module Projectile.Cannon ( Cannon(..)
                            , new
                            , prj
                            ) where

import Combat ( Damageable(..), Damaging(..), Projectile(..) )
import Animation ( Animation(..) )
import Updating
    ( SimpleTransient(..), Transient(..), InternallyUpdating(..) )
import Graphics.Gloss.Data.Picture ( Picture(Circle, Color) )
import Graphics.Gloss.Data.Color ( cyan, blue )
import Data.WrapAround ( WP, WM, distance )
import qualified Moving as M
    ( Colliding(..), Moving(..), Locatable(..), newLocation )
import Common ( Velocity, Angle, Time )
import Math ( remF, appPair, zeroOrLess )
import GHC.Float ( double2Float )

velocityC = 500.0

rangeC = 800.0

integrityMax = 60.0

damE = 4

radiusC = 12.0

data Cannon =
  Cannon { velocity :: Velocity
         , center :: WP
         , rangeLeft :: Double
         , wrapMap :: WM
         , impacted :: Bool
         , clock :: Time
         , integrity :: Double
         }

new a b c (d, e) =
  Cannon { velocity = (x + d, y + e)
           , center = c
           , rangeLeft = rangeC
           , wrapMap = a
           , impacted = False
           , clock = 0.0
           , integrity = integrityMax
           }
  where (x, y) = appPair ((* velocityC) . ($ b)) (cos, sin)

instance Animation Cannon where

  image s t = (Color (c r) . Circle) (double2Float radiusC)
    where c x | x < 0.10 = blue
              | otherwise = cyan
          r = remF (clock s) 0.2

instance M.Colliding Cannon where

  collisionRadius _ = radiusC

instance M.Moving Cannon where

  velocity = velocity

instance M.Locatable Cannon where

  center = center

expirationFormula s = f rangeLeft || f integrity where f g = (zeroOrLess . g) s

instance SimpleTransient Cannon where

  expired = expirationFormula

instance InternallyUpdating Cannon where

  preUpdate s t = s { clock = clock s + t }

  postUpdate s t = s { center = a, rangeLeft = r }
    where a = M.newLocation (wrapMap s) (center s) (velocity s) t
          r = max 0 (rangeLeft s - distance (wrapMap s) (center s) a)

instance Damaging Cannon where

  damageEnergy _ = damE

instance Transient Cannon where

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

instance Damageable Cannon where

  inflictDamage s d = s { integrity = integrity s - d }

-- | Func abstracting construction of 'Cannon' projectile
prj :: (M.Moving a)
    => a -- ^ object receiving projectile
    -> (a -> WM) -- ^ func which retrieves WM from object
    -> Angle -- ^ firing angle
    -> Projectile
prj a f b = Projectile (new (f a) b (M.center a) (M.velocity a))