Numeric Helpers

// Isomorphic numeric helpers used across data-viz.

export const clamp = (v: number, lo: number, hi: number): number =>
  v < lo ? lo : v > hi ? hi : v;

export const lerp = (a: number, b: number, t: number): number => a + (b - a) * t;

/** Inverse lerp: where does v sit in [a,b] as 0..1 (clamped). */
export const invLerp = (a: number, b: number, v: number): number =>
  b === a ? 0 : clamp((v - a) / (b - a), 0, 1);

/** Remap v from [inMin,inMax] to [outMin,outMax]. */
export const mapRange = (
  v: number,
  inMin: number,
  inMax: number,
  outMin: number,
  outMax: number,
): number => lerp(outMin, outMax, invLerp(inMin, inMax, v));

/** Round to n decimal places. */
export const round = (v: number, n = 0): number => {
  const p = 10 ** n;
  return Math.round(v * p) / p;
};

/** Perceptually softer compression for delta bars (matches the broadcast look). */
export const sqrtScale = (v: number): number => Math.sign(v) * Math.sqrt(Math.abs(v));

/** Catmull-Rom → cubic-bezier path data through points (smooth area/line charts). */
export function smoothPath(pts: { x: number; y: number }[]): string {
  if (pts.length < 2) return "";
  let d = "";
  for (let i = 0; i < pts.length - 1; i++) {
    const p0 = pts[i - 1] || pts[i];
    const p1 = pts[i];
    const p2 = pts[i + 1];
    const p3 = pts[i + 2] || p2;
    const c1x = p1.x + (p2.x - p0.x) / 6;
    const c1y = p1.y + (p2.y - p0.y) / 6;
    const c2x = p2.x - (p3.x - p1.x) / 6;
    const c2y = p2.y - (p3.y - p1.y) / 6;
    d += `C ${c1x.toFixed(2)} ${c1y.toFixed(2)} ${c2x.toFixed(2)} ${c2y.toFixed(2)} ${p2.x.toFixed(2)} ${p2.y.toFixed(2)} `;
  }
  return d;
}