{-|
Module      : Unit.Smart.Saucer
Description : Flying saucer
Copyright   : (c) Christopher Howard, 2016
License     : GPL-3
Maintainer  : ch.howard@zoho.com
-}

module Unit.Smart.Saucer ( Saucer(..)
                       , new
                       ) where

import Prelude (Maybe(..), (>), max, (-), Bool(..), length, (+), (!!), (>=), (&&), (.), (<=), (/), abs, otherwise, (==), return, (*), (<), pi, Double, Int, not, ($))
import Data.WrapAround ( WP, WM, vectorRelation, distance )
import Graphics.Gloss.Data.Picture ( Picture(Color, Scale, Text) )
import Graphics.Gloss.Data.Color ( white )
import GHC.Float ( double2Float )
import Data.Maybe ( isNothing, fromMaybe, fromJust )
import Sound.ALUT ( Vertex3(Vertex3), HasSetter(($=)), SourceRelative(Listener), Source, ObjectName(genObjectNames), stop, sourceRelative, sourcePosition, rolloffFactor, referenceDistance, play, buffer )

import Animation
import Math
import ResourceTracker
import Updating
import qualified Moving as M ( Colliding(..), Moving(..), Locatable(..), newVelocity, newLocation )
import Combat
import qualified Projectile.Pellet as P.Pellet ( range, new )
import AfterEffect ( AfterEffect(AfterEffect) )
import qualified AfterEffect.SimpleExplosion as SimpleExplosion ( new )
import Universe ( Arena(lance) )
import qualified Universe as U ()
import Common


radialVelocity = pi -- radians per second

maxVelocityMag = 300

kamikazeDamage = 6.0

maxIntegrity = 1

accelerationRate = 300

adjAngle = pi / 8

shotDelay = 0.10

data Saucer = Saucer { angle :: Angle -- radians
                     , velocity :: Velocity
                     , center :: WP
                     , idealTargetLocation :: Maybe WP
                     , wrapMap :: WM
                     , launchTube :: [Projectile]
                     , sinceLastShot :: Time
                     , integrity :: Double
                     , vision :: Maybe Arena
                     , resourceTracker :: ResourceTracker
                     , firingAnglesIndex :: Int
    
                     -- Sound
                     , queueShotSound :: Bool
                     , shotSoundSource :: Maybe Source
                     }

instance Audible Saucer where

  processAudio self lcenter =
    do self' <- if isNothing (shotSoundSource self)
                  then initializeShotSoundSource self
                  else return self
       if not (queueShotSound self)
               then return self'
               else do let (x, y) = vectorRelation
                                      (wrapMap self)
                                      (lcenter)
                                      (center self)
                       let s = fromJust $ shotSoundSource self
                       sourcePosition s $= (Vertex3 (double2Float x)
                                                    (double2Float (-y))
                                                    0)
                       play [s]
                       return self' { queueShotSound = False }

  terminateAudio self =
    if isNothing (shotSoundSource self)
      then return self
      else do stop [fromJust (shotSoundSource self)]
              return self

initializeShotSoundSource self =
  do [source] <- genObjectNames 1
     buffer source $= getSound (resourceTracker self) "energy-shot-02.wav"
     -- ...
     sourceRelative source $= Listener
     referenceDistance source $= audioReferenceDistance
--     maxDistance source $= audioMaxDistance
     rolloffFactor source $= audioRolloffFactor
     return self { shotSoundSource = Just source }

new :: ResourceTracker
        -> WM
        -> WP
        -> Angle
        -> Saucer
new rt wmap center' angle' =
  Saucer { center = center'
         , angle = angle'
         , idealTargetLocation = Nothing
         , velocity = (0.0, 0.0)
         , wrapMap = wmap
         , launchTube = []
         , sinceLastShot = 0.0
         , integrity = maxIntegrity
         , vision = Nothing
         , resourceTracker = rt
         , firingAnglesIndex = 0

         , queueShotSound = False
         , shotSoundSource = Nothing
         }

instance Observant Saucer where

  updateVision self arena = self { vision = Just arena }

updateAngle t self
 = case vision self of
     Nothing -> self
     Just a -> case lance a of
                Nothing -> self
                Just l -> let sDir = angle self in
                          let sDir' = if sDir == 0.0 / 0.0
                                        then 0.1
                                        else sDir in
                          let tDir = vectorDirection
                                       (vectorRelation
                                         (wrapMap self)
                                         (center self)
                                         (M.center l)) in
                          let adj
                                | tDir - sDir' > adjAngle = radialVelocity * t
                                | tDir - sDir' < (-1) * adjAngle = (-radialVelocity) * t
                                | otherwise = 0.0 in
                          self { angle = angle self + adj }

updateVelocity :: Time -> Saucer -> Saucer
updateVelocity t self =
  let thrustingVelocity = M.newVelocity
                              (velocity self)
                              accelerationRate
                              (angle self)
                              maxVelocityMag
                              t in
  let velocity' = case vision self of
                    Nothing -> velocity self
                    Just a ->
                      case lance a of
                        Nothing -> velocity self
                        Just l -> let sDir = angle self in
                                  let sDir' = if sDir == 0.0 / 0.0
                                                then 0.1
                                                else sDir in
                                  let tDir = vectorDirection
                                               (vectorRelation
                                                 (wrapMap self)
                                                 (center self)
                                                 (M.center l)) in
                                  if abs (tDir - sDir') <= adjAngle
                                    then thrustingVelocity
                                    else velocity self in
  self { velocity = velocity' }

instance Animation Saucer where
  image self _ = fromMaybe
                   (Scale 0.20 0.20
                     (Color white
                     (Text "Error! Missing image!")))
                   (getImage rt "saucer.bmp")
    where rt = resourceTracker self

instance M.Locatable Saucer where
  center = center

instance M.Moving Saucer where
  velocity = velocity

instance M.Colliding Saucer where
  collisionRadius _ = 20.0

instance InternallyUpdating Saucer where

  preUpdate self t = (updateFiringInformation t
                        . updateIdealTargetLocation t
                        . updateVelocity t
                        . updateAngle t) self

  postUpdate self t =
    let center' = fromMaybe (center self) (idealTargetLocation self) in
    self { center = center'
         , idealTargetLocation = Nothing
         }

updateFiringInformation t self =
  let inRange = case vision self of
                  Nothing -> False
                  Just a -> case lance a of
                              Nothing -> False
                              Just l -> Data.WrapAround.distance
                                         (wrapMap self)
                                         (center self)
                                         (M.center l) <= P.Pellet.range in
  let sinceLastShot' = sinceLastShot self + t in
    if sinceLastShot' >= shotDelay && inRange
      then self { sinceLastShot = 0.0
                , launchTube = projectile : launchTube self
                , queueShotSound = True
                , firingAnglesIndex =
                    if firingAnglesIndex self >= length firingAngles - 1
                      then 0
                      else firingAnglesIndex self + 1
                }
      else self { sinceLastShot = sinceLastShot' }
  where projectile = Projectile
                       (P.Pellet.new
                         (wrapMap self)
                         pAngle
                         (center self)
                         (velocity self))
        pAngle = firingAngles !! firingAnglesIndex self
        firingAngles = [ 0.0
                       , 3.142
                       , 0.785
                       , 3.927
                       , 1.571
                       , 4.712
                       , 2.356
                       , 5.498
                       ]

updateIdealTargetLocation :: Time -> Saucer -> Saucer
updateIdealTargetLocation t self =
  self { idealTargetLocation = Just (M.newLocation (wrapMap self)
                                                        (center self)
                                                        (velocity self)
                                                        t)
        }

instance Launcher Saucer where

  deployProjectiles self = (launchTube self, self { launchTube = [] })

instance Transient Saucer where

  expired' self = if integrity self > 0.0
                    then Nothing
                    else Just [aeffect]
    where aeffect = AfterEffect (SimpleExplosion.new (resourceTracker self)
                                                     (wrapMap self)
                                                     (center self)
                                                     (velocity self))

instance Damageable Saucer where

  inflictDamage self d = self { integrity = max 0.0 (integrity self - d) }

instance Damaging Saucer where

  damageEnergy self = kamikazeDamage