import { EASINGS, PI, SIN, StrokeOptions, Vec2d } from '@tldraw/primitives'
import { TLDashType, TLDrawShape, TLDrawShapeSegment } from '@tldraw/tlschema'

const PEN_EASING = (t: number) => t * 0.65 + SIN((t * PI) / 2) * 0.35

const simulatePressureSettings = (strokeWidth: number): StrokeOptions => {
	return {
		size: 1 + strokeWidth,
		thinning: 0.5,
		streamline: 0.62 + ((1 + strokeWidth) / 8) * 0.06,
		smoothing: 0.62,
		easing: EASINGS.easeOutSine,
		simulatePressure: true,
	}
}

const realPressureSettings = (strokeWidth: number): StrokeOptions => {
	return {
		size: 1 + strokeWidth * 1.2,
		thinning: 0.62,
		streamline: 0.62,
		smoothing: 0.62,
		simulatePressure: false,
		easing: PEN_EASING,
	}
}

const solidSettings = (strokeWidth: number): StrokeOptions => {
	return {
		size: 1 + strokeWidth,
		thinning: 0,
		streamline: 0.62 + ((1 + strokeWidth) / 8) * 0.06,
		smoothing: 0.62,
		simulatePressure: false,
		easing: EASINGS.linear,
	}
}

export function getFreehandOptions(
	shapeProps: { dash: TLDashType; isPen: boolean; isComplete: boolean },
	strokeWidth: number,
	forceComplete: boolean,
	forceSolid: boolean
): StrokeOptions {
	return {
		...(forceSolid
			? solidSettings(strokeWidth)
			: shapeProps.dash === 'draw'
			? shapeProps.isPen
				? realPressureSettings(strokeWidth)
				: simulatePressureSettings(strokeWidth)
			: solidSettings(strokeWidth)),
		last: shapeProps.isComplete || forceComplete,
	}
}

export function getPointsFromSegments(segments: TLDrawShapeSegment[]) {
	const points: Vec2d[] = []

	for (const segment of segments) {
		if (segment.type === 'free' || segment.points.length < 2) {
			points.push(...segment.points.map(Vec2d.Cast))
		} else {
			const pointsToInterpolate = Math.max(
				4,
				Math.floor(Vec2d.Dist(segment.points[0], segment.points[1]) / 16)
			)
			points.push(...Vec2d.PointsBetween(segment.points[0], segment.points[1], pointsToInterpolate))
		}
	}

	return points
}

export function getDrawShapeStrokeDashArray(shape: TLDrawShape, strokeWidth: number) {
	return {
		draw: 'none',
		solid: `none`,
		dotted: `0.1 ${strokeWidth * 2}`,
		dashed: `${strokeWidth * 2} ${strokeWidth * 2}`,
	}[shape.props.dash]
}