content: module Community where
  
  import Cell
  import Graphics.Gloss
  
  type Community = [Cell]
  
  -- does a (newly spawned) cell fit in the community?
  -- that is, does it overlap with any others?
  fits :: Cell -> Community -> Bool
  fits cell cells = not $ any (overlap cell) cells
  
  -- For each member of a community, produce one offspring
  -- The lists of Floats are the (random) parameters that determine size
  
  -- and location of each offspring.
  spawn :: Community -> [Float] -> [Float] -> [Int] -> [Cell]
  spawn = zipWith4 offspring
  
  zipWith4 :: (a -> b -> c -> d -> e) -> [a] -> [b] -> [c] -> [d] -> [e]
  zipWith4 f [] _ _ _ = []
  zipWith4 f _ [] _ _ = []
  zipWith4 f _ _ [] _ = []
  zipWith4 f _ _ _ [] = []
  zipWith4 f (b:bs) (c:cs) (d:ds) (e:es) =
      f b c d e : zipWith4 f bs cs ds es
  
  
  -- Given a collection of cells (one spawned by each member of the
  -- community) check if it fits, and if so add it to the community.
  -- That check must include new cells that have been added to the
  -- community in this process.
  survive :: [Cell] -> Community -> Community
  survive [] comm = comm
  survive (cell:cells) comm
      | fits cell comm  = survive cells (cell:comm)
      | otherwise       = survive cells comm
  
  age :: Community -> Community
  age [] = []
  age (Cell c r 0 : cells) = age cells
  age (Cell c r life : cells) = Cell c r (life-1) : age cells
  
  
  -- The next generation of a community
  generation :: Community ->  [Float] -> [Float] -> Community
  generation comm angles scales =
      survive (spawn comm angles scales (repeat 5)) (age comm)
  
  render :: Community -> Picture
  render comm
          = Pictures
          $ map Cell.render comm
  
  initial :: Community
  initial = [Cell (0,0) 50 5]
  
  
  