package main

import (
  "os"
  "image"
  "log"
  "image/png"
  "github.com/disintegration/gift"
  "lcthw.dev/go/jankifier/filters"
)

func LoadImage(filename string) image.Image {
  reader, err := os.Open(filename)
  if err != nil { log.Fatal(err) }
  defer reader.Close()

  img, _, err := image.Decode(reader)
  if err != nil { log.Fatal(err) }

  return img
}

func SaveImage(filename string, img image.Image) {
  out, err := os.Create(filename)
  if err != nil {
    log.Fatalf("can't write file %s: %v", filename, err)
  }
  defer out.Close()

  err = png.Encode(out, img)
  if err != nil {
    log.Fatalf("can't png encode %s: %v", filename, err)
  }
}

func JankImage(settings Conversion, in_file string, out_file string) {
  src := LoadImage(in_file)
  bounds := src.Bounds()

  resize := gift.Resize(bounds.Max.X / settings.PixelWidth, 0, gift.NearestNeighborResampling)
  posterize := filters.Posterize(uint16(settings.ColorDepth), settings.DitherType)
  upscale := filters.Upscale(bounds, settings.PixelWidth)
  sharpen := gift.UnsharpMask(1, 1, 0)

  g := gift.New(resize, posterize, upscale, sharpen)
  out_img := image.NewNRGBA(g.Bounds(bounds))
  g.Draw(out_img, src)

  SaveImage(out_file, out_img)
}