{-# LANGUAGE OverloadedStrings #-}
module OpenSuse.GuessChangeLog ( guessChangeLog, GuessedChangeLog(..) ) where
import OpenSuse.StripSpace
import qualified Control.Foldl as Fold
import Control.Monad.Except
import Data.Algorithm.Diff
import Data.Set ( Set )
import qualified Data.Set as Set
import qualified Data.Text as Text
import qualified Data.Text.IO as Text
import Prelude hiding ( FilePath )
import Turtle hiding ( l, x, stderr, stdout )
-- | Automatically guess the differences between to releases of a package by
-- looking at the change log file provided by upstream. The function as
-- arguments the paths of two directories that contain the extracted release
-- tarballs. The first arguments ought to point to the older release, the
-- second paths ought to point to the updated version.
--
-- The function uses the following algorithm to detect the relevant changes:
--
-- 1. Scan both directories for files that look like they might be change
-- logs.
--
-- 2. If both directories contain the same candidate file, e.g. @ChangeLog@,
-- then use that.
--
-- 3. Compute the differences between the change log files and check that all
-- modifications are additions at the top of the file.
--
-- 4. Return those additions as 'Text'.
guessChangeLog :: FilePath -> FilePath -> IO GuessedChangeLog
guessChangeLog oldDir = fmap (either id id) . guessChangeLog' oldDir
guessChangeLog' :: FilePath -> FilePath -> IO (Either GuessedChangeLog GuessedChangeLog)
guessChangeLog' oldDir newDir = runExceptT $ do
oldCLF <- Set.fromList <$> listShell (findChangeLogFiles oldDir)
newCLF <- Set.fromList <$> listShell (findChangeLogFiles newDir)
when (all null [oldCLF,newCLF]) (throwError NoChangeLogFiles)
let clf' = oldCLF `Set.intersection` newCLF
clf <- case Set.toAscList clf' of
[] -> throwError (NoCommonChangeLogFiles oldCLF newCLF)
[clf] -> return clf
_ -> throwError (MoreThanOneChangeLogFile clf')
old <- stripSpace <$> liftIO (Text.readFile (oldDir </> clf))
new <- stripSpace <$> liftIO (Text.readFile (newDir </> clf))
let changes = cleanupEmptyLines (getDiff (Text.lines old) (Text.lines new))
(top,diff) = span inBoth changes
(add,foot) = span inSecond diff
topAddOnly = all inBoth foot
when (all inBoth changes) (throwError (UndocumentedUpdate clf))
unless (length top < 10) (throwError (UnmodifiedTopIsTooLarge clf (fromIntegral (length top))))
unless topAddOnly (throwError (NotJustTopAdditions clf))
return (GuessedChangeLog clf (stripSpace (Text.unlines (map unDiff add))))
--
data GuessedChangeLog
= GuessedChangeLog FilePath Text
-- ^ Both releases contained the given change log file, and these files
-- differed so that the given text was added at the top of the new one.
-- The text undergoes some amount of cleanup, i.e. we'll trim leading
-- empty lines at the top, trailing whitespace, and trailing empty
-- lines at the end.
| NoChangeLogFiles
-- ^ Neither release contains a change log file.
| UndocumentedUpdate FilePath
-- ^ A change log file exists (and its name is returned), but it's
-- identical in both releases. In other words, upstream probably forgot
-- to document the release.
| NoCommonChangeLogFiles (Set FilePath) (Set FilePath)
-- ^ Both releases contain a set of files that look like they might be
-- a change log, but their intersection is empty! This happens, for
-- example, when upstream has renamed the file.
| MoreThanOneChangeLogFile (Set FilePath)
-- ^ Multiple change log files exists in both directories. Now, it
-- would probably work out okay if we'd just look at the diffs of both
-- of them, respectively, but it felt like a good idea to err on the
-- side of caution. This case is rare anyways.
| UnmodifiedTopIsTooLarge FilePath Word
-- ^ 'guessChangelog' accepts up to 10 lines of unmodified text at the
-- top of the upstream change log file because some people like to have
-- a short introduction text there etc. If that header becomes too
-- large, however, then we return this error because we expect upstream
-- to add text at the top, not in the middle of the file.
| NotJustTopAdditions FilePath
-- ^ This happens when upstream edits the file in ways other than just
-- adding at the top. Sometimes people re-format old entries or rewrite
-- URLs or fix typos, and in such a case it feels to risky to trust the
-- diff.
deriving (Show)
cleanupEmptyLines :: [Diff Text] -> [Diff Text]
cleanupEmptyLines [] = []
cleanupEmptyLines (Second t1 : Both "" "" : Second t2 : xs) = Second t1 : Second "" : Second t2 : cleanupEmptyLines xs
cleanupEmptyLines (First t1 : Both "" "" : First t2 : xs) = First t1 : First "" : First t2 : cleanupEmptyLines xs
cleanupEmptyLines (x:xs) = x : cleanupEmptyLines xs
inBoth :: Diff a -> Bool
inBoth (Both _ _) = True
inBoth _ = False
inSecond :: Diff a -> Bool
inSecond (Second _) = True
inSecond _ = False
unDiff :: Diff a -> a
unDiff (First txt) = txt
unDiff (Both txt _) = txt
unDiff (Second txt) = txt
-- | This function finds any file in the given directory path that looks like
-- it might be a change log, meaning its name contains the word "change" and
-- its suffix is not one that obviously designates source code.
findChangeLogFiles :: FilePath -> Shell FilePath
findChangeLogFiles dirPath =
onFiles (grepText changelogFilePattern) (filename <$> ls dirPath)
changelogFilePattern :: Pattern Text
changelogFilePattern = star dot <> asciiCI "change" <* invert codeSuffixPattern
codeSuffixPattern :: Pattern Text
codeSuffixPattern = choice [suffix ".hs", suffix ".c", suffix ".cpp"]
-- * Utility Functions
listShell :: MonadIO io => Shell a -> io [a]
listShell = flip fold Fold.list