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

import { getAggregateWorkingHours } from "@calcom/core/getAggregateWorkingHours";
import type { CurrentSeats } from "@calcom/core/getUserAvailability";
import { getUserAvailability } from "@calcom/core/getUserAvailability";
import dayjs, { Dayjs } from "@calcom/dayjs";
import { getDefaultEvent } from "@calcom/lib/defaultEvents";
import isTimeOutOfBounds from "@calcom/lib/isOutOfBounds";
import logger from "@calcom/lib/logger";
import { performance } from "@calcom/lib/server/perfObserver";
import getTimeSlots from "@calcom/lib/slots";
import prisma, { availabilityUserSelect } from "@calcom/prisma";
import { EventTypeMetaDataSchema } from "@calcom/prisma/zod-utils";
import { EventBusyDate } from "@calcom/types/Calendar";
import { TimeRange } from "@calcom/types/schedule";

import { TRPCError } from "@trpc/server";

import { router, publicProcedure } from "../../trpc";

const getScheduleSchema = z
  .object({
    // startTime ISOString
    startTime: z.string(),
    // endTime ISOString
    endTime: z.string(),
    // Event type ID
    eventTypeId: z.number().int().optional(),
    // Event type slug
    eventTypeSlug: z.string(),
    // invitee timezone
    timeZone: z.string().optional(),
    // or list of users (for dynamic events)
    usernameList: z.array(z.string()).optional(),
    debug: z.boolean().optional(),
    // to handle event types with multiple duration options
    duration: z
      .string()
      .optional()
      .transform((val) => val && parseInt(val)),
  })
  .refine(
    (data) => !!data.eventTypeId || !!data.usernameList,
    "Either usernameList or eventTypeId should be filled in."
  );

export type Slot = {
  time: string;
  attendees?: number;
  bookingUid?: string;
  users?: string[];
};

const checkIfIsAvailable = ({
  time,
  busy,
  eventLength,
  currentSeats,
}: {
  time: Dayjs;
  busy: EventBusyDate[];
  eventLength: number;
  currentSeats?: CurrentSeats;
}): boolean => {
  if (currentSeats?.some((booking) => booking.startTime.toISOString() === time.toISOString())) {
    return true;
  }

  const slotEndTime = time.add(eventLength, "minutes").utc();
  const slotStartTime = time.utc();

  return busy.every((busyTime) => {
    const startTime = dayjs.utc(busyTime.start).utc();
    const endTime = dayjs.utc(busyTime.end);

    if (endTime.isBefore(slotStartTime) || startTime.isAfter(slotEndTime)) {
      return true;
    }

    if (slotStartTime.isBetween(startTime, endTime, null, "[)")) {
      return false;
    } else if (slotEndTime.isBetween(startTime, endTime, null, "(]")) {
      return false;
    }

    // Check if start times are the same
    if (time.utc().isBetween(startTime, endTime, null, "[)")) {
      return false;
    }
    // Check if slot end time is between start and end time
    else if (slotEndTime.isBetween(startTime, endTime)) {
      return false;
    }
    // Check if startTime is between slot
    else if (startTime.isBetween(time, slotEndTime)) {
      return false;
    }

    return true;
  });
};

/** This should be called getAvailableSlots */
export const slotsRouter = router({
  getSchedule: publicProcedure.input(getScheduleSchema).query(async ({ input, ctx }) => {
    return await getSchedule(input, ctx);
  }),
});

async function getEventType(ctx: { prisma: typeof prisma }, input: z.infer<typeof getScheduleSchema>) {
  const eventType = await ctx.prisma.eventType.findUnique({
    where: {
      id: input.eventTypeId,
    },
    select: {
      id: true,
      minimumBookingNotice: true,
      length: true,
      seatsPerTimeSlot: true,
      timeZone: true,
      slotInterval: true,
      beforeEventBuffer: true,
      afterEventBuffer: true,
      bookingLimits: true,
      schedulingType: true,
      periodType: true,
      periodStartDate: true,
      periodEndDate: true,
      periodCountCalendarDays: true,
      periodDays: true,
      metadata: true,
      schedule: {
        select: {
          availability: true,
          timeZone: true,
        },
      },
      availability: {
        select: {
          date: true,
          startTime: true,
          endTime: true,
          days: true,
        },
      },
      users: {
        select: {
          ...availabilityUserSelect,
        },
      },
    },
  });
  if (!eventType) {
    return eventType;
  }

  return {
    ...eventType,
    metadata: EventTypeMetaDataSchema.parse(eventType.metadata),
  };
}

async function getDynamicEventType(ctx: { prisma: typeof prisma }, input: z.infer<typeof getScheduleSchema>) {
  // For dynamic booking, we need to get and update user credentials, schedule and availability in the eventTypeObject as they're required in the new availability logic
  const dynamicEventType = getDefaultEvent(input.eventTypeSlug);
  const users = await ctx.prisma.user.findMany({
    where: {
      username: {
        in: input.usernameList,
      },
    },
    select: {
      allowDynamicBooking: true,
      ...availabilityUserSelect,
    },
  });
  const isDynamicAllowed = !users.some((user) => !user.allowDynamicBooking);
  if (!isDynamicAllowed) {
    throw new TRPCError({
      message: "Some of the users in this group do not allow dynamic booking",
      code: "UNAUTHORIZED",
    });
  }
  return Object.assign({}, dynamicEventType, {
    users,
  });
}

function getRegularOrDynamicEventType(
  ctx: { prisma: typeof prisma },
  input: z.infer<typeof getScheduleSchema>
) {
  const isDynamicBooking = !input.eventTypeId;
  return isDynamicBooking ? getDynamicEventType(ctx, input) : getEventType(ctx, input);
}

/** This should be called getAvailableSlots */
export async function getSchedule(input: z.infer<typeof getScheduleSchema>, ctx: { prisma: typeof prisma }) {
  if (input.debug === true) {
    logger.setSettings({ minLevel: "debug" });
  }
  if (process.env.INTEGRATION_TEST_MODE === "true") {
    logger.setSettings({ minLevel: "silly" });
  }
  const startPrismaEventTypeGet = performance.now();
  const eventType = await getRegularOrDynamicEventType(ctx, input);
  const endPrismaEventTypeGet = performance.now();
  logger.debug(
    `Prisma eventType get took ${endPrismaEventTypeGet - startPrismaEventTypeGet}ms for event:${
      input.eventTypeId
    }`
  );
  if (!eventType) {
    throw new TRPCError({ code: "NOT_FOUND" });
  }

  const startTime =
    input.timeZone === "Etc/GMT"
      ? dayjs.utc(input.startTime)
      : dayjs(input.startTime).utc().tz(input.timeZone);
  const endTime =
    input.timeZone === "Etc/GMT" ? dayjs.utc(input.endTime) : dayjs(input.endTime).utc().tz(input.timeZone);

  if (!startTime.isValid() || !endTime.isValid()) {
    throw new TRPCError({ message: "Invalid time range given.", code: "BAD_REQUEST" });
  }
  let currentSeats: CurrentSeats | undefined = undefined;

  /* We get all users working hours and busy slots */
  const userAvailability = await Promise.all(
    eventType.users.map(async (currentUser) => {
      const {
        busy,
        workingHours,
        dateOverrides,
        currentSeats: _currentSeats,
        timeZone,
      } = await getUserAvailability(
        {
          userId: currentUser.id,
          username: currentUser.username || "",
          dateFrom: startTime.format(),
          dateTo: endTime.format(),
          eventTypeId: input.eventTypeId,
          afterEventBuffer: eventType.afterEventBuffer,
          beforeEventBuffer: eventType.beforeEventBuffer,
        },
        { user: currentUser, eventType, currentSeats }
      );
      if (!currentSeats && _currentSeats) currentSeats = _currentSeats;

      return {
        timeZone,
        workingHours,
        dateOverrides,
        busy,
      };
    })
  );
  // flattens availability of multiple users
  const dateOverrides = userAvailability.flatMap((availability) => availability.dateOverrides);
  const workingHours = getAggregateWorkingHours(userAvailability, eventType.schedulingType);
  const computedAvailableSlots: Record<string, Slot[]> = {};
  const availabilityCheckProps = {
    eventLength: eventType.length,
    currentSeats,
  };

  const isTimeWithinBounds = (_time: Parameters<typeof isTimeOutOfBounds>[0]) =>
    !isTimeOutOfBounds(_time, {
      periodType: eventType.periodType,
      periodStartDate: eventType.periodStartDate,
      periodEndDate: eventType.periodEndDate,
      periodCountCalendarDays: eventType.periodCountCalendarDays,
      periodDays: eventType.periodDays,
    });

  let currentCheckedTime = startTime;
  let getSlotsTime = 0;
  let checkForAvailabilityTime = 0;
  let getSlotsCount = 0;
  let checkForAvailabilityCount = 0;

  do {
    const startGetSlots = performance.now();
    // get slots retrieves the available times for a given day
    const timeSlots = getTimeSlots({
      inviteeDate: currentCheckedTime,
      eventLength: input.duration || eventType.length,
      workingHours,
      dateOverrides,
      minimumBookingNotice: eventType.minimumBookingNotice,
      frequency: eventType.slotInterval || input.duration || eventType.length,
    });

    const endGetSlots = performance.now();
    getSlotsTime += endGetSlots - startGetSlots;
    getSlotsCount++;
    // if ROUND_ROBIN - slots stay available on some() - if normal / COLLECTIVE - slots only stay available on every()
    const filterStrategy =
      !eventType.schedulingType || eventType.schedulingType === SchedulingType.COLLECTIVE
        ? ("every" as const)
        : ("some" as const);

    const availableTimeSlots = timeSlots.filter(isTimeWithinBounds).filter((time) =>
      userAvailability[filterStrategy]((schedule) => {
        const startCheckForAvailability = performance.now();
        const isAvailable = checkIfIsAvailable({ time, ...schedule, ...availabilityCheckProps });
        const endCheckForAvailability = performance.now();
        checkForAvailabilityCount++;
        checkForAvailabilityTime += endCheckForAvailability - startCheckForAvailability;
        return isAvailable;
      })
    );

    computedAvailableSlots[currentCheckedTime.format("YYYY-MM-DD")] = availableTimeSlots.map((time) => ({
      time: time.toISOString(),
      users: eventType.users.map((user) => user.username || ""),
      // Conditionally add the attendees and booking id to slots object if there is already a booking during that time
      ...(currentSeats?.some((booking) => booking.startTime.toISOString() === time.toISOString()) && {
        attendees:
          currentSeats[
            currentSeats.findIndex((booking) => booking.startTime.toISOString() === time.toISOString())
          ]._count.attendees,
        bookingUid:
          currentSeats[
            currentSeats.findIndex((booking) => booking.startTime.toISOString() === time.toISOString())
          ].uid,
      }),
    }));
    currentCheckedTime = currentCheckedTime.add(1, "day");
  } while (currentCheckedTime.isBefore(endTime));

  logger.debug(`getSlots took ${getSlotsTime}ms and executed ${getSlotsCount} times`);

  logger.debug(
    `checkForAvailability took ${checkForAvailabilityTime}ms and executed ${checkForAvailabilityCount} times`
  );
  logger.silly(`Available slots: ${JSON.stringify(computedAvailableSlots)}`);

  return {
    slots: computedAvailableSlots,
  };
}