From 8464fed4f6818e9564108ef8f267b04ed975459a Mon Sep 17 00:00:00 2001
From: Simon Michael <simon@joyful.com>
Date: Fri, 26 Nov 2021 12:31:36 -1000
Subject: [PATCH] ;tools: changelog: a silly tool that makes changelog work
 more pleasant

---
 bin/changelog.hs | 140 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 140 insertions(+)
 create mode 100755 bin/changelog.hs

diff --git a/bin/changelog.hs b/bin/changelog.hs
new file mode 100755
index 000000000..a83252dfb
--- /dev/null
+++ b/bin/changelog.hs
@@ -0,0 +1,140 @@
+#!/usr/bin/env stack
+{- stack script --resolver nightly-2021-11-19
+    --package data-default
+    --package extra
+    --package hledger-lib
+    --package process
+    --package text
+-}
+{- stack ghc
+    --package text
+-}
+-- changelog.hs CHANGELOGFILE
+--
+-- Manipulate a hledger changelog. Currently does one thing: prompts
+-- for a rewrite of the oldest uncategorised pending changelog item
+-- and updates the file, printing a diff.
+
+{-# LANGUAGE DeriveAnyClass #-}
+{-# LANGUAGE DeriveGeneric #-}
+-- {-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE RecordWildCards #-}
+
+import Data.Char
+import Data.Default
+import GHC.Generics
+import Data.List.Extra
+import qualified Data.Text as T
+import System.Environment
+import System.IO
+import System.Process
+import Text.Printf
+import Hledger.Utils
+
+-- The one-line heading for a top level section in the changelog,
+-- with the leading #(s) removed.
+type ChangelogHeading = String
+
+-- One change description in the changelog, with the list bullet and
+-- corresponding indentation removed.
+type ChangelogItem = String
+
+-- A top level section in the changelog, corresponding to one release.
+data ChangelogSection = ChangelogSection {
+   heading          :: ChangelogHeading
+  ,unknownitems     :: [ChangelogItem]
+  ,featureitems     :: [ChangelogItem]
+  ,improvementitems :: [ChangelogItem]
+  ,fixitems         :: [ChangelogItem]
+  }
+  deriving (Show, Generic, Default)
+
+main = do
+  (i:_) <- getArgs
+
+  -- read specified changelog
+  (preamble:first:rest) <- splitOn "\n# " <$> readFile i
+  let
+    o = i ++ ".new"
+    s@ChangelogSection{..} = readSection first
+  s' <- editOneUnknown s
+
+  -- write back to new file
+  writeFile o $ init $ unlines $
+     preamble :
+     showSection s' :
+     map ("# "++) rest
+
+  -- show the diff
+  system' $ printf "diff %s %s" i o
+
+  -- overwrite the old file
+  system' $ printf "mv %s %s" o i
+
+editOneUnknown :: ChangelogSection -> IO ChangelogSection
+editOneUnknown s@ChangelogSection{..}
+  | null unknownitems = return s
+  | otherwise = do
+    let u = last unknownitems
+    putStrLn "Old:\n"
+    putStrLn u
+    putStrLn "New: (prefix with feat:/imp:/fix: to categorise, ctrl-d to finish):\n" -- Just an = keeps it unchanged, empty string removes it.\n"
+    i <- getContents
+    let s' =
+          case i of
+            'f':'e':'a':'t':':':' ':t -> s{featureitems     = readItem t : featureitems}
+            'f':'i':'x':':':' ':t     -> s{fixitems         = readItem t : fixitems}
+            'i':'m':'p':':':' ':t     -> s{improvementitems = readItem t : improvementitems}
+            t                         -> s{improvementitems = readItem t : improvementitems}
+    return s'{unknownitems=init unknownitems}
+
+-- Parse a changelog section which may or may not have the Features/Improvements/Fixes subheadings.
+readSection :: String -> ChangelogSection
+readSection s =
+  let
+    (heading,rest) = break (=='\n') s
+    parts = splitOn "\nFeatures\n" rest
+    (unknownitems, featureitems, improvementitems, fixitems) =
+      case parts of
+        []       -> ([], [], [], [])
+        [u]      -> (readItems u, [], [], [])
+        (u:xs:_) -> (readItems u, readItems f, readItems i, readItems x)
+          where
+            (f:ys:_) = splitOn "\nImprovements\n" xs
+            (i:x:_)  = splitOn "\nFixes\n" ys
+  in ChangelogSection{..}
+  where
+    readItems = map readItem . filter (not.all isSpace) . splitOn "\n- "
+
+showSection ChangelogSection{..} =
+  unlines $
+       [("# "++heading), ""]
+    ++ map showItem unknownitems
+    ++ ["Features", ""]
+    ++ map showItem featureitems
+    ++ ["Improvements", ""]
+    ++ map showItem improvementitems
+    ++ ["Fixes", ""]
+    ++ map showItem fixitems
+
+readItem :: String -> ChangelogItem
+readItem "" = def
+readItem s =
+  let
+    (first:rest) = lines s
+    stripto2spaces (' ':' ':t) = t
+    stripto2spaces (' ':t) = t
+    stripto2spaces t = t
+  in unlines $
+     first :
+     map stripto2spaces rest
+
+showItem "" = ""
+showItem i =
+  let (first:rest) = lines i
+  in unlines $ ("- "++first) : map ("  "++) rest
+
+system' s = putStrLn s >> system s
+
+re = toRegex' . T.pack
+