import { wrap } from 'motion-utils';
import { motionValue } from '../../value/index.mjs';
import { animateMotionValue } from '../interfaces/motion-value.mjs';
import { getValueTransition } from './get-value-transition.mjs';

const MIN_LAYOUT_DISTANCE = 20;
function bezierPoint(t, origin, control, target) {
    const inv = 1 - t;
    return inv * inv * origin + 2 * inv * t * control + t * t * target;
}
function bezierTangentAngle(t, originX, controlX, targetX, originY, controlY, targetY) {
    const dx = 2 * (1 - t) * (controlX - originX) + 2 * t * (targetX - controlX);
    const dy = 2 * (1 - t) * (controlY - originY) + 2 * t * (targetY - controlY);
    return Math.atan2(dy, dx) * (180 / Math.PI);
}
function computeArcControlPoint(fromX, fromY, toX, toY, strength, peak) {
    const deltaX = toX - fromX;
    const deltaY = toY - fromY;
    const distance = Math.sqrt(deltaX * deltaX + deltaY * deltaY);
    if (distance > 0) {
        const normalPerpX = -deltaY / distance;
        const normalPerpY = deltaX / distance;
        const desiredHeight = strength * distance;
        return {
            x: fromX + deltaX * peak + normalPerpX * desiredHeight,
            y: fromY + deltaY * peak + normalPerpY * desiredHeight,
        };
    }
    return { x: fromX, y: fromY };
}
/**
 * The pure sampling factory: `(from, to) => (t) => point`. Internal —
 * used by {@link arc} and the unit tests. Not part of the public surface.
 */
function createArcPath({ strength = 0.5, peak = 0.5, direction, rotate = false, } = {}) {
    const rotationScale = rotate === true ? 1 : typeof rotate === "number" ? rotate : 0;
    // Auto-direction only: persists across calls to flip the bulge back
    // onto the same screen side when the dominant axis changes between
    // calls. Reuse the factory (module scope / useMemo) to keep this alive.
    let prevBulgeSign;
    const createInterpolator = (from, to) => {
        const dx = to.x - from.x;
        const dy = to.y - from.y;
        let signed;
        if (direction === "cw") {
            signed = -strength;
        }
        else if (direction === "ccw") {
            signed = strength;
        }
        else {
            const dom = Math.abs(dx) >= Math.abs(dy) ? dx : dy;
            signed = dom < 0 ? -strength : strength;
        }
        let control = computeArcControlPoint(from.x, from.y, to.x, to.y, signed, peak);
        if (direction === undefined) {
            const isVertical = Math.abs(dx) < Math.abs(dy);
            const midX = from.x + dx * peak;
            const midY = from.y + dy * peak;
            const bulgeSign = isVertical
                ? Math.sign(control.x - midX)
                : Math.sign(control.y - midY);
            if (prevBulgeSign !== undefined &&
                bulgeSign !== 0 &&
                bulgeSign !== prevBulgeSign) {
                signed = -signed;
                control = computeArcControlPoint(from.x, from.y, to.x, to.y, signed, peak);
            }
            else if (bulgeSign !== 0) {
                prevBulgeSign = bulgeSign;
            }
        }
        const tangent0 = rotationScale
            ? bezierTangentAngle(0, from.x, control.x, to.x, from.y, control.y, to.y)
            : 0;
        const tangent1 = rotationScale
            ? bezierTangentAngle(1, from.x, control.x, to.x, from.y, control.y, to.y)
            : 0;
        const tangentDelta = rotationScale
            ? wrap(-180, 180, tangent1 - tangent0)
            : 0;
        return (t) => {
            const out = {
                x: bezierPoint(t, from.x, control.x, to.x),
                y: bezierPoint(t, from.y, control.y, to.y),
            };
            if (rotationScale) {
                const raw = bezierTangentAngle(t, from.x, control.x, to.x, from.y, control.y, to.y);
                const baseline = tangent0 + tangentDelta * t;
                out.rotate = wrap(-180, 180, raw - baseline) * rotationScale;
            }
            return out;
        };
    };
    return createInterpolator;
}
/**
 * Creates a curved path for `transition.path`:
 *
 * ```ts
 * <motion.div animate={{ x: 200, y: 100 }} transition={{ path: arc() }} />
 * ```
 *
 * Reuse the returned value (module scope / useMemo / useRef) so its
 * continuity closure survives re-renders — a fresh `arc()` has no memory.
 */
function arc(options = {}) {
    const sample = createArcPath(options);
    const path = {
        interpolateProjection(delta) {
            // `from` is the current translate offset (carries any in-flight
            // displacement when interrupted); `to` is the new layout origin.
            // The distance floor avoids visible wobble on tiny shifts.
            const tx = delta.x.translate;
            const ty = delta.y.translate;
            if (Math.sqrt(tx * tx + ty * ty) < MIN_LAYOUT_DISTANCE) {
                return undefined;
            }
            return sample({ x: tx, y: ty }, { x: 0, y: 0 });
        },
        animateVisualElement(visualElement, target, transition, delay, animations) {
            if (!("x" in target || "y" in target))
                return;
            const xValue = visualElement.getValue("x", visualElement.latestValues["x"] ?? 0);
            const yValue = visualElement.getValue("y", visualElement.latestValues["y"] ?? 0);
            const xRaw = target.x;
            const yRaw = target.y;
            const xFrom = (Array.isArray(xRaw) && xRaw[0] != null
                ? xRaw[0]
                : xValue?.get()) ?? 0;
            const yFrom = (Array.isArray(yRaw) && yRaw[0] != null
                ? yRaw[0]
                : yValue?.get()) ?? 0;
            const xTo = (Array.isArray(xRaw)
                ? xRaw[xRaw.length - 1]
                : xRaw ?? xFrom);
            const yTo = (Array.isArray(yRaw)
                ? yRaw[yRaw.length - 1]
                : yRaw ?? yFrom);
            // Interruption needs no flag: x/y already hold the displaced
            // mid-arc position, so xFrom/yFrom carry the continuity geometry.
            const interpolate = sample({ x: xFrom, y: yFrom }, { x: xTo, y: yTo });
            // Drive a dedicated `pathRotation` value (composed onto `rotate`
            // at the build sites) rather than `rotate` itself, so a
            // concurrent rotate animation composes and nothing accumulates
            // on interrupt.
            const pathRotationValue = interpolate(0).rotate !== undefined
                ? visualElement.getValue("pathRotation", 0)
                : undefined;
            const pathTransition = {
                delay,
                ...getValueTransition(transition || {}, "x"),
            };
            delete pathTransition.path;
            const progress = motionValue(0);
            progress.start(animateMotionValue("", progress, [0, 1000], {
                ...pathTransition,
                isSync: true,
                velocity: 0,
                onUpdate: (latest) => {
                    const point = interpolate(latest / 1000);
                    xValue?.set(point.x);
                    yValue?.set(point.y);
                    if (pathRotationValue && point.rotate !== undefined) {
                        pathRotationValue.set(point.rotate);
                    }
                },
                onComplete: () => {
                    xValue?.set(xTo);
                    yValue?.set(yTo);
                    pathRotationValue?.set(0);
                },
                // Interrupt/cancel must clear our additive contribution
                // so it can't linger on top of the user's `rotate`.
                onStop: () => pathRotationValue?.set(0),
                onCancel: () => pathRotationValue?.set(0),
            }));
            if (progress.animation)
                animations.push(progress.animation);
            delete target.x;
            delete target.y;
        },
    };
    return path;
}

export { arc, createArcPath };
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