1 files changed, 34 insertions, 9 deletions
diff --git a/app/IssueEvent.hs b/app/IssueEvent.hs
index a7a190a..c82dba5 100644
--- a/app/IssueEvent.hs
+++ b/app/IssueEvent.hs
@@ -1,33 +1,58 @@
-module IssueEvent (IssueEvent (..)) where
+{-# OPTIONS_GHC -fno-warn-orphans #-}
 
-import Data.Binary (Binary)
+module IssueEvent
+  ( IssueEvent (..),
+  )
+where
+
+import Data.Binary (Binary (..))
+import Data.Function ((&))
+import Data.Text qualified as T
+import Data.Text.IO qualified as T
+import Data.Text.Lazy qualified as LT
+import Data.Text.Lazy.Encoding qualified as LT
 import GHC.Generics (Generic)
+import GHC.Records (HasField (..))
 import Git.CommitHash (CommitHash)
-import Issue (Issue)
+import Issue (Issue (..))
 import Issue.Render qualified as I
 import Patch (Patch)
+import Patch qualified as A
+import Process (sh)
 import Render ((<<<))
 import Render qualified as P
+import System.FilePath ((</>))
+import System.IO.Temp (withSystemTempDirectory)
+import System.Process.Typed (setWorkingDir)
 
 data IssueEvent
   = IssueCreated
       { hash :: CommitHash,
-        issue :: Issue,
-        patch :: Patch
+        issue :: Issue
       }
   | IssueChanged
       { hash :: CommitHash,
         oldIssue :: Issue,
-        issue :: Issue,
-        patch :: Patch
+        issue :: Issue
       }
   | IssueDeleted
       { hash :: CommitHash,
-        issue :: Issue,
-        patch :: Patch
+        issue :: Issue
       }
   deriving (Show, Generic, Binary)
 
+instance HasField "patch" IssueEvent (IO Patch) where
+  getField (IssueCreated {..}) = diff "" issue.rawText
+  getField (IssueChanged {..}) = diff oldIssue.rawText issue.rawText
+  getField (IssueDeleted {..}) = diff issue.rawText ""
+
+diff :: T.Text -> T.Text -> IO A.Patch
+diff old new = withSystemTempDirectory "diff" $ \tmp -> do
+  let cwd = tmp
+  T.writeFile (tmp </> "old") old
+  T.writeFile (tmp </> "new") new
+  A.parse . LT.toStrict . LT.decodeUtf8 <$> sh ("git diff --no-index -- old new || :" & setWorkingDir cwd)
+
 instance P.Render IssueEvent where
   render = P.render . P.Detailed