{-# LANGUAGE OverloadedLists #-}
module Pokemon.Stats (
      Proto(..)
    , Stat
    , Stats
    , attack
    , defense
    , speed
    , precision
    , specialAttack
    , specialDefense
    , index
    , get
    , modify
  ) where

import Data.Vector (Vector, (!), (//))

newtype Stat = Stat Int

attack :: Stat
attack = Stat 0

defense :: Stat
defense = Stat 1

speed :: Stat
speed = Stat 2

precision :: Stat
precision = Stat 3

specialAttack :: Stat
specialAttack = Stat 4

specialDefense :: Stat
specialDefense = Stat 5

data Proto = Proto {
      attack_ :: Int
    , defense_ :: Int
    , speed_ :: Int
    , precision_ :: Int
    , specialAttack_ :: Int
    , specialDefense_ :: Int
  }

newtype Stats = Stats (Vector Int)

index :: Proto -> Stats
index proto = Stats [
      (attack_ proto)
    , (defense_ proto)
    , (speed_ proto)
    , (precision_ proto)
    , (specialAttack_ proto)
    , (specialDefense_ proto)
  ]

get :: Stats -> Stat -> Int
get (Stats v) (Stat s) = v ! s

modify :: Stat -> (Int -> Int) -> Int -> Stats -> Maybe Stats
modify stat@(Stat s) f threshold stats@(Stats v) =
  let result = f $ stats `get` stat in
  if result < threshold
    then Nothing
    else Just . Stats $ v // [(s, result)]