import type { Prisma } from "@prisma/client";
import { z } from "zod";

import type { Dayjs } from "@calcom/dayjs";
import dayjs from "@calcom/dayjs";
import { parseBookingLimit, parseDurationLimit } from "@calcom/lib";
import { getWorkingHours } from "@calcom/lib/availability";
import { buildDateRanges, subtract } from "@calcom/lib/date-ranges";
import { HttpError } from "@calcom/lib/http-error";
import logger from "@calcom/lib/logger";
import { checkBookingLimit } from "@calcom/lib/server";
import { performance } from "@calcom/lib/server/perfObserver";
import { getTotalBookingDuration } from "@calcom/lib/server/queries";
import prisma, { availabilityUserSelect } from "@calcom/prisma";
import { BookingStatus } from "@calcom/prisma/enums";
import { EventTypeMetaDataSchema, stringToDayjs } from "@calcom/prisma/zod-utils";
import type { EventBusyDetails, IntervalLimit } from "@calcom/types/Calendar";

import { getBusyTimes } from "./getBusyTimes";

const availabilitySchema = z
  .object({
    dateFrom: stringToDayjs,
    dateTo: stringToDayjs,
    eventTypeId: z.number().optional(),
    username: z.string().optional(),
    userId: z.number().optional(),
    afterEventBuffer: z.number().optional(),
    beforeEventBuffer: z.number().optional(),
    duration: z.number().optional(),
    withSource: z.boolean().optional(),
  })
  .refine((data) => !!data.username || !!data.userId, "Either username or userId should be filled in.");

const getEventType = async (id: number) => {
  const eventType = await prisma.eventType.findUnique({
    where: { id },
    select: {
      id: true,
      seatsPerTimeSlot: true,
      bookingLimits: true,
      durationLimits: true,
      timeZone: true,
      length: true,
      metadata: true,
      schedule: {
        select: {
          availability: true,
          timeZone: true,
        },
      },
      availability: {
        select: {
          startTime: true,
          endTime: true,
          days: true,
          date: true,
        },
      },
    },
  });
  if (!eventType) {
    return eventType;
  }
  return {
    ...eventType,
    metadata: EventTypeMetaDataSchema.parse(eventType.metadata),
  };
};

type EventType = Awaited<ReturnType<typeof getEventType>>;

const getUser = (where: Prisma.UserWhereInput) =>
  prisma.user.findFirst({
    where,
    select: {
      ...availabilityUserSelect,
      credentials: true,
    },
  });

type User = Awaited<ReturnType<typeof getUser>>;

export const getCurrentSeats = (eventTypeId: number, dateFrom: Dayjs, dateTo: Dayjs) =>
  prisma.booking.findMany({
    where: {
      eventTypeId,
      startTime: {
        gte: dateFrom.format(),
        lte: dateTo.format(),
      },
      status: BookingStatus.ACCEPTED,
    },
    select: {
      uid: true,
      startTime: true,
      _count: {
        select: {
          attendees: true,
        },
      },
    },
  });

export type CurrentSeats = Awaited<ReturnType<typeof getCurrentSeats>>;

/** This should be called getUsersWorkingHoursAndBusySlots (...and remaining seats, and final timezone) */
export async function getUserAvailability(
  query: {
    withSource?: boolean;
    username?: string;
    userId?: number;
    dateFrom: string;
    dateTo: string;
    eventTypeId?: number;
    afterEventBuffer?: number;
    beforeEventBuffer?: number;
    duration?: number;
  },
  initialData?: {
    user?: User;
    eventType?: EventType;
    currentSeats?: CurrentSeats;
  }
) {
  const { username, userId, dateFrom, dateTo, eventTypeId, afterEventBuffer, beforeEventBuffer, duration } =
    availabilitySchema.parse(query);

  if (!dateFrom.isValid() || !dateTo.isValid()) {
    throw new HttpError({ statusCode: 400, message: "Invalid time range given." });
  }

  const where: Prisma.UserWhereInput = {};
  if (username) where.username = username;
  if (userId) where.id = userId;

  const user = initialData?.user || (await getUser(where));
  if (!user) throw new HttpError({ statusCode: 404, message: "No user found" });

  let eventType: EventType | null = initialData?.eventType || null;
  if (!eventType && eventTypeId) eventType = await getEventType(eventTypeId);

  /* Current logic is if a booking is in a time slot mark it as busy, but seats can have more than one attendee so grab
  current bookings with a seats event type and display them on the calendar, even if they are full */
  let currentSeats: CurrentSeats | null = initialData?.currentSeats || null;
  if (!currentSeats && eventType?.seatsPerTimeSlot) {
    currentSeats = await getCurrentSeats(eventType.id, dateFrom, dateTo);
  }

  const busyTimes = await getBusyTimes({
    credentials: user.credentials,
    // needed to correctly apply limits (weeks can be part of two months)
    startTime: dateFrom.startOf("week").toISOString(),
    endTime: dateTo.endOf("week").toISOString(),
    eventTypeId,
    userId: user.id,
    username: `${user.username}`,
    beforeEventBuffer,
    afterEventBuffer,
    selectedCalendars: user.selectedCalendars,
    seatedEvent: !!eventType?.seatsPerTimeSlot,
  });

  let bufferedBusyTimes: EventBusyDetails[] = busyTimes.map((a) => ({
    ...a,
    start: dayjs(a.start).toISOString(),
    end: dayjs(a.end).toISOString(),
    title: a.title,
    source: query.withSource ? a.source : undefined,
  }));

  const bookings = busyTimes.filter((busyTime) => busyTime.source?.startsWith(`eventType-${eventType?.id}`));

  const bookingLimits = parseBookingLimit(eventType?.bookingLimits);
  if (bookingLimits) {
    const bookingBusyTimes = await getBusyTimesFromBookingLimits(
      bookings,
      bookingLimits,
      dateFrom,
      dateTo,
      eventType
    );
    bufferedBusyTimes = bufferedBusyTimes.concat(bookingBusyTimes);
  }

  const durationLimits = parseDurationLimit(eventType?.durationLimits);
  if (durationLimits) {
    const durationBusyTimes = await getBusyTimesFromDurationLimits(
      bookings,
      durationLimits,
      dateFrom,
      dateTo,
      duration,
      eventType
    );
    bufferedBusyTimes = bufferedBusyTimes.concat(durationBusyTimes);
  }

  const userSchedule = user.schedules.filter(
    (schedule) => !user?.defaultScheduleId || schedule.id === user?.defaultScheduleId
  )[0];

  const schedule =
    !eventType?.metadata?.config?.useHostSchedulesForTeamEvent && eventType?.schedule
      ? eventType.schedule
      : userSchedule;

  const startGetWorkingHours = performance.now();

  const timeZone = schedule?.timeZone || eventType?.timeZone || user.timeZone;

  const availability = (
    schedule.availability || (eventType?.availability.length ? eventType.availability : user.availability)
  ).map((a) => ({
    ...a,
    userId: user.id,
  }));

  const workingHours = getWorkingHours({ timeZone }, availability);

  const endGetWorkingHours = performance.now();
  logger.debug(`getWorkingHours took ${endGetWorkingHours - startGetWorkingHours}ms for userId ${userId}`);

  const dateOverrides = availability
    .filter((availability) => !!availability.date)
    .map((override) => {
      const startTime = dayjs.utc(override.startTime);
      const endTime = dayjs.utc(override.endTime);
      return {
        start: dayjs.utc(override.date).hour(startTime.hour()).minute(startTime.minute()).toDate(),
        end: dayjs.utc(override.date).hour(endTime.hour()).minute(endTime.minute()).toDate(),
      };
    });

  const dateRanges = buildDateRanges({
    dateFrom,
    dateTo,
    availability,
    timeZone,
  });

  const formattedBusyTimes = bufferedBusyTimes.map((busy) => ({
    start: dayjs(busy.start),
    end: dayjs(busy.end),
  }));

  return {
    busy: bufferedBusyTimes,
    timeZone,
    dateRanges: subtract(dateRanges, formattedBusyTimes),
    workingHours,
    dateOverrides,
    currentSeats,
  };
}

const getDatesBetween = (dateFrom: Dayjs, dateTo: Dayjs, period: "day" | "week" | "month" | "year") => {
  const dates = [];
  let startDate = dayjs(dateFrom).startOf(period);
  const endDate = dayjs(dateTo).endOf(period);
  while (startDate.isBefore(endDate)) {
    dates.push(startDate);
    startDate = startDate.add(1, period);
  }
  return dates;
};

const getBusyTimesFromBookingLimits = async (
  bookings: EventBusyDetails[],
  bookingLimits: IntervalLimit,
  dateFrom: Dayjs,
  dateTo: Dayjs,
  eventType: EventType | undefined
) => {
  const busyTimes: EventBusyDetails[] = [];

  // Apply booking limit filter against our bookings
  for (const [key, limit] of Object.entries(bookingLimits)) {
    const limitKey = key as keyof IntervalLimit;

    if (limitKey === "PER_YEAR") {
      const yearlyBusyTime = await checkBookingLimit({
        eventStartDate: dateFrom.toDate(),
        limitingNumber: limit,
        eventId: eventType?.id as number,
        key: "PER_YEAR",
        returnBusyTimes: true,
      });
      if (!yearlyBusyTime) break;
      busyTimes.push({
        start: yearlyBusyTime.start.toISOString(),
        end: yearlyBusyTime.end.toISOString(),
      });
      break;
    }

    // Take PER_DAY and turn it into day and PER_WEEK into week etc.
    const filter = key.split("_")[1].toLowerCase() as "day" | "week" | "month" | "year";
    const dates = getDatesBetween(dateFrom, dateTo, filter);

    // loop through all dates and check if we have reached the limit
    for (const date of dates) {
      let total = 0;
      const startDate = date.startOf(filter);
      // this is parsed above with parseBookingLimit so we know it's safe.
      const endDate = date.endOf(filter);
      for (const booking of bookings) {
        const bookingEventTypeId = parseInt(booking.source?.split("-")[1] as string, 10);
        if (
          // Only check OUR booking that matches the current eventTypeId
          // we don't care about another event type in this case as we dont need to know their booking limits
          !(bookingEventTypeId == eventType?.id && dayjs(booking.start).isBetween(startDate, endDate))
        ) {
          continue;
        }
        // increment total and check against the limit, adding a busy time if condition is met.
        total++;
        if (total >= limit) {
          busyTimes.push({ start: startDate.toISOString(), end: endDate.toISOString() });
          break;
        }
      }
    }
  }

  return busyTimes;
};

const getBusyTimesFromDurationLimits = async (
  bookings: EventBusyDetails[],
  durationLimits: IntervalLimit,
  dateFrom: Dayjs,
  dateTo: Dayjs,
  duration: number | undefined,
  eventType: EventType | undefined
) => {
  const busyTimes: EventBusyDetails[] = [];
  // Start check from larger time periods to smaller time periods, to skip unnecessary checks
  for (const [key, limit] of Object.entries(durationLimits).reverse()) {
    // Use aggregate sql query if we are checking PER_YEAR
    if (key === "PER_YEAR") {
      const totalBookingDuration = await getTotalBookingDuration({
        eventId: eventType?.id as number,
        startDate: dateFrom.startOf("year").toDate(),
        endDate: dateFrom.endOf("year").toDate(),
      });
      if (totalBookingDuration + (duration ?? 0) > limit) {
        busyTimes.push({
          start: dateFrom.startOf("year").toISOString(),
          end: dateFrom.endOf("year").toISOString(),
        });
      }
      continue;
    }

    const filter = key.split("_")[1].toLowerCase() as "day" | "week" | "month" | "year";
    const dates = getDatesBetween(dateFrom, dateTo, filter);

    // loop through all dates and check if we have reached the limit
    for (const date of dates) {
      let total = (duration || eventType?.length) ?? 0;
      const startDate = date.startOf(filter);
      const endDate = date.endOf(filter);

      // add busy time if we have already reached the limit with just the selected duration
      if (total > limit) {
        busyTimes.push({ start: startDate.toISOString(), end: endDate.toISOString() });
        continue;
      }

      for (const booking of bookings) {
        const bookingEventTypeId = parseInt(booking.source?.split("-")[1] as string, 10);
        if (
          // Only check OUR booking that matches the current eventTypeId
          // we don't care about another event type in this case as we dont need to know their booking limits
          !(bookingEventTypeId == eventType?.id && dayjs(booking.start).isBetween(startDate, endDate))
        ) {
          continue;
        }
        // Add current booking duration to total and check against the limit, adding a busy time if condition is met.
        total += dayjs(booking.end).diff(dayjs(booking.start), "minute");
        if (total > limit) {
          busyTimes.push({ start: startDate.toISOString(), end: endDate.toISOString() });
          break;
        }
      }
    }
  }

  return busyTimes;
};