module Portage.Dependency (
  Dependency(..),
  simplify_deps,
  simplifyUseDeps,
  addDepUseFlag
  ) where

import Portage.Version
import Portage.Use
import Distribution.Text ( display, Text(..) )

import Portage.PackageId

import qualified Text.PrettyPrint as Disp
import Text.PrettyPrint ( (<>), hsep )

import Data.Maybe ( fromJust, catMaybes, mapMaybe )
import Data.List ( nub, groupBy, partition, sortBy )
import Data.Ord           (comparing)

data Dependency = AnyVersionOf               PackageName [UseFlag]
                | ThisVersionOf      Version PackageName [UseFlag]  -- ~package-version
                | LaterVersionOf     Version PackageName [UseFlag]  -- >package-version
                | EarlierVersionOf   Version PackageName [UseFlag]  -- <package-version
                | OrLaterVersionOf   Version PackageName [UseFlag]  -- >=package-version
                | OrEarlierVersionOf Version PackageName [UseFlag]  -- <=package-version
                | DependEither [Dependency]                         -- || ( depend1 depend2 ... )
                | DependIfUse  UseFlag    Dependency                -- use? ( depend )
                | ThisMajorOf        Version PackageName [UseFlag]  -- =package-version*
                | AllOf        [Dependency]                         -- ( depend1 depend2 ... )
    deriving (Eq,Show)

instance Text Dependency where
  disp = showDepend

(<->) :: Disp.Doc -> Disp.Doc -> Disp.Doc
a <-> b = a <> Disp.char '-' <> b

showDepend :: Dependency -> Disp.Doc
showDepend (AnyVersionOf         p u) = disp p <> dispUses u 
showDepend (ThisVersionOf      v p u) = Disp.char '~' <> disp p <-> disp v { versionRevision = 0 } <> dispUses u
showDepend (LaterVersionOf     v p u) = Disp.char '>' <> disp p <-> disp v <> dispUses u
showDepend (EarlierVersionOf   v p u) = Disp.char '<' <> disp p <-> disp v <> dispUses u
showDepend (OrLaterVersionOf   v p u) = Disp.text ">=" <> disp p <-> disp v <> dispUses u
showDepend (OrEarlierVersionOf v p u) = Disp.text "<=" <> disp p <-> disp v <> dispUses u
showDepend (DependEither       dp ) = Disp.text "|| ( " <> hsep (map showDepend dp) <> Disp.text " )"
showDepend (DependIfUse        useflag dep) = disp useflag <> Disp.text "? " <> pp_deps dep
    where -- special case to avoid double braces: test? ( ( ) )
          pp_deps (AllOf _) =                               disp dep
          pp_deps         _ = Disp.parens (Disp.text " " <> disp dep <> Disp.text " ")
showDepend (ThisMajorOf        v p u) = Disp.char '=' <> disp p <-> disp v <> Disp.char '*' <> dispUses u
showDepend (AllOf []) = Disp.empty
showDepend (AllOf              (d:dp) ) =
    Disp.text "( " <> showDepend d <> line
    <> Disp.hcat (map (\x -> Disp.text "\t\t\t" <> (showDepend x) <> line) dp)
    <> Disp.text "\t\t)"
    where line = Disp.char '\n'

{- Here goes code for dependencies simplification -}

simplify_group_table :: PackageName ->
                        [UseFlag]   ->
                        Maybe Version ->
                        Maybe Version ->
                        Maybe Version ->
                        Maybe Version ->
                        Maybe Version -> [Dependency]

-- simplify_group_table p ol       l        e        oe       exact
-- 1) trivial cases:
simplify_group_table    p u Nothing  Nothing  Nothing  Nothing  Nothing  = error $ display p ++ ": unsolvable constraints"
simplify_group_table    p u (Just v) Nothing  Nothing  Nothing  Nothing  = [OrLaterVersionOf v p u]
simplify_group_table    p u Nothing  (Just v) Nothing  Nothing  Nothing  = [LaterVersionOf v p u]
simplify_group_table    p u Nothing  Nothing  (Just v) Nothing  Nothing  = [EarlierVersionOf v p u]
simplify_group_table    p u Nothing  Nothing  Nothing  (Just v) Nothing  = [OrEarlierVersionOf v p u]
simplify_group_table    p u Nothing  Nothing  Nothing  Nothing  (Just v) = [ThisVersionOf v p u]

-- 2) simplification passes
simplify_group_table    p u (Just (Version v1 _ _ _)) Nothing (Just (Version v2 _ _ _)) Nothing Nothing
    -- special case: >=a-v.N a<v.(N+1)   => =a-v.N*
    | (init v1 == init v2) && (last v2 == last v1 + 1) = [ThisMajorOf (Version v1 Nothing [] 0) p u]
    | otherwise                                        = [OrLaterVersionOf (Version v1 Nothing [] 0) p u, EarlierVersionOf (Version v2 Nothing [] 0) p u]

-- TODO: simplify constraints of type: >=a-v1; > a-v2 and such

-- 3) otherwise sink:
simplify_group_table    p u (Just v)     l@(_)       e@(_)        oe@(_)       exact@(_) =   OrLaterVersionOf v p u: simplify_group_table p u Nothing  l e oe exact
simplify_group_table    p u ol@(Nothing) (Just v)    e@(_)        oe@(_)       exact@(_) =     LaterVersionOf v p u: simplify_group_table p u ol Nothing e oe exact
simplify_group_table    p u ol@(Nothing) l@(Nothing) (Just v)     oe@(_)       exact@(_) =   EarlierVersionOf v p u: simplify_group_table p u ol l Nothing oe exact
simplify_group_table    p u ol@(Nothing) l@(Nothing) e@(Nothing)  (Just v)     exact@(_) = OrEarlierVersionOf v p u: simplify_group_table p u ol l e Nothing  exact
-- already defined earlier
-- simplify_group_table    p ol@(Nothing) l@(Nothing) e@(Nothing)  oe@(Nothing) (Just v)  = OrEarlierVersionOf v p : simplify_group_table p ol l e oe Nothing

--  >a-v1 >a-v2         => >a-(max v1 v2)
-- key idea: all constraints are enforcing constraints, so we can't get
-- more, than one interval.
simplify_group :: [Dependency] -> [Dependency]
simplify_group [dep@(AnyVersionOf _package _u)] = [dep]
simplify_group [dep@(ThisMajorOf _v    _p _u)]  = [dep]
simplify_group deps = simplify_group_table package
                                           uses
                                           min_or_later_v   -- >=
                                           min_later_v      -- >
                                           max_earlier_v    -- <
                                           max_or_earlier_v -- <=
                                           exact_this_v     -- ==
    where
          package = fromJust.getPackage $ head deps
          uses    = fromJust.getUses    $ head deps
          max_earlier_v    = safe_minimum $ map earlier_v deps
          max_or_earlier_v = safe_minimum $ map or_earlier_v deps
          min_later_v      = safe_maximum $ map later_v deps
          min_or_later_v   = safe_maximum $ map or_later_v deps
          exact_this_v     = case catMaybes (map this_v deps) of
                                  []  -> Nothing
                                  [v] -> Just v
                                  xs  -> error $ "too many exact versions:" ++ show xs
          --
          earlier_v (EarlierVersionOf v _p _u) = Just v
          earlier_v _                       = Nothing

          or_earlier_v (OrEarlierVersionOf v _p _u) = Just v
          or_earlier_v _                         = Nothing

          later_v (LaterVersionOf v _p _u) = Just v
          later_v _                     = Nothing

          or_later_v (OrLaterVersionOf v _p _u) = Just v
          or_later_v _                     = Nothing

          this_v (ThisVersionOf v  _p _u) = Just v
          this_v _                     = Nothing
          --
          safe_minimum xs = case catMaybes xs of
                                 [] -> Nothing
                                 xs' -> Just $ minimum xs'
          safe_maximum xs = case catMaybes xs of
                                 [] -> Nothing
                                 xs' -> Just $ maximum xs'

-- divide packages to groups (by package name), simplify groups, merge again
simplify_deps :: [Dependency] -> [Dependency]
simplify_deps deps = (concatMap (simplify_group.nub) $
                       groupBy cmpPkgName $
                         sortBy (comparing getPackagePart) groupable)
                     ++ ungroupable
    where (ungroupable, groupable) = partition ((==Nothing).getPackage) deps
          --
          cmpPkgName p1 p2 = cmpMaybe (getPackage p1) (getPackage p2)
          cmpMaybe (Just p1) (Just p2) = p1 == p2
          cmpMaybe _         _         = False
          --
getPackage :: Dependency -> Maybe PackageName
getPackage (AllOf _dependency) = Nothing
getPackage (AnyVersionOf package _uses) = Just package
getPackage (ThisVersionOf      _version package _uses) = Just package
getPackage (LaterVersionOf     _version package _uses) = Just package
getPackage (EarlierVersionOf   _version package _uses) = Just package
getPackage (OrLaterVersionOf   _version package _uses) = Just package
getPackage (OrEarlierVersionOf _version package _uses) = Just package
getPackage (DependEither _dependency           ) = Nothing
getPackage (DependIfUse  _useFlag    _Dependency) = Nothing
getPackage (ThisMajorOf        _version package _uses) = Just package

getUses  :: Dependency -> Maybe [UseFlag]
getUses (AllOf _d) = Nothing
getUses (AnyVersionOf _p u) = Just u
getUses (ThisVersionOf _v _p u) = Just u
getUses (LaterVersionOf _v _p u) = Just u
getUses (EarlierVersionOf _v _p u) = Just u
getUses (OrLaterVersionOf _v _p u) = Just u
getUses (OrEarlierVersionOf _v _p u) = Just u
getUses (DependEither _d) = Nothing
getUses (DependIfUse _u _d) = Nothing
getUses (ThisMajorOf _v _p u) = Just u

--
getPackagePart :: Dependency -> PackageName
getPackagePart dep = fromJust (getPackage dep)

--
addDepUseFlag :: Dependency -> UseFlag -> Dependency
addDepUseFlag (AllOf d) n = AllOf $ map (flip addDepUseFlag n) d
addDepUseFlag (AnyVersionOf p u) n = AnyVersionOf p (n:u)
addDepUseFlag (ThisVersionOf v p u) n = ThisVersionOf v p (n:u)
addDepUseFlag (LaterVersionOf v p u) n = LaterVersionOf v p (n:u)
addDepUseFlag (EarlierVersionOf v p u) n = EarlierVersionOf v p (n:u)
addDepUseFlag (OrLaterVersionOf v p u) n = OrLaterVersionOf v p (n:u)
addDepUseFlag (OrEarlierVersionOf v p u) n = OrEarlierVersionOf v p (n:u)
addDepUseFlag (ThisMajorOf v p u) n = ThisMajorOf v p (n:u)
addDepUseFlag (DependEither d) n = DependEither $ map (flip addDepUseFlag n) d
addDepUseFlag (DependIfUse u d) n = DependIfUse u (addDepUseFlag d n)

--
-- | remove all Use dependencies that overlap with normal dependencies
simplifyUseDeps :: [Dependency]         -- list where use deps is taken
                    -> [Dependency]     -- list where common deps is taken
                    -> [Dependency]     -- result deps
simplifyUseDeps ds cs =
    let (u,o) = partition isUseDep ds
        c = mapMaybe getPackage cs
    in (mapMaybe (intersectD c) u)++o

intersectD :: [PackageName] -> Dependency -> Maybe Dependency
intersectD fs (DependIfUse u d) = intersectD fs d >>= Just . DependIfUse u
intersectD fs (DependEither ds) =
    let ds' = mapMaybe (intersectD fs) ds
    in if null ds' then Nothing else Just (DependEither ds')
intersectD fs (AllOf ds) =
    let ds' = mapMaybe (intersectD fs) ds
    in if null ds' then Nothing else Just (AllOf ds')
intersectD fs x =
    let pkg = fromJust $ getPackage x -- this is unsafe but will save from error later
    in if any (==pkg) fs then Nothing else Just x

isUseDep :: Dependency -> Bool
isUseDep (DependIfUse _ _) = True
isUseDep _ = False
--