import React from 'react';
import { WEEKDAYS_SHORT, addDays, fromIso, monthEnd, todayIso, weekdayIndex } from '../../lib/format';
import { Avatar } from '../ui/controls';
import type { CalendarUser } from '../../lib/api';
import { holidaysOn, userColor, type CalendarIndex } from './calendarData';

/**
 * Zeitleiste: Personen in Zeilen, Tage des Monats in Spalten. Zeigt auf einen
 * Blick, wo sich Urlaube ueberschneiden. Breiter als das Handy - die Tabelle
 * scrollt seitlich, die Namensspalte bleibt stehen.
 */
export const Timeline: React.FC<{
  month: string;
  index: CalendarIndex;
  users: CalendarUser[];
  selected: string | null;
  onSelect: (day: string) => void;
}> = ({ month, index, users, selected, onSelect }) => {
  const today = todayIso();
  const days: string[] = [];
  for (let d = month; d <= monthEnd(month); d = addDays(d, 1)) days.push(d);

  return (
    <div className="scrollbar-slim overflow-x-auto rounded-2xl border border-ink-200 bg-surface shadow-card">
      <table className="w-full border-separate border-spacing-0 text-xs">
        <thead>
          <tr>
            <th className="sticky left-0 z-20 min-w-[128px] border-b border-ink-200 bg-surface px-3 py-2 text-left text-[11px] font-extrabold uppercase tracking-wider text-ink-400 sm:min-w-[180px]">
              Mitarbeiter
            </th>
            {days.map((day) => {
              const weekend = weekdayIndex(day) >= 5;
              const holidays = holidaysOn(index, day);
              return (
                <th
                  key={day}
                  title={holidays.join(', ') || undefined}
                  onClick={() => onSelect(day)}
                  className={`min-w-[28px] cursor-pointer border-b border-ink-200 px-0 py-1.5 text-center font-extrabold ${
                    day === selected ? 'bg-brand-100 text-brand-700' : holidays.length ? 'bg-amber-50 text-amber-700' : weekend ? 'bg-ink-50 text-ink-400' : 'text-ink-600'
                  }`}
                >
                  <span className="block text-[9px] font-bold uppercase text-ink-400">{WEEKDAYS_SHORT[weekdayIndex(day)].slice(0, 2)}</span>
                  <span className={day === today ? 'rounded-full bg-brand-500 px-1 text-white' : ''}>{fromIso(day).getDate()}</span>
                </th>
              );
            })}
          </tr>
        </thead>
        <tbody>
          {users.map((user) => {
            const entries = index.byUser.get(user.id);
            const color = userColor(user);
            return (
              <tr key={user.id} className="group">
                <td className="sticky left-0 z-10 border-b border-ink-100 bg-surface px-3 py-1.5 group-hover:bg-ink-50">
                  <span className="flex min-w-0 items-center gap-2">
                    <Avatar id={user.id} name={user.name} color={user.color} size={22} external={user.is_external} />
                    <span className="max-w-[92px] truncate font-bold text-ink-800 sm:max-w-[140px]">{user.name}</span>
                  </span>
                </td>
                {days.map((day) => {
                  const entry = entries?.get(day);
                  const weekend = weekdayIndex(day) >= 5;
                  const vacation = entry?.kind === 'vacation';
                  // Aneinanderstossende Urlaubstage als ein Balken zeichnen.
                  const prev = entries?.get(addDays(day, -1))?.kind === 'vacation';
                  const next = entries?.get(addDays(day, 1))?.kind === 'vacation';
                  return (
                    <td
                      key={day}
                      title={entry ? `${user.name}: ${entry.label}${entry.half ? ' (halber Tag)' : ''}` : undefined}
                      onClick={() => onSelect(day)}
                      className={`h-9 cursor-pointer border-b border-ink-100 px-0 py-1 ${
                        day === selected ? 'bg-brand-50' : entry?.kind === 'holiday' ? 'bg-amber-50' : weekend ? 'bg-ink-50/70' : ''
                      }`}
                    >
                      {vacation && (
                        <span
                          className={`block h-5 ${prev ? '' : 'ml-0.5 rounded-l-md'} ${next ? '' : 'mr-0.5 rounded-r-md'}`}
                          style={{
                            background: entry.half ? `linear-gradient(to top, ${color} 50%, color-mix(in srgb, ${color} 25%, transparent) 50%)` : color,
                          }}
                        />
                      )}
                      {entry?.kind === 'holiday' && <span className="mx-auto block h-1.5 w-1.5 rounded-full bg-amber-400" />}
                    </td>
                  );
                })}
              </tr>
            );
          })}
        </tbody>
      </table>
    </div>
  );
};