import           Data.NonEmptyList (NonEmptyList)
import qualified Data.NonEmptyList as NonEmptyList

import           Data.IntMap  (IntMap)
import qualified Data.IntMap  as IMap
import           Data.NonEmptyList  (NonEmptyList)
import qualified Data.NonEmptyList  as NonEmptyList

import           Location

import           Location

type Index = [IndexItem]

type Index = IntMap IndexItem

empty = []

empty = IMap.empty

singleton x y = [IndexItem (x, NonEmptyList.singleton y)]

singleton x y = IMap.singleton (x ^. volume & fromVolume) (IndexItem (x, NonEmptyList.singleton y))

addLocation primer location [] = [IndexItem (primer, NonEmptyList.singleton location)]
addLocation primer@(Primer {_volume = vol'}) location (x@(IndexItem (Primer {_volume = vol}, _)):xs)
    | vol == vol' = (x & _IndexItem . _2 %~ NonEmptyList.push location):xs
    | otherwise = x:addLocation primer location xs

addLocation primer location map =
    let vol = fromVolume $ primer ^. volume
        f (IndexItem (p, ls)) (IndexItem (_, ls')) = IndexItem (p, NonEmptyList.merge ls ls')
        in IMap.insertWith f vol (IndexItem (primer, NonEmptyList.singleton location)) map

toDoc mod = vsep . map (mod . indexItemToDoc)

toDoc mod = vsep . map (mod . indexItemToDoc) . IMap.elems