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{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE OverloadedStrings #-}
module RestService (start) where
import qualified BizExpr as E
import Control.Concurrent
import Control.Concurrent.STM
import Control.Concurrent.STM.TArray
import Data.Aeson (FromJSON, ToJSON)
import qualified Data.IntMap as IM
import qualified Data.Map as M
import Data.Maybe (fromMaybe)
import qualified Data.Text as T
import qualified Data.Text.Lazy as L
import GHC.Generics
import qualified Network.HTTP.Types.Status as Status
import Network.HTTP.Types.URI
import Network.Wai
import Network.Wai.Handler.Warp
import Web.Scotty as S
addHeaders :: Middleware
addHeaders =
modifyResponse
( mapResponseHeaders
( [ ("Access-Control-Allow-Methods ", "GET, POST"),
("Access-Control-Allow-Headers", "Content-Type"),
("Access-Control-Allow-Origin", "*")
]
++
)
)
staticFilePaths :: [FilePath]
staticFilePaths = map ("./static/" ++) ["materialize.min.css", "materialize.min.js", "service.js"]
staticFiles :: ScottyM ()
staticFiles = do
mapM_ addFile staticFilePaths
where
addFile path = get (capture $ tail path) $ file path
data ExprReq = ExprReq {expression :: L.Text, result :: Maybe L.Text}
deriving (Show, Generic)
instance FromJSON ExprReq
instance ToJSON ExprReq
--numInc :: State -> IO Table
--numInc s = atomically $ (\x -> writeTVar s x >> return x) . () =<< readTVar s
getTable :: State -> Int -> IO (Maybe Table)
getTable s n = atomically $ IM.lookup n <$> readTVar s
setTable :: State -> Int -> Table -> IO (Maybe Table)
setTable s n t = atomically $ (\x -> writeTVar s x >> return (Just t)) . IM.insert n t =<< readTVar s
insertRow :: State -> Int -> TableRow -> IO (Maybe Table)
insertRow s n row = atomically $ do
tables <- readTVar s
case IM.lookup n tables of
Nothing -> return Nothing
Just table ->
let updatedTable = addRow table row
updatedTables = IM.insert n updatedTable tables
in writeTVar s updatedTables >> return (Just updatedTable)
routes :: State -> ScottyM ()
routes state = do
S.middleware addHeaders
staticFiles
get "/t/dummy" $
S.json $ evalTableExpressions (TableExpressions dummyTable ["sum(2,3,5)", "any(0,0,1)", "sum(age, -10)", "any(0,1)"])
get "/t/:id" $
S.json =<< liftIO . getTable state =<< S.pathParam "id"
get "/t/:id/e/:e" $ do
id <- S.pathParam "id"
ex <- S.pathParam "e"
S.json
. fmap (evalTableExpressions . flip TableExpressions [ex])
=<< liftIO (getTable state id)
post "/t/:id" $ do
id <- S.pathParam "id"
S.json =<< liftIO . setTable state id =<< S.jsonData
post "/t/:id/row" $ do
id <- S.pathParam "id"
S.json =<< liftIO . insertRow state id =<< S.jsonData
get "/:expr" $
S.text =<< S.pathParam "expr"
post "/eval" $
S.json . (ExprReq <*> eval M.empty) . expression =<< S.jsonData
eval :: E.Context -> L.Text -> Maybe L.Text
eval c = fmap L.pack . E.eval c . L.unpack
type TableHeading = L.Text
type TableRow = M.Map TableHeading TableCell
type TableCell = L.Text
type Tables = IM.IntMap Table
type Expression = L.Text
data TableExpressions = TableExpressions
{ table :: Table,
expressions :: [Expression]
}
deriving (Show, Generic)
evalTableExpressions :: TableExpressions -> Table
evalTableExpressions (TableExpressions table expressions) =
foldl applyExpression table expressions
applyExpression :: Table -> Expression -> Table
applyExpression table expr =
table
{ table_headings = table_headings table ++ [expr],
table_rows =
map
( \row ->
M.insert
expr
( fromMaybe "-" (eval row expr)
)
row
)
(table_rows table)
}
data Table = Table
{ table_name :: L.Text,
table_headings :: [TableHeading],
table_rows :: [TableRow]
}
deriving (Show, Generic)
instance FromJSON Table
instance ToJSON Table
type State = TVar Tables
dummyTable =
Table
{ table_name = "dummy table",
table_headings = ["name", "age", "height"],
table_rows =
map
M.fromList
[ [ ("name", "alice"),
("age", "30"),
("height", "1.60")
],
[ ("name", "bob"),
("age", "40")
],
[ ("name", "charles"),
("height", "1.80")
],
[ ("age", "30"),
("height", "1.60")
]
]
}
addRow :: Table -> TableRow -> Table
addRow t tr = t {table_rows = tr0 : table_rows t}
where
tr0 = M.filterWithKey (\k _ -> k `elem` table_headings t) tr
stateInit :: IO State
stateInit = newTVarIO $ IM.fromList [(-1, dummyTable)]
start :: IO ()
start = scottyOpts opts . routes =<< stateInit
opts :: Options
opts = Options 1 settings
where
settings = setPort 3000 defaultSettings
|
