-- paste into a GameSlot

-- create as many waves as you want
-- CHALLENGE:  use List.range and List.map to create many rows of waves, each one getting smaller
-- CHALLENGE^2:  add flying fish!

myShapes model = [ manyWaves (rgb 0 120 200) 13 10
                    |> move ( repeatDistance 10 10 0 model.time, 0 )
                    |> scale 0.9
                      -- ^^^ when we scale the waves in back down, we also scale down the speed, why???
                 , manyWaves (rgb 0 150 255) 13 10
                    |> move ( repeatDistance 10 10 0 model.time, -20 )
                 ]

-- we started with two waves created in the CurveCreator, as a model for ...
twoWaves = curve (-200,0) [Pull (-173,-40) (-100,0), Pull (-70,-38) (0,0), Pull (0,0) (0,-85), Pull (0,-86) (-201,-88) ]
  |> filled (rgb 0 150 255)
  |> move (100,0)
  
-- the manyWave function takes a colour, number of waves and a width and creates a single Bezier curve
-- with 2*numWaves 
manyWaves clr numWaves width =
  let
    -- Pulls along the top of the "water box"
    pulls = 
      -- step1:  create a list of points [-numWaves, ... -2,-1,0,1,2 ... numWaves]
      List.range -numWaves numWaves
      -- setp2:  turn each number into (x,y) coordinates of a point
        |> List.map ( \ idx -> (width * toFloat idx, 0) )
      -- step3:  turn each point into a pull
        |> List.map ( \ (x,y) -> Pull (x - 0.7 * width, y - width) (x,y) )
  in
    curve (-200,0) ( pulls ++ [ Pull ( 150, -90) (150,-90), Pull (-150,-90) (-150,-90) ] )
      |> filled clr

-- same old Msg type, update and initial model

type Msg = Tick Float GetKeyState

update msg model = case msg of
                     Tick t _ -> { time = t }

init = { time = 0 }

-- two functions from the Animation Slots

-- repeat an animation for a given duration
repeatDuration : Float -> Int -> Float -> Float -> Float
repeatDuration speed duration startPosition time =
  speed * (time - toFloat duration * toFloat (floor time // duration)) + startPosition

-- repeat an animation for a given distance
repeatDistance : Float -> Float -> Float -> Float -> Float
repeatDistance speed distance startPosition time =
  repeatDuration speed (round <| distance / speed) startPosition time