1 files changed, 61 insertions, 0 deletions
diff --git a/app/SlackBuilder/Updater.hs b/app/SlackBuilder/Updater.hs
new file mode 100644
index 0000000..5373f7e
--- /dev/null
+++ b/app/SlackBuilder/Updater.hs
@@ -0,0 +1,61 @@
+module SlackBuilder.Updater
+    ( latestPackagist
+    , latestText
+    ) where
+
+import Data.Aeson.TH (defaultOptions, deriveJSON)
+import Data.HashMap.Strict (HashMap)
+import qualified Data.HashMap.Strict as HashMap
+import Data.Text (Text)
+import qualified Data.Text as Text
+import qualified Data.Text.Encoding as Text.Encoding
+import Data.Vector (Vector)
+import qualified Data.Vector as Vector
+import Network.HTTP.Req
+    ( runReq
+    , defaultHttpConfig
+    , req
+    , GET(..)
+    , https
+    , jsonResponse
+    , NoReqBody(..)
+    , (/:)
+    , responseBody, useHttpsURI, bsResponse
+    )
+import Text.URI (mkURI)
+import SlackBuilder.CommandLine
+
+newtype PackagistPackage = PackagistPackage
+    { version :: Text
+    } deriving (Eq, Show)
+
+$(deriveJSON defaultOptions ''PackagistPackage)
+
+newtype PackagistResponse = PackagistResponse
+    { packages :: HashMap Text (Vector PackagistPackage)
+    } deriving (Eq, Show)
+
+$(deriveJSON defaultOptions ''PackagistResponse)
+
+latestPackagist :: PackagistArguments -> IO (Maybe Text)
+latestPackagist PackagistArguments{..} = do
+    packagistResponse <- runReq defaultHttpConfig $
+        let uri = https "repo.packagist.org" /: "p2"
+                /: vendor
+                /: name <> ".json"
+         in req GET uri NoReqBody jsonResponse mempty
+    let packagistPackages = packages $ responseBody packagistResponse
+        fullName = Text.intercalate "/" [vendor, name]
+
+    pure $ HashMap.lookup fullName packagistPackages
+        >>= fmap (version . fst) . Vector.uncons
+
+latestText :: TextArguments -> IO (Maybe Text)
+latestText (TextArguments textArguments) = do
+    uri <- useHttpsURI <$> mkURI textArguments
+    packagistResponse <- traverse (runReq defaultHttpConfig) $ go . fst <$> uri
+
+    pure $ Text.strip . Text.Encoding.decodeASCII . responseBody
+        <$> packagistResponse
+  where
+    go uri = req GET uri NoReqBody bsResponse mempty