export function activeStudents(students: Student[]): Student[] {
  return students.filter(student => student.signedInAt !== null);
}

/**
 * Sort students by name using a case-insensitive comparison.
 * Uses `localeCompare` with `sensitivity: 'base'` rather than `<` because the
 * same roster is also rendered by a Rails helper that orders with MySQL's
 * utf8mb4_general_ci collation; the two orderings must agree or pagination
 * drifts between the two views.
 */
export function sortByName(students: Student[]): Student[] {
  return [...students].sort((a, b) =>
    a.name.localeCompare(b.name, undefined, {sensitivity: 'base'}),
  );
}

export function activeStudents(students: Student[]): Student[] {
  return students.filter(student => student.signedInAt !== null);
}

export function sortByName(students: Student[]): Student[] {
  // Matches MySQL's utf8mb4_general_ci collation used by the Rails-rendered
  // roster, so pagination order agrees between the two views.
  return [...students].sort((a, b) =>
    a.name.localeCompare(b.name, undefined, {sensitivity: 'base'}),
  );
}

/**
 * Students who have signed in at least once.
 */
export function activeStudents(students: Student[]): Student[] {
  return students.filter(student => student.signedInAt !== null);
}

/**
 * Total students and how many of them are active (signed in at least once).
 */
export function rosterSummary(students: Student[]): {
  total: number;
  active: number;
} {

export function activeStudents(students: Student[]): Student[] {
  return students.filter(student => student.signedInAt !== null);
}

export function rosterSummary(students: Student[]): {
  total: number;
  active: number;
} {