// +build darwin linux

package main

import (
	"log"
	"image/color"

	"gioui.org/ui"
	"gioui.org/ui/app"
	"gioui.org/ui/layout"
	"gioui.org/ui/measure"
	"gioui.org/ui/text"

	"golang.org/x/image/font/sfnt"
	"golang.org/x/image/font/gofont/goregular"
)

var (
	face text.Face
	white = color.RGBA{A: 0xff, R: 0xff, G: 0xff, B: 0xff}
	gray = color.RGBA{A: 0xff, R: 0xb0, G: 0xb0, B: 0xb0}
	black = color.RGBA{A: 0xff, R: 0x00, G: 0x00, B: 0x00}

	labchan chan string
)

func main() {
	labchan = make(chan string)
	log.Print("Staring event loop")
	go eventloop()
	app.Main()
	log.Print("App closed")
}

func diffInsets(x, y app.Insets) bool {
	return  x.Top != y.Top ||
		x.Bottom != y.Bottom ||
		x.Left != y.Left ||
		x.Right != y.Right
}

func eventloop() {
	w := app.NewWindow(
		app.WithWidth(ui.Dp(400)),
		app.WithHeight(ui.Dp(400)),
		app.WithTitle("Hello"))
	q := w.Queue()
	var c ui.Config
	ops := new(ui.Ops)
	//var dims layout.Dimensions
	var cs layout.Constraints
	var faces measure.Faces

	regular, err := sfnt.Parse(goregular.TTF)
	if err != nil { log.Fatal("Cannot parse font.") }
	face = faces.For(regular, ui.Sp(16))

	sysinset := &layout.Inset{}
	margin := layout.UniformInset(ui.Dp(10))
	labels := []*text.Label{}
	list := &layout.List{Axis: layout.Vertical}

	resetSysinset := func(x app.Insets) {
		sysinset.Top = x.Top
		sysinset.Bottom = x.Bottom
		sysinset.Left = x.Left
		sysinset.Right = x.Right
	}

	for {
		select {
		case x := <-labchan:
			labels = append(labels,&text.Label{Face: face, Text: x})
		case e := <-w.Events():
			switch e := e.(type) {
			case app.DestroyEvent:
				return
			case app.UpdateEvent:
				c = &e.Config
				ops.Reset()
				faces.Reset(c)
				resetSysinset(e.Insets)
				cs = layout.RigidConstraints(e.Size)
				cs = sysinset.Begin(c, ops, cs)
				cs = margin.Begin(c, ops, cs)
				for list.Init(c, q, ops, cs, len(labels)); list.More(); list.Next() {
					list.End(labels[list.Index()].Layout(ops, list.Constraints()))
				}
				sysinset.End(margin.End(list.Layout()))
				w.Update(ops)
			}
		}
	}
}