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

lib/SlackBuilder/Package.hs

@@ -5,7 +5,8 @@
 -- | Contains data describing packages, methods to update them and to request
 -- information about them.
 module SlackBuilder.Package
-    ( Download(..)
+    ( DataBaseEntry(..)
+    , Download(..)
     , DownloadTemplate(..)
     , PackageDescription(..)
     , PackageUpdateData(..)
@@ -66,3 +67,15 @@ data Updater = Updater
     , is64 :: Bool
     , getVersion :: Text -> Text -> SlackBuilderT Download
     }
+
+data DataBaseEntry = DataBaseEntry
+    { name :: Text
+    , version :: Text
+    , arch :: Text
+    , build :: Text
+    } deriving Eq
+
+instance Show DataBaseEntry
+  where
+    show DataBaseEntry{..} = Text.unpack
+        $ Text.intercalate "-" [name, version, arch, build]

lib/SlackBuilder/Trans.hs

@@ -10,6 +10,7 @@ module SlackBuilder.Trans
     ) where
 
 import Control.Monad.Trans.Reader (ReaderT(..), asks)
+import Data.ByteString (ByteString)
 import Data.Text (Text)
 import qualified Data.Text as Text
 import SlackBuilder.Config
@@ -20,11 +21,14 @@ import System.FilePath ((</>))
 import Text.URI (URI)
 import qualified Text.URI as URI
 import qualified Codec.Compression.Lzma as Lzma
+import Text.Megaparsec (ParseErrorBundle(..), errorBundlePretty)
+import Conduit (Void)
 
 data SlackBuilderException
     = UpdaterNotFound Text
     | UnsupportedUrlType URI
     | LzmaDecompressionFailed Lzma.LzmaRet
+    | MalformedInfoFile (ParseErrorBundle ByteString Void)
     deriving Show
 
 instance Exception SlackBuilderException
@@ -55,6 +59,8 @@ instance Exception SlackBuilderException
         "No progress is possible"
     displayException (LzmaDecompressionFailed Lzma.LzmaRetProgError) =
         "Programming error"
+    displayException (MalformedInfoFile errorBundle) =
+        errorBundlePretty errorBundle
  
 newtype SlackBuilderT a = SlackBuilderT
     { runSlackBuilderT :: ReaderT Settings IO a