import React, { useMemo } from 'react'
import { useTranslation } from '../../i18n'
import { isWeekend } from './holidays'

const WEEKDAYS_EN = ['Mo', 'Tu', 'We', 'Th', 'Fr', 'Sa', 'Su']
const WEEKDAYS_DE = ['Mo', 'Di', 'Mi', 'Do', 'Fr', 'Sa', 'So']
const MONTHS_EN = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December']
const MONTHS_DE = ['Januar', 'Februar', 'März', 'April', 'Mai', 'Juni', 'Juli', 'August', 'September', 'Oktober', 'November', 'Dezember']

export default function VacayMonthCard({
  year, month, holidays, companyHolidaySet, companyHolidaysEnabled = true, entryMap,
  onCellClick, companyMode, blockWeekends
}) {
  const { language } = useTranslation()
  const weekdays = language === 'de' ? WEEKDAYS_DE : WEEKDAYS_EN
  const monthNames = language === 'de' ? MONTHS_DE : MONTHS_EN

  const weeks = useMemo(() => {
    const firstDay = new Date(year, month, 1)
    const daysInMonth = new Date(year, month + 1, 0).getDate()
    let startDow = firstDay.getDay() - 1
    if (startDow < 0) startDow = 6
    const cells = []
    for (let i = 0; i < startDow; i++) cells.push(null)
    for (let d = 1; d <= daysInMonth; d++) cells.push(d)
    while (cells.length % 7 !== 0) cells.push(null)
    const w = []
    for (let i = 0; i < cells.length; i += 7) w.push(cells.slice(i, i + 7))
    return w
  }, [year, month])

  const pad = (n) => String(n).padStart(2, '0')

  return (
    <div className="rounded-xl border overflow-hidden" style={{ background: 'var(--bg-card)', borderColor: 'var(--border-primary)' }}>
      <div className="px-3 py-2 border-b" style={{ borderColor: 'var(--border-secondary)' }}>
        <span className="text-xs font-semibold" style={{ color: 'var(--text-primary)' }}>{monthNames[month]}</span>
      </div>

      <div className="grid grid-cols-7 border-b" style={{ borderColor: 'var(--border-secondary)' }}>
        {weekdays.map((wd, i) => (
          <div key={wd} className="text-center text-[10px] font-medium py-1" style={{ color: i >= 5 ? 'var(--text-faint)' : 'var(--text-muted)' }}>
            {wd}
          </div>
        ))}
      </div>

      <div>
        {weeks.map((week, wi) => (
          <div key={wi} className="grid grid-cols-7">
            {week.map((day, di) => {
              if (day === null) return <div key={di} style={{ height: 28 }} />

              const dateStr = `${year}-${pad(month + 1)}-${pad(day)}`
              const weekend = di >= 5
              const holiday = holidays[dateStr]
              const isCompany = companyHolidaysEnabled && companyHolidaySet.has(dateStr)
              const dayEntries = entryMap[dateStr] || []
              const isBlocked = !!holiday || (weekend && blockWeekends) || (isCompany && !companyMode)

              return (
                <div
                  key={di}
                  className="relative flex items-center justify-center cursor-pointer transition-colors"
                  style={{
                    height: 28,
                    background: weekend ? 'var(--bg-secondary)' : 'transparent',
                    borderTop: '1px solid var(--border-secondary)',
                    borderRight: '1px solid var(--border-secondary)',
                    cursor: isBlocked ? 'default' : 'pointer',
                  }}
                  onClick={() => onCellClick(dateStr)}
                  onMouseEnter={e => { if (!isBlocked) e.currentTarget.style.background = 'var(--bg-hover)' }}
                  onMouseLeave={e => { e.currentTarget.style.background = weekend ? 'var(--bg-secondary)' : 'transparent' }}
                >
                  {holiday && <div className="absolute inset-0.5 rounded" style={{ background: 'rgba(239,68,68,0.12)' }} />}
                  {isCompany && <div className="absolute inset-0.5 rounded" style={{ background: 'rgba(245,158,11,0.15)' }} />}

                  {dayEntries.length === 1 && (
                    <div className="absolute inset-0.5 rounded" style={{ backgroundColor: dayEntries[0].person_color, opacity: 0.4 }} />
                  )}
                  {dayEntries.length === 2 && (
                    <div className="absolute inset-0.5 rounded" style={{
                      background: `linear-gradient(135deg, ${dayEntries[0].person_color} 50%, ${dayEntries[1].person_color} 50%)`,
                      opacity: 0.4,
                    }} />
                  )}
                  {dayEntries.length === 3 && (
                    <div className="absolute inset-0.5 rounded overflow-hidden" style={{ opacity: 0.4 }}>
                      <div className="absolute top-0 left-0 w-1/2 h-full" style={{ backgroundColor: dayEntries[0].person_color }} />
                      <div className="absolute top-0 right-0 w-1/2 h-1/2" style={{ backgroundColor: dayEntries[1].person_color }} />
                      <div className="absolute bottom-0 right-0 w-1/2 h-1/2" style={{ backgroundColor: dayEntries[2].person_color }} />
                    </div>
                  )}
                  {dayEntries.length >= 4 && (
                    <div className="absolute inset-0.5 rounded overflow-hidden" style={{ opacity: 0.4 }}>
                      <div className="absolute top-0 left-0 w-1/2 h-1/2" style={{ backgroundColor: dayEntries[0].person_color }} />
                      <div className="absolute top-0 right-0 w-1/2 h-1/2" style={{ backgroundColor: dayEntries[1].person_color }} />
                      <div className="absolute bottom-0 left-0 w-1/2 h-1/2" style={{ backgroundColor: dayEntries[2].person_color }} />
                      <div className="absolute bottom-0 right-0 w-1/2 h-1/2" style={{ backgroundColor: dayEntries[3].person_color }} />
                    </div>
                  )}

                  <span className="relative z-[1] text-[11px] font-medium" style={{
                    color: holiday ? '#dc2626' : weekend ? 'var(--text-faint)' : 'var(--text-primary)',
                    fontWeight: dayEntries.length > 0 ? 700 : 500,
                  }}>
                    {day}
                  </span>
                </div>
              )
            })}
          </div>
        ))}
      </div>
    </div>
  )
}
