package ui

import (
	"image/color"

	"opslag.de/schobers/geom"
)

type Button struct {
	ControlBase

	DisabledColor color.Color
	HoverColor    color.Color

	Icon       string  // optional: icon to display in front of the text.
	IconHeight float32 // overrides the height of the icon (overrides auto-scaling when text is provided).
	Text       string
	Type       ButtonType

	clicked ControlClickedEvents
}

type ButtonType int

const (
	ButtonTypeContained ButtonType = iota
	ButtonTypeIcon
	ButtonTypeOutlined
	ButtonTypeText
)

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

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

func (b *Button) desiredSize(ctx Context) geom.PointF32 {
	var pad = b.ActualTextPadding(ctx)
	var font = b.ActualFont(ctx)
	var w, h float32 = 0, font.Height()

	icon, iconW, iconH := b.icon(ctx)
	if len(b.Text) == 0 {
		if icon != nil && iconH > 0 {
			w = pad.Left + iconW + pad.Right
			h = iconH
		}
	} else {
		w += pad.Left + font.WidthOf(b.Text) + pad.Right
		if icon != nil && iconH > 0 {
			if b.IconHeight == 0 {
				iconW = iconW * h / iconH
				// iconH = h
			}
			w += iconW + pad.Right
		}
	}
	if w == 0 {
		return geom.ZeroPtF32
	}
	return geom.PtF32(w, pad.Top+h+pad.Bottom)
}

func (b *Button) icon(ctx Context) (Texture, float32, float32) {
	if b.Icon == "" {
		return nil, 0, 0
	}
	icon := ctx.Textures().Texture(b.Icon)
	iconW, iconH := float32(icon.Width()), float32(icon.Height())
	if b.IconHeight != 0 {
		iconW = b.IconHeight * iconW / iconH
		iconH = b.IconHeight
	}
	return icon, iconW, iconH
}

func (b *Button) ButtonClicked() ControlClickedEventHandler { return &b.clicked }

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

func (b *Button) Handle(ctx Context, e Event) bool {
	result := b.ControlBase.HandleNotify(ctx, e, b)
	if b.over {
		if b.Disabled {
			return true
		}
		ctx.Renderer().SetMouseCursor(MouseCursorPointer)
	}
	return result
}

func (b *Button) Notify(ctx Context, state interface{}) bool {
	switch state.(type) {
	case ControlClickedArgs:
		if !b.Disabled {
			if b.clicked.Notify(ctx, state) {
				return true
			}
		}
	}
	return b.ControlBase.Notify(ctx, state)
}

func (b *Button) disabledColor(p *Palette) color.Color {
	if b.DisabledColor != nil {
		return b.DisabledColor
	}
	return p.Disabled
}

func (b *Button) fillColor(p *Palette) color.Color {
	if b.Type == ButtonTypeIcon {
		return nil
	}

	if b.Disabled {
		if b.Background != nil {
			return b.disabledColor(p)
		}
		switch b.Type {
		case ButtonTypeContained:
			return b.disabledColor(p)
		default:
			return nil
		}
	}
	if b.Background != nil {
		if b.over && b.HoverColor != nil {
			return b.HoverColor
		}
		return b.Background
	}
	if b.over {
		if b.HoverColor != nil {
			return b.HoverColor
		}
		switch b.Type {
		case ButtonTypeContained:
			return p.PrimaryLight
		default:
			return p.PrimaryHighlight
		}
	}
	switch b.Type {
	case ButtonTypeContained:
		return p.Primary
	}
	return nil
}

func (b *Button) fontColor(c color.Color) color.Color {
	if b.Font.Color == nil {
		return c
	}
	return b.Font.Color
}

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

	pad := b.ActualTextPadding(ctx)
	bounds = pad.InsetRect(bounds)
	boundsH := bounds.Dy()
	pos := bounds.Min
	icon, iconW, iconH := b.icon(ctx)
	var iconOffsetY float32
	if icon != nil && iconH > 0 {
		if b.Text != "" {
			if b.IconHeight == 0 {
				iconH = boundsH
				scaled, _ := ctx.Textures().ScaledHeight(icon, iconH) // try to pre-scale scaled
				if scaled != nil {                                    // let the renderer scale
					icon = scaled
				}
				_, iconW = ScaleToHeight(SizeOfTexture(icon).ToF32(), iconH)
			}
			iconOffsetY = .5 * (boundsH - iconH)
		}
		ctx.Renderer().DrawTextureOptions(icon, geom.RectRelF32(pos.X, pos.Y+iconOffsetY, iconW, iconH), DrawOptions{Tint: textColor})
		pos.X += iconW + pad.Right
	}
	if len(b.Text) != 0 {
		font := b.ActualFont(ctx)
		ctx.Renderer().Text(font, geom.PtF32(pos.X, pos.Y+.5*(boundsH-font.Height())), textColor, b.Text)
	}

	if b.Type == ButtonTypeOutlined {
		b.RenderOutlineDefault(ctx, textColor)
	}
}