package ui

import (
	"image/color"

	"opslag.de/schobers/geom"
)

type ControlClickedArgs struct {
	Position geom.PointF32
	Button   MouseButton
}

type ControlClickedEventHandler interface {
	AddHandler(func(Context, ControlClickedArgs)) uint
}

type ControlClickedEvents struct {
	Events
}

func (e *ControlClickedEvents) AddHandler(handler func(Context, ControlClickedArgs)) uint {
	return e.Events.AddHandler(func(ctx Context, state interface{}) {
		args := state.(ControlClickedArgs)
		handler(ctx, args)
	})
}

type DragEndedArgs struct {
	Start geom.PointF32
	End   geom.PointF32
}

type DragEndedEventHandler interface {
	AddHandler(func(Context, DragEndedArgs)) uint
}

type DragEndedEvents struct {
	Events
}

func (e *DragEndedEvents) AddHandler(handler func(Context, DragEndedArgs)) uint {
	return e.Events.AddHandler(func(ctx Context, state interface{}) {
		args := state.(DragEndedArgs)
		handler(ctx, args)
	})
}

type DragMovedArgs struct {
	Start   geom.PointF32
	Current geom.PointF32
}

type DragMovedEventHandler interface {
	AddHandler(func(Context, DragMovedArgs)) uint
}

type DragMovedEvents struct {
	Events
}

func (e *DragMovedEvents) AddHandler(handler func(Context, DragMovedArgs)) uint {
	return e.Events.AddHandler(func(ctx Context, state interface{}) {
		args := state.(DragMovedArgs)
		handler(ctx, args)
	})
}

type DragStartedArgs struct {
	Start geom.PointF32
}

type DragStartedEventHandler interface {
	AddHandler(func(Context, DragStartedArgs)) uint
}

type DragStartedEvents struct {
	Events
}

func (e *DragStartedEvents) AddHandler(handler func(Context, DragStartedArgs)) uint {
	return e.Events.AddHandler(func(ctx Context, state interface{}) {
		args := state.(DragStartedArgs)
		handler(ctx, args)
	})
}

var _ Control = &ControlBase{}

type ControlBase struct {
	bounds  geom.RectangleF32
	offset  geom.PointF32
	parent  Control
	drag    Dragable
	over    bool
	pressed bool

	clicked     ControlClickedEvents
	dragEnded   DragEndedEvents
	dragMoved   DragMovedEvents
	dragStarted DragStartedEvents

	Background    color.Color
	Font          FontStyle
	TextAlignment HorizontalAlignment
	TextPadding   SideLengths

	Disabled bool

	Tooltip string
}

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) ControlClicked() ControlClickedEventHandler { return &c.clicked }

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

func (c *ControlBase) Disable() { c.Disabled = true }

func (c *ControlBase) DragEnded() DragEndedEventHandler { return &c.dragEnded }

func (c *ControlBase) DragMoved() DragMovedEventHandler { return &c.dragMoved }

func (c *ControlBase) DragStarted() DragStartedEventHandler { return &c.dragStarted }

func (c *ControlBase) Enable() { c.Disabled = false }

func (c *ControlBase) Handle(ctx Context, e Event) bool { return c.HandleNotify(ctx, e, c) }

func (c *ControlBase) HandleNotify(ctx Context, e Event, notifier Notifier) bool {
	defer func() {
		if c.Tooltip != "" && c.over {
			ctx.ShowTooltip(c.Tooltip)
		}
	}()

	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 start, ok := c.drag.IsDragging(); ok {
				var move = c.ToControlPosition(e.Pos())
				c.drag.Move(move)
				return notifier.Notify(ctx, DragMovedArgs{Start: start, Current: move})
			}
			var start = c.ToControlPosition(e.Pos())
			c.drag.Start(start)
			return notifier.Notify(ctx, DragStartedArgs{Start: start})
		}
	case *MouseLeaveEvent:
		c.over = false
	case *MouseButtonDownEvent:
		c.over = over(e.MouseEvent)
		if c.over && e.Button == MouseButtonLeft {
			c.pressed = true
			return notifier.Notify(ctx, ControlClickedArgs{Position: e.Pos(), Button: e.Button})
		}
	case *MouseButtonUpEvent:
		if e.Button == MouseButtonLeft {
			c.pressed = false
			if start, ok := c.drag.IsDragging(); ok {
				var end = c.ToControlPosition(e.Pos())
				c.drag.Cancel()
				return notifier.Notify(ctx, DragEndedArgs{Start: start, End: end})
			}
		}
	}
	return false
}

func (c *ControlBase) ActualFont(ctx Context) Font {
	name := c.FontName(ctx)
	return ctx.Fonts().Font(name)
}

func (c *ControlBase) ActualTextPadding(ctx Context) Sides {
	return c.TextPadding.Zero(ctx.Style().Dimensions.TextPadding)
}

func (c *ControlBase) FontColor(ctx Context, color color.Color) color.Color {
	if c.Disabled {
		return ctx.Style().Palette.TextOnDisabled
	}
	var text = c.Font.Color
	if text == nil {
		text = color
	}
	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) IsDisabled() bool { return c.Disabled }

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) IsPressed() bool { return c.pressed }

func (c *ControlBase) Notify(ctx Context, state interface{}) bool {
	switch state.(type) {
	case ControlClickedArgs:
		return c.clicked.Notify(ctx, state)
	case DragEndedArgs:
		return c.dragEnded.Notify(ctx, state)
	case DragMovedArgs:
		return c.dragMoved.Notify(ctx, state)
	case DragStartedArgs:
		return c.dragStarted.Notify(ctx, state)
	default:
		return false
	}
}

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

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

func (c *ControlBase) OutlineColor(ctx Context) color.Color {
	return c.FontColor(ctx, ctx.Style().Palette.Primary)
}

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) {
	c.RenderOutlineDefault(ctx, nil)
}

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

func (c *ControlBase) TextColor(ctx Context) color.Color {
	return c.FontColor(ctx, ctx.Style().Palette.Text)
}

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