package d2raster

import (
	
	
	
	

	
)

// animationValueAt validates and resolves a track with interruptible keyframe
// lookup. Retained vector definitions and each visible instance validate their
// own charged occurrence instead of caching mutable renderer state.
func ( *preflight) ( d2scene.Track) (d2scene.AnimationValue, error) {
	if .TargetIndex < 0 {
		return d2scene.AnimationValue{}, fmt.Errorf("d2scene: animation target index is negative")
	}
	if .Property > d2scene.AnimateDropShadow {
		return d2scene.AnimationValue{}, fmt.Errorf("d2scene: unknown animation property %d", .Property)
	}
	if .Delay < 0 {
		return d2scene.AnimationValue{}, fmt.Errorf("d2scene: animation delay is negative")
	}
	if .Duration <= 0 {
		return d2scene.AnimationValue{}, fmt.Errorf("d2scene: animation duration must be positive")
	}
	if len(.Keyframes) == 0 {
		return d2scene.AnimationValue{}, fmt.Errorf("d2scene: animation has no keyframes")
	}

	 := .Keyframes[0].Value.Kind
	 := animationKindForProperty(.Property)
	if  !=  {
		return d2scene.AnimationValue{}, fmt.Errorf("d2scene: animation property %d requires value kind %d", .Property, )
	}
	 := -1.0
	for ,  := range .Keyframes {
		if &255 == 0 {
			if  := .ctx.Err();  != nil {
				return d2scene.AnimationValue{}, 
			}
		}
		if !finite(.Offset) || .Offset < 0 || .Offset > 1 || .Offset <  {
			return d2scene.AnimationValue{}, fmt.Errorf("d2scene: animation keyframe %d has invalid offset", )
		}
		if .Value.Kind !=  {
			return d2scene.AnimationValue{}, fmt.Errorf("d2scene: animation keyframe %d changes value kind", )
		}
		if  := validateAnimationValue(.Value);  != nil {
			return d2scene.AnimationValue{}, fmt.Errorf("d2scene: animation keyframe %d: %w", , )
		}
		if  := validateAnimationEasing(.Easing);  != nil {
			return d2scene.AnimationValue{}, fmt.Errorf("d2scene: animation keyframe %d: %w", , )
		}
		 = .Offset
	}
	if  := .ctx.Err();  != nil {
		return d2scene.AnimationValue{}, 
	}

	 := .Keyframes[0]
	 := .Keyframes[len(.Keyframes)-1]
	if .options.Time <= .Delay {
		return .Value, nil
	}
	 := .options.Time - .Delay
	if !.Repeat &&  >= .Duration {
		return .Value, nil
	}
	if .Repeat {
		 %= .Duration
	}
	 := float64() / float64(.Duration)
	if  <= .Offset {
		return .Value, nil
	}
	 := sort.Search(len(.Keyframes)-1, func( int) bool {
		return .Keyframes[+1].Offset >= 
	}) + 1
	if  >= len(.Keyframes) {
		return .Value, nil
	}
	 := .Keyframes[]
	 := .Keyframes[-1]
	 := .Offset - .Offset
	if  == 0 {
		return .Value, nil
	}
	 := ( - .Offset) / 
	 = applyAnimationEasing(.Easing, )
	return interpolateRendererAnimationValue(.Value, .Value, )
}

func animationKindForProperty( d2scene.AnimationProperty) d2scene.AnimationValueKind {
	switch  {
	case d2scene.AnimateOpacity, d2scene.AnimateStrokeDashOffset:
		return d2scene.NumberAnimationValue
	case d2scene.AnimateTransform:
		return d2scene.TransformAnimationValue
	case d2scene.AnimateFillColor, d2scene.AnimateStrokeColor:
		return d2scene.ColorAnimationValue
	case d2scene.AnimateDropShadow:
		return d2scene.ShadowAnimationValue
	default:
		// The caller rejects unknown properties first, so the zero value is
		// unreachable for a valid track.
		return d2scene.NumberAnimationValue
	}
}

func validateAnimationValue( d2scene.AnimationValue) error {
	switch .Kind {
	case d2scene.NumberAnimationValue:
		if !finite(.Number) {
			return fmt.Errorf("non-finite animation number")
		}
	case d2scene.TransformAnimationValue:
		if !.Transform.IsFinite() {
			return fmt.Errorf("non-finite animation transform")
		}
	case d2scene.ColorAnimationValue:
		return nil
	case d2scene.ShadowAnimationValue:
		 := .Shadow
		if .SigmaX < 0 || .SigmaY < 0 || !finite(.SigmaX) || !finite(.SigmaY) || !finite(.OffsetX) || !finite(.OffsetY) {
			return fmt.Errorf("invalid animation shadow")
		}
	default:
		return fmt.Errorf("unknown animation value kind %d", .Kind)
	}
	return nil
}

func validateAnimationEasing( d2scene.Easing) error {
	switch .Kind {
	case d2scene.EaseLinear, d2scene.EaseStepStart, d2scene.EaseStepEnd:
		return nil
	case d2scene.EaseCubicBezier:
		if !finite(.X1) || !finite(.Y1) || !finite(.X2) || !finite(.Y2) || .X1 < 0 || .X1 > 1 || .X2 < 0 || .X2 > 1 {
			return fmt.Errorf("invalid cubic-bezier easing")
		}
		return nil
	default:
		return fmt.Errorf("unknown easing kind %d", .Kind)
	}
}

func applyAnimationEasing( d2scene.Easing,  float64) float64 {
	 = math.Max(0, math.Min(1, ))
	switch .Kind {
	case d2scene.EaseStepStart:
		if  == 0 {
			return 0
		}
		return 1
	case d2scene.EaseStepEnd:
		if  == 1 {
			return 1
		}
		return 0
	case d2scene.EaseCubicBezier:
		return rendererCubicBezierYForX(, .X1, .Y1, .X2, .Y2)
	default:
		return 
	}
}

func rendererCubicBezierYForX(, , , ,  float64) float64 {
	,  := 0.0, 1.0
	 := 
	for range 30 {
		 = ( + ) / 2
		 := rendererCubicScalar(0, , , 1, )
		if  <  {
			 = 
		} else {
			 = 
		}
	}
	return rendererCubicScalar(0, , , 1, )
}

func rendererCubicScalar(, , , ,  float64) float64 {
	 := 1 - 
	return *** + 3**** + 3**** + ***
}

func interpolateRendererAnimationValue(,  d2scene.AnimationValue,  float64) (d2scene.AnimationValue, error) {
	if .Kind != .Kind {
		return d2scene.AnimationValue{}, fmt.Errorf("d2scene: cannot interpolate different animation value kinds")
	}
	 := func(,  float64) float64 { return  + (-)* }
	switch .Kind {
	case d2scene.NumberAnimationValue:
		return d2scene.NumberValue((.Number, .Number)), nil
	case d2scene.TransformAnimationValue:
		return d2scene.TransformValue(d2scene.Matrix{
			A: (.Transform.A, .Transform.A),
			B: (.Transform.B, .Transform.B),
			C: (.Transform.C, .Transform.C),
			D: (.Transform.D, .Transform.D),
			E: (.Transform.E, .Transform.E),
			F: (.Transform.F, .Transform.F),
		}), nil
	case d2scene.ColorAnimationValue:
		return d2scene.ColorValue(interpolateRendererAnimationColor(.Color, .Color, )), nil
	case d2scene.ShadowAnimationValue:
		return d2scene.ShadowValue(d2scene.DropShadow{
			OffsetX: (.Shadow.OffsetX, .Shadow.OffsetX),
			OffsetY: (.Shadow.OffsetY, .Shadow.OffsetY),
			SigmaX:  (.Shadow.SigmaX, .Shadow.SigmaX),
			SigmaY:  (.Shadow.SigmaY, .Shadow.SigmaY),
			Color:   interpolateRendererAnimationColor(.Shadow.Color, .Shadow.Color, ),
		}), nil
	default:
		return d2scene.AnimationValue{}, fmt.Errorf("d2scene: unknown animation value kind %d", .Kind)
	}
}

func interpolateRendererAnimationColor(,  color.NRGBA,  float64) color.NRGBA {
	 := func(,  uint8) uint8 {
		return uint8(math.Round(float64() + (float64()-float64())*))
	}
	return color.NRGBA{
		R: (.R, .R),
		G: (.G, .G),
		B: (.B, .B),
		A: (.A, .A),
	}
}