{-
    Stepwise.hs - Functions that deal with stepwise manipulation of pattern
    Copyright (C) 2024, Alex McLean and contributors

    This library is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this library.  If not, see <http://www.gnu.org/licenses/>.
-}

module Sound.Tidal.Stepwise where

import Data.List (sort, sortOn, transpose)
import Data.Maybe (catMaybes, fromJust, fromMaybe, isJust, mapMaybe)
import Sound.Tidal.Core (stack, timecat, zoom, zoompat)
import Sound.Tidal.Pattern
import Sound.Tidal.Utils (enumerate, nubOrd, pairs)

-- _lcmsteps :: [Pattern a] -> Maybe Time
-- _lcmsteps pats = foldl1 lcmr <$> (sequence $ map steps pats)

s_patternify :: (a -> Pattern b -> Pattern c) -> (Pattern a -> Pattern b -> Pattern c)
s_patternify f (Pattern _ _ (Just a)) b = f a b
s_patternify f pa p = stepJoin $ (`f` p) <$> pa

s_patternify2 :: (a -> b -> c -> Pattern d) -> Pattern a -> Pattern b -> c -> Pattern d
s_patternify2 f a b p = stepJoin $ (\x y -> f x y p) <$> a <*> b

stepJoin :: Pattern (Pattern a) -> Pattern a
stepJoin pp = Pattern q first_t Nothing
  where
    q st@(State a c) = query (timecat $ retime $ slices $ query (rotL (sam $ start a) pp) (st {arc = Arc 0 1})) st
    first_t :: Maybe Rational
    first_t = steps $ timecat $ retime $ slices $ queryArc pp (Arc 0 1)
    retime :: [(Time, Pattern a)] -> [(Time, Pattern a)]
    retime xs = map (uncurry adjust) xs
      where
        occupied_perc = sum $ map fst $ filter (isJust . steps . snd) xs
        occupied_tactus = sum $ mapMaybe (steps . snd) xs
        total_tactus = occupied_tactus / occupied_perc
        adjust _ pat@(Pattern {steps = Just t}) = (t, pat)
        adjust dur pat = (dur * total_tactus, pat)
    -- break up events at all start/end points, into groups, including empty ones.
    slices :: [Event (Pattern a)] -> [(Time, Pattern a)]
    slices evs = map (\s -> (snd s - fst s, stack $ map (\x -> withContext (\c -> combineContexts [c, context x]) $ value x) $ fit s evs)) $ pairs $ sort $ nubOrd $ 0 : 1 : concatMap (\ev -> start (part ev) : stop (part ev) : []) evs
    -- list of slices of events within the given range
    fit :: (Rational, Rational) -> [Event (Pattern a)] -> [Event (Pattern a)]
    fit (b, e) evs = mapMaybe (match (b, e)) evs
    -- slice of event within the given range
    match :: (Rational, Rational) -> Event (Pattern a) -> Maybe (Event (Pattern a))
    match (b, e) ev = do
      a <- subArc (Arc b e) $ part ev
      return ev {part = a}

-- stepcat :: [Pattern a] -> Pattern a
-- stepcat pats = innerJoin $ timecat . map snd . sortOn fst <$> tpat (epats pats)
--   where
--     -- enumerated patterns, ignoring those without steps
--     epats :: [Pattern a] -> [(Int, Pattern a)]
--     epats = enumerate . filter (isJust . steps)
--     --
--     tpat :: [(Int, Pattern a)] -> Pattern [(Int, (Time, Pattern a))]
--     tpat = mapM (\(i, pat) -> (\t -> (i, (t, pat))) <$> fromJust (steps pat))

stepcat :: [Pattern a] -> Pattern a
stepcat pats = timecat $ map (\pat -> (fromMaybe 1 $ steps pat, pat)) pats

_take :: Time -> Pattern a -> Pattern a
-- raise error?
_take _ pat@(Pattern _ Nothing _) = pat
_take n pat@(Pattern _ (Just t) _) = setSteps (Just t') $ zoom (b, e) pat
  where
    b = if n >= 0 then 0 else 1 - (abs n / t)
    e = if n >= 0 then n / t else 1
    t' = min (abs n) t

steptake :: Pattern Time -> Pattern a -> Pattern a
steptake = s_patternify _take

_stepdrop :: Time -> Pattern a -> Pattern a
_stepdrop _ pat@(Pattern _ Nothing _) = pat
_stepdrop n pat@(Pattern _ (Just t) _) = steptake (pure $ f t) pat
  where
    f t
      | n >= 0 = t - n
      | otherwise = negate (t + n)

stepdrop :: Pattern Time -> Pattern a -> Pattern a
stepdrop = s_patternify _stepdrop

_expand :: Rational -> Pattern a -> Pattern a
_expand factor pat = withSteps (* factor) pat

_contract :: Rational -> Pattern a -> Pattern a
_contract factor pat = withSteps (/ factor) pat

expand :: Pattern Rational -> Pattern a -> Pattern a
expand = s_patternify _expand

contract :: Pattern Rational -> Pattern a -> Pattern a
contract = s_patternify _contract

_extend :: Rational -> Pattern a -> Pattern a
_extend factor pat = _expand factor $ _fast factor pat

extend :: Pattern Rational -> Pattern a -> Pattern a
extend = s_patternify _extend

-- | Successively plays a pattern from each group in turn
stepalt :: [[Pattern a]] -> Pattern a
stepalt groups = stepcat $ concat $ take (fromIntegral $ c * length groups) $ transpose $ map cycle groups
  where
    c = foldl1 lcm $ map length groups

{-
s_while :: Pattern Bool -> (Pattern a -> Pattern a) -> Pattern a -> Pattern a
s_while patb f pat@(Pattern _ (Just t) _) = while (_steps t patb) f pat
-- TODO raise exception?
s_while _ _ pat = pat

_s_nth :: Bool -> Bool -> Int -> (Pattern a -> Pattern a) -> Pattern a -> Pattern a
_s_nth lastone stepwise n f pat
  | n <= 1 = pat
  | otherwise = applyWhen stepwise (_fast t) $ s_cat $ applyWhen lastone reverse $ (f $ head cycles) : tail cycles
  where
    cycles = applyWhen lastone reverse $ separateCycles n $ applyWhen stepwise (_slow t) pat
    t = fromMaybe 1 $ steps pat

s_nthcycle :: Pattern Int -> (Pattern a -> Pattern a) -> Pattern a -> Pattern a
s_nthcycle (Pattern _ _ (Just i)) f pat = _s_nth True False i f pat
s_nthcycle tp f p = innerJoin $ (\t -> _s_nth True False t f p) <$> tp

s_nthcycle' :: Pattern Int -> (Pattern a -> Pattern a) -> Pattern a -> Pattern a
s_nthcycle' (Pattern _ _ (Just i)) f pat = _s_nth False False i f pat
s_nthcycle' tp f p = innerJoin $ (\t -> _s_nth False False t f p) <$> tp

s_nth :: Pattern Int -> (Pattern a -> Pattern a) -> Pattern a -> Pattern a
s_nth (Pattern _ _ (Just i)) f pat = _s_nth True True i f pat
s_nth tp f p = innerJoin $ (\t -> _s_nth True True t f p) <$> tp

s_nth' :: Pattern Int -> (Pattern a -> Pattern a) -> Pattern a -> Pattern a
s_nth' (Pattern _ _ (Just i)) f pat = _s_nth False True i f pat
s_nth' tp f p = innerJoin $ (\t -> _s_nth False True t f p) <$> tp

s_every :: Pattern Int -> (Pattern a -> Pattern a) -> Pattern a -> Pattern a
s_every = s_nth'

s_everycycle :: Pattern Int -> (Pattern a -> Pattern a) -> Pattern a -> Pattern a
s_everycycle = s_nthcycle'

-- | Like @s_taper@, but returns a list of repetitions
s_taperlist :: Pattern a -> [Pattern a]
s_taperlist pat@(Pattern _ (Just t) _) = pat : map (\r -> _s_sub r pat) [1 .. t]
-- TODO exception?
s_taperlist pat = [pat]

s_taperlistBy :: Int -> Int -> Pattern a -> [Pattern a]
s_taperlistBy amount times pat@(Pattern _ (Just t) _)
  | times == 1 = [pat]
  | times <= 0 = []
  | amount == 0 = [pat]
  | backwards = reverse l
  | otherwise = l
  where
    backwards = amount > 0
    n = toRational $ abs amount
    start = t - toRational (max 0 $ n * toRational (times - 1))
    l = map (\i -> zoom (0, (start + (n * toRational i)) / t) pat) [0 .. times - 2] ++ [pat]
s_taperlistBy _ _ _ = []

-- | Plays one fewer step from the pattern each repetition, down to nothing
s_taper :: Pattern a -> Pattern a
s_taper = s_cat . s_taperlist

-- | Plays one fewer step from the pattern each repetition, down to nothing
_s_taperBy :: Int -> Int -> Pattern a -> Pattern a
_s_taperBy amount times pat = s_cat $ s_taperlistBy amount times pat

-- | Plays one fewer step from the pattern each repetition, down to nothing
s_taperBy :: Pattern Int -> Pattern Int -> Pattern a -> Pattern a
s_taperBy = s_patternify2 _s_taperBy
-}