/** The length a written field should land in, as the agent aims for it. */
export interface Band {
  min?: number;
  max: number;
  unit: 'characters' | 'words';
}

export const countIn = (unit: Band['unit'], text: string): number =>
  unit === 'words' ? text.split(/\s+/).filter(Boolean).length : text.length;

/** "50–60 characters", "up to 75 characters". */
export const bandLabel = (band: Band): string =>
  band.min !== undefined
    ? `${band.min}–${band.max} ${band.unit}`
    : `up to ${band.max} ${band.unit}`;

/** How long the text is, counted the way its band counts: "58 characters", "3 words". */
export const measure = (band: Band, text: string): string => {
  const count = countIn(band.unit, text);
  return `${count} ${count === 1 ? band.unit.slice(0, -1) : band.unit}`;
};

export const outsideBand = (band: Band, text: string): boolean => {
  const count = countIn(band.unit, text);
  return count > band.max || (band.min !== undefined && count < band.min);
};