package filters

import (
  "image"
  "image/draw"
  "image/color"
  "github.com/disintegration/gift"
)

type UpscaleFilter struct {
  Size image.Rectangle
  PixelWidth int
}

func Upscale(size image.Rectangle, width int) gift.Filter {
  return UpscaleFilter{size, width}
}

func (filter UpscaleFilter) Bounds(src image.Rectangle) (dst_bounds image.Rectangle) {
  return filter.Size
}

func (filter UpscaleFilter) Draw(dst draw.Image, src image.Image, _ *gift.Options) {
  var from_x, from_y int
  var from color.Color
  bounds := filter.Size

  for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
    for x := bounds.Min.X; x < bounds.Max.X; x++ {
      if x % filter.PixelWidth == 0 {
        from_x = x / filter.PixelWidth
        from_y = y / filter.PixelWidth
        from = src.At(from_x, from_y)
      }

      dst.Set(x, y, from)
    }
  }
}