package main

import (
    "time"

    "github.com/google/gxui"
    "github.com/google/gxui/drivers/gl"
    "github.com/google/gxui/gxfont"
    "github.com/google/gxui/math"
    "github.com/google/gxui/samples/flags"
)

var hello = []string {"Hi", "Ave", "Привет", "Salam", "Hola", "Shalom"}

func appMain(driver gxui.Driver) {
    theme := flags.CreateTheme(driver)

    font, err := driver.CreateFont(gxfont.Default, 75)
    if err != nil {
        panic(err)
    }

    window := theme.CreateWindow(380, 100, "Hi")
    window.SetBackgroundBrush(gxui.CreateBrush(gxui.Gray50))

    label := theme.CreateLabel()
    label.SetFont(font)
    label.SetText("Hello world")

    window.AddChild(label)

    tickerSecond := time.NewTicker(time.Millisecond * 30)
    go func() {
        phase := float32(0)
        i := 0
        for range tickerSecond.C {
            a := 0.50 + 0.50*math.Cosf(phase * 10)
            c := gxui.Color{
                R: 0.75 + 0.25*math.Cosf((phase+0.000)*math.TwoPi),
                G: 0.75 + 0.25*math.Cosf((phase+0.333)*math.TwoPi),
                B: 0.75 + 0.25*math.Cosf((phase+0.666)*math.TwoPi),
                A: a,
            }

            if(a < 0.001){
                driver.Call(func() {
                    label.SetText(hello[i])
                })
                i++
                if(i == len(hello)){
                    i = 0
                }
            }
            phase += 0.01
            driver.Call(func() {
                label.SetColor(c)
            })
        }
    }()

    window.OnClose(tickerSecond.Stop)
    window.OnClose(driver.Terminate)
}

func main() {
    gl.StartDriver(appMain)
}