-----------------------------------------------------------------------------
--
-- Module      :  DCB
-- Copyright   :
-- License     :  AllRightsReserved
--
-- Maintainer  :
-- Stability   :
-- Portability :
--
-- |
--
-----------------------------------------------------------------------------

module DCB where

--import Stream hiding (map) --same as Data.Stream imported above?
import Data.Array.Accelerate (Z(..), DIM0, DIM1, DIM2, DIM3, Scalar, Vector, (:.)(..), Array,(!),
    Int8, Int, Float, Double, Acc, Exp, Elt)
import qualified Data.Array.Accelerate as A
-- change to Data.Array.Accelerate.CUDA as I and link accelerate-cuda to use GPU instead of CPU
-- depends on accelerate-cuda package in cabal, which needs the installed CUDA-stuff form
-- nVidia (nvcc, header-files, ...) and the propriatary driver
import Data.Array.Accelerate.Interpreter as I
type Matrix e = Array DIM2 e

type Attr  = Matrix Double
-- Adjecency-Matrix
type Adj   = Matrix Int8
-- Vector of the Adjecency-Matrix
type AdjV  = Vector Int
newtype Constraints = Matrix Double
-- Graph consists of a Vector denoting which colums of the matrix represents wich originating
-- column in the global adjencency-matrix, the reduces adjencency-matrix of the graph, a
-- matrix of constraints and a scalar denoting the density
type Density = Scalar Double

-- Graph
type Graph = (Vector Int, Adj, Constraints, Density)

-- Vector of Graphs
type MultiGraph e = (Vector Int, Array DIM3 e, Constraints, Density)

-- Multigraph correct output ?
preprocess :: Acc (Matrix Int8) -> Acc Attr -> Acc (MultiGraph Int8)
preprocess adj a = undefined

{--
createConstrMat :: Acc Attr -> Acc (Vector Int) -> Acc (Vector double) -> Acc (Matrix Double)
createConstrMat attr maxDist nodes =
    let
        (Z:._:.nAttr) = arrayShape attr
    in generate (Z:.nAttr:.3) (initConsrMat attr nodes) >-> {-- calculate first column --}
--}

-- generate function for initialising the constraints matrix of a subgraph
-- first column contains minimum value of each attribute, second column contains maximum value
-- zeroth column contains 0 after initialisation (should contain 1 if constraints are fulfilled
-- afterwards)
initConstrMat :: Acc Attr -> Acc (Vector Int) -> Exp DIM2 -> Exp Double
initConstrMat attr nodes ix =
    let
        (Z:.idAttr:.col) = A.unlift ix :: ((:.) ((:.) Z (Exp Int)) (Exp Int))
    in case col of
            1 -> A.the $A.minimum (A.map (\i -> attr!(A.index2 i idAttr)) nodes)
            2 -> A.the $A.maximum (A.map (\i -> attr!(A.index2 i idAttr)) nodes)
            _ -> 0.0

expand :: Acc (MultiGraph Int8)-> Acc Adj -> Acc Attr -> Acc (MultiGraph Int8)
expand g a att = undefined

-- constraint gets a Graph and an Attribute-Matrix and yields true, if the Graph still fulfills
-- all constraints defined via the Attribute-Matrix.
--constraint :: Acc Graph -> Acc Attr -> Acc (Scalar Bool)
constraint :: Acc Graph -> Int -> Acc Attr -> Acc (Maybe Graph)
constraint g newNode a = undefined


-- addPoint gets a graph and a tuple of an adjecancy-Vector with an int wich column of the
-- Adjacency-Matrix the Vector should represent to generate further Graphs
addPoint :: Acc Graph -> Acc (Adj, (Scalar Int)) -> Acc (MultiGraph Int8)
addPoint g a = undefined


-- addablePoints yields all valid addititons to a Graph
addablePoints :: Acc Adj -> Acc Graph-> Acc (Vector Int8)
addablePoints a g = undefined