import { useMemo, useState } from 'react'
import { Badge, Box, Divider, IconButton, Popover, Typography } from '@mui/material'
import { Bell } from 'lucide-react'
import { useNavigate } from 'react-router'
import { useNeedProfiles } from '../../hooks/useNeeds'
import { useMatches } from '../../hooks/useMatches'
import { ROUTES } from '../../lib/constants'

function loadSeenCounts(): Record<string, number> {
  try { return JSON.parse(localStorage.getItem('notif-seen-counts') ?? '{}') }
  catch { return {} }
}

function saveSeenCounts(counts: Record<string, number>) {
  localStorage.setItem('notif-seen-counts', JSON.stringify(counts))
}

export function NotificationButton() {
  const [anchorEl, setAnchorEl] = useState<null | HTMLElement>(null)
  const [seenCounts, setSeenCounts] = useState<Record<string, number>>(loadSeenCounts)
  const navigate = useNavigate()

  const { data: needs = [] } = useNeedProfiles()
  const { data: allMatches = [] } = useMatches()

  const profilesWithMatches = useMemo(() => {
    const active = needs.filter(n =>
      (!n.status || n.status === 'ACTIVE' || n.status === 'DRAFT') &&
      (n.notificationConfig?.enabled !== false),
    )
    return active
      .map(n => {
        const minScore = n.notificationConfig?.minScore ?? 80
        return {
          need: n,
          count: allMatches.filter(m => m.needId === n.id && m.matchScore >= minScore).length,
          minScore,
        }
      })
      .filter(x => x.count > 0)
  }, [needs, allMatches])

  // Badge only lights up for profiles with matches the user hasn't seen yet
  const newProfiles = useMemo(
    () => profilesWithMatches.filter(x => x.count > (seenCounts[x.need.id] ?? 0)),
    [profilesWithMatches, seenCounts],
  )
  const badgeCount = newProfiles.length

  function handleOpen(e: React.MouseEvent<HTMLElement>) {
    setAnchorEl(e.currentTarget)
    // Mark all current matches as seen
    const updated = { ...seenCounts }
    for (const { need, count } of profilesWithMatches) {
      updated[need.id] = count
    }
    setSeenCounts(updated)
    saveSeenCounts(updated)
  }

  function handleClose() { setAnchorEl(null) }

  function goToResults(needId: string) {
    navigate(ROUTES.DEMAND.RESULTS, { state: { fromNeedBuilder: true, activeNeedId: needId } })
    handleClose()
  }

  return (
    <>
      <IconButton size="small" sx={{ color: '#64748b' }} onClick={handleOpen}>
        <Badge badgeContent={badgeCount || null} color="error">
          <Bell size={20} />
        </Badge>
      </IconButton>

      <Popover
        open={!!anchorEl}
        anchorEl={anchorEl}
        onClose={handleClose}
        anchorOrigin={{ vertical: 'bottom', horizontal: 'right' }}
        transformOrigin={{ vertical: 'top', horizontal: 'right' }}
        slotProps={{ paper: { sx: { width: 300, p: 2 } } }}
      >
        <Typography variant="subtitle2" sx={{ mb: 1.25, fontWeight: 700, color: '#0f172a' }}>
          Neue Treffer
        </Typography>

        {profilesWithMatches.length === 0 ? (
          <Typography variant="caption" sx={{ color: 'text.secondary' }}>
            Keine aktiven Benachrichtigungen
          </Typography>
        ) : (
          <>
            {profilesWithMatches.map(({ need, count, minScore }) => (
              <Box
                key={need.id}
                onClick={() => goToResults(need.id)}
                sx={{
                  display: 'flex', justifyContent: 'space-between', alignItems: 'center',
                  px: 1, py: 0.875, borderRadius: 1, cursor: 'pointer',
                  '&:hover': { bgcolor: '#f8fafc' }, transition: 'background 0.1s',
                }}
              >
                <Box sx={{ minWidth: 0 }}>
                  <Typography variant="body2" sx={{ fontSize: '0.825rem', color: '#1e293b' }} noWrap>
                    {need.companyName}
                  </Typography>
                  <Typography variant="caption" sx={{ color: '#94a3b8', fontSize: '0.7rem' }}>
                    ab {minScore}%
                  </Typography>
                </Box>
                <Typography variant="caption" sx={{ color: '#15803d', fontWeight: 700, flexShrink: 0, ml: 1.5, fontSize: '0.78rem' }}>
                  {count} Treffer →
                </Typography>
              </Box>
            ))}
            <Divider sx={{ my: 1.25 }} />
            <Box
              onClick={() => { navigate(ROUTES.DEMAND.AI_SEARCH); handleClose() }}
              sx={{ textAlign: 'center', cursor: 'pointer', color: '#152642', fontSize: '0.8rem', fontWeight: 600, py: 0.25, '&:hover': { color: '#16304d' } }}
            >
              Alle Suchprofile anzeigen →
            </Box>
          </>
        )}
      </Popover>
    </>
  )
}