// SPDX-License-Identifier: Unlicense OR MIT

package main

// A simple Gio program. See https://gioui.org for more information.

import (
	"fmt"
	"log"
	"time"

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

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

func main() {
	go func() {
		w := app.NewWindow()
		if err := loop(w); err != nil {
			log.Fatal(err)
		}
	}()
	app.Main()
}

func loop(w *app.Window) error {
	regular, err := sfnt.Parse(goregular.TTF)
	if err != nil {
		panic("failed to load font")
	}
	var faces measure.Faces
	ops := new(ui.Ops)
	q := w.Queue()
	face := faces.For(regular, ui.Sp(16))
	lst := layout.List{Axis: layout.Vertical}
	for {
		e := <-w.Events()
		switch e := e.(type) {
		case app.DestroyEvent:
			return e.Err
		case app.UpdateEvent:
			stime := time.Now()
			c := e.Config
			ops.Reset()
			faces.Reset(&c)
			for lst.Init(&c, q, ops, layout.RigidConstraints(e.Size), 200); lst.More(); lst.Next() {
				lst.End(text.Label{Face: face, Text: fmt.Sprintf("label %d",lst.Index())}.Layout(ops, lst.Constraints()))
			}
			lst.Layout()
			w.Update(ops)
			log.Printf("Frame time: %s\n", time.Since(stime))
		}
	}
}