Preserve list position while navigating through directories

1 files changed, 85 insertions, 0 deletions

diff --git a/lib/Daffm/State.hs b/lib/Daffm/State.hs
new file mode 100644
index 0000000..cfa9aeb
--- /dev/null
+++ b/lib/Daffm/State.hs
@@ -0,0 +1,85 @@
+module Daffm.State where
+
+import qualified Brick.Widgets.Edit as Editor
+import qualified Brick.Widgets.List as L
+import Control.Applicative ((<|>))
+import Control.Monad (forM)
+import Daffm.Types (AppState (..), FileInfo (..), FileType (..), FocusTarget (..))
+import Data.Char (toLower)
+import Data.List (findIndex, sortBy)
+import qualified Data.Map.Strict as Map
+import Data.Maybe (fromMaybe)
+import qualified Data.Vector as Vec
+import System.Directory (listDirectory, makeAbsolute, setCurrentDirectory)
+import qualified System.PosixCompat as Posix
+
+mkEmptyAppState :: AppState
+mkEmptyAppState =
+  AppState
+    { stateFiles = L.list FocusMain (Vec.fromList []) 1,
+      stateCmdlineEditor = Editor.editor FocusCmdline Nothing "",
+      stateFocusTarget = FocusMain,
+      stateListPositionCache = Map.empty,
+      stateCwd = "",
+      stateParentDir = ""
+    }
+
+loadDirInAppState :: FilePath -> FilePath -> AppState -> IO AppState
+loadDirInAppState dir parentDir appState@(AppState {stateCwd, stateListPositionCache}) = do
+  setCurrentDirectory dir
+  files <- listFilesInDir dir
+  let prevDirPosM = findIndex ((== stateCwd) . filePath) files
+  let cachedPosM = Map.lookup dir stateListPositionCache
+  let pos = fromMaybe 0 (cachedPosM <|> prevDirPosM)
+  let list = L.listMoveTo pos $ L.list FocusMain (Vec.fromList files) 1
+  pure $
+    appState
+      { stateFiles = list,
+        stateCwd = dir,
+        stateParentDir = parentDir
+      }
+
+fileTypeFromStatus :: Posix.FileStatus -> FileType
+fileTypeFromStatus s =
+  if
+    | Posix.isBlockDevice s -> BlockDevice
+    | Posix.isCharacterDevice s -> CharacterDevice
+    | Posix.isNamedPipe s -> NamedPipe
+    | Posix.isRegularFile s -> RegularFile
+    | Posix.isDirectory s -> Directory
+    | Posix.isSocket s -> UnixSocket
+    | Posix.isSymbolicLink s -> SymbolicLink
+    | otherwise -> UnknownFileType
+
+getFileInfo :: FilePath -> IO FileInfo
+getFileInfo name = do
+  path <- makeAbsolute name
+  stat <- Posix.getSymbolicLinkStatus path
+  pure $
+    FileInfo
+      { filePath = path,
+        fileName = name,
+        fileSize = Posix.fileSize stat,
+        fileType = fileTypeFromStatus stat
+      }
+
+fileSorter :: FileInfo -> FileInfo -> Ordering
+fileSorter (FileInfo {fileType = Directory, fileName = fa}) (FileInfo {fileType = Directory, fileName = fb}) =
+  compare (toLower <$> fa) (toLower <$> fb)
+fileSorter (FileInfo {fileType = Directory}) _ = LT
+fileSorter _ (FileInfo {fileType = Directory}) = GT
+fileSorter (FileInfo {fileName = fa}) (FileInfo {fileName = fb}) =
+  compare (toLower <$> fa) (toLower <$> fb)
+
+listFilesInDir :: FilePath -> IO [FileInfo]
+listFilesInDir dir = do
+  files <- listDirectory dir
+  sortBy fileSorter <$> forM files getFileInfo
+
+cacheDirPosition :: AppState -> AppState
+cacheDirPosition appState@(AppState {stateListPositionCache, stateCwd, stateFiles}) =
+  appState
+    { stateListPositionCache = Map.insert stateCwd pos stateListPositionCache
+    }
+  where
+    pos = fromMaybe 0 $ L.listSelected stateFiles