])
    timeSheet
  where
    g = groupBy (\(tid1,_,_,_) (tid2,_,_,_) -> (tid1==tid2))