/** A unitless teaching illustration, not a model fitted to biological data. */
export type RecoveryParameters = {
  amplitude: number;
  speed: number;
  repeated: boolean;
  interval: number;
};
export const recoveryDefaults: RecoveryParameters = {
  amplitude: 55,
  speed: 55,
  repeated: false,
  interval: 38,
};
export const recoveryPresets: Record<string, RecoveryParameters> = {
  single: { ...recoveryDefaults },
  slow: { ...recoveryDefaults, speed: 20 },
  repeated: { ...recoveryDefaults, repeated: true, interval: 26 },
};
const clamp = (value: number, min: number, max: number, fallback: number) =>
  Math.min(max, Math.max(min, Number.isFinite(value) ? value : fallback));
export function normalizeRecovery(p: RecoveryParameters): RecoveryParameters {
  return {
    amplitude: clamp(p.amplitude, 15, 85, 55),
    speed: clamp(p.speed, 10, 90, 55),
    repeated: Boolean(p.repeated),
    interval: clamp(p.interval, 20, 55, 38),
  };
}
export function recoveryResponse(
  time: number,
  raw: RecoveryParameters,
): number {
  const p = normalizeRecovery(raw);
  const response = (since: number) =>
    since <= 0
      ? 0
      : (p.amplitude / 100) *
        (1 - Math.exp(-since / 2)) *
        Math.exp(-since / (5 + (100 - p.speed) * 0.22));
  return (
    response(time - 12) + (p.repeated ? response(time - 12 - p.interval) : 0)
  );
}
// Fixed axes prevent rescaling from disguising changes in amplitude.
export function recoveryTrajectory(p: RecoveryParameters): string {
  return Array.from({ length: 241 }, (_, i) => {
    const time = (i / 240) * 100;
    return `${i === 0 ? "M" : "L"}${(40 + time * 6.2).toFixed(2)} ${(244 - recoveryResponse(time, p) * 165).toFixed(2)}`;
  }).join(" ");
}