-- | Cabal utilities for XDR processing.
module Network.ONCRPC.XDR.Cabal
  ( ppRPCGenSuffixHandler
  ) where

import           Data.Char (toLower)
import           Data.Coerce
import           Data.List (intercalate, isPrefixOf)
import           Data.Maybe (fromMaybe, mapMaybe)
import           Distribution.PackageDescription (BuildInfo(customFieldsBI))
import           Distribution.Verbosity (Verbosity)
import           Distribution.Simple.LocalBuildInfo (LocalBuildInfo, ComponentLocalBuildInfo)
import           Distribution.Simple.PreProcess (PreProcessor(..), PPSuffixHandler, Suffix(..))
import           Distribution.Simple.Utils (info)
import           System.FilePath ((</>), dropExtension, splitDirectories)

import           Network.ONCRPC.XDR.Generate

runRPCGen :: [(String, String)] -> (FilePath, FilePath) -> (FilePath, FilePath) -> Verbosity -> IO ()
runRPCGen custom (indir, infile) (outdir, outfile) verb = do
  info verb $ "hdrpcgen " ++ inpath ++ " with " ++ show opts
  writeFile outpath
    =<< generateFromFile opts inpath
  where
  opts = GenerateOptions
    { generateModuleName = modname
    , generateReidentOptions = ReidentOptions
      { reidentUpperPrefix = fromMaybe "" $ opt "upper-prefix"
      , reidentLowerPrefix = fromMaybe "" $ opt "lower-prefix"
      , reidentJoinField = joinopt "field"
      , reidentJoinProcedure = joinopt "procedure"
      }
    }
  joinopt t = case (maybe False boolish $ opt $ t ++ "s-unique", opt $ "join-" ++ t) of
    (False, j) -> Just $ fromMaybe "'" j
    (True, Nothing) -> Nothing
    (True, Just _) ->
      error "x-rpcgen join and unique options are mutually exclusive"
  boolish s = map toLower s `isPrefixOf` "true"
  opt f = lookup f custom
  inpath = indir </> infile
  outpath = outdir </> outfile
  modname = intercalate "." $ splitDirectories $ dropExtension infile

ppRPCGenCustomField :: (String, String) -> Maybe (String, String)
ppRPCGenCustomField ('x':'-':'r':'p':'c':'g':'e':'n':'-':f,v) = Just (f,v)
ppRPCGenCustomField _ = Nothing

ppRPCGen :: BuildInfo -> LocalBuildInfo -> ComponentLocalBuildInfo -> PreProcessor
ppRPCGen bi _ _ = PreProcessor
  { platformIndependent = True
  , runPreProcessor = runRPCGen $ mapMaybe ppRPCGenCustomField $ customFieldsBI bi
  , ppOrdering = undefined
  }

-- |Pre-processor for hsrpcgen.
-- You can use it by setting @'Distribution.Simple.UserHooks' { 'Distribution.Simple.hookedPrepProcessors' = ['ppRPCGenSuffixHandler'] }@.
-- Note that this will override the default alex @.x@ file handler.
-- You can also specify custom cabal fields corresponding to 'ReidentOptions' and command-line flags prefixed with @x-rpcgen-@: @{upper,lower}-prefix@, @join-{field,procedure}@, and @{field,procedure}s-unique}@.
ppRPCGenSuffixHandler :: PPSuffixHandler
ppRPCGenSuffixHandler = (coerce "x", ppRPCGen)