package ui

import (
	"image/color"

	"github.com/nfnt/resize"
	"opslag.de/schobers/geom"
)

type Button struct {
	ControlBase

	Type ButtonType
	Text string
	Icon Image

	IconScale float32

	scale float32
	icon  Image
}

type ButtonType int

const (
	ButtonTypeContained ButtonType = iota
	ButtonTypeIcon
	ButtonTypeOutlined
	ButtonTypeText
)

func BuildButton(text string, fn func(b *Button)) *Button { return BuildIconButton(nil, text, fn) }

func BuildIconButton(i Image, text string, fn func(b *Button)) *Button {
	var b = &Button{Text: text, Icon: i}
	if fn != nil {
		fn(b)
	}
	return b
}

func (b *Button) desiredSize(ctx Context) geom.PointF32 {
	var pad = ctx.Style().Dimensions.TextPadding
	var font = ctx.Renderer().Font(b.FontName(ctx))
	var w, h float32 = 0, font.Height()
	if len(b.Text) != 0 {
		w += pad + font.WidthOf(b.Text)
	}
	if b.Icon != nil && b.Icon.Height() > 0 {
		iconW := b.Icon.Width() * h / b.Icon.Height()
		if b.IconScale > 0 {
			iconW *= b.IconScale
		}
		w += pad + iconW
	}
	if w == 0 {
		return geom.ZeroPtF32
	}
	return geom.PtF32(w+pad, pad+h+pad)
}

func (b *Button) DesiredSize(ctx Context) geom.PointF32 {
	return b.desiredSize(ctx)
}

func (b *Button) Handle(ctx Context, e Event) {
	b.ControlBase.Handle(ctx, e)
	if b.over {
		ctx.Renderer().SetMouseCursor(MouseCursorPointer)
	}
}

func (b *Button) fillColor(p *Palette) color.Color {
	if b.Background != nil {
		return b.Background
	}
	if b.over {
		switch b.Type {
		case ButtonTypeContained:
			return p.PrimaryHighlight
		case ButtonTypeIcon:
		default:
			return p.PrimaryLight
		}
	}
	switch b.Type {
	case ButtonTypeContained:
		return p.Primary
	case ButtonTypeIcon:
	default:
	}
	return nil
}

func (b *Button) scaledIcon(ctx Context, height float32) Image {
	scale := height / b.Icon.Height()
	if b.IconScale > 0 {
		scale *= b.IconScale
	}
	if geom.IsNaN32(scale) {
		return nil
	}
	if scale == 1 {
		b.scale = 1
		return b.Icon
	}
	if b.icon == nil || b.scale != scale {
		if b.icon != nil {
			b.icon.Destroy()
			b.icon = nil
		}
		w := uint(b.Icon.Width() * scale)
		if w == 0 {
			return nil
		}
		im := resize.Resize(w, 0, b.Icon.Image(), resize.Bilinear)
		icon, err := ctx.Renderer().CreateImage(im)
		if err != nil {
			return nil
		}
		b.icon = icon
		b.scale = scale
	}
	return b.icon
}

func (b *Button) textColor(p *Palette) color.Color {
	if b.Font.Color != nil {
		return b.Font.Color
	}
	switch b.Type {
	case ButtonTypeContained:
		return p.TextOnPrimary
	case ButtonTypeIcon:
		if b.over {
			return p.Primary
		}
		return p.Text
	default:
		return p.Primary
	}
}

func (b *Button) Render(ctx Context) {
	var style = ctx.Style()
	var palette = style.Palette
	textColor := b.textColor(palette)
	fillColor := b.fillColor(palette)
	if fillColor != nil {
		ctx.Renderer().FillRectangle(b.bounds, fillColor)
	}
	size := b.desiredSize(ctx)
	bounds := b.bounds
	deltaX, deltaY := bounds.Dx()-size.X, bounds.Dy()-size.Y
	bounds.Min.X += .5 * deltaX
	bounds.Min.Y += .5 * deltaY

	var pad = style.Dimensions.TextPadding
	bounds = bounds.Inset(pad)
	pos := bounds.Min
	pos.X += pad
	if b.Icon != nil && b.Icon.Height() > 0 {
		icon := b.scaledIcon(ctx, bounds.Dy())
		if icon != nil {
			ctx.Renderer().DrawImageOptions(icon, geom.PtF32(pos.X, pos.Y+.5*(bounds.Dy()-icon.Height())), DrawOptions{Tint: textColor})
			pos.X += icon.Width() + pad
		}
	}
	if len(b.Text) != 0 {
		var fontName = b.FontName(ctx)
		var font = ctx.Renderer().Font(fontName)
		ctx.Renderer().Text(geom.PtF32(pos.X, pos.Y+.5*(bounds.Dy()-font.Height())), fontName, textColor, b.Text)
	}
	if b.Type == ButtonTypeOutlined {
		ctx.Renderer().Rectangle(b.bounds, palette.TextDisabled, 1)
	}
}