package ui

import (
	"opslag.de/schobers/galleg/allegro5"
	"opslag.de/schobers/geom"
)

type scroll struct {
	Wrapper
	Content Control
	Bar     *ContentScrollbar
}

func Scroll(c Control, o Orientation) Control {
	var dock = NewDockPanel(nil)
	var bar = &ContentScrollbar{Orientation: o}
	switch o {
	case OrientationHorizontal:
		dock.Append(DockBottom, TopMargin(bar, ScrollbarWidth))
		dock.Append(DockBottom, c)
	case OrientationVertical:
		dock.Append(DockRight, LeftMargin(bar, ScrollbarWidth))
		dock.Append(DockRight, c)
	}
	var s = &scroll{Wrap(dock), c, bar}
	bar.OnChanged = func(v float64) {

	}
	return s
}

func (s *scroll) Handle(ctx Context, ev allegro5.Event) {
	s.Wrapper.Handle(ctx, ev)
	switch e := ev.(type) {
	case *allegro5.MouseMoveEvent:
		if 0 != e.DeltaZ && !s.Bar.IsOver && geom.PtF(float64(e.X), float64(e.Y)).In(s.Bounds) {
			var d = e.DeltaZ
			if allegro5.IsAnyKeyDown(allegro5.KeyLShift, allegro5.KeyRShift) {
				d *= 10
			}
			s.Bar.increment(d)
		}
	}
}

func (s *scroll) Render(ctx Context) {
	var bounds = s.Content.Rect()
	var w, h = bounds.Dx(), bounds.Dy()
	var bmp, err = allegro5.NewVideoBitmap(int(w), int(h))
	if nil != err {
		return
	}
	defer bmp.Destroy()
	bmp.SetAsTarget()
	switch s.Bar.Orientation {
	case OrientationHorizontal:
		Arrange(ctx, s.Content, geom.RectF(-s.Bar.Value, 0, w, h))
	case OrientationVertical:
		Arrange(ctx, s.Content, geom.RectF(0, -s.Bar.Value, w, h))
	}
	s.Content.Render(ctx)
	ctx.Display().SetAsTarget()
	var min = s.Bounds.Min.To32()
	bmp.Draw(min.X, min.Y)
	s.Bar.Render(ctx)
}

func (s *scroll) Arrange(ctx Context, rect geom.RectangleF) {
	var sz = s.Content.DesiredSize(ctx)
	switch s.Bar.Orientation {
	case OrientationHorizontal:
		s.Bar.Length = sz.X
	case OrientationVertical:
		s.Bar.Length = sz.Y
	}
	s.Wrapper.Arrange(ctx, rect)
}