List installed packages from a repository

lib/SlackBuilder/Info.hs

@@ -7,6 +7,7 @@ module SlackBuilder.Info
     ( PackageInfo(..)
     , generate
     , parseInfoFile
+    , readInfoFile
     ) where
 
 import Control.Applicative (Alternative(..))
@@ -26,7 +27,7 @@ import Crypto.Hash (Digest, MD5, digestFromByteString)
 import Data.Void (Void)
 import Data.Word (Word8)
 import Numeric (readHex, showHex)
-import Text.Megaparsec (Parsec, count, eof, takeWhile1P)
+import Text.Megaparsec (Parsec, count, eof, parse, takeWhile1P)
 import Text.Megaparsec.Byte (space, string, hexDigitChar)
 import Text.URI
     ( URI(..)
@@ -34,6 +35,14 @@ import Text.URI
     , render
     )
 import qualified Data.Word8 as Word8
+import SlackBuilder.Trans
+    ( SlackBuilderT(..)
+    , SlackBuilderException(..)
+    , relativeToRepository
+    )
+import System.FilePath ((</>), (<.>))
+import Control.Monad.IO.Class (MonadIO(..))
+import Conduit (MonadThrow(throwM))
 
 type GenParser = Parsec Void ByteString
 
@@ -110,6 +119,17 @@ parseInfoFile = PackageInfo . Char8.unpack
         *> packageName
         <* "\"\n"
 
+readInfoFile :: Text -> Text -> SlackBuilderT PackageInfo
+readInfoFile category packageName' = do
+    let packageName'' = Text.unpack packageName'
+
+    infoPath <- relativeToRepository
+        $ Text.unpack category </> packageName'' </> packageName'' <.> "info"
+    infoContents <- liftIO $ ByteString.readFile infoPath
+
+    either (throwM . MalformedInfoFile) pure
+        $ parse parseInfoFile infoPath infoContents
+
 generate :: PackageInfo -> Text
 generate pkg = Lazy.Text.toStrict $ Text.Builder.toLazyText builder
   where