refactor(letter): introduce existentially quantified letter class SomeLetter

src/Handler/PrintCenter.hs

@@ -2,7 +2,7 @@
 --
 -- SPDX-License-Identifier: AGPL-3.0-or-later
 
-{-# LANGUAGE TypeApplications, ExistentialQuantification #-}
+{-# LANGUAGE TypeApplications #-}
 {-# OPTIONS_GHC -fno-warn-orphans #-}
 
 module Handler.PrintCenter
@@ -25,7 +25,6 @@ import qualified Database.Esqueleto.Utils as E
 import Database.Esqueleto.Utils.TH
 
 import Utils.Print
-import Utils.Print.Letters (MDLetter)
 
 -- import Data.Aeson (encode)
 import qualified Data.Text as Text
@@ -39,7 +38,6 @@ import Handler.Utils
 single :: (k,a) -> Map k a
 single = uncurry Map.singleton
 
-data SomeLetter = forall l . (MDLetter l) => SomeLetter l -- a record selector would be useless here due to the escaped type variable
 
 data LRQF = LRQF 
     { lrqfLetter  :: Text 
@@ -313,9 +311,7 @@ postPrintSendR = do
 
   ((sendResult, sendWidget), sendEnctype) <- runFormPost $ makeRenewalForm def_lrqf
   let procFormSend lrqf = do
-        ok <- (runDB (lrqf2letter lrqf) >>= \case
-                (entUsr, SomeLetter l) -> printLetter (Just uid) (entUsr, l)
-              ) >>= \case 
+        ok <- (runDB (lrqf2letter lrqf) >>= printLetter (Just uid)) >>= \case
           Left err -> do
             let msg = "PDF printing failed with error: " <> err
             $logErrorS "LPR" msg

src/Utils/Print.hs

@@ -19,6 +19,7 @@ module Utils.Print
   , mkMeta, appMeta, applyMetas              -- multiple values
   -- , MDMail
   -- , MDLetter
+  , SomeLetter(..)
   , LetterRenewQualificationF(..)
   , LetterExpireQualificationF(..)
   -- , LetterCourseCertificate()
@@ -55,6 +56,7 @@ import Jobs.Handler.SendNotification.Utils
 
 import Utils.Print.Instances ()
 import Utils.Print.Letters
+import Utils.Print.SomeLetter
 import Utils.Print.RenewQualification
 import Utils.Print.ExpireQualification
 import Utils.Print.CourseCertificate
@@ -148,7 +150,7 @@ renderLetter rcvrEnt@Entity{entityVal=rcvr} mdl apcIdent = do
   now <- liftIO getCurrentTime  
   formatter@DateTimeFormatter{ format } <- getDateTimeFormatterUser' rcvr
   let lang = selectDeEn $ rcvr & userLanguages   -- select either German or English only, default de; see Utils.Lang
-      kind = getLetterKind $ pure mdl
+      kind = getLetterKind        mdl
       tmpl = getTemplate          mdl
       meta = addApcIdent apcIdent
           <> letterMeta mdl formatter lang rcvrEnt
@@ -170,7 +172,7 @@ renderLetters rcvrEnt@Entity{entityVal=rcvr} mdls apcIdent
       now <- liftIO getCurrentTime  
       formatter@DateTimeFormatter{ format } <- getDateTimeFormatterUser' rcvr
       let lang = selectDeEn $ rcvr & userLanguages   -- select either German or English only, default de; see Utils.Lang      
-          kind = getLetterKind $ pure l
+          kind = getLetterKind l
           
           templateCombine _   err@Left{}  = pure err
           templateCombine mdl (Right doc1) =
@@ -286,7 +288,7 @@ sendEmailOrLetter recipient letter = do
                 $logWarnS "LETTER" $ "PDF printing to send letter with lpr returned ExitSuccess and the following message: " <> msg
                 return True
       Right pdf -> do -- send email
-        let pdfPass = case encrypPDFfor (pure letter) of 
+        let pdfPass = case encryptPDFfor letter of 
               NoPassword          -> Nothing
               PasswordSupervisor  -> rcvrUsr   ^. _userPinPassword
               PasswordUnderling   -> underling ^. _userPinPassword

src/Utils/Print/CourseCertificate.hs

@@ -36,7 +36,7 @@ data LetterCourseCertificate = LetterCourseCertificate
 
 
 instance MDLetter LetterCourseCertificate where  
-  encrypPDFfor      _ = NoPassword
+  encryptPDFfor     _ = NoPassword
   getLetterKind     _ = Plain
   getLetterEnvelope _ = 'c'
   getTemplate LetterCourseCertificate{ccCourseContent = Just ccc} =

src/Utils/Print/ExpireQualification.hs

@@ -48,7 +48,7 @@ instance MDMail LetterExpireQualificationF where
     in $(ihamletFile "templates/mail/qualificationExpired.hamlet")
 
 instance MDLetter LetterExpireQualificationF where  
-  encrypPDFfor      _ = NoPassword
+  encryptPDFfor     _ = NoPassword
   getLetterKind     _ = Din5008
   getLetterEnvelope _ = 'e'
   getTemplate       _ = decodeUtf8 $(Data.FileEmbed.embedFile "templates/letter/fraport_f_expiry.md")

src/Utils/Print/Letters.hs

@@ -225,15 +225,15 @@ class MDLetter l where
   -- NOTE: METAs "date", "rcvr-name", "address" are set automatically by renderLetter for each receiver
   getPJId           :: l -> PrintJobIdentification
   getLetterEnvelope :: l -> Char
-  getLetterKind     :: Proxy l -> LetterKind
+  getLetterKind     :: l -> LetterKind
   getTemplate       :: l -> Text
-  encrypPDFfor      :: Proxy l -> EncryptPDFfor
+  encryptPDFfor     :: l -> EncryptPDFfor
 
 letterApcIdent :: (MDLetter l, MonadHandler m) => l -> CryptoUUIDUser -> UTCTime -> m Text
 letterApcIdent l uuid now = do
   -- now  <- liftIO getCurrentTime
   tnow <- formatTime' "%y%m%d-%H" now
-  return $ mkApcIdent uuid (getLetterEnvelope l) (getLetterKind $ pure l) tnow (pjiApcAcknowledge $ getPJId l)
+  return $ mkApcIdent uuid (getLetterEnvelope l) (getLetterKind l) tnow (pjiApcAcknowledge $ getPJId l)
 
 letterFileName :: (MDLetter l) => l -> FilePath
 letterFileName = Text.unpack . (<> ".pdf") . text2asciiAlphaNum . pjiFileName . getPJId

src/Utils/Print/RenewQualification.hs

@@ -53,7 +53,7 @@ instance MDMail LetterRenewQualificationF where
     in $(ihamletFile "templates/mail/body/qualificationRenewal.hamlet")
 
 instance MDLetter LetterRenewQualificationF where  
-  encrypPDFfor      _ = PasswordUnderling
+  encryptPDFfor      _ = PasswordUnderling
   getLetterKind     _ = PinLetter
   getLetterEnvelope _ = 'f' -- maybe 'q' (Char.toLower . fst) $ Text.uncons (qualShort l)
   getTemplate       _ = decodeUtf8 $(Data.FileEmbed.embedFile "templates/letter/fraport_renewal.md")

src/Utils/Print/SomeLetter.hs

@@ -0,0 +1,23 @@
+-- SPDX-FileCopyrightText: 2023 Steffen Jost <s.jost@fraport.de>
+--
+-- SPDX-License-Identifier: AGPL-3.0-or-later
+
+{-# LANGUAGE ExistentialQuantification #-}
+
+module Utils.Print.SomeLetter where 
+
+import Utils.Print.Letters
+
+data SomeLetter = forall l . (MDLetter l, MDMail l) => SomeLetter l -- a record selector would be useless here due to the escaped type variable
+
+instance MDMail SomeLetter where 
+  getMailSubject    (SomeLetter l)  = getMailSubject l
+  getMailBody       (SomeLetter l)  = getMailBody l
+
+instance MDLetter SomeLetter where
+  letterMeta        (SomeLetter l)  = letterMeta l
+  getPJId           (SomeLetter l)  = getPJId l
+  getLetterEnvelope (SomeLetter l)  = getLetterEnvelope l
+  getLetterKind     (SomeLetter l)  = getLetterKind l
+  getTemplate       (SomeLetter l)  = getTemplate l
+  encryptPDFfor     (SomeLetter l)  = encryptPDFfor l

templates/letter/fraport_f_expiry.md

@@ -50,7 +50,7 @@ $if(is-de)$
 
 <!-- deutsche Version des Briefes  -->
 $if(supervisor)$
-  leider hat $licenceholder$
+  leider hat **$licenceholder$**
 $else$
   leider haben Sie
 $endif$
@@ -62,7 +62,7 @@ Die Qualifikation „Vorfeldführerschein“ ist somit nicht mehr gültig.
 
 
 $if(supervisor)$
-**$licenceholder$** darf 
+$licenceholder$ darf 
 $else$
   Sie dürfen
 $endif$
@@ -94,7 +94,7 @@ $if(supervisor)$
 $else$
   you
 $endif$
-did not pass the required knowledge test within the alotted time
+did not pass the required knowledge test within the allotted time
 for the renewal of the apron driving licence.
 
 
@@ -124,7 +124,7 @@ Email
   : $email$
 
 $else$
-Please contact you employer to book a course for you.
+Please contact your employer to book a course for you.
 $endif$
 
 $endif$