import { describe, expect, it } from 'bun:test';
import {
  classifyRisk,
  lastAttendedAt,
  monthlyAttendanceRate,
  trailingAbsentStreak,
} from '@/modules/analytics/lib/risk';

const day = 24 * 60 * 60 * 1000;
const at = (offsetDays: number) => new Date(Date.now() - offsetDays * day);

function entry(status: 'PRESENT' | 'ABSENT' | 'EXCUSED', offsetDays: number) {
  return { status, occurredAt: at(offsetDays) };
}

describe('trailingAbsentStreak', () => {
  it('devuelve 0 sin registros', () => {
    expect(trailingAbsentStreak([])).toBe(0);
  });

  it('cuenta ausencias consecutivas sin justificar desde la más reciente', () => {
    expect(trailingAbsentStreak([entry('ABSENT', 0)])).toBe(1);
    expect(trailingAbsentStreak([entry('ABSENT', 0), entry('ABSENT', 7), entry('ABSENT', 14)])).toBe(3);
  });

  it('rompe la cadena con PRESENT o EXCUSED', () => {
    expect(
      trailingAbsentStreak([entry('ABSENT', 0), entry('ABSENT', 7), entry('PRESENT', 14)]),
    ).toBe(2);
    expect(trailingAbsentStreak([entry('EXCUSED', 0), entry('ABSENT', 7)])).toBe(0);
    expect(trailingAbsentStreak([entry('PRESENT', 0)])).toBe(0);
  });
});

describe('lastAttendedAt', () => {
  it('devuelve la clase PRESENT más reciente', () => {
    const result = lastAttendedAt([
      entry('PRESENT', 0),
      entry('ABSENT', 7),
      entry('ABSENT', 14),
    ]);
    expect(result).not.toBeNull();
    expect(result?.getTime()).toBe(at(0).getTime());
  });

  it('devuelve null si nunca asistió', () => {
    expect(lastAttendedAt([entry('ABSENT', 0), entry('EXCUSED', 7)])).toBeNull();
    expect(lastAttendedAt([])).toBeNull();
  });
});

describe('monthlyAttendanceRate', () => {
  it('razón de PRESENT sobre el total de sesiones', () => {
    expect(monthlyAttendanceRate([entry('PRESENT', 0), entry('PRESENT', 7), entry('ABSENT', 14)], 5)).toBe(40);
  });

  it('devuelve 0 sin sesiones o sin presentes', () => {
    expect(monthlyAttendanceRate([], 3)).toBe(0);
    expect(monthlyAttendanceRate([entry('ABSENT', 0)], 3)).toBe(0);
  });
});

describe('classifyRisk', () => {
  it('HIGH con 3 o más ausencias consecutivas', () => {
    expect(classifyRisk(3, 80)).toBe('HIGH');
    expect(classifyRisk(5, 20)).toBe('HIGH');
  });

  it('MEDIUM con 2 ausencias consecutivas o asistencia menor al 50%', () => {
    expect(classifyRisk(2, 90)).toBe('MEDIUM');
    expect(classifyRisk(1, 40)).toBe('MEDIUM');
    expect(classifyRisk(2, 40)).toBe('MEDIUM');
  });

  it('sin riesgo si no cumple ningún umbral', () => {
    expect(classifyRisk(1, 60)).toBeNull();
    expect(classifyRisk(0, 60)).toBeNull();
  });
});