import { useNavigate } from 'react-router-dom';
import { useQuery } from '@tanstack/react-query';
import {
  Box,
  Typography,
  Card,
  CardContent,
  Grid,
  Table,
  TableBody,
  TableCell,
  TableContainer,
  TableHead,
  TableRow,
  TablePagination,
  Chip,
  TextField,
  InputAdornment,
  MenuItem,
  Skeleton,
} from '@mui/material';
import SearchIcon from '@mui/icons-material/Search';
import PendingActionsIcon from '@mui/icons-material/PendingActions';
import CheckCircleIcon from '@mui/icons-material/CheckCircle';
import TimerIcon from '@mui/icons-material/Timer';
import DescriptionIcon from '@mui/icons-material/Description';
import { usePaginatedList } from '../../../hooks/usePaginatedList';
import { proposalsApi, type ProposalListItem } from '../../../lib/api/proposals';
import { adminApi, type DashboardStats } from '../../../lib/api/admin';
import { QUERY_KEYS } from '../../../constants/queryKeys';
import { SERVICE_CATEGORIES, PRIORITIES } from '../../../constants';

const STATUS_COLORS: Record<string, 'default' | 'info' | 'warning' | 'success'> = {
  Draft: 'default',
  InReview: 'info',
  Approved: 'success',
  Sent: 'success',
  Revised: 'warning',
};

const PRIORITY_COLORS: Record<string, 'default' | 'warning' | 'error'> = {
  Standard: 'default',
  Urgent: 'warning',
  Emergency: 'error',
};

function formatCurrency(amount: number): string {
  return new Intl.NumberFormat('en-US', { style: 'currency', currency: 'USD' }).format(amount);
}

function formatDate(iso: string): string {
  return new Date(iso).toLocaleDateString('en-US', { month: 'short', day: 'numeric', year: 'numeric' });
}

function StatCard({ icon, label, value, color }: { icon: React.ReactNode; label: string; value: string; color: string }) {
  return (
    <Card sx={{ borderRadius: '8px', transition: 'transform 0.2s, box-shadow 0.2s', '&:hover': { transform: 'translateY(-2px)', boxShadow: '0 4px 8px rgba(0,0,0,0.15)' } }}>
      <CardContent sx={{ textAlign: 'center', py: 2.5 }}>
        <Box sx={{ color, display: 'flex', justifyContent: 'center', mb: 1 }}>{icon}</Box>
        <Typography sx={{ fontSize: '12px', color: '#666', textTransform: 'uppercase', letterSpacing: '0.5px', mb: 1 }}>
          {label}
        </Typography>
        <Typography sx={{ fontSize: '32px', fontWeight: 700, color: '#003a5d' }}>
          {value}
        </Typography>
      </CardContent>
    </Card>
  );
}

export default function AdminDashboard() {
  const navigate = useNavigate();

  const { data: stats, isLoading: statsLoading } = useQuery<DashboardStats>({
    queryKey: [QUERY_KEYS.dashboard],
    queryFn: adminApi.getDashboard,
  });

  const {
    rows,
    search,
    setSearch,
    page,
    setPage,
    pageSize,
    setPageSize,
    totalCount,
    loading,
    err,
  } = usePaginatedList<ProposalListItem>(proposalsApi.getAll);

  return (
    <Box>
      <Typography variant="h5" sx={{ mb: 3 }}>Admin Dashboard</Typography>

      <Grid container spacing={2} sx={{ mb: 3 }}>
        <Grid size={{ xs: 12, sm: 6, md: 3 }}>
          {statsLoading ? (
            <Skeleton variant="rectangular" height={80} sx={{ borderRadius: 1 }} />
          ) : (
            <StatCard
              icon={<PendingActionsIcon fontSize="large" />}
              label="Pending Review"
              value={String(stats?.pendingCount ?? 0)}
              color="#1565c0"
            />
          )}
        </Grid>
        <Grid size={{ xs: 12, sm: 6, md: 3 }}>
          {statsLoading ? (
            <Skeleton variant="rectangular" height={80} sx={{ borderRadius: 1 }} />
          ) : (
            <StatCard
              icon={<CheckCircleIcon fontSize="large" />}
              label="Approved This Week"
              value={String(stats?.approvedThisWeek ?? 0)}
              color="#2e7d32"
            />
          )}
        </Grid>
        <Grid size={{ xs: 12, sm: 6, md: 3 }}>
          {statsLoading ? (
            <Skeleton variant="rectangular" height={80} sx={{ borderRadius: 1 }} />
          ) : (
            <StatCard
              icon={<TimerIcon fontSize="large" />}
              label="Avg Turnaround"
              value={stats ? `${Math.round(stats.avgTurnaroundHours)}h` : '-'}
              color="#f57c00"
            />
          )}
        </Grid>
        <Grid size={{ xs: 12, sm: 6, md: 3 }}>
          {statsLoading ? (
            <Skeleton variant="rectangular" height={80} sx={{ borderRadius: 1 }} />
          ) : (
            <StatCard
              icon={<DescriptionIcon fontSize="large" />}
              label="Total Proposals"
              value={String(stats?.totalProposals ?? 0)}
              color="#5e35b1"
            />
          )}
        </Grid>
      </Grid>

      <Card>
        <CardContent sx={{ pb: 0 }}>
          <Box sx={{ display: 'flex', gap: 2, mb: 2, flexWrap: 'wrap' }}>
            <TextField
              size="small"
              placeholder="Search..."
              value={search}
              onChange={(e) => setSearch(e.target.value)}
              sx={{ width: 240 }}
              slotProps={{
                input: {
                  startAdornment: (
                    <InputAdornment position="start">
                      <SearchIcon fontSize="small" />
                    </InputAdornment>
                  ),
                },
              }}
            />
            <TextField
              size="small"
              select
              label="Category"
              value=""
              sx={{ width: 160 }}
              onChange={() => {}}
            >
              <MenuItem value="">All</MenuItem>
              {SERVICE_CATEGORIES.map((c) => (
                <MenuItem key={c} value={c}>{c}</MenuItem>
              ))}
            </TextField>
            <TextField
              size="small"
              select
              label="Priority"
              value=""
              sx={{ width: 140 }}
              onChange={() => {}}
            >
              <MenuItem value="">All</MenuItem>
              {PRIORITIES.map((p) => (
                <MenuItem key={p} value={p}>{p}</MenuItem>
              ))}
            </TextField>
          </Box>

          {err && (
            <Typography color="error" sx={{ mb: 2 }}>{err}</Typography>
          )}

          <TableContainer>
            <Table size="small">
              <TableHead>
                <TableRow>
                  <TableCell>Proposal #</TableCell>
                  <TableCell>Customer</TableCell>
                  <TableCell>WO #</TableCell>
                  <TableCell>Category</TableCell>
                  <TableCell>Priority</TableCell>
                  <TableCell>Status</TableCell>
                  <TableCell align="right">Bid Amount</TableCell>
                  <TableCell>Submitted</TableCell>
                  <TableCell>Submitted By</TableCell>
                </TableRow>
              </TableHead>
              <TableBody>
                {loading
                  ? Array.from({ length: 5 }).map((_, i) => (
                      <TableRow key={i}>
                        {Array.from({ length: 9 }).map((_, j) => (
                          <TableCell key={j}><Skeleton variant="text" /></TableCell>
                        ))}
                      </TableRow>
                    ))
                  : rows.map((row) => (
                      <TableRow
                        key={row.id}
                        hover
                        sx={{ cursor: 'pointer' }}
                        onClick={() => navigate(`/admin/proposals/${row.id}`)}
                      >
                        <TableCell sx={{ fontWeight: 600 }}>{row.proposalNumber}</TableCell>
                        <TableCell>{row.customerName}</TableCell>
                        <TableCell>{row.workOrderNumber}</TableCell>
                        <TableCell>{row.serviceCategory}</TableCell>
                        <TableCell>
                          <Chip label={row.priority} size="small" color={PRIORITY_COLORS[row.priority] || 'default'} />
                        </TableCell>
                        <TableCell>
                          <Chip label={row.status} size="small" color={STATUS_COLORS[row.status] || 'default'} />
                        </TableCell>
                        <TableCell align="right">{formatCurrency(row.totalBidAmount)}</TableCell>
                        <TableCell>{formatDate(row.submittedAt)}</TableCell>
                        <TableCell>{row.submittedByName || '-'}</TableCell>
                      </TableRow>
                    ))}
                {!loading && rows.length === 0 && (
                  <TableRow>
                    <TableCell colSpan={9} align="center" sx={{ py: 4 }}>
                      <Typography color="text.secondary">No proposals in queue</Typography>
                    </TableCell>
                  </TableRow>
                )}
              </TableBody>
            </Table>
          </TableContainer>

          <TablePagination
            component="div"
            count={totalCount}
            page={page - 1}
            onPageChange={(_, newPage) => setPage(newPage + 1)}
            rowsPerPage={pageSize}
            onRowsPerPageChange={(e) => setPageSize(parseInt(e.target.value, 10))}
            rowsPerPageOptions={[12, 24, 48]}
          />
        </CardContent>
      </Card>
    </Box>
  );
}