{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE ScopedTypeVariables #-}

module Crypto.Hash.KeccakSpec (spec) where

import Crypto.Hash.Keccak (hashKeccak256)
import Data.ByteArray (convert)
import qualified Data.ByteString as BS
import qualified Data.ByteString.Base16 as B16
import Test.Hspec
import Test.QuickCheck

-- Arbitrary instance for ByteString
instance Arbitrary BS.ByteString where
  arbitrary = BS.pack <$> arbitrary

spec :: Spec
spec = do
  describe "hashKeccak256" $ do
    it "produces correct hash for empty string" $ do
      let result = convert (hashKeccak256 "") :: BS.ByteString
          Right expected = B16.decode "c5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470"
      result `shouldBe` expected

    it "produces correct hash for 'hello'" $ do
      let result = convert (hashKeccak256 "hello") :: BS.ByteString
          Right expected = B16.decode "1c8aff950685c2ed4bc3174f3472287b56d9517b9c948127319a09a7a36deac8"
      result `shouldBe` expected

    it "produces correct hash for 'Hello, World!'" $ do
      let result = convert (hashKeccak256 "Hello, World!") :: BS.ByteString
          Right expected = B16.decode "acaf3289d7b601cbd114fb36c4d29c85bbfd5e133f14cb355c3fd8d99367964f"
      result `shouldBe` expected

    it "always produces 32 bytes" $ property $ \(bs :: BS.ByteString) ->
      let result = convert (hashKeccak256 bs) :: BS.ByteString
       in BS.length result == 32

    it "produces different hashes for different inputs" $ property $ \(x :: BS.ByteString, y :: BS.ByteString) ->
      x /= y ==>
        let hashX = convert (hashKeccak256 x) :: BS.ByteString
            hashY = convert (hashKeccak256 y) :: BS.ByteString
         in hashX /= hashY

    it "is deterministic" $ property $ \(bs :: BS.ByteString) ->
      let hash1 = convert (hashKeccak256 bs) :: BS.ByteString
          hash2 = convert (hashKeccak256 bs) :: BS.ByteString
       in hash1 == hash2