From 4923efefb912e019feffe1ab0866c3d50cf7b093 Mon Sep 17 00:00:00 2001
From: Simon Michael <simon@joyful.com>
Date: Sun, 19 Jun 2016 09:00:04 -0700
Subject: [PATCH] ui: basic editor integration

The E key (on all screens) edits the main journal file using
$HLEDGER_UI_EDITOR or $EDITOR or "emacs -nw",
jumping to the end if it's Emacs.
---
 hledger-ui/Hledger/UI/AccountsScreen.hs    |  3 +
 hledger-ui/Hledger/UI/Editor.hs            | 75 ++++++++++++++++++++++
 hledger-ui/Hledger/UI/ErrorScreen.hs       | 15 +++--
 hledger-ui/Hledger/UI/RegisterScreen.hs    |  3 +
 hledger-ui/Hledger/UI/TransactionScreen.hs |  3 +
 hledger-ui/Hledger/UI/UIUtils.hs           |  3 +
 hledger-ui/hledger-ui.cabal                |  2 +
 hledger-ui/package.yaml                    |  1 +
 8 files changed, 99 insertions(+), 6 deletions(-)
 create mode 100644 hledger-ui/Hledger/UI/Editor.hs

diff --git a/hledger-ui/Hledger/UI/AccountsScreen.hs b/hledger-ui/Hledger/UI/AccountsScreen.hs
index 8550ded25..1cfe009eb 100644
--- a/hledger-ui/Hledger/UI/AccountsScreen.hs
+++ b/hledger-ui/Hledger/UI/AccountsScreen.hs
@@ -14,6 +14,7 @@ import Brick
 import Brick.Widgets.List
 import Brick.Widgets.Edit
 import Brick.Widgets.Border (borderAttr)
+import Control.Monad
 import Control.Monad.IO.Class (liftIO)
 import Data.List
 import Data.Maybe
@@ -32,6 +33,7 @@ import Hledger.UI.UIOptions
 import Hledger.UI.UITypes
 import Hledger.UI.UIState
 import Hledger.UI.UIUtils
+import Hledger.UI.Editor
 import Hledger.UI.RegisterScreen
 import Hledger.UI.ErrorScreen
 
@@ -266,6 +268,7 @@ asHandle ui0@UIState{
         EvKey (KChar c)   [] | c `elem` ['h','?'] -> continue $ setMode Help ui
         EvKey (KChar 'g') [] -> liftIO (uiReloadJournalIfChanged copts d j ui) >>= continue
         EvKey (KChar 'a') [] -> suspendAndResume $ clearScreen >> setCursorPosition 0 0 >> add copts j >> uiReloadJournalIfChanged copts d j ui
+        EvKey (KChar 'E') [] -> suspendAndResume $ void (runEditor endPos j) >> uiReloadJournalIfChanged copts d j ui
         EvKey (KChar '0') [] -> continue $ regenerateScreens j d $ setDepth (Just 0) ui
         EvKey (KChar '1') [] -> continue $ regenerateScreens j d $ setDepth (Just 1) ui
         EvKey (KChar '2') [] -> continue $ regenerateScreens j d $ setDepth (Just 2) ui
diff --git a/hledger-ui/Hledger/UI/Editor.hs b/hledger-ui/Hledger/UI/Editor.hs
new file mode 100644
index 000000000..579312b9f
--- /dev/null
+++ b/hledger-ui/Hledger/UI/Editor.hs
@@ -0,0 +1,75 @@
+{- | Editor integration. -}
+
+-- {-# LANGUAGE OverloadedStrings #-}
+
+module Hledger.UI.Editor
+where
+
+import Control.Applicative ((<|>))
+import Data.List
+import Safe
+import System.Environment
+import System.Exit
+import System.FilePath
+import System.Process
+
+import Hledger
+
+-- | A shell command line for invoking an editor, containing one placeholder ("FILE")
+-- which will be replaced with a quoted file path. This exists because some desirable
+-- editor commands do not fit the simple "$EDITOR FILE" pattern.
+type EditorCommandTemplate = String
+
+-- | Editors we know how to create more specific command lines for.
+data EditorType = Emacs | Other
+
+-- | A position we can move to in a text editor: a line number
+-- and optionally character number. 1 (or 0) means the first; a negative number
+-- counts back from the end (so -1 means the last line, -2 the second last etc.)
+type TextPosition = (Int, Maybe Int)
+
+endPos :: Maybe TextPosition
+endPos = Just (1,Nothing)
+
+-- | Construct a shell command template for starting the user's preferred text editor,
+-- optionally at a given position.
+-- XXX The position parameter is currently ignored and assumed to be end-of-file.
+--
+-- The basic editor command will be the value of environment variable $HLEDGER_UI_EDITOR,
+-- or $EDITOR, or "emacs -nw". If a position is specified, and the command looks like one of
+-- the editors we know (currently only emacs and emacsclient), it is modified so as to jump
+-- to that position.
+--
+-- Some examples:
+-- $EDITOR=vi            -> "vi FILE"
+-- $EDITOR=emacs         -> "emacs FILE -f end-of-buffer"
+-- $EDITOR not set       -> "emacs -nw FILE -f end-of-buffer"
+--
+editorCommandTemplate :: Maybe TextPosition -> IO EditorCommandTemplate
+editorCommandTemplate mpos = do
+  hledger_ui_editor_env <- lookupEnv "HLEDGER_UI_EDITOR"
+  editor_env            <- lookupEnv "EDITOR"
+  let Just exe = hledger_ui_editor_env <|> editor_env <|> Just "emacs -nw"
+  return $
+   case (identifyEditor exe, mpos) of
+    (Emacs,_) -> exe ++ " FILE -f end-of-buffer"
+    _         -> exe ++ " FILE"
+
+-- Identify the editor type, if we know it, from the value of $HLEDGER_EDITOR_UI or $EDITOR.
+identifyEditor :: String -> EditorType
+identifyEditor cmd
+  | "emacs" `isPrefixOf` exe = Emacs
+  | otherwise = Other
+  where
+    exe = lowercase $ takeFileName $ headDef "" $ words' cmd
+
+fillEditorCommandTemplate :: FilePath -> EditorCommandTemplate -> String
+fillEditorCommandTemplate f t = regexReplace "FILE" (singleQuoteIfNeeded f) t
+
+-- | Try running $EDITOR, or a default edit command, on the main journal file,
+-- blocking until it exits, and returning the exit code; or raise an error.
+runEditor :: Maybe TextPosition -> Journal -> IO ExitCode
+runEditor mpos j = do
+  fillEditorCommandTemplate (journalFilePath j) <$> editorCommandTemplate mpos
+  >>= runCommand
+  >>= waitForProcess
diff --git a/hledger-ui/Hledger/UI/ErrorScreen.hs b/hledger-ui/Hledger/UI/ErrorScreen.hs
index 88686f544..df6dd1db9 100644
--- a/hledger-ui/Hledger/UI/ErrorScreen.hs
+++ b/hledger-ui/Hledger/UI/ErrorScreen.hs
@@ -8,6 +8,7 @@ module Hledger.UI.ErrorScreen
  )
 where
 
+import Control.Monad
 import Control.Monad.IO.Class (liftIO)
 import Data.Monoid
 import Data.Time.Calendar (Day)
@@ -19,6 +20,7 @@ import Hledger.UI.UIOptions
 import Hledger.UI.UITypes
 import Hledger.UI.UIState
 import Hledger.UI.UIUtils
+import Hledger.UI.Editor
 
 errorScreen :: Screen
 errorScreen = ErrorScreen{
@@ -59,7 +61,7 @@ esDraw _ = error "draw function called with wrong screen type, should not happen
 
 esHandle :: UIState -> Event -> EventM (Next UIState)
 esHandle ui@UIState{
-   aScreen=s@ErrorScreen{}
+   aScreen=ErrorScreen{}
   ,aopts=UIOpts{cliopts_=copts}
   ,ajournal=j
   ,aMode=mode
@@ -76,11 +78,12 @@ esHandle ui@UIState{
         EvKey (KChar 'q') [] -> halt ui
         EvKey KEsc        [] -> continue $ resetScreens d ui
         EvKey (KChar c)   [] | c `elem` ['h','?'] -> continue $ setMode Help ui
-        EvKey (KChar 'g') [] -> do
-          (ej, _) <- liftIO $ journalReloadIfChanged copts d j
-          case ej of
-            Left err -> continue ui{aScreen=s{esError=err}} -- show latest parse error
-            Right j' -> continue $ regenerateScreens j' d $ popScreen ui  -- return to previous screen, and reload it
+        EvKey (KChar 'E') [] -> suspendAndResume $ void (runEditor endPos j) >> uiReloadJournalIfChanged copts d j (popScreen ui)
+        EvKey (KChar 'g') [] -> liftIO (uiReloadJournalIfChanged copts d j (popScreen ui)) >>= continue
+--           (ej, _) <- liftIO $ journalReloadIfChanged copts d j
+--           case ej of
+--             Left err -> continue ui{aScreen=s{esError=err}} -- show latest parse error
+--             Right j' -> continue $ regenerateScreens j' d $ popScreen ui  -- return to previous screen, and reload it
         _ -> continue ui
 
 esHandle _ _ = error "event handler called with wrong screen type, should not happen"
diff --git a/hledger-ui/Hledger/UI/RegisterScreen.hs b/hledger-ui/Hledger/UI/RegisterScreen.hs
index b8cae0951..fcafb68d8 100644
--- a/hledger-ui/Hledger/UI/RegisterScreen.hs
+++ b/hledger-ui/Hledger/UI/RegisterScreen.hs
@@ -9,6 +9,7 @@ module Hledger.UI.RegisterScreen
 where
 
 import Lens.Micro.Platform ((^.))
+import Control.Monad
 import Control.Monad.IO.Class (liftIO)
 import Data.List
 import Data.List.Split (splitOn)
@@ -32,6 +33,7 @@ import Hledger.UI.UIOptions
 import Hledger.UI.UITypes
 import Hledger.UI.UIState
 import Hledger.UI.UIUtils
+import Hledger.UI.Editor
 import Hledger.UI.TransactionScreen
 import Hledger.UI.ErrorScreen
 
@@ -248,6 +250,7 @@ rsHandle ui@UIState{
         EvKey (KChar c)   [] | c `elem` ['h','?'] -> continue $ setMode Help ui
         EvKey (KChar 'g') [] -> liftIO (uiReloadJournalIfChanged copts d j ui) >>= continue
         EvKey (KChar 'a') [] -> suspendAndResume $ clearScreen >> setCursorPosition 0 0 >> add copts j >> uiReloadJournalIfChanged copts d j ui
+        EvKey (KChar 'E') [] -> suspendAndResume $ void (runEditor endPos j) >> uiReloadJournalIfChanged copts d j ui
         EvKey (KChar 'F') [] -> scrollTop >> (continue $ regenerateScreens j d $ toggleFlat ui)
         EvKey (KChar 'Z') [] -> scrollTop >> (continue $ regenerateScreens j d $ toggleEmpty ui)
         EvKey (KChar 'C') [] -> scrollTop >> (continue $ regenerateScreens j d $ toggleCleared ui)
diff --git a/hledger-ui/Hledger/UI/TransactionScreen.hs b/hledger-ui/Hledger/UI/TransactionScreen.hs
index cf0f88af6..a7b5931c2 100644
--- a/hledger-ui/Hledger/UI/TransactionScreen.hs
+++ b/hledger-ui/Hledger/UI/TransactionScreen.hs
@@ -8,6 +8,7 @@ module Hledger.UI.TransactionScreen
  )
 where
 
+import Control.Monad
 import Control.Monad.IO.Class (liftIO)
 import Data.List
 import Data.Monoid
@@ -25,6 +26,7 @@ import Hledger.UI.UIOptions
 import Hledger.UI.UITypes
 import Hledger.UI.UIState
 import Hledger.UI.UIUtils
+import Hledger.UI.Editor
 import Hledger.UI.ErrorScreen
 
 transactionScreen :: Screen
@@ -122,6 +124,7 @@ tsHandle ui@UIState{aScreen=s@TransactionScreen{tsTransaction=(i,t)
         EvKey (KChar 'q') [] -> halt ui
         EvKey KEsc        [] -> continue $ resetScreens d ui
         EvKey (KChar c)   [] | c `elem` ['h','?'] -> continue $ setMode Help ui
+        EvKey (KChar 'E') [] -> suspendAndResume $ void (runEditor endPos j) >> uiReloadJournalIfChanged copts d j ui
         EvKey (KChar 'g') [] -> do
           d <- liftIO getCurrentDay
           (ej, _) <- liftIO $ journalReloadIfChanged copts d j
diff --git a/hledger-ui/Hledger/UI/UIUtils.hs b/hledger-ui/Hledger/UI/UIUtils.hs
index df3c1dcdd..ca1a5dcd1 100644
--- a/hledger-ui/Hledger/UI/UIUtils.hs
+++ b/hledger-ui/Hledger/UI/UIUtils.hs
@@ -19,6 +19,8 @@ import Hledger
 import Hledger.UI.UITypes
 import Hledger.UI.UIState
 
+-- ui
+
 -- | Draw the help dialog, called when help mode is active.
 helpDialog :: Widget
 helpDialog =
@@ -33,6 +35,7 @@ helpDialog =
              str "MISC"
             ,renderKey ("h", "toggle help")
             ,renderKey ("a", "add transaction")
+            ,renderKey ("E", "open editor")
             ,renderKey ("g", "reload data")
             ,renderKey ("q", "quit")
             ,str " "
diff --git a/hledger-ui/hledger-ui.cabal b/hledger-ui/hledger-ui.cabal
index a153393cf..d9ed0d711 100644
--- a/hledger-ui/hledger-ui.cabal
+++ b/hledger-ui/hledger-ui.cabal
@@ -70,6 +70,7 @@ executable hledger-ui
     , HUnit
     , microlens >= 0.4 && < 0.5
     , microlens-platform >= 0.2.3.1 && < 0.4
+    , process >= 1.2
     , safe >= 0.2
     , split >= 0.1 && < 0.3
     , text >= 1.2 && < 1.3
@@ -92,6 +93,7 @@ executable hledger-ui
   other-modules:
       Hledger.UI
       Hledger.UI.AccountsScreen
+      Hledger.UI.Editor
       Hledger.UI.ErrorScreen
       Hledger.UI.Main
       Hledger.UI.RegisterScreen
diff --git a/hledger-ui/package.yaml b/hledger-ui/package.yaml
index b5aa5050e..15576b09e 100644
--- a/hledger-ui/package.yaml
+++ b/hledger-ui/package.yaml
@@ -75,6 +75,7 @@ executables:
       - HUnit
       - microlens >= 0.4 && < 0.5
       - microlens-platform >= 0.2.3.1 && < 0.4
+      - process >= 1.2
       - safe >= 0.2
       - split >= 0.1 && < 0.3
       - text >= 1.2 && < 1.3