package ui

import (
	"image/color"

	"opslag.de/schobers/geom"
)

type ClickFn func(pos geom.PointF32, btn MouseButton)
type DragEndFn func(start, end geom.PointF32)
type DragMoveFn func(start, move geom.PointF32)
type DragStartFn func(start geom.PointF32)
type MouseEnterFn func()
type MouseLeaveFn func()

var _ Control = &ControlBase{}

type ControlBase struct {
	bounds    geom.RectangleF32
	offset    geom.PointF32
	parent    Control
	dragStart *geom.PointF32
	over      bool
	pressed   bool

	onClick     ClickFn
	onDragEnd   DragEndFn
	onDragMove  DragMoveFn
	onDragStart DragStartFn

	Background    color.Color
	Font          FontStyle
	TextAlignment HorizontalAlignment
}

func (c *ControlBase) Arrange(ctx Context, bounds geom.RectangleF32, offset geom.PointF32, parent Control) {
	c.bounds = bounds
	c.offset = offset
	c.parent = parent
}

func (c *ControlBase) Bounds() geom.RectangleF32 { return c.bounds }

func (c *ControlBase) DesiredSize(Context) geom.PointF32 { return geom.ZeroPtF32 }

func (c *ControlBase) Handle(ctx Context, e Event) {
	var over = func(e MouseEvent) bool {
		pos := e.Pos()
		if !c.IsInBounds(pos) {
			return false
		}
		parent := c.Parent()
		for parent != nil {
			if !parent.IsInBounds(pos) {
				return false
			}
			parent = parent.Parent()
		}
		return true
	}
	switch e := e.(type) {
	case *MouseMoveEvent:
		c.over = over(e.MouseEvent)
		if c.pressed {
			if c.dragStart == nil {
				var start = c.ToControlPosition(e.Pos())
				c.dragStart = &start
				if c.onDragStart != nil {
					c.onDragStart(start)
				}
			} else {
				var start = *c.dragStart
				var move = c.ToControlPosition(e.Pos())
				if c.onDragMove != nil {
					c.onDragMove(start, move)
				}
			}
		}
	case *MouseLeaveEvent:
		c.over = false
	case *MouseButtonDownEvent:
		c.over = over(e.MouseEvent)
		if c.over && e.Button == MouseButtonLeft {
			c.pressed = true
		}
	case *MouseButtonUpEvent:
		if e.Button == MouseButtonLeft {
			if c.dragStart != nil {
				var start = *c.dragStart
				var end = c.ToControlPosition(e.Pos())
				c.dragStart = nil
				if c.onDragEnd != nil {
					c.onDragEnd(start, end)
				}
			}
			if c.pressed {
				if c.onClick != nil {
					c.onClick(c.ToControlPosition(e.Pos()), e.Button)
				}
			}
			c.pressed = false
		}
	}
}

func (c *ControlBase) FontColor(ctx Context) color.Color {
	var text = c.Font.Color
	if text == nil {
		text = ctx.Style().Palette.Text
	}
	return text
}

func (c *ControlBase) FontName(ctx Context) string {
	var name = c.Font.Name
	if len(name) == 0 {
		name = ctx.Style().Fonts.Default
	}
	return name
}

func (c *ControlBase) IsInBounds(p geom.PointF32) bool {
	bounds := c.bounds
	if bounds.Min.X < 0 {
		bounds.Min.X = 0
	}
	if bounds.Min.Y < 0 {
		bounds.Min.Y = 0
	}
	return c.ToControlPosition(p).In(c.bounds)
}

func (c *ControlBase) IsOver() bool { return c.over }

func (c *ControlBase) Parent() Control { return c.parent }

func (c *ControlBase) IsPressed() bool { return c.pressed }

func (c *ControlBase) Offset() geom.PointF32 { return c.offset }

func (c *ControlBase) OnClick(fn ClickFn) { c.onClick = fn }

func (c *ControlBase) OnDragStart(fn DragStartFn) {
	c.onDragStart = fn
}

func (c *ControlBase) OnDragMove(fn DragMoveFn) {
	c.onDragMove = fn
}

func (c *ControlBase) OnDragEnd(fn DragEndFn) { c.onDragEnd = fn }

func (c *ControlBase) Render(Context) {}

func (c *ControlBase) RenderBackground(ctx Context) {
	if c.Background != nil {
		ctx.Renderer().FillRectangle(c.bounds, c.Background)
	}
}

func (c *ControlBase) RenderOutline(ctx Context) {
	style := ctx.Style()
	width := style.Dimensions.OutlineWidth
	color := style.Palette.Primary
	if c.Font.Color != nil {
		color = c.Font.Color
	}
	ctx.Renderer().Rectangle(c.bounds.Inset(.5*width), color, width)
}

func (c *ControlBase) ToControlPosition(p geom.PointF32) geom.PointF32 { return p.Sub(c.offset) }