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/paint"
	"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.UpdateEvent) {
	ctx.c = &e.Config
	ctx.ops.Reset()
	ctx.cs = layout.RigidConstraints(e.Size)
	ctx.Faces.Reset(ctx.c)
}

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) {
	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) {
	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 Stack WidgetCombinator

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

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

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
	})
}
func Rigid() Widget {
	return NewfWidget(func(ctx *Context) {
		extra.data[extra.cur].(*FlexOpts).flexible = 0
	})
}

type AxisOpt struct { axis layout.Axis }
func Axis(x layout.Axis) AxisOpt { return AxisOpt{ x } }
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 }

// NewFlex returns a WidgetCombinator that wraps the layout.Flex element.
func NewFlex(fos ...FlexOption) Flex {
	opts := &FlexOpts{}
	for _,o := range fos { o.DoFlexOption(opts) }
	f := layout.Flex{
		Axis: opts.axis,
		Alignment: opts.alignment,
	}
	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))
			}
			ctx.dims = f.Layout(fcs...)
			fcs = fcs[0:0] // truncate
		})
	}
}

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
}

//NewInset returns a WidgetCombinator that wraps the layout.Inset element.
func NewInset(insos ...InsetOption) WidgetCombinator {
	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 {
		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 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) {
	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
	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()
}

// 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 paint.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{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 {
	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) }
}

type Grid struct {
	Cols int
	Height, Width int

	macro ui.MacroOp
	ops *ui.Ops
	cs layout.Constraints
	mode gridMode
	row, col int
}

type GridChild struct {
	dims layout.Dimens
	macro ui.MacroOp
}

type gridMode uint8
const (
	modeNone gridMode = iota
	modeBegun
)

func (g *Grid) Init(ops *ui.Ops, cs layout.Constraints) layout.Constraints {
	g.mode = modeBegun
	g.ops = ops
	g.cs = cs
	g.row, g.col = 0, 0

	cs.Height.Min = 0

	if g.Height != 0 { g.cs.Height.Max = g.Height }
	if g.Width != 0 { g.cs.Width.Max = g.Width }

	cs.Width.Max = g.cs.Width.Max / g.Cols
	if g.Cols > 1 {
		cs.Width.Min = cs.Width.Max
	}
	return cs
}

func (g *Grid) Begin() {
	g.macro.Record(g.ops)
}

func (g *Grid) End(dims layout.Dimens) GridChild {
	if g.mode != modeBegun {
		panic("Must call Grid.Begin() before adding children.")
	}
	g.macro.Stop()
	return GridChild{ dims: dims, macro: g.macro }
}

func (g *Grid) Layout(cs ...GridChild) layout.Dimens {
	rowheight := 0
	height := 0
	var width float32
	var maxwidth float32
	for _,c := range cs {
		var stack ui.StackOp
		stack.Push(g.ops)
		c.macro.Add(g.ops)
		stack.Pop()
		if c.dims.Size.Y > rowheight {
			rowheight = c.dims.Size.Y
		}
		g.col = g.col+1
		var x float32
		if g.Cols == 1 {
			x = float32(c.dims.Size.X)
			if x > maxwidth { maxwidth = x }
		} else {
			x = float32(g.cs.Width.Max / g.Cols)
		}
		if g.col < g.Cols {
			ui.TransformOp{}.Offset(f32.Point{X: x}).Add(g.ops)
			width = width + x
		} else {
			g.col = 0
			ui.TransformOp{}.Offset(f32.Point{ X: -width, Y: float32(rowheight) }).Add(g.ops)
			g.row = g.row + 1
			height = height + rowheight
			width = 0
			rowheight = 0
		}
	}
	if height == 0 { height = rowheight }
	g.mode = modeNone
	var dwidth int
	if g.Cols == 1 {
		dwidth = int(maxwidth)
	} else {
		dwidth = g.cs.Width.Max
	}
	return layout.Dimens{ Size: image.Point{ dwidth, height } }
}

func toPointF(p image.Point) f32.Point {
	return f32.Point{X: float32(p.X), Y: float32(p.Y)}
}

type GridOption interface { DoGridOption(*Grid) }

type HeightOpt struct { height int }
func Height(x int) HeightOpt { return HeightOpt{ x } }
func (x HeightOpt) DoGridOption(g *Grid) { g.Height = x.height }

func NewGrid(cols int, gops ...GridOption) WidgetCombinator {
	g := &Grid{ Cols: cols }
	for _, gop := range gops {
		gop.DoGridOption(g)
	}
	gcs := make([]GridChild,0)
	return func(ws ...Widget) Widget {
		return NewfWidget(func(ctx *Context) {
			cs := g.Init(ctx.ops, ctx.cs)
			ctx.cs = cs
			for _,w := range ws {
				g.Begin()
				w.Layout(ctx)
				ctx.cs = cs // widget layout can modify constraints...
				gcs = append(gcs,g.End(ctx.dims))
			}
			ctx.dims = g.Layout(gcs...)
			gcs = gcs[0:0]
		})
	}
}