package sdlui

import (
	"errors"
	"image"
	"image/color"
	_ "image/jpeg" // add JPEG for CreateSurfacePath
	_ "image/png"  // add PNG for CreateSurfacePath
	"math"
	"unsafe"

	"github.com/veandco/go-sdl2/sdl"
	"github.com/veandco/go-sdl2/ttf"
	"opslag.de/schobers/geom"
	"opslag.de/schobers/zntg"
	"opslag.de/schobers/zntg/ui"
)

var errNotImplemented = errors.New(`not implemented`)

type Renderer struct {
	window    *sdl.Window
	renderer  *sdl.Renderer
	refresh   uint32
	resources ui.Resources

	mouse   geom.PointF32
	cursor  ui.MouseCursor
	cursors map[sdl.SystemCursor]*sdl.Cursor
}

var _ ui.Renderer = &Renderer{}
var _ ui.Texture = &Renderer{}

type NewRendererOptions struct {
	Location  sdl.Point
	Resizable bool
	VSync     bool
}

func NewRenderer(title string, width, height int32, opts NewRendererOptions) (*Renderer, error) {
	var clean zntg.Actions
	defer func() { clean.Do() }()

	if err := sdl.Init(sdl.INIT_EVERYTHING); err != nil {
		return nil, err
	}
	clean = clean.Add(sdl.Quit)

	if err := ttf.Init(); err != nil {
		return nil, err
	}
	clean = clean.Add(ttf.Quit)

	if opts.VSync {
		sdl.SetHint(sdl.HINT_RENDER_VSYNC, "1")
	}
	sdl.SetHint(sdl.HINT_RENDER_SCALE_QUALITY, "1")
	windowFlags := uint32(sdl.WINDOW_SHOWN)
	if opts.Resizable {
		windowFlags |= sdl.WINDOW_RESIZABLE
	}
	window, err := sdl.CreateWindow(title, opts.Location.X, opts.Location.Y, width, height, windowFlags)
	if err != nil {
		return nil, err
	}
	clean = clean.AddErr(window.Destroy)

	rendererFlags := uint32(sdl.RENDERER_ACCELERATED)
	if opts.VSync {
		rendererFlags |= sdl.RENDERER_PRESENTVSYNC
	}
	renderer, err := sdl.CreateRenderer(window, -1, rendererFlags)
	if err != nil {
		return nil, err
	}
	renderer.SetDrawBlendMode(sdl.BLENDMODE_BLEND)
	clean = clean.AddErr(renderer.Destroy)

	refresh := sdl.RegisterEvents(1)
	if refresh == math.MaxUint32 {
		return nil, errors.New("couldn't register user event")
	}
	clean = nil

	return &Renderer{
		window:    window,
		renderer:  renderer,
		refresh:   refresh,
		resources: &ui.OSResources{},
		cursors:   map[sdl.SystemCursor]*sdl.Cursor{},
	}, nil
}

// Events

func (r *Renderer) WindowBounds() geom.RectangleF32 {
	x, y := r.window.GetPosition()
	w, h := r.window.GetSize()
	return geom.RectF32(float32(x), float32(y), float32(x+w), float32(y+h))
}

func (r *Renderer) PushEvents(t ui.EventTarget, wait bool) bool {
	r.renderer.Present()

	waitOrPoll := func() sdl.Event {
		if wait {
			return sdl.WaitEvent()
		}
		return sdl.PollEvent()
	}

	cursor := r.cursor
	var pushed bool
	for event := waitOrPoll(); event != nil; event = sdl.PollEvent() {
		pushed = true
		r.cursor = ui.MouseCursorDefault
		var unhandled bool

		switch e := event.(type) {
		case *sdl.WindowEvent:
			switch e.Event {
			case sdl.WINDOWEVENT_CLOSE:
				t.Handle(&ui.DisplayCloseEvent{EventBase: eventBase(e)})
			case sdl.WINDOWEVENT_MOVED:
				t.Handle(&ui.DisplayMoveEvent{EventBase: eventBase(e), Bounds: r.WindowBounds()})
			case sdl.WINDOWEVENT_RESIZED:
				t.Handle(&ui.DisplayResizeEvent{EventBase: eventBase(e), Bounds: r.WindowBounds()})
			case sdl.WINDOWEVENT_ENTER:
				t.Handle(&ui.MouseEnterEvent{MouseEvent: ui.MouseEvent{EventBase: eventBase(e), X: r.mouse.X, Y: r.mouse.Y}})
			case sdl.WINDOWEVENT_LEAVE:
				t.Handle(&ui.MouseLeaveEvent{MouseEvent: ui.MouseEvent{EventBase: eventBase(e), X: r.mouse.X, Y: r.mouse.Y}})
			default:
				unhandled = true
			}

		case *sdl.KeyboardEvent:
			if e.Type == sdl.KEYDOWN {
				t.Handle(&ui.KeyDownEvent{EventBase: eventBase(e), Key: key(e.Keysym.Sym), Modifiers: keyModifiers(e.Keysym.Mod)})
			} else if e.Type == sdl.KEYUP {
				t.Handle(&ui.KeyDownEvent{EventBase: eventBase(e), Key: 0, Modifiers: 0})
			} else {
				unhandled = true
			}
		case *sdl.TextInputEvent:
			if e.Type == sdl.TEXTINPUT {
				text := e.GetText()
				for _, character := range text {
					t.Handle(&ui.TextInputEvent{
						EventBase: eventBase(e),
						Character: character,
					})
				}
			} else {
				unhandled = true
			}

		case *sdl.MouseButtonEvent:
			if e.Type == sdl.MOUSEBUTTONDOWN {
				t.Handle(&ui.MouseButtonDownEvent{MouseEvent: mouseEvent(e, e.X, e.Y), Button: mouseButton(e.Button)})
			} else {
				t.Handle(&ui.MouseButtonUpEvent{MouseEvent: mouseEvent(e, e.X, e.Y), Button: mouseButton(e.Button)})
			}
		case *sdl.MouseMotionEvent:
			r.mouse = geom.PtF32(float32(e.X), float32(e.Y))
			t.Handle(&ui.MouseMoveEvent{MouseEvent: ui.MouseEvent{EventBase: eventBase(e), X: r.mouse.X, Y: r.mouse.Y}, MouseWheel: 0})
		case *sdl.MouseWheelEvent:
			t.Handle(&ui.MouseMoveEvent{MouseEvent: ui.MouseEvent{EventBase: eventBase(e), X: r.mouse.X, Y: r.mouse.Y}, MouseWheel: float32(e.Y)})
		case *sdl.UserEvent:
			if r.refresh == e.Type {
				t.Handle(&ui.RefreshEvent{EventBase: eventBase(e)})
			} else {
				unhandled = true
			}
		default:
			unhandled = true // not handled by EventTarget.Handle
		}

		if unhandled {
			r.cursor = cursor
		}
	}

	if r.cursor != cursor {
		switch r.cursor {
		case ui.MouseCursorDefault:
			sdl.SetCursor(r.SystemCursor(sdl.SYSTEM_CURSOR_ARROW))
		case ui.MouseCursorNotAllowed:
			sdl.SetCursor(r.SystemCursor(sdl.SYSTEM_CURSOR_NO))
		case ui.MouseCursorPointer:
			sdl.SetCursor(r.SystemCursor(sdl.SYSTEM_CURSOR_HAND))
		case ui.MouseCursorText:
			sdl.SetCursor(r.SystemCursor(sdl.SYSTEM_CURSOR_IBEAM))
		}
	}
	return pushed
}

func (r *Renderer) Refresh() {
	windowID, _ := r.window.GetID()
	e := &sdl.UserEvent{
		Type:     r.refresh,
		WindowID: windowID,
	}
	sdl.PushEvent(e)
}

// Lifetime

func (r *Renderer) Destroy() error {
	r.renderer.Destroy()
	r.window.Destroy()
	ttf.Quit()
	sdl.Quit()
	r.resources.Destroy()
	return nil
}

// Drawing

func (r *Renderer) Clear(c color.Color) {
	if c == color.Transparent {
		return
	}
	r.SetDrawColorGo(c)
	r.renderer.Clear()
}

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

func (r *Renderer) createTexture(source ui.ImageSource, keepSource bool) (ui.Texture, error) {
	m, err := source.CreateImage()
	if err != nil {
		return nil, err
	}
	rgba := NRGBAImage(m)
	width := int32(rgba.Bounds().Dx())
	height := int32(rgba.Bounds().Dy())
	surface, err := sdl.CreateRGBSurfaceWithFormatFrom(
		unsafe.Pointer(&rgba.Pix[0]),
		width, height, 32, int32(rgba.Stride), sdl.PIXELFORMAT_ABGR8888)
	if err != nil {
		return nil, err
	}
	defer surface.Free()
	texture, err := r.renderer.CreateTextureFromSurface(surface)
	if err != nil {
		return nil, err
	}
	texture.SetBlendMode(sdl.BLENDMODE_BLEND)
	if keepSource {
		return &TextureImageSource{&Texture{texture}, source}, nil
	}
	return &Texture{texture}, nil
}

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

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

func (r *Renderer) CreateTexturePath(path string, source bool) (ui.Texture, error) {
	return r.createTexture(ui.ImageSourceResource{Resources: r.resources, Name: path}, source)
}

func (r *Renderer) CreateTextureTarget(w, h float32) (ui.Texture, error) {
	format, err := r.window.GetPixelFormat()
	if err != nil {
		return nil, err
	}
	texture, err := r.renderer.CreateTexture(format, sdl.TEXTUREACCESS_TARGET, int32(w), int32(h))
	if err != nil {
		return nil, err
	}
	texture.SetBlendMode(sdl.BLENDMODE_BLEND)
	return &Texture{texture}, nil
}

func (r *Renderer) DefaultTarget() ui.Texture { return r }

func (r *Renderer) drawTexture(t sdlTexture, src, dst sdl.Rect, opts ui.DrawOptions) {
	if opts.Tint != nil {
		t.SetColor(opts.Tint)
	}
	r.renderer.Copy(t.Native(), &src, &dst)
}

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

func (r *Renderer) DrawTextureOptions(t ui.Texture, dst geom.RectangleF32, opts ui.DrawOptions) {
	texture, ok := t.(sdlTexture)
	if !ok {
		return
	}
	width, height, err := texture.Size()
	if err != nil {
		return
	}
	r.drawTexture(texture, Rect(0, 0, width, height), RectAbs(int32(dst.Min.X), int32(dst.Min.Y), int32(dst.Max.X), int32(dst.Max.Y)), opts)
}

func (r *Renderer) DrawTexturePoint(t ui.Texture, dst geom.PointF32) {
	r.DrawTexturePointOptions(t, dst, ui.DrawOptions{})
}

func (r *Renderer) DrawTexturePointOptions(t ui.Texture, dst geom.PointF32, opts ui.DrawOptions) {
	texture, ok := t.(sdlTexture)
	if !ok {
		return
	}
	width, height, err := texture.Size()
	if err != nil {
		return
	}
	r.drawTexture(texture, Rect(0, 0, width, height), Rect(int32(dst.X), int32(dst.Y), width, height), opts)
}

func (r *Renderer) FillRectangle(rect geom.RectangleF32, c color.Color) {
	r.SetDrawColorGo(c)
	r.renderer.FillRect(SDLRectanglePtr(rect))
}

func (r *Renderer) Rectangle(rect geom.RectangleF32, c color.Color, thickness float32) {
	r.SetDrawColorGo(c)
	if rect.Dx() == 0 { // SDL doesn't draw a 1 px wide line when Dx() == 0 && thickness == 1
		offset := int32(rect.Min.X - .5*thickness)
		for thick := int32(thickness); thick > 0; thick-- {
			r.renderer.DrawLine(offset, int32(rect.Min.Y), offset, int32(rect.Max.Y))
			offset++
		}
	} else if rect.Dy() == 0 {
		offset := int32(rect.Min.Y - .5*thickness)
		for thick := int32(thickness); thick > 0; thick-- {
			r.renderer.DrawLine(int32(rect.Min.X), offset, int32(rect.Max.X), offset)
			offset++
		}
	} else {
		for thick := int32(thickness); thick > 0; thick-- {
			r.renderer.DrawRect(SDLRectanglePtr(rect))
			rect = rect.Inset(1)
		}
	}
}

func (r *Renderer) RenderTo(t ui.Texture) {
	texture, ok := t.(sdlTexture)
	if ok {
		err := r.renderer.SetRenderTarget(texture.Native())
		if err != nil {
			panic(err)
		}
	} else {
		r.RenderToDisplay()
	}
}

func (r *Renderer) RenderToDisplay() {
	r.renderer.SetRenderTarget(nil)
}

func (r *Renderer) SetDrawColor(c sdl.Color) {
	r.renderer.SetDrawColor(c.R, c.G, c.B, c.A)
}

func (r *Renderer) SetDrawColorGo(c color.Color) {
	r.SetDrawColor(ColorSDL(c))
}

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

func (r *Renderer) Size() geom.PointF32 {
	w, h, err := r.renderer.GetOutputSize()
	if err != nil {
		return geom.PtF32(geom.NaN32(), geom.NaN32())
	}
	return geom.PtF32(float32(w), float32(h))
}

func (r *Renderer) SystemCursor(id sdl.SystemCursor) *sdl.Cursor {
	if cursor, ok := r.cursors[id]; ok {
		return cursor
	}
	cursor := sdl.CreateSystemCursor(id)
	r.cursors[id] = cursor
	return cursor
}

func (r *Renderer) Target() ui.Texture {
	target := r.renderer.GetRenderTarget()
	if target == nil {
		return r
	}
	return &Texture{target}
}

func (r *Renderer) Text(font ui.Font, p geom.PointF32, color color.Color, text string) {
	f := font.(*Font)

	surface, err := f.RenderUTF8Blended(text, ColorSDL(color))
	if err != nil {
		return
	}
	defer surface.Free()
	texture, err := r.renderer.CreateTextureFromSurface(surface)
	if err != nil {
		return
	}
	defer texture.Destroy()

	r.DrawTexturePoint(&Texture{texture}, p)
}

func (r *Renderer) TextAlign(font ui.Font, p geom.PointF32, color color.Color, text string, align ui.HorizontalAlignment) {
	switch align {
	case ui.AlignLeft:
		r.Text(font, p, color, text)
	case ui.AlignCenter:
		width := font.WidthOf(text)
		r.Text(font, p.Add2D(-.5*width, 0), color, text)
	case ui.AlignRight:
		width := font.WidthOf(text)
		r.Text(font, p.Add2D(-width, 0), color, text)
	}
}

// Resources

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

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

// Texture

func (r *Renderer) Image() image.Image { return nil }

func (r *Renderer) Height() float32 { return r.Size().Y }

func (r *Renderer) Width() float32 { return r.Size().X }