module Waterfall.IO
(  writeSTL
, writeSTEP
) where 

import Waterfall.Internal.Solid (Solid(..))
import qualified OpenCascade.BRepMesh.IncrementalMesh as BRepMesh.IncrementalMesh
import qualified OpenCascade.StlAPI.Writer as StlWriter
import qualified OpenCascade.STEPControl.Writer as StepWriter
import qualified OpenCascade.STEPControl.StepModelType as StepModelType
import Control.Monad.IO.Class (liftIO)
import Control.Monad (void, unless)
import System.IO (hPutStrLn, stderr)
import Data.Acquire

-- | Write a `Solid` to a (binary) STL file at a given path
--
-- Because BRep representations of objects can store arbitrary precision curves,
-- but STL files store triangulated surfaces, 
-- this function takes a "deflection" argument used to discretize curves.
--
-- The deflection is the maximum allowable distance between a curve and the generated triangulation.
writeSTL :: Double -> FilePath -> Solid -> IO ()
writeSTL linDeflection filepath (Solid run) = (`withAcquire` pure) $ do
    s <- run
    mesh <- BRepMesh.IncrementalMesh.fromShapeAndLinDeflection s linDeflection
    liftIO $ BRepMesh.IncrementalMesh.perform mesh
    writer <- StlWriter.new
    liftIO $ do
            StlWriter.setAsciiMode writer False
            res <- StlWriter.write writer s filepath
            unless res (hPutStrLn stderr ("failed to write " <> filepath))
    return ()

-- | Write a `Solid` to a STEP file at a given path
--
-- STEP files can be imported by [FreeCAD](https://www.freecad.org/)
writeSTEP :: FilePath -> Solid -> IO ()
writeSTEP filepath (Solid run) = (`withAcquire` pure) $ do
    s <- run
    writer <- StepWriter.new
    _ <- liftIO $ StepWriter.transfer writer s StepModelType.Asls True
    void . liftIO $ StepWriter.write writer filepath