{-# LANGUAGE DeriveDataTypeable, FlexibleInstances, OverloadedStrings, TypeSynonymInstances #-}
module Debian.Relation.Common where

-- Standard GHC Modules

import Data.Data (Data)
import Data.List as List (map, intersperse)
import Data.Monoid (mconcat, (<>))
import Data.Function
import Data.Set as Set (Set, toList)
import Data.Typeable (Typeable)
import Debian.Arch (Arch, prettyArch)
import Debian.Pretty (Pretty(pretty), Doc, text, empty)
import Prelude hiding (map)
import Text.ParserCombinators.Parsec

-- Local Modules

import Debian.Version

-- Datatype for relations

type Relations = AndRelation
type AndRelation = [OrRelation]
type OrRelation = [Relation]

data Relation = Rel BinPkgName (Maybe VersionReq) (Maybe ArchitectureReq) deriving (Eq, Read, Show)

newtype SrcPkgName = SrcPkgName {unSrcPkgName :: String} deriving (Read, Show, Eq, Ord, Data, Typeable)
newtype BinPkgName = BinPkgName {unBinPkgName :: String} deriving (Read, Show, Eq, Ord, Data, Typeable)

class Pretty a => PkgName a where
    pkgNameFromString :: String -> a

instance PkgName BinPkgName where
    pkgNameFromString = BinPkgName

instance PkgName SrcPkgName where
    pkgNameFromString = SrcPkgName

class ParseRelations a where
    -- |'parseRelations' parse a debian relation (i.e. the value of a
    -- Depends field). Return a parsec error or a value of type
    -- 'Relations'
    parseRelations :: a -> Either ParseError Relations

-- | This needs to be indented for use in a control file: intercalate "\n     " . lines . show
prettyRelations :: [[Relation]] -> Doc
prettyRelations xss = mconcat . intersperse (text "\n, ") . List.map prettyOrRelation $ xss

prettyOrRelation :: [Relation] -> Doc
prettyOrRelation xs = mconcat . intersperse (text " | ") . List.map prettyRelation $ xs

prettyRelation :: Relation -> Doc
prettyRelation (Rel name ver arch) =
    pretty name <> maybe empty prettyVersionReq ver <> maybe empty prettyArchitectureReq arch

instance Ord Relation where
    compare (Rel pkgName1 mVerReq1 _mArch1) (Rel pkgName2 mVerReq2 _mArch2) =
	case compare pkgName1 pkgName2 of
	     LT -> LT
	     GT -> GT
	     EQ -> compare mVerReq1 mVerReq2

data ArchitectureReq
    = ArchOnly (Set Arch)
    | ArchExcept (Set Arch)
    deriving (Eq, Ord, Read, Show)

prettyArchitectureReq :: ArchitectureReq -> Doc
prettyArchitectureReq (ArchOnly arch) = text " [" <> mconcat (List.map prettyArch (toList arch)) <> text "]"
prettyArchitectureReq (ArchExcept arch) = text " [" <> mconcat (List.map ((text "!") <>) (List.map prettyArch (toList arch))) <> text "]"

data VersionReq
    = SLT DebianVersion
    | LTE DebianVersion
    | EEQ  DebianVersion
    | GRE  DebianVersion
    | SGR DebianVersion
      deriving (Eq, Read, Show)

prettyVersionReq :: VersionReq -> Doc
prettyVersionReq (SLT v) = text " (<< " <> prettyDebianVersion v <> text ")"
prettyVersionReq (LTE v) = text " (<= " <> prettyDebianVersion v <> text ")"
prettyVersionReq (EEQ v) = text " (= " <> prettyDebianVersion v <> text ")"
prettyVersionReq (GRE v) = text " (>= " <> prettyDebianVersion v <> text ")"
prettyVersionReq (SGR v) = text " (>> " <> prettyDebianVersion v <> text ")"

-- |The sort order is based on version number first, then on the kind of
-- relation, sorting in the order <<, <= , ==, >= , >>
instance Ord VersionReq where
    compare = compare `on` extr
      where extr (SLT v) = (v,0 :: Int)
            extr (LTE v) = (v,1 :: Int)
            extr (EEQ v) = (v,2 :: Int)
            extr (GRE v) = (v,3 :: Int)
            extr (SGR v) = (v,4 :: Int)

-- |Check if a version number satisfies a version requirement.
checkVersionReq :: Maybe VersionReq -> Maybe DebianVersion -> Bool
checkVersionReq Nothing _ = True
checkVersionReq _ Nothing = False
checkVersionReq (Just (SLT v1)) (Just v2) = v2 < v1
checkVersionReq (Just (LTE v1)) (Just v2) = v2 <= v1
checkVersionReq (Just (EEQ v1)) (Just v2) = v2 == v1
checkVersionReq (Just (GRE v1)) (Just v2) = v2 >= v1
checkVersionReq (Just (SGR v1)) (Just v2) = v2 > v1

instance Pretty BinPkgName where
    pretty = pretty . unBinPkgName

instance Pretty SrcPkgName where
    pretty = pretty . unSrcPkgName

instance Pretty Relations where
    pretty = prettyRelations

instance Pretty OrRelation where
    pretty = prettyOrRelation

instance Pretty Relation where
    pretty = prettyRelation

instance Pretty VersionReq where
    pretty = prettyVersionReq

instance Pretty ArchitectureReq where
    pretty = prettyArchitectureReq