package allg5ui

import (
	"image"
	"image/color"
	"math"
	"unicode"

	"opslag.de/schobers/zntg"

	"opslag.de/schobers/allg5"
	"opslag.de/schobers/geom"
	"opslag.de/schobers/zntg/ui"
)

var _ ui.Renderer = &Renderer{}

func NewRenderer(w, h int, opts allg5.NewDisplayOptions) (*Renderer, error) {
	var clean zntg.Actions
	defer func() { clean.Do() }()

	var err = allg5.Init(allg5.InitAll)
	if err != nil {
		return nil, err
	}

	disp, err := allg5.NewDisplay(w, h, opts)
	if err != nil {
		return nil, err
	}
	clean = clean.Add(disp.Destroy)

	eq, err := allg5.NewEventQueue()
	if err != nil {
		return nil, err
	}
	clean = clean.Add(eq.Destroy)

	user := allg5.NewUserEventSource()
	eq.RegisterKeyboard()
	eq.RegisterMouse()
	eq.RegisterDisplay(disp)
	eq.RegisterUserEvents(user)

	allg5.CaptureNewBitmapFlags().Mutate(func(m allg5.FlagMutation) {
		m.Set(allg5.NewBitmapFlagMinLinear)
	})
	clean = nil

	return &Renderer{disp, eq, nil, user, &ui.OSResources{}, dispPos(disp), ui.KeyState{}, ui.KeyModifierNone, ui.MouseCursorDefault}, nil
}

// Renderer implements ui.Renderer using Allegro 5.
type Renderer struct {
	disp *allg5.Display
	eq   *allg5.EventQueue
	unh  func(allg5.Event)
	user *allg5.UserEventSource
	res  ui.Resources

	dispPos   geom.Point
	keys      ui.KeyState
	modifiers ui.KeyModifier
	cursor    ui.MouseCursor
}

// Renderer implementation (events)

func (r *Renderer) PushEvents(t ui.EventTarget, wait bool) bool {
	r.disp.Flip()

	var ev = eventWait(r.eq, wait)
	if ev == nil {
		return false
	}

	cursor := r.cursor
	r.cursor = ui.MouseCursorDefault
	var unhandled bool
	for ev != nil {
		switch e := ev.(type) {
		case *allg5.DisplayCloseEvent:
			t.Handle(&ui.DisplayCloseEvent{EventBase: eventBase(e)})
		case *allg5.DisplayResizeEvent:
			t.Handle(&ui.DisplayResizeEvent{EventBase: eventBase(e), Bounds: geom.RectF32(float32(e.X), float32(e.Y), float32(e.X+e.Width), float32(e.Y+e.Height))})
		case *allg5.KeyCharEvent:
			if r.modifiers&ui.KeyModifierControl == ui.KeyModifierNone && !unicode.IsControl(e.UnicodeCharacter) {
				t.Handle(&ui.TextInputEvent{EventBase: eventBase(e), Character: e.UnicodeCharacter})
			} else {
				unhandled = true
			}
		case *allg5.KeyDownEvent:
			key := key(e.KeyCode)
			r.keys[key] = true
			r.modifiers = r.keys.Modifiers()
			t.Handle(&ui.KeyDownEvent{EventBase: eventBase(e), Key: key, Modifiers: r.modifiers})
		case *allg5.KeyUpEvent:
			key := key(e.KeyCode)
			r.keys[key] = false
			r.modifiers = r.keys.Modifiers()
			t.Handle(&ui.KeyUpEvent{EventBase: eventBase(e), Key: key, Modifiers: r.modifiers})
		case *allg5.MouseButtonDownEvent:
			t.Handle(&ui.MouseButtonDownEvent{MouseEvent: mouseEvent(e.MouseEvent), Button: ui.MouseButton(e.Button)})
		case *allg5.MouseButtonUpEvent:
			t.Handle(&ui.MouseButtonUpEvent{MouseEvent: mouseEvent(e.MouseEvent), Button: ui.MouseButton(e.Button)})
		case *allg5.MouseEnterEvent:
			t.Handle(&ui.MouseLeaveEvent{MouseEvent: mouseEvent(e.MouseEvent)})
		case *allg5.MouseLeaveEvent:
			t.Handle(&ui.MouseLeaveEvent{MouseEvent: mouseEvent(e.MouseEvent)})
		case *allg5.MouseMoveEvent:
			t.Handle(&ui.MouseMoveEvent{MouseEvent: mouseEvent(e.MouseEvent), MouseWheel: float32(e.DeltaZ)})
		case *allg5.UserEvent:
			t.Handle(&ui.RefreshEvent{EventBase: eventBase(e)})
		default:
			if r.unh != nil {
				r.unh(e)
			}
			unhandled = true
		}
		ev = r.eq.Get()
	}
	dispPos := dispPos(r.disp)
	if dispPos != r.dispPos {
		r.dispPos = dispPos
		w := r.disp.Width()
		h := r.disp.Height()
		t.Handle(&ui.DisplayMoveEvent{Bounds: r.dispPos.RectRel2D(w, h).ToF32()})
	}

	if !unhandled && cursor != r.cursor {
		switch r.cursor {
		case ui.MouseCursorNone:
			r.disp.SetMouseCursor(allg5.MouseCursorNone)
		case ui.MouseCursorDefault:
			r.disp.SetMouseCursor(allg5.MouseCursorDefault)
		case ui.MouseCursorNotAllowed:
			r.disp.SetMouseCursor(allg5.MouseCursorUnavailable)
		case ui.MouseCursorPointer:
			r.disp.SetMouseCursor(allg5.MouseCursorLink)
		case ui.MouseCursorText:
			r.disp.SetMouseCursor(allg5.MouseCursorEdit)
		}
	}
	return true
}

func (r *Renderer) RegisterRecorder(rec *allg5.Recorder) {
	r.eq.RegisterRecorder(rec)
}

func (r *Renderer) Refresh() {
	r.user.EmitEvent()
}

// Renderer implementation (lifetime)

func (r *Renderer) Destroy() error {
	r.user.Destroy()
	r.eq.Destroy()
	r.disp.Destroy()
	r.res.Destroy()
	return nil
}

// Renderer implementation (drawing)

func (r *Renderer) Clear(c color.Color) {
	allg5.ClearToColor(newColor(c))
}

func (r *Renderer) CreateFontPath(path string, size int) (ui.Font, error) {
	path, err := r.res.FetchResource(path)
	if err != nil {
		return nil, err
	}
	f, err := allg5.LoadTTFFont(path, size)
	if err != nil {
		return nil, err
	}
	return &font{f}, nil
}

func (r *Renderer) createTexture(source ui.ImageSource, keepSource bool) (ui.Texture, error) {
	im, err := source.CreateImage()
	if err != nil {
		return nil, err
	}
	bmp, err := allg5.NewBitmapFromImage(im, true)
	if err != nil {
		return nil, err
	}
	if keepSource {
		return &texture{bmp, source}, nil
	}
	return &texture{bmp, nil}, nil
}

func (r *Renderer) CreateTexture(source ui.ImageSource) (ui.Texture, error) {
	return r.createTexture(source, true)
}

func (r *Renderer) CreateTextureGo(im image.Image, source bool) (ui.Texture, error) {
	return r.createTexture(ui.ImageSourceGo{Image: im}, source)
}

func (r *Renderer) CreateTexturePath(path string, source bool) (ui.Texture, error) {
	resourcePath, err := r.res.FetchResource(path)
	if err != nil {
		return nil, err
	}
	bmp, err := allg5.LoadBitmap(resourcePath)
	if err != nil {
		return nil, err
	}
	if source {
		return &texture{bmp, ui.ImageSourceResource{Resources: r.res, Name: path}}, nil
	}
	return &texture{bmp, nil}, nil
}

func (r *Renderer) CreateTextureTarget(w, h float32) (ui.Texture, error) {
	bmp, err := allg5.NewVideoBitmap(int(w), int(h))
	if err != nil {
		return nil, err
	}
	return &texture{bmp, nil}, nil
}

func (r *Renderer) DefaultTarget() ui.Texture {
	return &texture{r.disp.Target(), nil}
}

func (r *Renderer) Display() *allg5.Display { return r.disp }

func (r *Renderer) DrawTexture(texture ui.Texture, p geom.RectangleF32) {
	r.DrawTextureOptions(texture, p, ui.DrawOptions{})
}

func (r *Renderer) DrawTextureOptions(texture ui.Texture, p geom.RectangleF32, opts ui.DrawOptions) {
	bmp, ok := r.mustGetSubBitmap(texture, opts.Source)
	if ok {
		defer bmp.Destroy()
	}
	x, y := snap(p.Min)
	var o allg5.DrawOptions
	if opts.Tint != nil {
		tint := newColor(opts.Tint)
		o.Tint = &tint
	}
	w, h := p.Dx(), p.Dy()
	bmpW, bmpH := float32(bmp.Width()), float32(bmp.Height())
	if w != bmpW || h != bmpH {
		o.Scale = &allg5.Scale{Horizontal: w / bmpW, Vertical: h / bmpH}
	}
	bmp.DrawOptions(x, y, o)
}

func (r *Renderer) DrawTexturePoint(texture ui.Texture, p geom.PointF32) {
	bmp := r.mustGetBitmap(texture)
	x, y := snap(p)
	bmp.Draw(x, y)
}

func (r *Renderer) DrawTexturePointOptions(texture ui.Texture, p geom.PointF32, opts ui.DrawOptions) {
	bmp, ok := r.mustGetSubBitmap(texture, opts.Source)
	if ok {
		defer bmp.Destroy()
	}
	var o allg5.DrawOptions
	if opts.Tint != nil {
		tint := newColor(opts.Tint)
		o.Tint = &tint
	}
	x, y := snap(p)
	bmp.DrawOptions(x, y, o)
}

func (r *Renderer) FillRectangle(rect geom.RectangleF32, c color.Color) {
	allg5.DrawFilledRectangle(rect.Min.X, rect.Min.Y, rect.Max.X, rect.Max.Y, newColor(c))
}

func (r *Renderer) mustGetBitmap(t ui.Texture) *allg5.Bitmap {
	texture, ok := t.(*texture)
	if !ok {
		panic("texture must be created on same renderer")
	}
	return texture.bmp
}

func (r *Renderer) mustGetSubBitmap(t ui.Texture, source *geom.RectangleF32) (*allg5.Bitmap, bool) {
	texture, ok := t.(*texture)
	if !ok {
		panic("texture must be created on same renderer")
	}
	if source == nil {
		return texture.bmp, false
	}
	src := source.ToInt()
	return texture.bmp.Sub(src.Min.X, src.Min.Y, src.Dx(), src.Dy()), true
}

func (r *Renderer) Rectangle(rect geom.RectangleF32, c color.Color, thickness float32) {
	minX, minY := snap(rect.Min)
	maxX, maxY := snap(rect.Max)
	allg5.DrawRectangle(minX, minY, maxX, maxY, newColor(c), thickness)
}

func (r *Renderer) RenderTo(texture ui.Texture) {
	bmp := r.mustGetBitmap(texture)
	bmp.SetAsTarget()
}

func (r *Renderer) RenderToDisplay() {
	r.disp.SetAsTarget()
}

func (r *Renderer) Resources() ui.Resources { return r.res }

func (r *Renderer) Size() geom.PointF32 {
	return geom.PtF32(float32(r.disp.Width()), float32(r.disp.Height()))
}

func (r *Renderer) SetIcon(texture ui.Texture) {
	bmp := r.mustGetBitmap(texture)
	r.disp.SetIcon(bmp)
}

func (r *Renderer) SetMouseCursor(c ui.MouseCursor) {
	r.cursor = c
}

func (r *Renderer) SetPosition(p geom.PointF32) { r.disp.SetPosition(int(p.X), int(p.Y)) }

func (r *Renderer) SetResourceProvider(factory func() ui.Resources) {
	if r.res != nil {
		r.res.Destroy()
	}
	r.res = factory()
}

func (r *Renderer) SetUnhandledEventHandler(handler func(allg5.Event)) {
	r.unh = handler
}

func (r *Renderer) SetWindowTitle(t string) {
	r.disp.SetWindowTitle(t)
}

func (r *Renderer) Target() ui.Texture {
	return &texture{allg5.CurrentTarget(), nil}
}

func (r *Renderer) text(f ui.Font, p geom.PointF32, c color.Color, t string, align allg5.HorizontalAlignment) {
	font, ok := f.(*font)
	if !ok {
		return
	}
	x, y := snap(p)
	font.Draw(x, y, newColor(c), align, t)
}

func (r *Renderer) Text(font ui.Font, p geom.PointF32, c color.Color, t string) {
	r.text(font, p, c, t, allg5.AlignLeft)
}

func (r *Renderer) TextAlign(font ui.Font, p geom.PointF32, c color.Color, t string, align ui.HorizontalAlignment) {
	var alignment = allg5.AlignLeft
	switch align {
	case ui.AlignCenter:
		alignment = allg5.AlignCenter
	case ui.AlignRight:
		alignment = allg5.AlignRight
	}
	r.text(font, p, c, t, alignment)
}

func (r *Renderer) TextTexture(font ui.Font, color color.Color, text string) (ui.Texture, error) {
	return ui.TextTexture(r, font, color, text)
}

// Utility functions

func eventWait(eq *allg5.EventQueue, wait bool) allg5.Event {
	if wait {
		return eq.GetWait()
	}
	return eq.Get()
}

func eventBase(e allg5.Event) ui.EventBase {
	return ui.EventBase{StampInSeconds: e.Stamp()}
}

func keyModifiers(mods allg5.KeyMod) ui.KeyModifier {
	var m ui.KeyModifier
	if mods&allg5.KeyModShift == allg5.KeyModShift {
		m |= ui.KeyModifierShift
	} else if mods&allg5.KeyModCtrl == allg5.KeyModCtrl {
		m |= ui.KeyModifierControl
	} else if mods&allg5.KeyModAlt == allg5.KeyModAlt {
		m |= ui.KeyModifierAlt
	}
	return m
}

func mouseEvent(e allg5.MouseEvent) ui.MouseEvent {
	return ui.MouseEvent{EventBase: eventBase(e), X: float32(e.X), Y: float32(e.Y)}
}

func newColor(c color.Color) allg5.Color {
	if c == nil {
		return newColor(color.Black)
	}
	return allg5.NewColorGo(c)
}

func snap(p geom.PointF32) (float32, float32) {
	return float32(math.Round(float64(p.X))), float32(math.Round(float64(p.Y)))
}

func dispPos(disp *allg5.Display) geom.Point {
	x, y := disp.Position()
	return geom.Pt(x, y)
}