package allg5ui

import (
	"image"
	"image/color"

	"opslag.de/schobers/geom"

	"opslag.de/schobers/zntg/allg5"
	"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
	}

	eq.RegisterKeyboard()
	eq.RegisterMouse()
	eq.RegisterDisplay(disp)

	return &Renderer{disp, eq, map[string]*font{}}, nil
}

// Renderer implements ui.Renderer using Allegro 5.
type Renderer struct {
	disp *allg5.Display
	eq   *allg5.EventQueue
	ft   map[string]*font
}

// Renderer implementation (events)

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

	var ev = eventWait(r.eq, wait)
	for nil != ev {
		switch e := ev.(type) {
		case *allg5.DisplayCloseEvent:
			t.Handle(&ui.DisplayCloseEvent{EventBase: eventBase(e)})
		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.MouseMoveEvent:
			t.Handle(&ui.MouseMoveEvent{MouseEvent: mouseEvent(e.MouseEvent), MouseWheel: float32(e.DeltaZ)})
		}
		ev = r.eq.Get()
	}
}

// Renderer implementation (lifetime)

func (r *Renderer) Destroy() error {
	r.eq.Destroy()
	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) DrawImage(p geom.PointF32, im ui.Image) {
	bmp := r.mustGetBitmap(im)
	bmp.Draw(p.X, p.Y)
}

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) {
	allg5.DrawRectangle(rect.Min.X, rect.Min.Y, rect.Max.X, rect.Max.Y, newColor(c), thickness)
}

func (r *Renderer) RegisterFont(path, name string, size int) error {
	var f, err = allg5.LoadTTFFont(path, int(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) 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) {
	var f = r.ft[font]
	if f == nil {
		return
	}
	f.f.Draw(p.X, p.Y, newColor(c), allg5.AlignLeft, t)
}

// 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 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)
	}
	var r, g, b, a = c.RGBA()
	var r8, g8, b8, a8 = byte(r >> 8), byte(g >> 8), byte(b >> 8), byte(a >> 8)
	return allg5.NewColorAlpha(r8, g8, b8, a8)
}