import scala.swing.Swing.pair2Dimension
import scala.swing.{ MainFrame, Panel, Rectangle }
import java.awt.{ Color, Graphics2D, geom }

object PlotCoordPairs extends scala.swing.SimpleSwingApplication {

  //min/max of display-x resp. y
  val (dx0, dy0) = (70, 30)
  val (dxm, dym) = (670, 430)

  val (prefSizeX, prefSizeY) = (720, 480)

  private def ui = new Panel {

    import math._
    val xmax = {
      val f1 = pow(10, log10(xs.max).toInt)
      val f2 = if (f1 < 10) 10 else round(xs.max / f1) * f1
      if (f2 >= xs.max) f2 else (round(xs.max / f1) + 1) * f1
    }
    val ymax = {
      val f1 = pow(10, log10(ys.max).toInt)
      val f2 = if (f1 < 10) 10 else round(ys.max / f1) * f1
      if (f2 >= ys.max) f2 else (round(ys.max / f1) + 1) * f1
    }

    val (xinterv, yinterv) = (xmax / xs.size, ymax / xs.size)

    case class Coord(x: Double, y: Double) {
      val (dx, dy) = ((x / xmax * (dxm - dx0) + dx0).toInt, (dym - y / ymax * (dym - dy0)).toInt)
    }

    val pcentre = Coord(0, 0)
    val pxmax = Coord(xmax, 0)
    val pymax = Coord(0, ymax)

    background = Color.white
    preferredSize = (prefSizeX, prefSizeY)

    //axes:
    val a_path = new geom.GeneralPath
    a_path.moveTo(pxmax.dx, pxmax.dy)
    a_path.lineTo(pcentre.dx, pcentre.dy) //x-axis
    a_path.lineTo(pymax.dx, pymax.dy) //y-axis
    // interval ticks:
    xs.map(i => Coord(i * xinterv, 0)).map(p => {
      a_path.moveTo(p.dx, p.dy)
      a_path.lineTo(p.dx, p.dy + 5)
    })
    xs.map(i => Coord(0, i * yinterv)).map(p => {
      a_path.moveTo(p.dx, p.dy)
      a_path.lineTo(p.dx - 5, p.dy)
    })

    //grid:
    val g_path = new geom.GeneralPath
    (1 to xs.size).
      map(i => Coord(i * xinterv, 0)).map(p => {
        g_path.moveTo(p.dx, p.dy);
        g_path.lineTo(Coord(p.x, ymax).dx, Coord(p.x, ymax).dy)
      })
    (1 to xs.size).map(i => Coord(0, i * yinterv)).map(p => {
      g_path.moveTo(p.dx, p.dy);
      g_path.lineTo(Coord(xmax, p.y).dx, Coord(xmax, p.y).dy)
    })

    //labeling:
    val xlabels = (0 to xs.size).map(i => {
      val p = Coord(i * xinterv, 0)
      Triple(p.x.toInt.toString, p.dx - 3, p.dy + 20)
    })
    val ylabels = (0 to xs.size).map(i => {
      val p = Coord(0, i * yinterv)
      Triple(p.y.toInt.toString, p.dx - 30, p.dy + 5)
    })

    //curve:
    val path = new geom.GeneralPath
    val curve = xs.map(i => Coord(xs(i), ys(i)))
    path.moveTo(curve.head.dx, curve.head.dy)
    curve.map(p => path.lineTo(p.dx, p.dy))
    //...flag all function values:
    val rects = curve.map(p => new Rectangle(p.dx - 3, p.dy - 3, 6, 6))

    override def paintComponent(g: Graphics2D) = {
      super.paintComponent(g)

      g.setColor(Color.lightGray)
      g.draw(g_path)
      g.setColor(Color.black)
      g.draw(a_path)
      xlabels.map(t => g.drawString(t._1, t._2, t._3))
      ylabels.map(t => g.drawString(t._1, t._2, t._3))
      g.draw(path)
      rects.map(g.draw(_))
    }
  }

  val xs = 0 to 9
  val ys: List[Double] = List(2.7, 2.8, 31.4, 38.1, 58.0, 76.2, 100.5, 130.0, 149.3, 180.0)

  def top = new MainFrame {
    title = "Rosetta Code >>> Task: Plot coordinate pairs | Language: Scala"
    contents = ui
  }
}