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--
-- | Generate C methods that process NASA Core Flight System messages dealing
-- with the structs defined in a header file.
--
-- This module makes use of "Language.Trans.CStructs2MsgHandlers", which does
-- most of the work.
module Command.CStructs2MsgHandlers
    ( cstructs2MsgHandlers
    , ErrorCode
    )
  where

-- External imports: auxiliary
import Data.String.Extra as S ( safeReadFile )

-- Internal imports: auxiliary
import Command.Result ( Result (..) )
import Data.Location  ( Location (..) )

-- Internal imports: C parsing and AST
import qualified Language.C.AbsC as C ( TranslationUnit )
import qualified Language.C.ParC as C ( myLexer, pTranslationUnit )

-- Internal imports: transformation of C structs to handling methods.
import qualified Language.Trans.CStructs2MsgHandlers as T ( cstructs2MsgHandlers )

-- | Print message handlers that copy data and make it available to Copilot.
cstructs2MsgHandlers :: FilePath -- ^ Path to a readable, valid C header file
                                 -- containing struct definitions.
                     -> IO (Result ErrorCode)
cstructs2MsgHandlers :: String -> IO (Result ErrorCode)
cstructs2MsgHandlers String
fp = do
    Either String TranslationUnit
result <- String -> IO (Either String TranslationUnit)
parseCFile String
fp

    case TranslationUnit -> Either String String
T.cstructs2MsgHandlers (TranslationUnit -> Either String String)
-> Either String TranslationUnit -> Either String String
forall (m :: * -> *) a b. Monad m => (a -> m b) -> m a -> m b
=<< Either String TranslationUnit
result of
      Right String
content -> String -> IO ()
putStrLn String
content IO () -> IO (Result ErrorCode) -> IO (Result ErrorCode)
forall a b. IO a -> IO b -> IO b
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> Result ErrorCode -> IO (Result ErrorCode)
forall a. a -> IO a
forall (m :: * -> *) a. Monad m => a -> m a
return Result ErrorCode
forall a. Result a
Success

      Left String
msg -> Result ErrorCode -> IO (Result ErrorCode)
forall a. a -> IO a
forall (m :: * -> *) a. Monad m => a -> m a
return (Result ErrorCode -> IO (Result ErrorCode))
-> Result ErrorCode -> IO (Result ErrorCode)
forall a b. (a -> b) -> a -> b
$ ErrorCode -> String -> Location -> Result ErrorCode
forall a. a -> String -> Location -> Result a
Error ErrorCode
ecCStructError String
msg (String -> Location
LocationFile String
fp)

  where

    -- Parse a C file, returning 'Left' with some message when there is a parse
    -- error.
    --
    parseCFile :: FilePath -> IO (Either String C.TranslationUnit)
    parseCFile :: String -> IO (Either String TranslationUnit)
parseCFile String
fp' = do
      Either String String
content <- String -> IO (Either String String)
S.safeReadFile String
fp'
      Either String TranslationUnit -> IO (Either String TranslationUnit)
forall a. a -> IO a
forall (m :: * -> *) a. Monad m => a -> m a
return (Either String TranslationUnit
 -> IO (Either String TranslationUnit))
-> Either String TranslationUnit
-> IO (Either String TranslationUnit)
forall a b. (a -> b) -> a -> b
$ [Token] -> Either String TranslationUnit
C.pTranslationUnit ([Token] -> Either String TranslationUnit)
-> (String -> [Token]) -> String -> Either String TranslationUnit
forall b c a. (b -> c) -> (a -> b) -> a -> c
. String -> [Token]
C.myLexer (String -> Either String TranslationUnit)
-> Either String String -> Either String TranslationUnit
forall (m :: * -> *) a b. Monad m => (a -> m b) -> m a -> m b
=<< Either String String
content

-- * Error codes

-- | Encoding of reasons why the command can fail.
--
-- The error code used is 1 for user error.
type ErrorCode = Int

-- | Error: the C header file cannot be read due to the file being unreadable
-- or the format being incorrect.
ecCStructError :: ErrorCode
ecCStructError :: ErrorCode
ecCStructError = ErrorCode
1