package giowrap

import (
	"image"
	"image/color"
	//"log"
	"sync"

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

	"gioui.org/ui/f32"
	"gioui.org/ui/gesture"
	"gioui.org/ui/paint"
	"gioui.org/ui/pointer"
)

type Extra struct {
	cur, max int
	sync.Mutex
	data []interface{}
}

var extra Extra

func (e *Extra) New() int {
	e.Lock()
	if e.data == nil {
		e.data = make([]interface{}, 0)
	}
	ret := e.max
	e.max = e.max + 1
	e.data = append(e.data, nil)
	e.Unlock()
	return ret
}

type Context struct {
	Faces measure.Faces

	w         *app.Window
	c         *app.Config
	q         input.Queue
	ops       *ui.Ops
	cs        layout.Constraints
	dims      layout.Dimensions
	container Widget
}

func NewContext(w *app.Window) *Context {
	return &Context{
		w:   w,
		ops: new(ui.Ops),
		q:   w.Queue(),
	}
}

func (ctx *Context) Reset(e *app.UpdateEvent) {
	Mallocs("ctx.Reset() ctx.c")
	ctx.c = &e.Config
	ctx.ops.Reset()
	ctx.cs = layout.RigidConstraints(e.Size)
	ctx.Faces.Reset(ctx.c)
	Mallocs("ctx.Reset() done")
}

func (ctx *Context) Update() {
	ctx.w.Update(ctx.ops)
}

type Layout func(*Context)

type Widget interface {
	Layout(*Context)
}

type WidgetCombinator func(...Widget) Widget

type Label struct {
	l *text.Label
}

type FaceOpt struct{ face text.Face }

func Face(x text.Face) FaceOpt { return FaceOpt{x} }

type AlignOpt struct{ alignment text.Alignment }

func Align(x text.Alignment) AlignOpt { return AlignOpt{x} }

type LabelOpts struct {
	FaceOpt
	c *color.RGBA
	AlignOpt
}
type LabelOption interface{ DoLabelOption(*LabelOpts) }

func (x FaceOpt) DoLabelOption(o *LabelOpts)  { o.face = x.face }
func (x AlignOpt) DoLabelOption(o *LabelOpts) { o.alignment = x.alignment }
func (x ColorOpt) DoLabelOption(o *LabelOpts) { o.c = &x.c }

func NewLabel(t string, lops ...LabelOption) *Label {
	ret := &Label{}
	opts := &LabelOpts{}
	for _, o := range lops {
		o.DoLabelOption(opts)
	}
	ret.l = &text.Label{
		Face:      opts.face,
		Text:      t,
		Alignment: opts.alignment,
	}
	if opts.c != nil { // got a color option...
		ops := new(ui.Ops)
		ret.l.Material.Record(ops)
		paint.ColorOp{Color: *opts.c}.Add(ops)
		ret.l.Material.Stop()
	}
	return ret
}

func (l *Label) Layout(ctx *Context) {
	Mallocs("Label.Layout()")
	ctx.dims = l.l.Layout(ctx.ops, ctx.cs)
}

func (l *Label) SetText(t string) {
	l.l.Text = t
}

type Editor struct {
	e *text.Editor
}

type SinglelineOpt struct{ singleline bool }

func Singleline(x bool) SinglelineOpt { return SinglelineOpt{x} }

type EditorOpts struct {
	FaceOpt
	SinglelineOpt
}
type EditorOption interface{ DoEditorOption(*EditorOpts) }

func (x FaceOpt) DoEditorOption(o *EditorOpts)       { o.face = x.face }
func (x SinglelineOpt) DoEditorOption(o *EditorOpts) { o.singleline = x.singleline }

func NewEditor(t string, eops ...EditorOption) *Editor {
	ret := &Editor{}
	opts := &EditorOpts{}
	for _, o := range eops {
		o.DoEditorOption(opts)
	}
	ret.e = &text.Editor{Face: opts.face, SingleLine: opts.singleline}
	ret.SetText(t)
	return ret
}

func (e *Editor) Layout(ctx *Context) {
	Mallocs("Editor.Layout()")
	ctx.dims = e.e.Layout(ctx.c, ctx.q, ctx.ops, ctx.cs)
}

func (e *Editor) Text() string     { return e.e.Text() }
func (e *Editor) SetText(s string) { e.e.SetText(s) }
func (e *Editor) Focus()           { e.e.Focus() }

type Stack WidgetCombinator

type stackWidget struct {
	s   layout.Stack
	scs []layout.StackChild
	ws  []Widget
}

func NewStack() Stack {
	ret := &stackWidget{}
	ret.s = layout.Stack{Alignment: layout.Center}
	ret.scs = make([]layout.StackChild, 0)

	return func(ws ...Widget) Widget {
		ret.ws = ws
		return ret
	}
}

func (sw *stackWidget) Layout(ctx *Context) {
	sw.s.Init(ctx.ops, ctx.cs)
	for _, w := range sw.ws {
		ctx.cs = sw.s.Rigid()
		w.Layout(ctx)
		sw.scs = append(sw.scs, sw.s.End(ctx.dims))
	}
	ctx.dims = sw.s.Layout(sw.scs...)
	sw.scs = sw.scs[0:0]
}

type List = WidgetCombinator

type AxisOpt struct{ axis layout.Axis }

func Axis(x layout.Axis) AxisOpt { return AxisOpt{x} }

var Horizontal = AxisOpt{layout.Horizontal}
var Vertical = AxisOpt{layout.Vertical}

type ListOpts struct {
	AxisOpt
}
type ListOption interface{ DoListOption(*ListOpts) }

func (x AxisOpt) DoListOption(o *ListOpts) { o.axis = x.axis }

type listWidget struct {
	l  layout.List
	ws []Widget
}

func NewList(los ...ListOption) List {
	ret := &listWidget{}
	opts := &ListOpts{}
	for _, o := range los {
		o.DoListOption(opts)
	}
	ret.l = layout.List{Axis: opts.axis}

	return func(ws ...Widget) Widget {
		ret.ws = ws
		return ret
	}
}

func (lw *listWidget) Layout(ctx *Context) {
	for lw.l.Init(ctx.c, ctx.q, ctx.ops, ctx.cs, len(lw.ws)); lw.l.More(); lw.l.Next() {
		ctx.cs = lw.l.Constraints()
		lw.ws[lw.l.Index()].Layout(ctx)
		lw.l.End(ctx.dims)
	}
	ctx.dims = lw.l.Layout()
}

func HScroll(c WidgetCombinator) WidgetCombinator {
	return NewList(Axis(layout.Horizontal))
}

func VScroll(c WidgetCombinator) WidgetCombinator {
	return NewList(Axis(layout.Vertical))
}

type Flex = WidgetCombinator

type AlignmentOpt struct{ alignment layout.Alignment }

func Alignment(x layout.Alignment) AlignmentOpt { return AlignmentOpt{x} }

type FlexOpts struct {
	AxisOpt
	AlignmentOpt
	flexible float32
}

type FlexOption interface{ DoFlexOption(*FlexOpts) }

func (x AxisOpt) DoFlexOption(o *FlexOpts)      { o.axis = x.axis }
func (x AlignmentOpt) DoFlexOption(o *FlexOpts) { o.alignment = x.alignment }

type flexWidget struct {
	f        func(*Context)
	flexible float32
}

type flexOptWidget struct {
	flexible float32
}

func (fo flexOptWidget) Layout(ctx *Context) {
	Mallocs("flexOptWidget.Layout()")
	ctx.container.(*flexWidget).flexible = fo.flexible
}

// This "Widget" does nothing except set the Flexible field of a FlexOpts
// struct within the Extra data structure
func Flexible(v float32) Widget {
	return flexOptWidget{v}
}
func Rigid() Widget {
	return flexOptWidget{0}
}

// NewFlex returns a WidgetCombinator that wraps the layout.Flex element.

func (fw *flexWidget) Layout(ctx *Context) {
	fw.f(ctx)
}

func NewFlex(fos ...FlexOption) Flex {
	opts := &FlexOpts{}
	for _, o := range fos {
		o.DoFlexOption(opts)
	}
	f := layout.Flex{
		Axis:      opts.axis,
		Alignment: opts.alignment,
	}
	fcs := make([]layout.FlexChild, 0)
	return func(ws ...Widget) Widget {
		ret := &flexWidget{}
		ret.f = func(ctx *Context) {
			oldContainer := ctx.container
			ctx.container = ret
			f.Init(ctx.ops, ctx.cs)
			for _, w := range ws {
				ctx.cs = f.Rigid()
				w.Layout(ctx)
				fcs = append(fcs, f.End(ctx.dims))
			}
			ctx.dims = f.Layout(fcs...)
			fcs = fcs[0:0]
			ctx.container = oldContainer
		}
		return ret
	}
}

type InsetOpts struct {
	top, right, bottom, left ui.Value
}

type InsetOption interface{ DoInsetOption(*InsetOpts) }

type TopOpt struct{ top ui.Value }

func Top(x ui.Value) TopOpt { return TopOpt{x} }

type RightOpt struct{ right ui.Value }

func Right(x ui.Value) RightOpt { return RightOpt{x} }

type BottomOpt struct{ bottom ui.Value }

func Bottom(x ui.Value) BottomOpt { return BottomOpt{x} }

type LeftOpt struct{ left ui.Value }

func Left(x ui.Value) LeftOpt { return LeftOpt{x} }

func (x TopOpt) DoInsetOption(o *InsetOpts)    { o.top = x.top }
func (x RightOpt) DoInsetOption(o *InsetOpts)  { o.right = x.right }
func (x BottomOpt) DoInsetOption(o *InsetOpts) { o.bottom = x.bottom }
func (x LeftOpt) DoInsetOption(o *InsetOpts)   { o.left = x.left }

type SizeOpt struct{ size ui.Value }

func Size(x ui.Value) SizeOpt { return SizeOpt{x} }
func (x SizeOpt) DoInsetOption(o *InsetOpts) {
	o.top = x.size
	o.right = x.size
	o.bottom = x.size
	o.left = x.size
}

type insetWidget func(*Context)

func (iw insetWidget) Layout(ctx *Context) {
	iw(ctx)
}

//NewInset returns a WidgetCombinator that wraps the layout.Inset element.
func NewInset(insos ...InsetOption) func(...Widget) Widget {
	opts := InsetOpts{}
	for _, o := range insos {
		o.DoInsetOption(&opts)
	}
	ins := layout.Inset{Top: opts.top, Right: opts.right, Bottom: opts.bottom, Left: opts.left}

	return func(ws ...Widget) Widget {
		Mallocs("NewInset() return")
		var ret insetWidget
		ret = func(ctx *Context) {
			oldContainer := ctx.container
			ctx.container = ret
			ctx.cs = ins.Begin(ctx.c, ctx.ops, ctx.cs)
			for _, w := range ws {
				w.Layout(ctx)
			}
			ctx.dims = ins.End(ctx.dims)
			ctx.container = oldContainer
		}
		return ret
	}
}

type Background struct {
	Color  color.RGBA
	Radius ui.Value
	Inset  layout.Inset

	macro ui.MacroOp
}

type Enclosure interface {
	Begin(*Context)
	End(*Context)
}

type encloseWidget struct {
	enc Enclosure
	ws  []Widget
}

func Enclose(e Enclosure, ws ...Widget) Widget {
	return &encloseWidget{e, ws}
}

func (e *encloseWidget) Layout(ctx *Context) {
	oldContainer := ctx.container
	ctx.container = e
	e.enc.Begin(ctx)
	for _, w := range e.ws {
		w.Layout(ctx)
	}
	e.enc.End(ctx)
	ctx.container = oldContainer
}

type BackgroundOpts struct {
	c      color.RGBA
	radius ui.Value
}

type BackgroundOption interface{ DoBackgroundOption(*BackgroundOpts) }

type ColorOpt struct{ c color.RGBA }

func Color(x color.RGBA) ColorOpt                       { return ColorOpt{x} }
func (x ColorOpt) DoBackgroundOption(o *BackgroundOpts) { o.c = x.c }

type RadiusOpt struct{ radius ui.Value }

func Radius(x ui.Value) RadiusOpt                        { return RadiusOpt{x} }
func (x RadiusOpt) DoBackgroundOption(o *BackgroundOpts) { o.radius = x.radius }

func NewBackground(bos ...BackgroundOption) WidgetCombinator {
	opts := &BackgroundOpts{}
	for _, o := range bos {
		o.DoBackgroundOption(opts)
	}
	bg := &Background{
		Color:  opts.c,
		Radius: opts.radius,
		Inset:  layout.UniformInset(opts.radius),
	}
	return func(ws ...Widget) Widget {
		return Enclose(bg, ws...)
	}
}

func (bg *Background) Begin(ctx *Context) {
	Mallocs("Background.Begin()")
	bg.macro.Record(ctx.ops)
	ctx.cs = bg.Inset.Begin(ctx.c, ctx.ops, ctx.cs)
	Mallocs("Background.Begin() done")
}

func (bg *Background) End(ctx *Context) {
	Mallocs("Background.End()")
	ctx.dims = bg.Inset.End(ctx.dims)
	bg.macro.Stop()
	var stack ui.StackOp
	stack.Push(ctx.ops)
	w, h := float32(ctx.dims.Size.X), float32(ctx.dims.Size.Y)
	if r := float32(ctx.c.Px(bg.Radius)); r > 0 {
		if r > w/2 {
			r = w / 2
		}
		if r > h/2 {
			r = h / 2
		}
		Rrect(ctx.ops, w, h, r, r, r, r)
	}
	paint.ColorOp{Color: bg.Color}.Add(ctx.ops)
	paint.PaintOp{Rect: f32.Rectangle{Max: f32.Point{X: w, Y: h}}}.Add(ctx.ops)
	bg.macro.Add(ctx.ops)
	stack.Pop()
	Mallocs("Background.End() done")
}

// https://pomax.github.io/bezierinfo/#circles_cubic.
func Rrect(ops *ui.Ops, width, height, se, sw, nw, ne float32) {
	Mallocs("Rrect() start")
	w, h := float32(width), float32(height)
	Mallocs("Rrect() const")
	const c = 0.55228475 // 4*(sqrt(2)-1)/3
	var b paint.PathBuilder
	Mallocs("Rrect() init")
	b.Init(ops)
	Mallocs("Rrect() move")
	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()
	Mallocs("Rrect() end")
}

type fillWidget struct {
	axis layout.Axis
}

func FillWidth(ws ...Widget) Widget {
	return Enclose(fillWidget{layout.Horizontal}, ws...)
}
func FillHeight(ws ...Widget) Widget {
	return Enclose(fillWidget{layout.Vertical}, ws...)
}

func (fw fillWidget) Begin(ctx *Context) {
	switch fw.axis {
	case layout.Horizontal:
		ctx.cs.Width.Min = ctx.cs.Width.Max
	case layout.Vertical:
		ctx.cs.Height.Min = ctx.cs.Height.Max
	}
}

func (fw fillWidget) End(*Context) {
}

type Clickable interface {
	Widget
	Clicked(*Context) bool
}

//cWidget is a clickable Widget that provides the Clicked() method.
type cWidget struct {
	w     Widget
	click *gesture.Click
}

func (w *cWidget) Layout(ctx *Context) {
	Mallocs("cWidget.Layout()")
	w.w.Layout(ctx)
	pointer.RectAreaOp{image.Rect(0, 0, ctx.dims.Size.X, ctx.dims.Size.Y)}.Add(ctx.ops)
	w.click.Add(ctx.ops)
}

func (w cWidget) Clicked(ctx *Context) bool {
	Mallocs("cWidget.Clicked()")
	for e, ok := w.click.Next(ctx.q); ok; e, ok = w.click.Next(ctx.q) {
		if e.Type == gesture.TypeClick {
			ctx.w.Invalidate()
			return true
		}
	}
	return false
}

//Clickable converts any Widget into a clickable Widget.
func AsClickable(w Widget) *cWidget {
	return &cWidget{w: w, click: new(gesture.Click)}
}