package main

import (
	"image"
	"image/draw"
	"os"

	"github.com/faiface/gui"

	_ "image/gif"
	_ "image/jpeg"
	_ "image/png"

	_ "golang.org/x/image/bmp"
)

func Viewer(env gui.Env, theme *Theme, view <-chan string) {
	redraw := func(r image.Rectangle, img image.Image) func(draw.Image) image.Rectangle {
		return func(drw draw.Image) image.Rectangle {
			draw.Draw(drw, r, &image.Uniform{theme.Empty}, image.ZP, draw.Src)
			DrawCentered(drw, r, img, draw.Over)
			return r
		}
	}

	invalid := DrawText("Invalid image", theme.Face, theme.Text)

	var (
		r   image.Rectangle
		img image.Image
	)

	for {
		select {
		case path := <-view:
			func() {
				f, err := os.Open(path)
				if err != nil {
					img = invalid
					return
				}
				defer f.Close()
				img, _, err = image.Decode(f)
				if err != nil {
					img = invalid
					return
				}
			}()
			env.Draw() <- redraw(r, img)

		case e, ok := <-env.Events():
			if !ok {
				close(env.Draw())
				return
			}

			var minX, minY, maxX, maxY int
			switch {
			case e.Matches("resize/%d/%d/%d/%d", &minX, &minY, &maxX, &maxY):
				r = image.Rect(minX, minY, maxX, maxY)
				env.Draw() <- redraw(r, img)
			}
		}
	}
}