"use client";

import ShiftCard from "@/components/molecules/cards/ShiftCard";
import { useShift } from "@/lib/shift-context";
import { useMemo, useState } from "react";

import type { MobileShiftViewProps } from "./ShiftSchedule.types";

const DAY_HEADERS = ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"];
const MONTH_NAMES = [
  "January",
  "February",
  "March",
  "April",
  "May",
  "June",
  "July",
  "August",
  "September",
  "October",
  "November",
  "December",
];

function formatDateKey(d: Date): string {
  const y = d.getFullYear();
  const m = (d.getMonth() + 1).toString().padStart(2, "0");
  const day = d.getDate().toString().padStart(2, "0");
  return `${y}-${m}-${day}`;
}

function isToday(d: Date): boolean {
  const today = new Date(2026, 3, 10);
  return formatDateKey(d) === formatDateKey(today);
}

export default function MobileShiftView({
  onShiftClick,
}: MobileShiftViewProps) {
  const { currentDate, getShiftsForDate, goToNextMonth, goToPrevMonth } =
    useShift();
  const [selectedDate, setSelectedDate] = useState<Date>(new Date(2026, 3, 10));

  const calendarDays = useMemo(() => {
    const year = currentDate.getFullYear();
    const month = currentDate.getMonth();
    const firstDay = new Date(year, month, 1);
    const lastDay = new Date(year, month + 1, 0);

    let startOffset = firstDay.getDay() - 1;
    if (startOffset < 0) startOffset = 6;

    const days: (Date | null)[] = [];
    for (let i = 0; i < startOffset; i++) days.push(null);
    for (let d = 1; d <= lastDay.getDate(); d++)
      days.push(new Date(year, month, d));
    while (days.length % 7 !== 0) days.push(null);
    return days;
  }, [currentDate]);

  const selectedShifts = useMemo(
    () => getShiftsForDate(selectedDate),
    [selectedDate, getShiftsForDate],
  );

  const dayOfWeek = DAY_HEADERS[(selectedDate.getDay() + 6) % 7];

  return (
    <div className="space-y-4">
      {/* Month calendar card */}
      <div className="overflow-hidden rounded-2xl border border-(--color-border-light) bg-white shadow-sm">
        {/* Month navigation */}
        <div className="flex items-center justify-between border-b border-(--color-border-light) bg-gradient-to-r from-(--color-primary)/8 to-(--color-primary)/3 px-4 py-3">
          <button
            title="Previous month"
            type="button"
            onClick={goToPrevMonth}
            className="flex h-8 w-8 cursor-pointer items-center justify-center rounded-full border-none bg-white/70 text-(--color-text-muted) shadow-sm transition hover:bg-white hover:text-(--color-primary)"
          >
            <i className="fa-solid fa-chevron-left text-xs"></i>
          </button>
          <h3 className="text-sm font-bold text-(--color-primary-dark)">
            {MONTH_NAMES[currentDate.getMonth()]} {currentDate.getFullYear()}
          </h3>
          <button
            title="Next month"
            type="button"
            onClick={goToNextMonth}
            className="flex h-8 w-8 cursor-pointer items-center justify-center rounded-full border-none bg-white/70 text-(--color-text-muted) shadow-sm transition hover:bg-white hover:text-(--color-primary)"
          >
            <i className="fa-solid fa-chevron-right text-xs"></i>
          </button>
        </div>

        <div className="p-3">
          {/* Day headers */}
          <div className="mb-1 grid grid-cols-7">
            {DAY_HEADERS.map((day, i) => (
              <div
                key={day}
                className={`py-1 text-center text-[10px] font-bold uppercase ${
                  i >= 5 ? "text-rose-400" : "text-(--color-text-muted)"
                }`}
              >
                {day}
              </div>
            ))}
          </div>

          {/* Calendar grid */}
          <div className="grid grid-cols-7">
            {calendarDays.map((date, i) => {
              if (!date) return <div key={`empty-${i}`} className="p-1" />;

              const today = isToday(date);
              const selected =
                formatDateKey(date) === formatDateKey(selectedDate);
              const dayShifts = getShiftsForDate(date);
              const isWeekend = date.getDay() === 0 || date.getDay() === 6;

              return (
                <button
                  type="button"
                  key={i}
                  onClick={() => setSelectedDate(date)}
                  className="flex cursor-pointer flex-col items-center border-none bg-transparent p-1 transition"
                >
                  <span
                    className={`flex h-8 w-8 items-center justify-center rounded-full text-xs font-bold transition ${
                      today
                        ? "bg-(--color-primary) text-white shadow-sm"
                        : selected
                          ? "bg-(--color-primary)/15 text-(--color-primary) ring-2 ring-(--color-primary)/30"
                          : isWeekend
                            ? "text-rose-500"
                            : "text-(--color-text-secondary)"
                    }`}
                  >
                    {date.getDate()}
                  </span>
                  <div className="mt-0.5 flex min-h-2 items-center justify-center gap-px">
                    {dayShifts.length > 0 && (
                      <span className="h-1.5 w-1.5 rounded-full bg-(--color-primary)/60" />
                    )}
                  </div>
                </button>
              );
            })}
          </div>
        </div>
      </div>

      {/* Selected day shifts */}
      <div>
        <div className="mb-3 flex items-center justify-between px-1">
          <h3 className="text-sm font-bold text-(--color-primary-dark)">
            {dayOfWeek}, {selectedDate.getDate()}/{selectedDate.getMonth() + 1}/
            {selectedDate.getFullYear()}
          </h3>
          <span
            className={`rounded-full px-2.5 py-1 text-xs font-semibold ${
              selectedShifts.length > 0
                ? "bg-(--color-primary)/10 text-(--color-primary)"
                : "bg-gray-100 text-(--color-text-muted)"
            }`}
          >
            {selectedShifts.length} shifts
          </span>
        </div>

        {selectedShifts.length === 0 ? (
          <div className="rounded-2xl border border-dashed border-(--color-border-light) py-10 text-center">
            <i className="fa-regular fa-calendar-xmark mb-3 text-3xl text-gray-200"></i>
            <p className="text-sm font-medium text-(--color-text-muted)">
              No shifts
            </p>
            <p className="mt-0.5 text-xs text-(--color-text-muted)">
              No shifts created for this day
            </p>
          </div>
        ) : (
          <div className="space-y-2.5">
            {selectedShifts.map((shift) => (
              <ShiftCard key={shift.id} shift={shift} onClick={onShiftClick} />
            ))}
          </div>
        )}
      </div>
    </div>
  );
}