import {
  Medication,
  Dose,
  Frequency,
  CustomReminder,
  ReminderInstance,
} from '../types';

export const generateSchedule = (
  medications: Medication[],
  forDate: Date
): Dose[] => {
  const schedule: Dose[] = [];
  const today = new Date(forDate);
  today.setHours(0, 0, 0, 0);

  medications.forEach(med => {
    const [startHour, startMinute] = med.startTime.split(':').map(Number);

    const createDose = (hour: number, minute: number): Dose => {
      const scheduledTime = new Date(today);
      scheduledTime.setHours(hour, minute, 0, 0);
      const dateString = scheduledTime.toISOString().split('T')[0];
      const timeString = scheduledTime
        .toTimeString()
        .split(' ')[0]
        .replace(/:/g, '');
      return {
        id: `${med._id}-${dateString}-${timeString}`,
        medicationId: med._id,
        scheduledTime,
      };
    };

    switch (med.frequency) {
      case Frequency.Daily:
        schedule.push(createDose(startHour, startMinute));
        break;
      case Frequency.TwiceADay:
        schedule.push(createDose(startHour, startMinute));
        schedule.push(createDose((startHour + 12) % 24, startMinute));
        break;
      case Frequency.ThreeTimesADay:
        schedule.push(createDose(startHour, startMinute));
        schedule.push(createDose((startHour + 8) % 24, startMinute));
        schedule.push(createDose((startHour + 16) % 24, startMinute));
        break;
      case Frequency.EveryXHours:
        if (med.hoursBetween && med.hoursBetween > 0) {
          for (let h = 0; h < 24; h += med.hoursBetween) {
            schedule.push(createDose((startHour + h) % 24, startMinute));
          }
        }
        break;
    }
  });

  return schedule.sort(
    (a, b) => a.scheduledTime.getTime() - b.scheduledTime.getTime()
  );
};

export const generateReminderSchedule = (
  reminders: CustomReminder[],
  forDate: Date
): ReminderInstance[] => {
  const schedule: ReminderInstance[] = [];
  const today = new Date(forDate);
  today.setHours(0, 0, 0, 0);

  reminders.forEach(reminder => {
    const [startHour, startMinute] = reminder.startTime.split(':').map(Number);
    const [endHour, endMinute] = reminder.endTime.split(':').map(Number);

    const firstReminderTime = new Date(today);
    firstReminderTime.setHours(startHour, startMinute, 0, 0);

    const endOfWindowTime = new Date(today);
    endOfWindowTime.setHours(endHour, endMinute, 0, 0);

    let currentReminderTime = firstReminderTime;

    while (currentReminderTime.getTime() <= endOfWindowTime.getTime()) {
      const dateString = currentReminderTime.toISOString().split('T')[0];
      const timeString = currentReminderTime
        .toTimeString()
        .split(' ')[0]
        .replace(/:/g, '');

      schedule.push({
        id: `${reminder._id}-${dateString}-${timeString}`,
        reminderId: reminder._id,
        title: reminder.title,
        icon: reminder.icon,
        scheduledTime: new Date(currentReminderTime),
      });

      currentReminderTime = new Date(
        currentReminderTime.getTime() + reminder.frequencyMinutes * 60000
      );
    }
  });

  return schedule.sort(
    (a, b) => a.scheduledTime.getTime() - b.scheduledTime.getTime()
  );
};