package allg5ui

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

	"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 err = allg5.Init(allg5.InitAll)
	if err != nil {
		return nil, err
	}
	disp, err := allg5.NewDisplay(w, h, opts)
	if err != nil {
		return nil, err
	}

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

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

	return &Renderer{disp, eq, nil, map[string]*font{}, user, ui.MouseCursorDefault, ui.MouseCursorDefault}, nil
}

// Renderer implements ui.Renderer using Allegro 5.
type Renderer struct {
	disp      *allg5.Display
	eq        *allg5.EventQueue
	unh       func(allg5.Event)
	ft        map[string]*font
	user      *allg5.UserEventSource
	cursor    ui.MouseCursor
	newCursor ui.MouseCursor
}

// Renderer implementation (events)

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

	r.newCursor = ui.MouseCursorDefault
	var ev = eventWait(r.eq, wait)
	if ev == nil {
		return
	}
	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:
			t.Handle(&ui.KeyPressEvent{EventBase: eventBase(e), Key: key(e.KeyCode), Modifiers: keyModifiers(e.Modifiers), Character: e.UnicodeCharacter})
		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)
			}
		}
		ev = r.eq.Get()
	}

	if r.newCursor != r.cursor {
		r.cursor = r.newCursor
		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)
		}
	}
}

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()
	for _, f := range r.ft {
		f.Destroy()
	}
	r.ft = nil
	r.disp.Destroy()
	return nil
}

// Renderer implementation (drawing)

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

func (r *Renderer) CreateImage(im image.Image) (ui.Image, error) {
	bmp, err := allg5.NewBitmapFromImage(im, true)
	if err != nil {
		return nil, err
	}
	return &uiImage{bmp}, nil
}

func (r *Renderer) CreateImagePath(path string) (ui.Image, error) {
	bmp, err := allg5.LoadBitmap(path)
	if err != nil {
		return nil, err
	}
	return &uiImage{bmp}, nil
}

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

func (r *Renderer) DefaultTarget() ui.Image {
	return &uiImage{r.disp.Target()}
}

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

func (r *Renderer) DrawImage(im ui.Image, p geom.PointF32) {
	bmp := r.mustGetBitmap(im)
	x, y := snap(p)
	bmp.Draw(x, y)
}

func (r *Renderer) DrawImageOptions(im ui.Image, p geom.PointF32, opts ui.DrawOptions) {
	bmp := r.mustGetBitmap(im)
	var o allg5.DrawOptions
	if opts.Tint != nil {
		tint := newColor(opts.Tint)
		o.Tint = &tint
	}
	if opts.Scale != nil {
		o.Scale = &allg5.Scale{Horizontal: opts.Scale.X, Vertical: opts.Scale.Y}
	}
	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) Font(name string) ui.Font {
	return r.ft[name]
}

func (r *Renderer) mustGetBitmap(im ui.Image) *allg5.Bitmap {
	m, ok := im.(*uiImage)
	if !ok {
		panic("image must be created on same renderer")
	}
	return m.bmp
}

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) RegisterFont(name, path string, size int) error {
	var f, err = allg5.LoadTTFFont(path, size)
	if err != nil {
		return err
	}
	var prev = r.ft[name]
	if prev != nil {
		prev.Destroy()
	}
	r.ft[name] = newFont(f)
	return nil
}

func (r *Renderer) RegisterFonts(path string, fonts ...FontDefinition) error {
	for _, f := range fonts {
		err := r.RegisterFont(path, f.Name, f.Size)
		if err != nil {
			return err
		}
	}
	return nil
}

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

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

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

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

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

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.Image {
	return &uiImage{allg5.CurrentTarget()}
}

func (r *Renderer) text(p geom.PointF32, font string, c color.Color, t string, align allg5.HorizontalAlignment) {
	var f = r.ft[font]
	if f == nil {
		return
	}
	x, y := snap(p)
	f.f.Draw(x, y, newColor(c), align, t)
}

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

func (r *Renderer) TextAlign(p geom.PointF32, font string, 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(p, font, c, t, alignment)
}

// 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 key(key allg5.Key) ui.Key {
	switch key {
	case allg5.KeyBackspace:
		return ui.KeyBackspace
	case allg5.KeyDelete:
		return ui.KeyDelete
	case allg5.KeyDown:
		return ui.KeyDown
	case allg5.KeyEnd:
		return ui.KeyEnd
	case allg5.KeyEscape:
		return ui.KeyEscape
	case allg5.KeyHome:
		return ui.KeyHome
	case allg5.KeyLeft:
		return ui.KeyLeft
	case allg5.KeyRight:
		return ui.KeyRight
	case allg5.KeyUp:
		return ui.KeyUp
	}
	return ui.KeyNone
}

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)))
}