{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TypeApplications #-}
{-# LANGUAGE RankNTypes #-}

module Cursor.TextSpec
    ( spec
    ) where

import Test.Hspec
import Test.QuickCheck
import Test.Validity

import Control.Monad

import Cursor.Text
import Cursor.Text.Gen ()

spec :: Spec
spec = do
    eqSpec @TextCursor
    genValidSpec @TextCursor
    describe "emptyTextCursor" $ it "is valid" $ shouldBeValid emptyTextCursor
    describe "makeTextCursor" $
        it "produces valid list cursors" $ producesValidsOnValids makeTextCursor
    describe "makeTextCursorWithSelection" $
        it "produces valid list cursors" $
        producesValidsOnValids2 makeTextCursorWithSelection
    describe "rebuildTextCursor" $ do
        it "produces valid lists" $ producesValidsOnValids rebuildTextCursor
        it "is the inverse of makeTextCursor" $
            inverseFunctionsIfFirstSucceedsOnValid
                makeTextCursor
                rebuildTextCursor
        it "is the inverse of makeTextCursorWithSelection for any index" $
            forAllUnchecked $ \i ->
                inverseFunctionsIfFirstSucceedsOnValid
                    (makeTextCursorWithSelection i)
                    rebuildTextCursor
    describe "textCursorNull" $
        it "produces valid bools" $ producesValidsOnValids textCursorNull
    describe "textCursorLength" $
        it "produces valid ints" $ producesValidsOnValids textCursorLength
    describe "textCursorIndex" $
        it "produces valid indices" $ producesValidsOnValids textCursorIndex
    describe "textCursorSelectPrev" $ do
        it "produces valid cursors" $
            producesValidsOnValids textCursorSelectPrev
        it "is a movement" $ isMovementM textCursorSelectPrev
        it "selects the previous position" pending
    describe "textCursorSelectNext" $ do
        it "produces valid cursors" $
            producesValidsOnValids textCursorSelectNext
        it "is a movement" $ isMovementM textCursorSelectNext
        it "selects the next position" pending
    describe "textCursorSelectIndex" $ do
        it "produces valid cursors" $
            producesValidsOnValids2 textCursorSelectIndex
        it "is a movement" $
            forAllUnchecked $ \ix -> isMovement (textCursorSelectIndex ix)
        it "selects the position at the given index" pending
        it
            "produces a cursor that has the given selection for valid selections in the cursor" $
            forAllValid $ \tc ->
                forAll (choose (0, textCursorLength tc)) $ \i ->
                    textCursorIndex (textCursorSelectIndex i tc) `shouldBe` i
    describe "textCursorSelectStart" $ do
        it "produces valid cursors" $
            producesValidsOnValids textCursorSelectStart
        it "is a movement" $ isMovement textCursorSelectStart
        it "is idempotent" $ idempotent textCursorSelectStart
        it "selects the starting position" pending
    describe "textCursorSelectEnd" $ do
        it "produces valid cursors" $ producesValidsOnValids textCursorSelectEnd
        it "is a movement" $ isMovement textCursorSelectEnd
        it "is idempotent" $ idempotent textCursorSelectEnd
        it "selects the end position" pending
    describe "textCursorPrevChar" $ do
        it "produces valid items" $ producesValidsOnValids textCursorPrevChar
        it "returns the item before the position" pending
    describe "textCursorNextChar" $ do
        it "produces valid items" $ producesValidsOnValids textCursorNextChar
        it "returns the item after the position" pending
    describe "textCursorInsert" $ do
        it "produces valids" $
            forAllValid $ \d -> producesValidsOnValids (textCursorInsert d)
        it "inserts an item before the cursor" $ pending
    describe "textCursorAppend" $ do
        it "produces valids" $
            forAllValid $ \d -> producesValidsOnValids (textCursorAppend d)
        it "inserts an item after the cursor" $ pending
    describe "textCursorRemove" $ do
        it "produces valids" $ validIfSucceedsOnValid textCursorRemove
        it "removes an item before the cursor" $ pending
    describe "textCursorDelete" $ do
        it "produces valids" $ validIfSucceedsOnValid textCursorDelete
        it "removes an item before the cursor" $ pending
    describe "textCursorSplit" $ do
        it "produces valids" $ producesValidsOnValids textCursorSplit
        it
            "produces two list cursors that rebuild to the rebuilding of the original" $
            forAllValid $ \lc ->
                let (lc1, lc2) = textCursorSplit lc
                 in (rebuildTextCursor lc1 <> rebuildTextCursor lc2) `shouldBe`
                    rebuildTextCursor lc
    describe "textCursorCombine" $ do
        it "produces valids" $ producesValidsOnValids2 textCursorCombine
        it
            "produces a list that rebuilds to the rebuilding of the original two cursors" $
            forAllValid $ \lc1 ->
                forAllValid $ \lc2 ->
                    let lc = textCursorCombine lc1 lc2
                     in rebuildTextCursor lc `shouldBe`
                        (rebuildTextCursor lc1 <> rebuildTextCursor lc2)

isMovementM :: (TextCursor -> Maybe TextCursor) -> Property
isMovementM func =
    forAllValid $ \tc ->
        case func tc of
            Nothing -> pure () -- Fine
            Just tc' ->
                let t = rebuildTextCursor tc
                    t' = rebuildTextCursor tc'
                 in unless (t == t') $
                    expectationFailure $
                    unlines
                        [ "Cursor before:\n" ++ show tc
                        , "Text before:  \n" ++ show t
                        , "Cursor after: \n" ++ show tc'
                        , "Text after:   \n" ++ show t'
                        ]

isMovement :: (TextCursor -> TextCursor) -> Property
isMovement func =
    forAllValid $ \lec ->
        rebuildTextCursor lec `shouldBe` rebuildTextCursor (func lec)