module Alignment where

import Category
import Control.Comonad.Cofree
import Control.Monad.Free
import Data.Copointed
import Data.Either
import Data.Foldable (foldl')
import Data.Functor.Both
import Data.Functor.Identity
import qualified Data.List as List
import Data.Maybe
import qualified Data.OrderedMap as Map
import qualified Data.Set as Set
import Diff
import Line
import Patch
import Prelude hiding (fst, snd)
import qualified Prelude
import Range
import Row
import Source hiding ((++))
import SplitDiff
import Syntax
import Term

-- | Assign line numbers to the lines on each side of a list of rows.
numberedRows :: [Row a] -> [Both (Int, Line a)]
numberedRows = foldl' numberRows []
  where numberRows rows row = ((,) <$> ((+) <$> count rows <*> (valueOf <$> unRow row)) <*> unRow row) : rows
        count = maybe (pure 0) (fmap Prelude.fst) . maybeFirst
        valueOf EmptyLine = 0
        valueOf _ = 1

-- | Determine whether a line contains any patches.
hasChanges :: Line (SplitDiff leaf Info) -> Bool
hasChanges = or . fmap (or . (True <$))

-- | Split a diff, which may span multiple lines, into rows of split diffs.
splitDiffByLines :: Diff leaf Info -> Both Int -> Both (Source Char) -> ([Row (SplitDiff leaf Info)], Both Range)
splitDiffByLines diff previous sources = case diff of
  Free (Annotated annotation syntax) -> (splitAnnotatedByLines sources (ranges annotation) (Diff.categories <$> annotation) syntax, ranges annotation)
  Pure patch -> splitPatchByLines patch previous sources
  where ranges annotations = characterRange <$> annotations

-- | Split a patch, which may span multiple lines, into rows of split diffs.
splitPatchByLines :: Patch (Term leaf Info) -> Both Int -> Both (Source Char) -> ([Row (SplitDiff leaf Info)], Both Range)
splitPatchByLines patch previous sources = case patch of
  Insert term -> let (lines, range) = splitTermByLines term (snd sources) in
    (makeRow EmptyLine . fmap (Pure . SplitInsert) <$> lines, both (rangeAt $ fst previous) range)
  Delete term -> let (lines, range) = splitTermByLines term (fst sources) in
    (flip makeRow EmptyLine . fmap (Pure . SplitDelete) <$> lines, both range (rangeAt $ snd previous))
  Replace leftTerm rightTerm -> (zipWithDefaults makeRow (pure mempty) $ fmap (fmap (Pure . SplitReplace)) <$> lines, ranges)
    where (lines, ranges) = transpose $ splitTermByLines <$> both leftTerm rightTerm <*> sources

-- | Takes a term and a source and returns a list of lines and their range within source.
splitTermByLines :: Term leaf Info -> Source Char -> ([Line (Term leaf Info)], Range)
splitTermByLines (Info range categories :< syntax) source = flip (,) range $ case syntax of
  Leaf a -> pure . (:< Leaf a) . (`Info` categories) <$> actualLineRanges range source
  Indexed children -> adjoinChildLines (Indexed . fmap copoint) (Identity <$> children)
  Fixed children -> adjoinChildLines (Fixed . fmap copoint) (Identity <$> children)
  Keyed children -> adjoinChildLines (Keyed . Map.fromList) (Map.toList children)
  where adjoin :: Copointed f => [Line (Range, Maybe (f (Term leaf Info)))] -> [Line (Range, Maybe (f (Term leaf Info)))]
        adjoin = reverse . foldl (adjoinLinesBy (openRangePair source)) []

        adjoinChildLines :: (Copointed f, Functor f) => ([f (Term leaf Info)] -> Syntax leaf (Term leaf Info)) -> [f (Term leaf Info)] -> [Line (Term leaf Info)]
        adjoinChildLines constructor children = let (lines, previous) = foldl childLines ([], start range) children in
          fmap (wrapLineContents $ wrap constructor) . adjoin $ lines ++ (pure . flip (,) Nothing <$> actualLineRanges (safeRange previous $ end range) source)

        wrap :: Copointed f => ([f (Term leaf Info)] -> Syntax leaf (Term leaf Info)) -> [(Range, Maybe (f (Term leaf Info)))] -> Term leaf Info
        wrap constructor children = (Info (unionRanges $ Prelude.fst <$> children) categories :<) . constructor . catMaybes $ Prelude.snd <$> children

        childLines :: (Copointed f, Functor f) => ([Line (Range, Maybe (f (Term leaf Info)))], Int) -> f (Term leaf Info) -> ([Line (Range, Maybe (f (Term leaf Info)))], Int)
        childLines (lines, previous) child = let (childLines, childRange) = splitTermByLines (copoint child) source in
          (adjoin $ lines ++ (pure . flip (,) Nothing <$> actualLineRanges (safeRange previous $ start childRange) source) ++ (fmap ((,) childRange . Just . (<$ child)) <$> childLines), end childRange)

-- | Split a annotated diff into rows of split diffs.
splitAnnotatedByLines :: Both (Source Char) -> Both Range -> Both (Set.Set Category) -> Syntax leaf (Diff leaf Info) -> [Row (SplitDiff leaf Info)]
splitAnnotatedByLines sources ranges categories syntax = case syntax of
  Leaf a -> wrapRowContents (((Free . (`Annotated` Leaf a)) .) <$> ((. unionRanges) . flip Info <$> categories)) <$> contextRows ranges sources
  Indexed children -> adjoinChildRows (Indexed . fmap copoint) (Identity <$> children)
  Fixed children -> adjoinChildRows (Fixed . fmap copoint) (Identity <$> children)
  Keyed children -> adjoinChildRows (Keyed . Map.fromList) (List.sortOn (diffRanges . Prelude.snd) $ Map.toList children)
  where contextRows :: Both Range -> Both (Source Char) -> [Row Range]
        contextRows ranges sources = zipWithDefaults makeRow (pure mempty) (fmap pure <$> (actualLineRanges <$> ranges <*> sources))

        adjoin :: Copointed f => [Row (Range, Maybe (f (SplitDiff leaf Info)))] -> [Row (Range, Maybe (f (SplitDiff leaf Info)))]
        adjoin = reverse . foldl (adjoinRowsBy (openRangePair <$> sources)) []

        adjoinChildRows :: (Copointed f, Functor f) => ([f (SplitDiff leaf Info)] -> Syntax leaf (SplitDiff leaf Info)) -> [f (Diff leaf Info)] -> [Row (SplitDiff leaf Info)]
        adjoinChildRows constructor children = let (rows, previous) = foldl childRows ([], start <$> ranges) children in
          fmap (wrapRowContents (wrap constructor <$> categories)) . adjoin $ rows ++ (fmap (flip (,) Nothing) <$> contextRows (makeRanges previous (end <$> ranges)) sources)

        wrap :: Copointed f => ([f (SplitDiff leaf Info)] -> Syntax leaf (SplitDiff leaf Info)) -> Set.Set Category -> [(Range, Maybe (f (SplitDiff leaf Info)))] -> SplitDiff leaf Info
        wrap constructor categories children = Free . Annotated (Info (unionRanges $ Prelude.fst <$> children) categories) . constructor . catMaybes $ Prelude.snd <$> children

        childRows :: (Copointed f, Functor f) => ([Row (Range, Maybe (f (SplitDiff leaf Info)))], Both Int) -> f (Diff leaf Info) -> ([Row (Range, Maybe (f (SplitDiff leaf Info)))], Both Int)
        childRows (rows, previous) child = let (childRows, childRanges) = splitDiffByLines (copoint child) previous sources in
          (adjoin $ rows ++ (fmap (flip (,) Nothing) <$> contextRows (makeRanges previous (start <$> childRanges)) sources) ++ (rowMap ((. (Just . (<$ child))) . (,) <$> childRanges) <$> childRows), end <$> childRanges)

        makeRanges :: Both Int -> Both Int -> Both Range
        makeRanges a b = runBothWith safeRange <$> sequenceA (both a b)

-- | Produces the starting indices of a diff.
diffRanges :: Diff leaf Info -> Both (Maybe Range)
diffRanges (Free (Annotated infos _)) = Just . characterRange <$> infos
diffRanges (Pure patch) = fmap (characterRange . copoint) <$> unPatch patch

-- | Returns a function that takes an Either, applies either the left or right
-- | MaybeOpen, and returns Nothing or the original either.
openEither :: MaybeOpen a -> MaybeOpen b -> MaybeOpen (Either a b)
openEither ifLeft ifRight which = either (fmap (const which) . ifLeft) (fmap (const which) . ifRight) which

-- | MaybeOpen test for (Range, a) pairs.
openRangePair :: Source Char -> MaybeOpen (Range, a)
openRangePair source pair = pair <$ openRange source (Prelude.fst pair)

-- | Given a source and a range, returns nothing if it ends with a `\n`;
-- | otherwise returns the range.
openRange :: Source Char -> MaybeOpen Range
openRange source range = case (source `at`) <$> maybeLastIndex range of
  Just '\n' -> Nothing
  _ -> Just range

-- | Given a source and something that has a term, returns nothing if the term
-- | ends with a `\n`; otherwise returns the term.
openTerm :: Copointed f => Source Char -> MaybeOpen (f (Term leaf Info))
openTerm source term = const term <$> openRange source (case copoint term of (Info range _ :< _) -> range)

-- | Given a source and something that has a split diff, returns nothing if the
-- | diff ends with a `\n`; otherwise returns the diff.
openDiff :: Copointed f => Source Char -> MaybeOpen (f (SplitDiff leaf Info))
openDiff source diff = const diff <$> case copoint diff of
  (Free (Annotated (Info range _) _)) -> openRange source range
  (Pure patch) -> let Info range _ :< _ = getSplitTerm patch in openRange source range