{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE Rank2Types          #-}
module Naqsha.Geometry.Coordinate.GeoHashSpec where

import Data.Bits
import Data.Group
import Data.Monoid
import Data.String

import Test.Hspec
import Test.Hspec.QuickCheck

import Naqsha.Geometry
import Naqsha.Geometry.Coordinate.GeoHash as GeoHash
import Naqsha.Arbitrary()

approxEq :: Geo -> Geo -> Bool
approxEq (Geo x1 y1) (Geo x2 y2) = abs dx <= err && abs dy <= err
  where dx = fromEnum $ toAngle x1 <> invert (toAngle x2)
        dy = fromEnum $ toAngle y1 <> invert (toAngle y2)
        err = bit $ 64 - accuracy

spec :: Spec
spec = do
  prop "fromString . show = id"          $ \ (g :: GeoHash) -> (fromString  $ show g) `shouldBe` g
  prop "encode . decode  = id"           $ \ (g :: GeoHash) -> (encode $ decode g)    `shouldBe` g
  prop "decode . encode  = id (approx)"  $ \ (g :: Geo)     -> (decode $ encode g)    `approxEq` g