module Data.Text.ParagraphLayout.Internal.Rich (layoutRich)
where

import Control.Applicative (ZipList (ZipList), getZipList)
import Data.List.NonEmpty (nonEmpty)
import qualified Data.List.NonEmpty as NonEmpty
import Data.Text (Text)
import Data.Text.ICU (Breaker, LocaleName, breakCharacter, breakLine)

import Data.Text.ParagraphLayout.Internal.Break
import Data.Text.ParagraphLayout.Internal.Fragment
import Data.Text.ParagraphLayout.Internal.Layout
import Data.Text.ParagraphLayout.Internal.ParagraphOptions
import qualified Data.Text.ParagraphLayout.Internal.ResolvedSpan as RS
import Data.Text.ParagraphLayout.Internal.Rich.Paragraph
import Data.Text.ParagraphLayout.Internal.Rich.ParagraphLayout
import Data.Text.ParagraphLayout.Internal.Run
import Data.Text.ParagraphLayout.Internal.TextOptions
import Data.Text.ParagraphLayout.Internal.Tree
import Data.Text.ParagraphLayout.Internal.WithSpan

-- | Lay out a rich text paragraph.
layoutRich :: Paragraph d -> ParagraphLayout d
layoutRich p@(Paragraph _ _ _ opts) = paragraphLayout $ map unwrap frags
    where
        unwrap (WithSpan rs frag) =
            frag { fragmentUserData = RS.spanUserData rs }
        frags = case nonEmpty wrappedRuns of
            Just xs -> layoutAndAlignLines maxWidth xs
            Nothing -> []
        wrappedRuns = spansToRunsWrapped spans
        maxWidth = paragraphMaxWidth opts
        spans = resolveSpans p

-- | Split a number of spans into a flat array of runs and add a wrapper
-- so that each run can be traced back to its originating span.
spansToRunsWrapped :: [RS.ResolvedSpan d] -> [WithSpan d Run]
spansToRunsWrapped ss = concat $ map spanToRunsWrapped ss

-- | Split a span into runs and add a wrapper
-- so that each run can be traced back to its originating span.
spanToRunsWrapped :: RS.ResolvedSpan d -> [WithSpan d Run]
spanToRunsWrapped s = map (WithSpan s) (spanToRuns s)

resolveSpans :: Paragraph d -> [RS.ResolvedSpan d]
resolveSpans p@(Paragraph _ pStart root _) = do
    let leaves = flatten root
    let sTexts = paragraphSpanTexts p
    let sBounds = paragraphSpanBounds p
    let sStarts = NonEmpty.init sBounds
    let pText = paragraphText p

    (i, leaf, sStart, sText) <- getZipList $ (,,,)
        <$> ZipList [0 ..]
        <*> ZipList leaves
        <*> ZipList sStarts
        <*> ZipList sTexts
    let (TextLeaf userData _ textOpts _) = leaf
    let lang = textLanguage textOpts
    let lBreaks = paragraphBreaks breakLine pText lang
    let cBreaks = paragraphBreaks breakCharacter pText lang
    return RS.ResolvedSpan
        { RS.spanUserData = userData
        , RS.spanIndex = i
        , RS.spanOffsetInParagraph = sStart - pStart
        -- TODO: Consider adding checks for array bounds.
        , RS.spanText = sText
        , RS.spanTextOptions = textOpts
        , RS.spanLineBreaks = subOffsetsDesc (sStart - pStart) lBreaks
        , RS.spanCharacterBreaks = subOffsetsDesc (sStart - pStart) cBreaks
        }

paragraphBreaks :: (LocaleName -> Breaker a) -> Text -> String -> [(Int, a)]
paragraphBreaks breakFunc txt lang =
    breaksDesc (breakFunc (locale lang LBAuto)) txt