src/useDayPicker.ts

import { createContext, useContext } from "react";

import type { CalendarDay } from "./classes/CalendarDay.js";
import type { CalendarMonth } from "./classes/CalendarMonth.js";
import type { DayPickerProps } from "./types/props.js";
import type { SelectedValue, SelectHandler } from "./types/selection.js";
import type {
  ClassNames,
  CustomComponents,
  Formatters,
  Labels,
  Mode,
  Modifiers,
  Styles,
} from "./types/shared.js";

/** @ignore */
export const dayPickerContext = createContext<
  | DayPickerContext<{
      mode?: Mode | undefined;
      required?: boolean | undefined;
    }>
  | undefined
>(undefined);

/**
 * Represents the context for the DayPicker component, providing various
 * properties and methods to interact with the calendar.
 *
 * @template T - The type of the DayPicker props, which must optionally include
 *   `mode` and `required` properties. This type can be used to refine the type
 *   returned by the hook.
 */
export type DayPickerContext<
  T extends { mode?: Mode | undefined; required?: boolean | undefined },
> = {
  /** The months displayed in the calendar. */
  months: CalendarMonth[];
  /** The next month to display. */
  nextMonth: Date | undefined;
  /** The previous month to display. */
  previousMonth: Date | undefined;
  /** Navigate to the specified month. Will fire the `onMonthChange` callback. */
  goToMonth: (month: Date) => void;
  /** Returns the modifiers for the given day. */
  getModifiers: (day: CalendarDay) => Modifiers;
  /** The selected date(s). */
  selected: SelectedValue<T> | undefined;
  /** Set a selection. */
  select: SelectHandler<T> | undefined;
  /** Whether the given date is selected. */
  isSelected: ((date: Date) => boolean) | undefined;
  /** The components used internally by DayPicker. */
  components: CustomComponents;
  /** The class names for the UI elements. */
  classNames: ClassNames;
  /** The styles for the UI elements. */
  styles: Partial<Styles> | undefined;
  /** The labels used in the user interface. */
  labels: Labels;
  /** The formatters used to format the UI elements. */
  formatters: Formatters;
  /**
   * The props as passed to the DayPicker component.
   *
   * @since 9.3.0
   */
  dayPickerProps: DayPickerProps;
};

/**
 * Provides access to the DayPicker context, which includes properties and
 * methods to interact with the DayPicker component. This hook must be used
 * within a custom component.
 *
 * @template T - Use this type to refine the returned context type with a
 *   specific selection mode.
 * @returns The context to work with DayPicker.
 * @throws {Error} If the hook is used outside of a DayPicker provider.
 * @group Hooks
 * @see https://daypicker.dev/guides/custom-components
 */
export function useDayPicker<
  T extends { mode?: Mode | undefined; required?: boolean | undefined },
>(): DayPickerContext<T> {
  const context = useContext(dayPickerContext);
  if (context === undefined) {
    throw new Error("useDayPicker() must be used within a custom component.");
  }
  return context;
}