import {
  compareAsc,
  getYear,
  getMonth,
  getWeek,
  getDate,
  endOfWeek,
  startOfWeek,
  eachDayOfInterval,
  addWeeks,
} from "date-fns";
import { toLocalTime, formatDate } from "./date";
import { graphql } from "@/gql";
import { EventFragment, EventOccurrence } from "@/gql/graphql";

export type { EventFragment } from "@/gql/graphql";

export type SingularEvent = EventFragment & {
  occurrence: EventOccurrence;
};

const EventFragmentDefinition = graphql(`
  fragment Event on EventPage {
    __typename
    id
    slug
    title
    body {
      id
      blockType
      field
      ... on RichTextBlock {
        rawValue
        value
      }
    }
    featuredImage {
      url
      width
      height
    }
    facebookUrl
    ticketUrl
    priceRegular
    priceMember
    priceStudent
    occurrences {
      ... on EventOccurrence {
        __typename
        id
        start
        end
        venue {
          __typename
          id
          slug
          title
        }
      }
    }
  }
`);

export const allEventsQuery = graphql(`
  query allEvents {
    events: pages(contentType: "events.EventPage") {
      ... on EventPage {
        ...Event
      }
    }
  }
`);

export function getSingularEvents(events: EventFragment[]) {
  return events
    .map((event) => {
      return event.occurrences
        ?.filter((x): x is EventOccurrence => isDefined(x))
        .map((occurrence) => {
          const eventOccurrence = structuredClone(event);
          eventOccurrence.occurrence = occurrence;
          return eventOccurrence;
        });
    })
    .flat()
    .filter((x): x is SingularEvent => isDefined(x));
}

function isDefined<T>(val: T | undefined | null): val is T {
  return val !== undefined && val !== null;
}

interface EventsByDate {
  [yearMonth: string]: {
    [week: number]: {
      [day: number]: SingularEvent[];
    };
  };
}

export function organizeEventsByDate(events: SingularEvent[]): EventsByDate {
  const sortedEvents = events.sort((a, b) =>
    compareAsc(new Date(a.occurrence.start), new Date(b.occurrence.start))
  );

  const eventsByDate: EventsByDate = {};

  const minDate = new Date(sortedEvents[0]?.occurrence.start);
  const maxDate = new Date(
    sortedEvents[sortedEvents.length - 1]?.occurrence.start
  );

  let currentDate = startOfWeek(minDate, { weekStartsOn: 1 });
  while (currentDate <= maxDate) {
    const yearMonth = formatDate(currentDate, "yyyy-MM");
    const week = formatDate(currentDate, "w");
    const daysOfWeek = eachDayOfInterval({
      start: currentDate,
      end: endOfWeek(currentDate, { weekStartsOn: 1 }),
    });

    if (!eventsByDate[yearMonth]) {
      eventsByDate[yearMonth] = {};
    }
    if (!eventsByDate[yearMonth][week]) {
      eventsByDate[yearMonth][week] = {};
    }
    daysOfWeek.forEach((day) => {
      const formattedDay = formatDate(day, "yyyy-MM-dd");
      if (!eventsByDate[yearMonth][week][formattedDay]) {
        eventsByDate[yearMonth][week][formattedDay] = [];
      }
    });

    currentDate = addWeeks(currentDate, 1);
  }

  sortedEvents.forEach((event) => {
    const start = toLocalTime(event.occurrence.start);
    const yearMonth = formatDate(start, "yyyy-MM");
    const week = formatDate(start, "w");
    const day = formatDate(start, "yyyy-MM-dd");
    eventsByDate[yearMonth][week][day].push(event);
  });

  return eventsByDate;
}