package ui

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

type Spacing struct {
	Proxy

	Margin SideLengths
	Width  *Length
	Height *Length
}

func BuildSpacing(content Control, fn func(*Spacing)) *Spacing {
	s := &Spacing{}
	s.Content = content
	if fn != nil {
		fn(s)
	}
	return s
}

func sumLengths(lengths ...float32) (float32, int) {
	var fixed float32
	var infinite int
	for _, l := range lengths {
		if geom.IsNaN32(l) {
			infinite++
		} else {
			fixed += l
		}
	}
	return fixed, infinite
}

func addMargin(bounds geom.PointF32, size geom.PointF32, margin SideLengths) geom.RectangleF32 {
	var left = margin.Left.Value()
	var top = margin.Top.Value()
	var w, hor = sumLengths(left, size.X, margin.Right.Value())
	var h, ver = sumLengths(top, size.Y, margin.Bottom.Value())
	var rem = geom.PtF32(geom.Max32(0, bounds.X-w), geom.Max32(0, bounds.Y-h))
	if geom.IsNaN32(left) {
		left = rem.X / float32(hor)
	} else if rem.X == 0 {
		left = (left * bounds.X) / w
	}
	if geom.IsNaN32(size.X) {
		size.X = rem.X / float32(hor)
	} else if rem.X == 0 {
		size.X = (size.X * bounds.X) / w
	} else if hor == 0 { // nothing stretches
		size.X += rem.X
	}
	if geom.IsNaN32(top) {
		top = rem.Y / float32(ver)
	} else if rem.Y == 0 {
		top = (top * bounds.Y) / h
	}
	if geom.IsNaN32(size.Y) {
		size.Y = rem.Y / float32(ver)
	} else if rem.Y == 0 {
		size.Y = (size.Y * bounds.Y) / h
	} else if ver == 0 { // nothing stretches
		size.Y += rem.Y
	}
	return geom.RectF32(left, top, left+size.X, top+size.Y)
}

func (s *Spacing) Arrange(ctx Context, bounds geom.RectangleF32, offset geom.PointF32) {
	var size = s.Proxy.DesiredSize(ctx)
	var w, h = s.Width.Zero(size.X), s.Height.Zero(size.Y)
	var content = addMargin(geom.PtF32(bounds.Dx(), bounds.Dy()), geom.PtF32(w, h), s.Margin).Add(bounds.Min)
	s.Proxy.Arrange(ctx, content, offset)
}

func (s *Spacing) Center() {
	s.Margin.Left = Infinite()
	s.Margin.Top = Infinite()
	s.Margin.Right = Infinite()
	s.Margin.Bottom = Infinite()
}

func (s *Spacing) DesiredSize(ctx Context) geom.PointF32 {
	var size = s.Proxy.DesiredSize(ctx)
	var w, h = s.Width.Zero(size.X), s.Height.Zero(size.Y)
	var margin = func(l *Length) float32 {
		var v = l.Value()
		if geom.IsNaN32(v) {
			return 0
		}
		return v
	}
	return geom.PtF32(
		margin(s.Margin.Left)+w+margin(s.Margin.Right),
		margin(s.Margin.Top)+h+margin(s.Margin.Bottom))
}

func (s *Spacing) SetSize(w, h float32) {
	s.Width = Fixed(w)
	s.Height = Fixed(h)
}

// FixedSize wraps the Control c to fill exactly the space specified.
func FixedSize(c Control, w, h float32) *Spacing {
	return BuildSpacing(c, func(s *Spacing) {
		s.Width = Fixed(w)
		s.Height = Fixed(h)
	})
}

// FixedHeight wraps the Control c to fill exactly the height specified. Width is taken from Control c.
func FixedHeight(c Control, h float32) *Spacing {
	return BuildSpacing(c, func(s *Spacing) {
		s.Height = Fixed(h)
	})
}

// FixedWidth wraps the Control c to fill exactly the width specified. Height is taken from Control c.
func FixedWidth(c Control, w float32) Control {
	return BuildSpacing(c, func(s *Spacing) {
		s.Width = Fixed(w)
	})
}

// Margin wraps the Control c to have equal margins on all sides.
func Margin(c Control, m float32) *Spacing {
	return Margins(c, m, m, m, m)
}

// MarginAxes wraps the Control c to have same margins horizontally (left, right) and vertically (top, left).
func MarginAxes(c Control, hor, ver float32) *Spacing {
	return Margins(c, hor, ver, hor, ver)
}

// Margins wraps the Control c to have different margins on all sides.
func Margins(c Control, left, top, right, bottom float32) *Spacing {
	return BuildSpacing(c, func(s *Spacing) {
		s.Margin.Left = Fixed(left)
		s.Margin.Top = Fixed(top)
		s.Margin.Right = Fixed(right)
		s.Margin.Bottom = Fixed(bottom)
	})
}

func stretch(c Control, w, h bool) *Spacing {
	return BuildSpacing(c, func(s *Spacing) {
		if w {
			s.Width = Infinite()
		}
		if h {
			s.Height = Infinite()
		}
	})
}

// Stretch wraps the Control c to stretch in both directions.
func Stretch(c Control) *Spacing { return stretch(c, true, true) }

// StretchHeight wraps the Control c to stretch vertically. Width is taken from Control c.
func StretchHeight(c Control) *Spacing { return stretch(c, false, true) }

// StretchWidth wraps the Control c to stretch horizontally. Height is taken from Control c.
func StretchWidth(c Control) *Spacing { return stretch(c, true, false) }