package main

import (
	"image"
	"image/color"

	"gioui.org/f32"
	"gioui.org/gesture"
	"gioui.org/io/pointer"
	"gioui.org/layout"
	"gioui.org/op"
	"gioui.org/op/paint"
	"gioui.org/text"
	"gioui.org/unit"
)

var (
	black    = color.RGBA{A: 0xff, R: 0, G: 0, B: 0}
	white    = color.RGBA{A: 0xff, R: 0xff, G: 0xff, B: 0xff}
	gray     = color.RGBA{A: 0xff, R: 0xf0, G: 0xf0, B: 0xf0}
	darkgray = color.RGBA{A: 0xff, R: 0xa0, G: 0xa0, B: 0xa0}
)

type Overlay struct {
	Size       unit.Value
	Text       string
	Click      gesture.Click
	Color      color.RGBA
	Background color.RGBA
	Alignment  text.Alignment
}

func (b *Overlay) Layout(gtx *layout.Context, family text.Family) {
	ins := layout.UniformInset(unit.Dp(1))
	ins.Layout(gtx, func() {
		st := layout.Stack{}
		c2 := st.Rigid(gtx, func() {
			l := text.Label{
				Size:      b.Size,
				Text:      b.Text,
				Alignment: b.Alignment,
			}
			ins := layout.UniformInset(unit.Dp(4))
			l.Material.Record(gtx.Ops)
			paint.ColorOp{Color: b.Color}.Add(gtx.Ops)
			l.Material.Stop()
			ins.Layout(gtx, func() {
				l.Layout(gtx, family)
			})
			pointer.RectAreaOp{image.Rect(0, 0, gtx.Dimensions.Size.X, gtx.Dimensions.Size.Y)}.Add(gtx.Ops)
		})
		c1 := st.Expand(gtx, func() {
			layoutRRect(b.Background, gtx)
		})
		st.Layout(gtx, c1, c2)
	})
}

type SelButton struct {
	Button
	SelColor color.RGBA
	Selected bool
}

type Button struct {
	Size       unit.Value
	Label      string
	Click      gesture.Click
	Color      color.RGBA
	Background color.RGBA
	Alignment  text.Alignment
	clicked    bool
}

func layoutRRect(col color.RGBA, gtx *layout.Context) {
	r := float32(gtx.Config.Px(unit.Dp(4)))
	sz := image.Point{X: gtx.Constraints.Width.Min, Y: gtx.Constraints.Height.Min}
	w, h := float32(sz.X), float32(sz.Y)
	rrect(gtx.Ops, w, h, r, r, r, r)
	paint.ColorOp{Color: col}.Add(gtx.Ops)
	paint.PaintOp{Rect: f32.Rectangle{Max: f32.Point{X: w, Y: h}}}.Add(gtx.Ops)
	gtx.Dimensions = layout.Dimensions{Size: sz}
}

// https://pomax.github.io/bezierinfo/#circles_cubic.
func rrect(ops *op.Ops, width, height, se, sw, nw, ne float32) {
	w, h := float32(width), float32(height)
	const c = 0.55228475 // 4*(sqrt(2)-1)/3
	var b paint.Path
	b.Begin(ops)
	b.Move(f32.Point{X: w, Y: h - se})
	b.Cube(f32.Point{X: 0, Y: se * c}, f32.Point{X: -se + se*c, Y: se}, f32.Point{X: -se, Y: se}) // SE
	b.Line(f32.Point{X: sw - w + se, Y: 0})
	b.Cube(f32.Point{X: -sw * c, Y: 0}, f32.Point{X: -sw, Y: -sw + sw*c}, f32.Point{X: -sw, Y: -sw}) // SW
	b.Line(f32.Point{X: 0, Y: nw - h + sw})
	b.Cube(f32.Point{X: 0, Y: -nw * c}, f32.Point{X: nw - nw*c, Y: -nw}, f32.Point{X: nw, Y: -nw}) // NW
	b.Line(f32.Point{X: w - ne - nw, Y: 0})
	b.Cube(f32.Point{X: ne * c, Y: 0}, f32.Point{X: ne, Y: ne - ne*c}, f32.Point{X: ne, Y: ne}) // NE
	b.End()
}

func (b *Button) Layout(gtx *layout.Context, family text.Family) {
	b.clicked = false
	for _, ev := range b.Click.Events(gtx) {
		if ev.Type == gesture.TypeClick {
			b.clicked = true
		}
	}
	ins := layout.UniformInset(unit.Dp(1))
	ins.Layout(gtx, func() {
		st := layout.Stack{}
		c2 := st.Rigid(gtx, func() {
			l := text.Label{
				Size:      b.Size,
				Text:      b.Label,
				Alignment: b.Alignment,
			}
			ins := layout.UniformInset(unit.Dp(4))
			//paint.ColorOp{Color: b.Color}.Add(ops)
			ins.Layout(gtx, func() {
				l.Layout(gtx, family)
			})
			pointer.RectAreaOp{image.Rect(0, 0, gtx.Dimensions.Size.X, gtx.Dimensions.Size.Y)}.Add(gtx.Ops)
			b.Click.Add(gtx.Ops)
		})
		c1 := st.Expand(gtx, func() {
			layoutRRect(b.Background, gtx)
		})
		st.Layout(gtx, c1, c2)
	})
}

func (b *Button) Clicked() bool {
	return b.clicked
}

func (b *SelButton) Clicked() bool {
	if b.clicked {
		b.Selected = !b.Selected
		b.SelColor, b.Background = b.Background, b.SelColor
		return true
	} else {
		return false
	}
}