Don't crash if the database doesn't exist

package.yaml

@@ -32,6 +32,7 @@ dependencies:
 - brick >= 2.1.1 && < 2.2
 - vty >= 6.1 && < 6.2
 - mtl >= 2.3.1 && < 2.4
+- easy-file >= 0.2.5 && < 0.3
 
 ghc-options:
 - -Wall

passman.cabal

@@ -4,7 +4,7 @@ cabal-version: 2.2
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: fb2b45c8e1d5aead518c67637b3af5e78b55b8f0c5a95a34c20ca5d957527fa0
+-- hash: d18a8e1efd32ff2d20b0b1f5ac8186be5242411bd72a6a017fd9f97d401a9836
 
 name:           passman
 version:        0.3.1.1
@@ -46,6 +46,7 @@ library
     , brick >=2.1.1 && <2.2
     , bytestring >=0.11.4.0 && <0.12
     , containers >=0.6.2.1 && <0.7
+    , easy-file >=0.2.5 && <0.3
     , microlens >=0.4.11.2 && <0.5
     , microlens-mtl >=0.2.0.3 && <0.3
     , microlens-th >=0.4.3.6 && <0.5
@@ -70,6 +71,7 @@ executable passman
     , brick >=2.1.1 && <2.2
     , bytestring >=0.11.4.0 && <0.12
     , containers >=0.6.2.1 && <0.7
+    , easy-file >=0.2.5 && <0.3
     , microlens >=0.4.11.2 && <0.5
     , microlens-mtl >=0.2.0.3 && <0.3
     , microlens-th >=0.4.3.6 && <0.5
@@ -110,6 +112,7 @@ test-suite passman-test
     , brick >=2.1.1 && <2.2
     , bytestring >=0.11.4.0 && <0.12
     , containers >=0.6.2.1 && <0.7
+    , easy-file >=0.2.5 && <0.3
     , microlens >=0.4.11.2 && <0.5
     , microlens-mtl >=0.2.0.3 && <0.3
     , microlens-th >=0.4.3.6 && <0.5

src/Password/App.hs

@@ -41,7 +41,7 @@ passmanApp = App
   { appDraw         = drawFunc
   , appChooseCursor = showFirstCursor
   , appHandleEvent  = eventHandler
-  , appStartEvent   = return ()
+  , appStartEvent   = loadDatabase
   , appAttrMap      = const $ attrMap (style 0) []
   }
 

src/Password/App/Event.hs

@@ -24,7 +24,7 @@ License along with this program.  If not, see
 
 {-# LANGUAGE LambdaCase, OverloadedStrings #-}
 
-module Password.App.Event (eventHandler) where
+module Password.App.Event (eventHandler, loadDatabase) where
 
 import Brick (BrickEvent (VtyEvent), EventM, halt)
 import Brick.Forms (handleFormEvent)
@@ -39,13 +39,24 @@ import Brick.Keybindings
   , onEvent
   )
 import Control.Monad (unless)
-import Control.Monad.State.Class (gets)
+import Control.Monad.IO.Class (liftIO)
+import Control.Monad.State.Class (gets, put)
+import Data.Aeson (decodeFileStrict)
 import Graphics.Vty.Input.Events (Event (EvKey))
 import Lens.Micro ((^.))
 import Lens.Micro.Mtl (zoom)
+import System.EasyFile
+  ( createDirectoryIfMissing
+  , doesFileExist
+  , getAppUserDataDirectory
+  , (</>)
+  )
 
 import Password.App.Types
 
+dbFile :: String
+dbFile = "database.json"
+
 data KEventID = QuitKE deriving (Eq, Ord, Show)
 
 -- | The main event handler
@@ -55,6 +66,16 @@ eventHandler e@(VtyEvent (EvKey k m)) = do
   handleKey disp k m >>= flip unless (fallbackHandler e)
 eventHandler e = fallbackHandler e
 
+loadDatabase :: EventM ResName AppState ()
+loadDatabase = zoom database $ liftIO
+  ( do
+    dir <- mkAppDir
+    let fn = dir </> dbFile
+    doesFileExist fn >>= \case
+      True  -> decodeFileStrict fn
+      False -> return Nothing
+  ) >>= mapM_ put
+
 fallbackHandler :: BrickEvent ResName () -> EventM ResName AppState ()
 fallbackHandler e = gets (^.appMode) >>= \case
   InitMode _ -> zoom (appMode.initState.setPassForm) $
@@ -76,4 +97,10 @@ getKeyDispatcher s = either (error "can't build dispatcher") id $
 keyBindingsFor :: AppState -> [(KEventID, [Binding])]
 keyBindingsFor = const [(QuitKE, [ctrl 'c'])]
 
+mkAppDir :: IO FilePath
+mkAppDir = do
+  path <- getAppUserDataDirectory "passman"
+  createDirectoryIfMissing True path
+  return path
+
 --jl

src/Password/App/Types.hs

@@ -33,6 +33,7 @@ module Password.App.Types (
   -- * Lenses
   -- ** AppState
   randGen,
+  database,
   appMode,
   -- ** AppMode
   initState,
@@ -51,11 +52,16 @@ import Lens.Micro (_1, _2)
 import Lens.Micro.TH (makeLenses)
 import System.Random (StdGen, initStdGen)
 
+import Password
+
 -- | The application state
 data AppState = AppState
   { _randGen :: StdGen
   -- ^ The random number generator
+  , _database :: PWDatabase
+  -- ^ The password database
   , _appMode :: AppMode
+  -- ^ The current operating mode
   }
 
 -- | The applicaiton's mode
@@ -88,6 +94,7 @@ concat <$> mapM makeLenses
 mkInitialState :: MonadIO m => m AppState
 mkInitialState = AppState
   <$> initStdGen
+  <*> return newPWDatabase
   <*> return (InitMode newInitState)
 
 -- | New `InitState` value