'use client';

import { useState } from 'react';
import { useQuery } from '@tanstack/react-query';
import { api } from '@/lib/api';
import { Card, CardContent } from '@/components/ui/card';
import { Input } from '@/components/ui/input';
import { Skeleton } from '@/components/ui/skeleton';
import { Search, ChevronRight } from 'lucide-react';
import { format } from 'date-fns';

interface Invoice {
  id: string;
  invoiceNumber: string;
  dueDate: string;
  subtotal: string;
  lateFee: string;
  total: string;
  amountPaid: string;
  balance: string;
  status: string;
  client?: { firstName: string; lastName: string; accountNumber: string };
}

interface InvoicesResponse {
  data: Invoice[];
  total: number;
}

const statusColors: Record<string, string> = {
  SENT: 'bg-blue-100 text-blue-700',
  PARTIAL: 'bg-yellow-100 text-yellow-700',
  PAID: 'bg-green-100 text-green-700',
  OVERDUE: 'bg-red-100 text-red-700',
  DRAFT: 'bg-gray-100 text-gray-500',
  VOID: 'bg-gray-100 text-gray-400',
};

const peso = (v: string | number) =>
  '₱' + Number(v ?? 0).toLocaleString('en-PH', { minimumFractionDigits: 2 });

export default function InvoicesPage() {
  const [search, setSearch] = useState('');
  const [statusFilter, setStatusFilter] = useState('');
  const [page, setPage] = useState(1);

  const { data, isLoading } = useQuery<InvoicesResponse>({
    queryKey: ['invoices', search, statusFilter, page],
    queryFn: async () => {
      const params = new URLSearchParams({ page: String(page), limit: '20' });
      if (search) params.set('search', search);
      if (statusFilter) params.set('status', statusFilter);
      const res = await api.get(`/api/v1/invoices?${params}`);
      return res.data;
    },
    staleTime: 30_000,
  });

  const invoices = data?.data ?? [];
  const total = data?.total ?? 0;

  return (
    <div>
      <div className="flex items-center justify-between mb-6">
        <div>
          <h1 className="text-2xl font-bold text-slate-800">Invoices</h1>
          <p className="text-slate-500 text-sm mt-1">{total} invoices</p>
        </div>
      </div>

      <div className="flex gap-3 mb-4">
        <div className="relative flex-1">
          <Search size={16} className="absolute left-3 top-1/2 -translate-y-1/2 text-slate-400" />
          <Input
            placeholder="Search by invoice # or client..."
            className="pl-9"
            value={search}
            onChange={(e) => { setSearch(e.target.value); setPage(1); }}
          />
        </div>
        <select
          className="border rounded-md px-3 py-2 text-sm text-slate-700 bg-white"
          value={statusFilter}
          onChange={(e) => { setStatusFilter(e.target.value); setPage(1); }}
        >
          <option value="">All Statuses</option>
          {['SENT', 'PARTIAL', 'PAID', 'OVERDUE', 'DRAFT', 'VOID'].map((s) => (
            <option key={s} value={s}>{s}</option>
          ))}
        </select>
      </div>

      <Card className="border shadow-sm">
        <CardContent className="p-0">
          <div className="overflow-x-auto">
            <table className="w-full text-sm">
              <thead>
                <tr className="border-b bg-slate-50">
                  <th className="text-left px-4 py-3 font-medium text-slate-500">Invoice #</th>
                  <th className="text-left px-4 py-3 font-medium text-slate-500 hidden md:table-cell">Client</th>
                  <th className="text-left px-4 py-3 font-medium text-slate-500 hidden lg:table-cell">Due Date</th>
                  <th className="text-right px-4 py-3 font-medium text-slate-500">Total</th>
                  <th className="text-right px-4 py-3 font-medium text-slate-500 hidden md:table-cell">Balance</th>
                  <th className="text-left px-4 py-3 font-medium text-slate-500">Status</th>
                  <th className="px-4 py-3"></th>
                </tr>
              </thead>
              <tbody>
                {isLoading
                  ? Array.from({ length: 8 }).map((_, i) => (
                      <tr key={i} className="border-b">
                        {Array.from({ length: 7 }).map((_, j) => (
                          <td key={j} className="px-4 py-3"><Skeleton className="h-4 w-20" /></td>
                        ))}
                      </tr>
                    ))
                  : invoices.map((inv) => (
                      <tr key={inv.id} className="border-b hover:bg-slate-50 cursor-pointer transition-colors">
                        <td className="px-4 py-3 font-mono text-xs text-slate-600">{inv.invoiceNumber}</td>
                        <td className="px-4 py-3 text-slate-700 hidden md:table-cell">
                          {inv.client
                            ? `${inv.client.firstName} ${inv.client.lastName}`
                            : '—'}
                          <div className="text-xs text-slate-400">{inv.client?.accountNumber}</div>
                        </td>
                        <td className="px-4 py-3 text-slate-600 hidden lg:table-cell">
                          {inv.dueDate ? format(new Date(inv.dueDate), 'MMM d, yyyy') : '—'}
                        </td>
                        <td className="px-4 py-3 text-right font-medium text-slate-800">{peso(inv.total)}</td>
                        <td className="px-4 py-3 text-right text-slate-600 hidden md:table-cell">
                          {Number(inv.balance) > 0 ? (
                            <span className="text-red-600 font-medium">{peso(inv.balance)}</span>
                          ) : (
                            <span className="text-green-600">Paid</span>
                          )}
                        </td>
                        <td className="px-4 py-3">
                          <span className={`px-2 py-0.5 rounded-full text-xs font-medium ${statusColors[inv.status] ?? 'bg-gray-100 text-gray-500'}`}>
                            {inv.status}
                          </span>
                        </td>
                        <td className="px-4 py-3 text-slate-400"><ChevronRight size={16} /></td>
                      </tr>
                    ))}
              </tbody>
            </table>
          </div>

          {!isLoading && invoices.length === 0 && (
            <div className="text-center py-12 text-slate-400">No invoices found</div>
          )}

          {total > 20 && (
            <div className="flex items-center justify-between px-4 py-3 border-t">
              <p className="text-sm text-slate-500">
                Showing {(page - 1) * 20 + 1}–{Math.min(page * 20, total)} of {total}
              </p>
              <div className="flex gap-2">
                <button disabled={page === 1} onClick={() => setPage(p => p - 1)}
                  className="px-3 py-1 text-sm border rounded-md disabled:opacity-40">Prev</button>
                <button disabled={page * 20 >= total} onClick={() => setPage(p => p + 1)}
                  className="px-3 py-1 text-sm border rounded-md disabled:opacity-40">Next</button>
              </div>
            </div>
          )}
        </CardContent>
      </Card>
    </div>
  );
}