{--
let tl=tileFromLatLong 48.90 1.80 10
let tr=tileFromLatLong 48.90 2.62 10
let br=tileFromLatLong 48.70 2.70 10
let bl=tileFromLatLong 48.70 2.80 10

let max = tileFromLatLong 48.9031 2.5214 10
let min = tileFromLatLong 48.8146 2.1732 10

 [(x,[11266..11278]) | x <- [16581..16613]]

map (\(x,y) -> map (\y'-> "/15/" ++ show x ++ "/" ++ show y' ++ ".png") y) [(x,[11266..11278]) | x <- [16581..16613]]
map (\(x,y) -> map (\y'-> "http//http://tile.openstreetmap.org/" ++ show zlevel ++ "/" ++ show x ++ "/" ++ show y' ++ ".png") y) [(x,[11266..11278]) | x <- [16581..16613]]

--}

module HSlippyMap (
    Tile, tlat, tlong, tx, ty, tz,
    tilesFromBBox,
    tileFromLatLong,
    tileFromXY
) where

type Lat = Float
type Long = Float
type X = Integer
type Y = Integer
type ZLevel = Integer

data Tile = Tile {
  tlat :: Lat,
  tlong :: Long,
  tx :: X,
  ty :: Y,
  tz :: ZLevel } deriving (Read, Eq)

instance Show Tile where
  show (Tile lat long x y z) = "http://tile.openstreetmap.org/" ++ show z ++ "/" ++ show x ++ "/" ++ show y ++ ".png"

-- ajouter un test si z1 == z2 puis maybe
tilesFromBBox :: Tile -> Tile -> [Tile]
tilesFromBBox min max = concat $ map (\(x,y) -> map (\y'-> Tile (tlat min) (tlong min) x y' z) y) [(x,[(minimum [tymin, tymax])..(maximum [tymin,tymax])]) | x <- [(minimum [txmin, txmax])..(maximum [txmin, txmax])]]
    where
      txmax = tx max
      txmin = tx min
      tymax = ty min
      tymin = ty min     
      z = tz min

tileFromLatLong :: Lat -> Long -> ZLevel -> Tile
tileFromLatLong lat lon z = Tile lat lon x y z
    where
        x = long2tilex lon z
        y = lat2tiley lat z

tileFromXY :: X -> Y -> ZLevel -> Tile
tileFromXY x y z = Tile lat lon x y z
    where
        lat = tilex2long x z
        lon = tiley2lat y z

long2tilex lon z = floor((lon + 180) / 360 * (2** fromInteger z::Long))

lat2tiley lat z = floor((1.0 - log( tan(lat * pi/180.0) + 1.0 / cos(lat * pi/180.0)) / pi) / 2.0 * (2 ** fromInteger z::Long))

tilex2long x z = (fromInteger x::Long) / (2.0 ** fromInteger z::Long) * 360.0 - 180

tiley2lat y z = 180.0 / pi * atan(0.5 * (exp n - exp(-n)))
    where
        n = pi - 2.0 * pi * (fromInteger y::Long) / (2.0 ** fromInteger z::Long)