package giowrap

import (
	"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"
	gdraw "gioui.org/ui/draw"
	"gioui.org/ui/gesture"
	"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.Dimens
}

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

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

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

type Layout func(*Context)

type Widget interface {
	Layout(*Context)
}

type WidgetCombinator func(...Widget) Widget

type Label struct {
	l *text.Label
}

type LabelOpts struct {
	face text.Face
	alignment text.Alignment
}
type LabelOption func(*LabelOpts)
func LabelFace(x text.Face) LabelOption {
	return func(o *LabelOpts) { o.face = x }
}
func LabelAlignment(x text.Alignment) LabelOption {
	return func(o *LabelOpts) { o.alignment = x }
}

func NewLabel(t string, lops ...LabelOption) *Label {
	ret := &Label{}
	opts := &LabelOpts{}
	for _,o := range lops { o(opts) }
	ret.l = &text.Label{
		Face: opts.face,
		Text: t,
		Alignment: opts.alignment,
	}
	return ret
}

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

type Editor struct {
	e *text.Editor
}

type EditorOpts struct {
	face text.Face
	singleline bool
}
type EditorOption func(*EditorOpts)
func EditorFace(x text.Face) EditorOption {
	return func(o *EditorOpts) { o.face = x }
}
func EditorSingleline() EditorOption {
	return func(o *EditorOpts) { o.singleline = true }
}

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

func (e *Editor) Layout(ctx *Context) {
	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 fWidget struct {
	l Layout
}

func NewfWidget(l Layout) fWidget {
	return fWidget{ l: l }
}

func (fw fWidget) Layout(ctx *Context) {
	fw.l(ctx)
}

type Flex WidgetCombinator

// This "Widget" does nothing except set the Flexible field of a FlexOpts
// struct within the Extra data structure
func Flexible(v float32) Widget {
	return NewfWidget(func(ctx *Context) {
		extra.data[extra.cur].(*FlexOpts).flexible = v
	})
}

type FlexOpts struct {
	axis layout.Axis
	mainAxisAlignment layout.MainAxisAlignment
	crossAxisAlignment layout.CrossAxisAlignment
	flexible float32
}

type FlexOption func(*FlexOpts)

func FlexAxis(x layout.Axis) FlexOption {
	return func(o *FlexOpts) { o.axis = x }
}

func MainAxisAlignment(x layout.MainAxisAlignment) FlexOption {
	return func(o *FlexOpts) { o.mainAxisAlignment = x }
}
func CrossAxisAlignment(x layout.CrossAxisAlignment) FlexOption {
	return func(o *FlexOpts) { o.crossAxisAlignment = x }
}

// NewFlex returns a WidgetCombinator that wraps the layout.Flex element.
func NewFlex(fos ...FlexOption) Flex {
	opts := &FlexOpts{}
	for _,o := range fos { o(opts) }
	f := layout.Flex{
		Axis: opts.axis,
		MainAxisAlignment: opts.mainAxisAlignment,
		CrossAxisAlignment: opts.crossAxisAlignment,
	}
	index := extra.New()
	extra.data[index] = opts
	// do not call "make" inside the Layout function
	fcs := make([]layout.FlexChild,0)

	return func(ws ...Widget) Widget {
		return NewfWidget(func(ctx *Context) {
		// ensure child widgets write options to the right place
			extra.cur = index
			opts := extra.data[index].(*FlexOpts)
			f.Init(ctx.ops, ctx.cs)
			for _, w := range ws {
				if opts.flexible != 0 {
					ctx.cs = f.Flexible(opts.flexible)
				} else {
					ctx.cs = f.Rigid()
				}
				w.Layout(ctx)
				fcs = append(fcs, f.End(ctx.dims))
			}
			f.Layout(fcs...)
			fcs = fcs[0:0] // truncate
		})
	}
}

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

type InsetOption func(*InsetOpts)

func InsetTop(x ui.Value) InsetOption {
	return func(o *InsetOpts) { o.top = x }
}
func InsetRight(x ui.Value) InsetOption {
	return func(o *InsetOpts) { o.right = x }
}
func InsetBottom(x ui.Value) InsetOption {
	return func(o *InsetOpts) { o.bottom = x }
}
func InsetLeft(x ui.Value) InsetOption {
	return func(o *InsetOpts) { o.left = x }
}
func InsetSize(x ui.Value) InsetOption {
	return func(o *InsetOpts) {
		o.top = x
		o.right = x
		o.bottom = x
		o.left = x
	}
}

//NewInset returns a WidgetCombinator that wraps the layout.Inset element.
func NewInset(insos ...InsetOption) WidgetCombinator {
	opts := &InsetOpts{}
	for _,o := range insos { o(opts) }
	ins := layout.Inset{ Top: opts.top, Right: opts.right, Bottom: opts.bottom, Left: opts.left }
	return func(ws ...Widget) Widget {
		return NewfWidget(func(ctx *Context) {
			ctx.cs = ins.Begin(ctx.c, ctx.ops, ctx.cs)
			for _, w := range ws {
				w.Layout(ctx)
			}
			ctx.dims = ins.End(ctx.dims)
		})
	}
}

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

	macro ui.MacroOp
}

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

func Enclose(e Enclosure, ws ...Widget) Widget {
	return NewfWidget(func(ctx *Context) {
		e.Begin(ctx)
		for _,w := range ws {
			w.Layout(ctx)
		}
		e.End(ctx)
	})
}

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

type BackgroundOption func(*BackgroundOpts)
func BgColor(c color.RGBA) BackgroundOption {
	return func(o *BackgroundOpts) { o.c = c }
}
func BgRadius(x ui.Value) BackgroundOption {
	return func(o *BackgroundOpts) { o.radius = x }
}

func NewBackground(bos ...BackgroundOption) WidgetCombinator {
	opts := &BackgroundOpts{}
	for _,o := range bos { o(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) {
	bg.macro.Record(ctx.ops)
	ctx.cs = bg.Inset.Begin(ctx.c, ctx.ops, ctx.cs)
}

func (bg *Background) End(ctx *Context) {
	ctx.dims = bg.Inset.End(ctx.dims)
	bg.macro.Stop()
	//var stack ui.StackOp
	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)
	}
	gdraw.ColorOp{Color: bg.Color}.Add(ctx.ops)
	gdraw.DrawOp{Rect: f32.Rectangle{Max: f32.Point{X: w, Y: h}}}.Add(ctx.ops)
	bg.macro.Add(ctx.ops)
}

// https://pomax.github.io/bezierinfo/#circles_cubic.
func Rrect(ops *ui.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 gdraw.PathBuilder
	b.Init(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()
}

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) {
	w.w.Layout(ctx)
	pointer.RectAreaOp{Size: ctx.dims.Size}.Add(ctx.ops)
	w.click.Add(ctx.ops)
}

func (w cWidget) Clicked(ctx *Context) bool {
	for _,e := range w.click.Events(ctx.q) {
		if e.Type == gesture.TypeClick {
			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) }
}