From c1ff403387064ff0027b9e762cc6f6a8fa20c8d9 Mon Sep 17 00:00:00 2001
From: Alexander Foremny <aforemny@posteo.de>
Date: Thu, 7 Dec 2023 03:58:21 +0100
Subject: chore: move remaining `History.*` modules outside of `History`

---
 app/Cache.hs | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100644 app/Cache.hs

(limited to 'app/Cache.hs')

diff --git a/app/Cache.hs b/app/Cache.hs
new file mode 100644
index 0000000..52d18ca
--- /dev/null
+++ b/app/Cache.hs
@@ -0,0 +1,33 @@
+module Cache
+  ( cached,
+    cachedMaybe,
+  )
+where
+
+import Data.Binary (Binary, decodeFileOrFail, encodeFile)
+import Data.Text qualified as T
+import Debug
+import Git qualified
+import System.Directory (createDirectoryIfMissing, doesFileExist)
+import System.FilePath ((</>))
+
+cached :: Binary a => T.Text -> IO a -> IO a
+cached key func = do
+  root <- Git.getRootDir
+  createDirectoryIfMissing True (root </> ".anissue")
+  let file = (root </> ".anissue" </> T.unpack key)
+  doesFileExist file >>= \case
+    True ->
+      decodeFileOrFail file >>= \case
+        Left e -> debug "e" e `seq` generate file
+        Right blob -> pure blob
+    False -> generate file
+  where
+    generate file = do
+      blob <- func
+      encodeFile (debug "cache miss" file) blob
+      pure blob
+
+cachedMaybe :: Binary a => Maybe T.Text -> IO a -> IO a
+cachedMaybe Nothing func = func
+cachedMaybe (Just key) func = cached key func
-- 
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