cal/calcom/packages/features/bookings/Booker/components/hooks/useBookingForm.ts

import { zodResolver } from "@hookform/resolvers/zod";
import { useRef, useEffect } from "react";
import { useForm } from "react-hook-form";
import { z } from "zod";

import type { EventLocationType } from "@calcom/app-store/locations";
import { useBookerStore } from "@calcom/features/bookings/Booker/store";
import getBookingResponsesSchema from "@calcom/features/bookings/lib/getBookingResponsesSchema";
import type { BookerEvent } from "@calcom/features/bookings/types";
import { useLocale } from "@calcom/lib/hooks/useLocale";

import { useInitialFormValues } from "./useInitialFormValues";

export interface IUseBookingForm {
  event?: Pick<BookerEvent, "bookingFields"> | null;
  sessionEmail?: string | null;
  sessionName?: string | null;
  sessionUsername?: string | null;
  hasSession: boolean;
  extraOptions: Record<string, string | string[]>;
  prefillFormParams: {
    guests: string[];
    name: string | null;
  };
}

export type UseBookingFormReturnType = ReturnType<typeof useBookingForm>;

export const useBookingForm = ({
  event,
  sessionEmail,
  sessionName,
  sessionUsername,
  hasSession,
  extraOptions,
  prefillFormParams,
}: IUseBookingForm) => {
  const rescheduleUid = useBookerStore((state) => state.rescheduleUid);
  const bookingData = useBookerStore((state) => state.bookingData);
  const { t } = useLocale();
  const bookerFormErrorRef = useRef<HTMLDivElement>(null);

  const bookingFormSchema = z
    .object({
      responses: event
        ? getBookingResponsesSchema({
            bookingFields: event.bookingFields,
            view: rescheduleUid ? "reschedule" : "booking",
          })
        : // Fallback until event is loaded.
          z.object({}),
    })
    .passthrough();

  type BookingFormValues = {
    locationType?: EventLocationType["type"];
    responses: z.infer<typeof bookingFormSchema>["responses"] | null;
    // Key is not really part of form values, but only used to have a key
    // to set generic error messages on. Needed until RHF has implemented root error keys.
    globalError: undefined;
  };
  const isRescheduling = !!rescheduleUid && !!bookingData;

  const { initialValues, key } = useInitialFormValues({
    eventType: event,
    rescheduleUid,
    isRescheduling,
    email: sessionEmail,
    name: sessionName,
    username: sessionUsername,
    hasSession,
    extraOptions,
    prefillFormParams,
  });

  const bookingForm = useForm<BookingFormValues>({
    defaultValues: initialValues,
    resolver: zodResolver(
      // Since this isn't set to strict we only validate the fields in the schema
      bookingFormSchema,
      {},
      {
        // bookingFormSchema is an async schema, so inform RHF to do async validation.
        mode: "async",
      }
    ),
  });

  useEffect(() => {
    // initialValues would be null initially as the async schema parsing is happening. Let's show the form in first render without any prefill values
    // But ensure that when initialValues is available, the form is reset and rerendered with the prefill values
    bookingForm.reset(initialValues);
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [key]);

  const email = bookingForm.watch("responses.email");
  const name = bookingForm.watch("responses.name");

  const beforeVerifyEmail = () => {
    bookingForm.clearErrors();

    // It shouldn't be possible that this method is fired without having event data,
    // but since in theory (looking at the types) it is possible, we still handle that case.
    if (!event) {
      bookingForm.setError("globalError", { message: t("error_booking_event") });
      return;
    }
  };

  const errors = {
    hasFormErrors: Boolean(bookingForm.formState.errors["globalError"]),
    formErrors: bookingForm.formState.errors["globalError"],
  };

  return {
    bookingForm,
    bookerFormErrorRef,
    key,
    formEmail: email,
    formName: name,
    beforeVerifyEmail,
    formErrors: errors,
    errors,
  };
};