package main

import (
	"image"
	"image/color"

	"gioui.org/gesture"
	"gioui.org/io/event"
	"gioui.org/layout"
	"gioui.org/op/clip"
	"gioui.org/op/paint"
	"gioui.org/text"
	"gioui.org/unit"
	"gioui.org/widget/material"
)

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

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

func (b *Overlay) Layout(gtx C) D {
	ins := layout.UniformInset(unit.Dp(1))
	return ins.Layout(gtx, func(gtx C) D {
		st := layout.Stack{}
		c2 := layout.Stacked(func(gtx C) D {
			l := material.Label(th, b.Size, b.Text)
			ins := layout.UniformInset(unit.Dp(4))
			l.Color = b.Color
			return ins.Layout(gtx, func(gtx C) D {
				return l.Layout(gtx)
			})
		})
		c1 := layout.Expanded(func(gtx C) D {
			return layoutRRect(b.Background, gtx)
		})
		return st.Layout(gtx, c1, c2)
	})
}

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

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

func layoutRRect(col color.NRGBA, gtx C) D {
	r := gtx.Dp(4)
	sz := image.Point{X: gtx.Constraints.Min.X, Y: gtx.Constraints.Min.Y}
	// Push the rounded-rect clip, paint, then restore the previous clip.
	stk := clip.UniformRRect(image.Rectangle{Max: sz}, r).Push(gtx.Ops)
	paint.ColorOp{Color: col}.Add(gtx.Ops)
	paint.PaintOp{}.Add(gtx.Ops)
	stk.Pop()
	return layout.Dimensions{Size: sz}
}

func (b *Button) Layout(gtx C) D {
	mwidth := gtx.Constraints.Min.X
	b.clicked = false
	ins := layout.UniformInset(unit.Dp(1))
	return ins.Layout(gtx, func(gtx C) D {
		st := layout.Stack{}
		c2 := layout.Stacked(func(gtx C) D {
			l := material.Label(th, b.Size, b.Label)
			l.Color = b.Color
			ins := layout.UniformInset(unit.Dp(4))
			ret := ins.Layout(gtx, func(gtx C) D {
				return l.Layout(gtx)
			})
			// Register the click handler for the label area.
			stk := clip.Rect(image.Rectangle{Max: ret.Size}).Push(gtx.Ops)
			event.Op(gtx.Ops, b)
			b.Click.Add(gtx.Ops)
			stk.Pop()
			for {
				ev, ok := b.Click.Update(gtx.Source)
				if !ok {
					break
				}
				if ev.Kind == gesture.KindClick {
					b.clicked = true
				}
			}
			return ret
		})
		c1 := layout.Expanded(func(gtx C) D {
			gtx.Constraints.Min.X = mwidth
			return layoutRRect(b.Background, gtx)
		})
		return st.Layout(gtx, c1, c2)
	})
}

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

func (b *SelButton) Toggle() {
	b.Selected = !b.Selected
	b.SelColor, b.Background = b.Background, b.SelColor
}

func (b *SelButton) Select() {
	if !b.Selected {
		b.Toggle()
	}
}

func (b *SelButton) Deselect() {
	if b.Selected {
		b.Toggle()
	}
}

func (b *SelButton) Clicked() bool {
	if b.clicked {
		b.Toggle()
		return true
	} else {
		return false
	}
}