Read settings.json and list the directory

-basically chat-gpt bootstrapping this script

backfill_settings.json

@@ -1,4 +1,5 @@
 {
   "postgrest_url": "http://localhost:3000",
-  "jwt": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJyb2xlIjoiY2hhbl9hcmNoaXZlciJ9.rGIKZokTDKTuQLIv8138bUby5PELfDipYYIDpJzH02c"
+  "jwt": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJyb2xlIjoiY2hhbl9hcmNoaXZlciJ9.rGIKZokTDKTuQLIv8138bUby5PELfDipYYIDpJzH02c",
+  "backup_read_root": "/home/phil/linixy/tmp/leftypol_back/lainchan.leftypol.org"
 }

chan-delorean.cabal

@@ -71,7 +71,11 @@ executable chan-delorean
     -- other-extensions:
 
     -- Other library packages from which modules are imported.
-    build-depends:    base ^>=4.16.4.0
+    build-depends:    base ^>=4.16.4.0,
+                      aeson,
+                      bytestring,
+                      cmdargs,
+                      directory
 
     -- Directories containing source files.
     hs-source-dirs:   src

shell.nix

@@ -4,7 +4,7 @@ let
   inherit (nixpkgs) pkgs;
 
   f = { mkDerivation, base, stdenv, cabal-install,
-        aeson, safe-exceptions
+        aeson, safe-exceptions, bytestring, cmdargs
       }:
       mkDerivation {
         pname = "chan-delorean";
@@ -13,7 +13,7 @@ let
         isLibrary = false;
         isExecutable = true;
         executableHaskellDepends = [
-          base safe-exceptions aeson
+          base safe-exceptions aeson bytestring cmdargs
         ];
         testHaskellDepends = [ cabal-install ];
         license = "unknown";

src/Backfill.hs

@@ -1,4 +1,55 @@
+{-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE OverloadedStrings #-}
+
 module Main where
 
+import System.Exit
+import Data.Aeson (FromJSON, decode)
+import qualified Data.ByteString.Lazy as B
+import System.Console.CmdArgs
+import GHC.Generics
+import System.Directory (listDirectory)
+
+data SettingsCLI = SettingsCLI
+  { jsonFile :: FilePath
+  } deriving (Show, Data, Typeable)
+
+data JSONSettings = JSONSettings
+  { postgrest_url :: String
+  , jwt :: String
+  , backup_read_root :: FilePath
+  } deriving (Show, Generic)
+
+instance FromJSON JSONSettings
+
+settingsCLI :: SettingsCLI
+settingsCLI = SettingsCLI
+    { jsonFile = def &= args &= typ "settings-jsonfile-path"
+    } &= summary "Backfill v0.0.1"
+
+
+-- Function to list all files and directories inside the backup_read_root
+listBackupContents :: JSONSettings -> IO ()
+listBackupContents settings =
+   listDirectory (backup_read_root settings) >>= mapM_ print
+
 main :: IO ()
-main = putStrLn "Hello, Haskell!"
+main = do
+    settingsValue <- cmdArgs settingsCLI
+    let filePath = jsonFile settingsValue
+    if null filePath
+    then do
+        putStrLn "Error: No JSON settings file provided."
+        exitFailure
+    else do
+        putStrLn $ "Loading settings from: " ++ filePath
+        content <- B.readFile filePath
+        case decode content :: Maybe JSONSettings of
+            Nothing -> do
+                putStrLn "Error: Invalid JSON format."
+                exitFailure
+            Just settings -> do
+                putStrLn "JSON successfully read!"
+                print settings  -- print the decoded JSON settings
+                listBackupContents settings