module Data.Text.ParagraphLayout.Internal.BiDiLevelsSpec where

import Data.Text (Text)
import Data.Text.Glyphize (Direction (DirLTR, DirRTL))

import Test.Hspec
import Data.Text.ParagraphLayout.Internal.BiDiLevels
import Data.Text.ParagraphLayout.RunLengthEncoding
import Data.Text.ParagraphLayout.TextData

-- | Test that `textLevels` produces the levels of the lengths given in
-- "Data.Text.ParagraphLayout.TextData" and values given here.
shouldHaveLevels :: (Direction, a, Text, [Int]) -> [Level] -> SpecWith ()
shouldHaveLevels (dir, _, text, runLens) runLevels = it description $
    actualLevels `shouldBe` runLengthDecode rls
    where
        TextLevels actualLevels _ = result
        result = textLevels dir text
        rls = zip runLens runLevels
        description = case rls of
            [] -> "should be empty"
            [(_, lvl)] -> "should all have level " ++ show lvl
            _ -> "should have multiple levels"

-- | Override the paragraph direction of sample data.
setDirection :: Direction -> (Direction, a, b, c) -> (Direction, a, b, c)
setDirection dir (_, a, b, c) = (dir, a, b, c)

-- | Override the paragraph direction of sample data to LTR.
setLTR :: (Direction, a, b, c) -> (Direction, a, b, c)
setLTR = setDirection DirLTR

-- | Override the paragraph direction of sample data to RTL.
setRTL :: (Direction, a, b, c) -> (Direction, a, b, c)
setRTL = setDirection DirRTL

spec :: Spec
spec = do

    describe "textLevels" $ do

        -- Empty input should produce empty output.
        -- Infinite list of level 0 is also acceptable.
        describe "on English input" $
            englishEmpty `shouldHaveLevels` []

        -- Empty input should produce empty output.
        -- Infinite list of level 1 is also acceptable.
        describe "on Arabic empty" $
            arabicEmpty `shouldHaveLevels` []

        -- All LTR text without numbers should always stay at the base level.
        describe "on English word in LTR" $
            setLTR englishWord `shouldHaveLevels` [0]

        -- All characters in a RTL paragraph must be at least at level 1.
        describe "on English word in RTL" $
            setRTL englishWord `shouldHaveLevels` [2]

        describe "on Arabic word in LTR" $
            setLTR arabicHello `shouldHaveLevels` [1]

        describe "on Arabic word in RTL" $
            setRTL arabicHello `shouldHaveLevels` [1]

        describe "on Serbian mixed script" $
            serbianMixedScript `shouldHaveLevels` [0]

        describe "on mixed direction with base LTR" $
            mixedDirectionSimple DirLTR `shouldHaveLevels` [0, 1, 0]

        describe "on mixed direction with base RTL" $
            mixedDirectionSimple DirRTL `shouldHaveLevels` [2, 1, 2]

        describe "on Arabic around English" $
            arabicAroundEnglish `shouldHaveLevels` [1, 2, 1, 2, 1]

        describe "on English around Arabic" $
            englishAroundArabic `shouldHaveLevels` [0, 1, 0]

        describe "on numbers in RTL run in LTR" $
            mixedDirectionNumbers `shouldHaveLevels` [0, 1, 2, 1]