import { useContext, useEffect, useMemo } from "react";
import { DateTime, Info } from "luxon";
import classNames from "classnames";
import { useTranslation } from "next-i18next";

import { EventContext, ShowDateContext } from "../../utils/contexts/calendar";

const colorVariants = {
  // https://tailwindcss.com/docs/content-configuration#dynamic-class-names
  amber: "bg-amber-500",
  blue: "bg-blue-500",
  cyan: "bg-cyan-500",
  emerald: "bg-emerald-500",
  fuchsia: "bg-fuchsia-500",
  gray: "bg-gray-500",
  green: "bg-green-500",
  indigo: "bg-indigo-500",
  lime: "bg-lime-500",
  neutral: "bg-neutral-500",
  orange: "bg-orange-500",
  pink: "bg-pink-500",
  purple: "bg-purple-500",
  red: "bg-red-500",
  rose: "bg-rose-500",
  sky: "bg-sky-500",
  slate: "bg-slate-500",
  stone: "bg-stone-500",
  teal: "bg-teal-500",
  violet: "bg-violet-500",
  white: "bg-white-500",
  yellow: "bg-yellow-500",
  zinc: "bg-zinc-500",
};

const cellStyle = "relative w-10 flex items-center justify-center flex-col";
const monthButton = "pl-6 pr-6 ml-2 mr-2 hover:bg-theme-100/20 dark:hover:bg-white/5 rounded-md cursor-pointer";

export function Day({ weekNumber, weekday, events }) {
  const currentDate = DateTime.now();
  const { showDate, setShowDate } = useContext(ShowDateContext);

  const cellDate = showDate.set({ weekday, weekNumber }).startOf("day");
  const filteredEvents = events?.filter(
    (event) => event.date?.startOf("day").toUnixInteger() === cellDate.toUnixInteger(),
  );

  const dayStyles = (displayDate) => {
    let style = "h-9 ";

    if ([6, 7].includes(displayDate.weekday)) {
      // weekend style
      style += "text-red-500 ";
      // different month style
      style += displayDate.month !== showDate.month ? "text-red-500/40 " : "";
    } else if (displayDate.month !== showDate.month) {
      // different month style
      style += "text-gray-500 ";
    }

    // selected same day style
    style +=
      displayDate.toFormat("MM-dd-yyyy") === showDate.toFormat("MM-dd-yyyy")
        ? "text-black-500 bg-theme-100/20 dark:bg-white/10 rounded-md "
        : "";

    if (displayDate.toFormat("MM-dd-yyyy") === currentDate.toFormat("MM-dd-yyyy")) {
      // today style
      style += "text-black-500 bg-theme-100/20 dark:bg-black/20 rounded-md ";
    } else {
      style += "hover:bg-theme-100/20 dark:hover:bg-white/5 rounded-md cursor-pointer ";
    }

    return style;
  };

  return (
    <button
      key={`day${weekday}${weekNumber}}`}
      type="button"
      className={classNames(dayStyles(cellDate), cellStyle)}
      style={{ width: "14%" }}
      onClick={() => setShowDate(cellDate)}
    >
      {cellDate.day}
      <span className="flex justify-center items-center absolute w-full -mb-6">
        {filteredEvents &&
          filteredEvents
            .slice(0, 4)
            .map((event) => (
              <span
                key={event.date.toLocaleString() + event.color + event.title}
                className={classNames("inline-flex h-1 w-1 m-0.5 rounded", colorVariants[event.color] ?? "gray")}
              />
            ))}
      </span>
    </button>
  );
}

export function Event({ event }) {
  return (
    <div
      key={event.title}
      className="text-theme-700 dark:text-theme-200 text-xs relative h-5 w-full rounded-md bg-theme-200/50 dark:bg-theme-900/20 mt-1"
    >
      <span className="absolute left-2 text-left text-xs mt-[2px] truncate text-ellipsis" style={{ width: "96%" }}>
        {event.title}
      </span>
    </div>
  );
}

const dayInWeekId = {
  monday: 1,
  tuesday: 2,
  wednesday: 3,
  thursday: 4,
  friday: 5,
  saturday: 6,
  sunday: 7,
};

export default function MonthlyView({ service }) {
  const { widget } = service;
  const { i18n } = useTranslation();
  const { showDate, setShowDate } = useContext(ShowDateContext);
  const { events } = useContext(EventContext);
  const currentDate = DateTime.now().setLocale(i18n.language).startOf("day");

  useEffect(() => {
    if (!showDate) {
      setShowDate(currentDate);
    }
  });

  const dayNames = Info.weekdays("short", { locale: i18n.language });

  const firstDayInWeekCalendar = widget?.firstDayInWeek ? widget?.firstDayInWeek?.toLowerCase() : "monday";
  for (let i = 1; i < dayInWeekId[firstDayInWeekCalendar]; i += 1) {
    dayNames.push(dayNames.shift());
  }

  const daysInWeek = useMemo(
    () => [...Array(7).keys()].map((i) => i + dayInWeekId[firstDayInWeekCalendar]),
    [firstDayInWeekCalendar],
  );

  if (!showDate) {
    return <div className="w-full text-center" />;
  }

  const firstWeek = DateTime.local(showDate.year, showDate.month, 1).setLocale(i18n.language);

  const weekIncrementChange = dayInWeekId[firstDayInWeekCalendar] > firstWeek.weekday ? -1 : 0;
  let weekNumbers = [...Array(Math.ceil(5) + 1).keys()].map((i) => firstWeek.weekNumber + weekIncrementChange + i);

  if (weekNumbers.includes(55)) {
    // if we went too far with the weeks, it's the beginning of the year
    weekNumbers = weekNumbers.map((weekNum) => weekNum - 52);
  }

  const eventsArray = Object.keys(events).map((eventKey) => events[eventKey]);

  return (
    <div className="w-full text-center">
      <div className="flex-col">
        <span>
          <button
            type="button"
            onClick={() => setShowDate(showDate.minus({ months: 1 }).startOf("day"))}
            className={classNames(monthButton)}
          >
            &lt;
          </button>
        </span>
        <span>
          <button type="button" onClick={() => setShowDate(currentDate.startOf("day"))}>
            {showDate.setLocale(i18n.language).toFormat("MMMM y")}
          </button>
        </span>
        <span>
          <button
            type="button"
            onClick={() => setShowDate(showDate.plus({ months: 1 }).startOf("day"))}
            className={classNames(monthButton)}
          >
            &gt;
          </button>
        </span>
      </div>

      <div className="p-2 w-full">
        <div className="flex justify-between flex-wrap">
          {dayNames.map((name) => (
            <span key={name} className={classNames(cellStyle)} style={{ width: "14%" }}>
              {name}
            </span>
          ))}
        </div>

        <div
          className={classNames(
            "flex justify-between flex-wrap",
            !eventsArray.length && widget?.integrations?.length && "animate-pulse",
          )}
        >
          {weekNumbers.map((weekNumber) =>
            daysInWeek.map((dayInWeek) => (
              <Day
                key={`week${weekNumber}day${dayInWeek}}`}
                weekNumber={weekNumber}
                weekday={dayInWeek}
                events={eventsArray}
              />
            )),
          )}
        </div>

        <div className="flex flex-col pt-1 pb-1">
          {eventsArray
            ?.filter((event) => showDate.startOf("day").toUnixInteger() === event.date?.startOf("day").toUnixInteger())
            .map((event) => (
              <Event key={`event${event.title}`} event={event} />
            ))}
        </div>
      </div>
    </div>
  );
}