package com.mobimeo.gtfs

import cats.effect._
import java.nio.file.Paths
import com.mobimeo.gtfs.model.Stop
import org.locationtech.jts.geom.Coordinate
import org.locationtech.jts.algorithm.ConvexHull
import org.locationtech.jts.geom.GeometryFactory
import org.locationtech.jts.io.geojson._

object HullMain extends IOApp {
  def run(args: List[String]): IO[ExitCode] =
    args match {
      case file :: result :: _ =>
        Blocker[IO].use { blocker =>
          Gtfs[IO](Paths.get(file), blocker).use { gtfs =>
            gtfs.read
              .stops[Stop]
              .collect {
                case Stop(_, _, _, _, Some(lat), Some(lon), _, _, _, _, _, _, _, _) =>
                  new Coordinate(lon, lat)
              }
              .compile
              .to(Array)
              .flatMap { coordinates =>
                val factory = new GeometryFactory
                val writer  = new GeoJsonWriter
                val hull    = new ConvexHull(coordinates, factory)
                val geojson = writer.write(hull.getConvexHull())
                fs2.Stream
                  .emit(geojson)
                  .covary[IO]
                  .through(fs2.text.utf8Encode)
                  .through(fs2.io.file.writeAll(Paths.get(result), blocker))
                  .compile
                  .drain
              }
              .as(ExitCode.Success)
          }
        }
      case _ =>
        IO(println("Files expected")).as(ExitCode.Error)
    }
}