module Projectile.Pellet ( Pellet(..)
                         , new
                         , range
                         ) where

import Combat ( Damaging(..), Damageable(..) )
import Animation ( Animation(..) )
import Updating
    ( Transient(..), SimpleTransient(..), InternallyUpdating(..) )
import Graphics.Gloss.Data.Picture ( Picture(Circle, Color) )
import Graphics.Gloss.Data.Color ( makeColor8 )
import Data.WrapAround ( WP, WM, distance )
import qualified Moving as M
    ( Moving(..), Locatable(..), Colliding(..), newLocation )
import Common ( Velocity, Angle )
import Math ( vecCoord, addV, zeroOrLess, moreThanZero )

velocityC = 600
rangeC = 300
punch = 0.3
range = rangeC

data Pellet = Pellet { velocity :: Velocity
                     , center :: WP
                     , rangeLeft :: Double
                     , wmap :: WM
                     , impacted :: Bool
                     }

-- angle is radians
new :: WM -> Angle -> WP -> Velocity -> Pellet
new a b c d =
  Pellet { velocity = addV (vecCoord b velocityC) d
         , center = c
         , rangeLeft = rangeC
         , wmap = a
         , impacted = False
         }

instance Animation Pellet where

  image _ _ = Color (makeColor8 172 172 172 255) (Circle 1)

instance M.Colliding Pellet where

  collisionRadius _ = 1

instance M.Moving Pellet where

  velocity = velocity

instance M.Locatable Pellet where

  center = center

expFormula s = impacted s || (zeroOrLess . rangeLeft) s

instance SimpleTransient Pellet where

  expired = expFormula

instance InternallyUpdating Pellet where

  preUpdate s t = s

  postUpdate s t =
    s { center = a
      , rangeLeft = max 0 (rangeLeft s - distance (wmap s) (center s) a)
      }

    where a = M.newLocation (wmap s) (center s) (velocity s) t

instance Damaging Pellet where

  damageEnergy b = punch

instance Transient Pellet where

  expired' s = if expFormula s then Just [] else Nothing

instance Damageable Pellet where

  inflictDamage s d = if moreThanZero d then s { impacted = True } else s