package gioui

import (
	"fmt"
	"image"
	"image/color"

	"github.com/vsariola/sointu/tracker"
	"golang.org/x/exp/shiny/materialdesign/icons"

	"gioui.org/font"
	"gioui.org/op/clip"
	"gioui.org/op/paint"
	"gioui.org/widget"
	"gioui.org/x/component"

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

type NumberInput struct {
	Int            tracker.Int
	dragStartValue int
	dragStartXY    float32
	clickDecrease  gesture.Click
	clickIncrease  gesture.Click
	tipArea        component.TipArea
}

type NumericUpDownStyle struct {
	NumberInput     *NumberInput
	Color           color.NRGBA
	Font            font.Font
	TextSize        unit.Sp
	BorderColor     color.NRGBA
	IconColor       color.NRGBA
	BackgroundColor color.NRGBA
	CornerRadius    unit.Dp
	Border          unit.Dp
	ButtonWidth     unit.Dp
	UnitsPerStep    unit.Dp
	Tooltip         component.Tooltip
	Width           unit.Dp
	Height          unit.Dp
	shaper          text.Shaper
}

func NewNumberInput(v tracker.Int) *NumberInput {
	return &NumberInput{Int: v}
}

func NumericUpDown(th *material.Theme, number *NumberInput, tooltip string) NumericUpDownStyle {
	bgColor := th.Palette.Fg
	bgColor.R /= 4
	bgColor.G /= 4
	bgColor.B /= 4
	return NumericUpDownStyle{
		NumberInput:     number,
		Color:           white,
		BorderColor:     th.Palette.Fg,
		IconColor:       th.Palette.ContrastFg,
		BackgroundColor: bgColor,
		CornerRadius:    unit.Dp(4),
		ButtonWidth:     unit.Dp(16),
		Border:          unit.Dp(1),
		UnitsPerStep:    unit.Dp(8),
		TextSize:        th.TextSize * 14 / 16,
		Tooltip:         Tooltip(th, tooltip),
		Width:           unit.Dp(70),
		Height:          unit.Dp(20),
		shaper:          *th.Shaper,
	}
}

func (s *NumericUpDownStyle) Layout(gtx C) D {
	if s.Tooltip.Text.Text != "" {
		return s.NumberInput.tipArea.Layout(gtx, s.Tooltip, s.actualLayout)
	}
	return s.actualLayout(gtx)
}

func (s *NumericUpDownStyle) actualLayout(gtx C) D {
	size := image.Pt(gtx.Dp(s.Width), gtx.Dp(s.Height))
	gtx.Constraints.Min = size
	rr := gtx.Dp(s.CornerRadius)
	border := gtx.Dp(s.Border)
	c := clip.UniformRRect(image.Rectangle{Max: gtx.Constraints.Min}, rr).Push(gtx.Ops)
	paint.Fill(gtx.Ops, s.BorderColor)
	c.Pop()
	off := op.Offset(image.Pt(border, border)).Push(gtx.Ops)
	c2 := clip.UniformRRect(image.Rectangle{Max: image.Pt(
		gtx.Constraints.Min.X-border*2,
		gtx.Constraints.Min.Y-border*2,
	)}, rr-border).Push(gtx.Ops)
	gtx.Constraints.Min.X -= int(border * 2)
	gtx.Constraints.Min.Y -= int(border * 2)
	gtx.Constraints.Max = gtx.Constraints.Min
	layout.Flex{Axis: layout.Horizontal, Alignment: layout.Middle}.Layout(gtx,
		layout.Rigid(s.button(gtx.Constraints.Max.Y, widgetForIcon(icons.NavigationArrowBack), -1, &s.NumberInput.clickDecrease)),
		layout.Flexed(1, s.layoutText),
		layout.Rigid(s.button(gtx.Constraints.Max.Y, widgetForIcon(icons.NavigationArrowForward), 1, &s.NumberInput.clickIncrease)),
	)
	off.Pop()
	c2.Pop()
	return layout.Dimensions{Size: size}
}

func (s *NumericUpDownStyle) button(height int, icon *widget.Icon, delta int, click *gesture.Click) layout.Widget {
	return func(gtx C) D {
		width := gtx.Dp(s.ButtonWidth)
		return layout.Background{}.Layout(gtx,
			func(gtx C) D {
				if icon != nil {
					return icon.Layout(gtx, s.IconColor)
				}
				return layout.Dimensions{Size: image.Point{X: width, Y: height}}
			},
			func(gtx C) D {
				gtx.Constraints = layout.Exact(image.Pt(width, height))
				return s.layoutClick(gtx, delta, click)
			})
	}
}

func (s *NumericUpDownStyle) layoutText(gtx C) D {
	return layout.Background{}.Layout(gtx,
		func(gtx C) D {
			paint.FillShape(gtx.Ops, s.BackgroundColor, clip.Rect(image.Rect(0, 0, gtx.Constraints.Max.X, gtx.Constraints.Max.Y)).Op())
			paint.ColorOp{Color: s.Color}.Add(gtx.Ops)
			return widget.Label{Alignment: text.Middle}.Layout(gtx, &s.shaper, s.Font, s.TextSize, fmt.Sprintf("%v", s.NumberInput.Int.Value()), op.CallOp{})
		},
		func(gtx C) D {
			gtx.Constraints.Min = gtx.Constraints.Max
			return s.layoutDrag(gtx)
		})
}

func (s *NumericUpDownStyle) layoutDrag(gtx layout.Context) layout.Dimensions {
	{ // handle dragging
		pxPerStep := float32(gtx.Dp(s.UnitsPerStep))
		for {
			ev, ok := gtx.Event(pointer.Filter{
				Target: s.NumberInput,
				Kinds:  pointer.Press | pointer.Drag | pointer.Release,
			})
			if !ok {
				break
			}
			if e, ok := ev.(pointer.Event); ok {
				switch e.Kind {
				case pointer.Press:
					s.NumberInput.dragStartValue = s.NumberInput.Int.Value()
					s.NumberInput.dragStartXY = e.Position.X - e.Position.Y

				case pointer.Drag:
					var deltaCoord float32
					deltaCoord = e.Position.X - e.Position.Y - s.NumberInput.dragStartXY
					s.NumberInput.Int.Set(s.NumberInput.dragStartValue + int(deltaCoord/pxPerStep+0.5))
				}
			}
		}

		// Avoid affecting the input tree with pointer events.
		stack := op.Offset(image.Point{}).Push(gtx.Ops)
		// register for input
		dragRect := image.Rect(0, 0, gtx.Constraints.Min.X, gtx.Constraints.Min.Y)
		area := clip.Rect(dragRect).Push(gtx.Ops)
		event.Op(gtx.Ops, s.NumberInput)
		area.Pop()
		stack.Pop()
	}
	return layout.Dimensions{Size: gtx.Constraints.Min}
}

func (s *NumericUpDownStyle) layoutClick(gtx layout.Context, delta int, click *gesture.Click) layout.Dimensions {
	// handle clicking
	for {
		ev, ok := click.Update(gtx.Source)
		if !ok {
			break
		}
		switch ev.Kind {
		case gesture.KindClick:
			s.NumberInput.Int.Add(delta)
		}
	}
	// Avoid affecting the input tree with pointer events.
	stack := op.Offset(image.Point{}).Push(gtx.Ops)

	// register for input
	clickRect := image.Rect(0, 0, gtx.Constraints.Min.X, gtx.Constraints.Min.Y)
	area := clip.Rect(clickRect).Push(gtx.Ops)
	click.Add(gtx.Ops)
	area.Pop()
	stack.Pop()
	return layout.Dimensions{Size: gtx.Constraints.Min}
}