'use strict';

const { FULL_PAYMENT_DISCOUNT, CLASS_REQUEST_DEPOSIT_RATE } = require('../constants/registration');

const getFinalTuition = (cls = {}) => {
  const tuitionFee = Math.max(0, Number(cls.tuitionFee) || 0);
  const classDiscount = cls.hasDiscount ? Math.max(0, Number(cls.discount) || 0) : 0;
  return Math.max(0, tuitionFee - Math.min(classDiscount, tuitionFee));
};

const calculateMidpointDueDate = (cls = {}, course = {}) => {
  const startDate = cls.startDate ? new Date(cls.startDate) : null;
  if (!startDate || Number.isNaN(startDate.getTime())) return null;

  const sectionCount = Math.max(1, Number(course.sectionCount) || 1);
  const sessionsPerWeek = Math.max(1, (cls.days || []).length || 1);
  const totalWeeks = sectionCount / sessionsPerWeek;
  const weeksUntilDue = totalWeeks / 2;

  const due = new Date(startDate);
  due.setDate(due.getDate() + Math.round(weeksUntilDue * 7));
  return due;
};

const calculateEnrollmentPricing = (cls = {}, course = {}, paymentPlan = 'full') => {
  const tuitionFee = getFinalTuition(cls);

  if (paymentPlan === 'installments') {
    const totalAmount = tuitionFee;
    const amountDueNow = Math.ceil(totalAmount / 2);
    const secondInstallmentAmount = Math.max(0, totalAmount - amountDueNow);

    return {
      type: 'enrollment',
      paymentPlan: 'installments',
      tuitionFee,
      classDiscount: cls.hasDiscount ? Math.max(0, Number(cls.discount) || 0) : 0,
      paymentDiscount: 0,
      totalAmount,
      amountDueNow,
      secondInstallmentAmount,
      secondInstallmentDueDate: calculateMidpointDueDate(cls, course)
    };
  }

  const paymentDiscount = Math.min(FULL_PAYMENT_DISCOUNT, tuitionFee);
  const totalAmount = Math.max(0, tuitionFee - paymentDiscount);

  return {
    type: 'enrollment',
    paymentPlan: 'full',
    tuitionFee,
    classDiscount: cls.hasDiscount ? Math.max(0, Number(cls.discount) || 0) : 0,
    paymentDiscount,
    totalAmount,
    amountDueNow: totalAmount,
    secondInstallmentAmount: 0,
    secondInstallmentDueDate: null
  };
};

const calculateClassRequestPricing = (cls = {}) => {
  const tuitionFee = getFinalTuition(cls);
  const amountDueNow = Math.ceil(tuitionFee * CLASS_REQUEST_DEPOSIT_RATE);

  return {
    type: 'class_request',
    paymentPlan: 'deposit',
    tuitionFee,
    classDiscount: cls.hasDiscount ? Math.max(0, Number(cls.discount) || 0) : 0,
    paymentDiscount: 0,
    totalAmount: amountDueNow,
    amountDueNow,
    secondInstallmentAmount: 0,
    secondInstallmentDueDate: null
  };
};

const calculateRegistrationPricing = (cls = {}, course = {}, { type = 'enrollment', paymentPlan = 'full' } = {}) => {
  if (type === 'class_request') {
    return calculateClassRequestPricing(cls);
  }
  return calculateEnrollmentPricing(cls, course, paymentPlan);
};

module.exports = {
  FULL_PAYMENT_DISCOUNT,
  CLASS_REQUEST_DEPOSIT_RATE,
  getFinalTuition,
  calculateMidpointDueDate,
  calculateEnrollmentPricing,
  calculateClassRequestPricing,
  calculateRegistrationPricing
};