"use client";

import { useState } from "react";
import { useQuery } from "@tanstack/react-query";
import { RefreshCw, CreditCard, AlertCircle } from "lucide-react";
import { Card, CardContent, CardHeader } from "@/components/ui/Card";
import { Table, TableHead, TableBody, TableRow, Th, Td, EmptyState } from "@/components/ui/Table";
import { Badge } from "@/components/ui/Badge";
import { Button } from "@/components/ui/Button";
import { Modal } from "@/components/ui/Modal";
import { formatDate, formatCurrency } from "@/lib/utils";
import api from "@/lib/api";

interface Payment {
  id: string; clientId: string;
  client?: { firstName: string; lastName: string; accountNumber: string };
  invoice?: { invoiceNumber: string; total: string };
  invoiceId?: string;
  amount: string; channel: string;
  referenceNumber?: string; orNumber?: string; notes?: string;
  paymentDate?: string; createdAt: string;
  recordedBy?: { firstName: string; lastName: string };
}
interface PaymentsResponse { data: Payment[]; total: number; page: number; limit: number; }

const channelVariant: Record<string, "success" | "warning" | "muted" | "default"> = {
  CASH: "success", GCASH: "default", MAYA: "default", BANK_TRANSFER: "warning", CHECK: "muted",
};

const channelFilters = ["", "CASH", "GCASH", "MAYA", "BANK_TRANSFER", "CHECK"];

export default function PaymentsPage() {
  const [search, setSearch] = useState("");
  const [channelFilter, setChannelFilter] = useState("");
  const [page, setPage] = useState(1);
  const [selected, setSelected] = useState<Payment | null>(null);

  const { data, isLoading, isError, refetch } = useQuery<PaymentsResponse>({
    queryKey: ["payments", search, channelFilter, page],
    queryFn: async () => {
      const params = new URLSearchParams({ page: String(page), limit: "20" });
      if (search) params.set("search", search);
      if (channelFilter) params.set("channel", channelFilter);
      const res = await api.get<PaymentsResponse>(`/api/v1/payments?${params}`);
      return res.data;
    },
  });

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

  return (
    <div className="space-y-6">
      <div className="flex items-center justify-between">
        <div>
          <h1 className="text-2xl font-bold text-gray-900">Payments</h1>
          <p className="text-sm text-gray-500 mt-1">{total} total payments</p>
        </div>
        <Button onClick={() => refetch()} variant="outline" size="sm"><RefreshCw size={14} className="mr-1" />Refresh</Button>
      </div>

      <Card>
        <CardHeader>
          <div className="flex flex-wrap gap-3 items-center">
            <input className="flex-1 min-w-[200px] border rounded-lg px-3 py-2 text-sm focus:outline-none focus:ring-2 focus:ring-blue-500"
              placeholder="Search by client..."
              value={search} onChange={e => { setSearch(e.target.value); setPage(1); }} />
            <div className="flex gap-2 flex-wrap">
              {channelFilters.map(c => (
                <button key={c} onClick={() => { setChannelFilter(c); setPage(1); }}
                  className={`px-3 py-1.5 rounded-lg text-xs font-medium transition-colors ${channelFilter === c ? "bg-blue-600 text-white" : "bg-gray-100 text-gray-600 hover:bg-gray-200"}`}>
                  {c || "All"}
                </button>
              ))}
            </div>
          </div>
        </CardHeader>
        <CardContent className="p-0">
          <Table>
            <TableHead>
              <TableRow><Th>Date</Th><Th>Client</Th><Th>Amount</Th><Th>Method</Th><Th>Reference</Th><Th>Invoice</Th><Th></Th></TableRow>
            </TableHead>
            <TableBody>
              {isLoading ? (
                Array.from({ length: 8 }).map((_, i) => (
                  <TableRow key={i}><Td colSpan={7}><div className="h-4 bg-gray-100 rounded animate-pulse" /></Td></TableRow>
                ))
              ) : isError ? (
                <TableRow><Td colSpan={7}><div className="flex items-center gap-2 py-6 justify-center text-red-400 text-sm"><AlertCircle size={16} />Failed to load payments. <button onClick={() => refetch()} className="underline">Retry</button></div></Td></TableRow>
              ) : payments.length === 0 ? (
                <EmptyState colSpan={7} message="No payments found" icon={<CreditCard size={24} />} />
              ) : payments.map(p => (
                <TableRow key={p.id} data-testid="payment-row" onClick={() => setSelected(p)} className="cursor-pointer hover:bg-blue-50 transition-colors">
                  <Td className="text-sm">{p.paymentDate ? formatDate(p.paymentDate) : formatDate(p.createdAt)}</Td>
                  <Td className="font-medium">
                    {p.client ? `${p.client.firstName} ${p.client.lastName}` : "—"}
                    <div className="text-xs text-gray-400">{p.client?.accountNumber}</div>
                  </Td>
                  <Td className="font-semibold text-green-700">{formatCurrency(Number(p.amount))}</Td>
                  <Td><Badge variant={channelVariant[p.channel] ?? "muted"}>{p.channel}</Badge></Td>
                  <Td className="text-xs text-gray-500">{p.referenceNumber ?? p.orNumber ?? "—"}</Td>
                  <Td className="text-xs font-mono text-gray-500">{p.invoice?.invoiceNumber ?? (p.invoiceId ? p.invoiceId.slice(0, 8) : "—")}</Td>
                  <Td className="text-gray-400 text-xs">View →</Td>
                </TableRow>
              ))}
            </TableBody>
          </Table>
          {total > 20 && (
            <div className="flex items-center justify-between px-4 py-3 border-t text-sm text-gray-500">
              <span>Showing {(page - 1) * 20 + 1}–{Math.min(page * 20, total)} of {total}</span>
              <div className="flex gap-2">
                <button disabled={page === 1} onClick={() => setPage(p => p - 1)} className="px-3 py-1 border rounded-md disabled:opacity-40">Prev</button>
                <button disabled={page * 20 >= total} onClick={() => setPage(p => p + 1)} className="px-3 py-1 border rounded-md disabled:opacity-40">Next</button>
              </div>
            </div>
          )}
        </CardContent>
      </Card>

      {/* Payment Detail Modal */}
      <Modal isOpen={!!selected} onClose={() => setSelected(null)} title="Payment Details">
        {selected && (
          <div className="space-y-4">
            <div className="bg-gray-50 rounded-lg p-4 space-y-2.5 text-sm">
              <div className="flex justify-between items-center">
                <span className="text-gray-500">Client</span>
                <span className="font-medium">{selected.client ? `${selected.client.firstName} ${selected.client.lastName}` : "—"}</span>
              </div>
              <div className="flex justify-between items-center">
                <span className="text-gray-500">Account #</span>
                <span className="font-mono text-xs">{selected.client?.accountNumber ?? "—"}</span>
              </div>
              <hr />
              <div className="flex justify-between items-center">
                <span className="text-gray-500">Amount</span>
                <span className="text-xl font-bold text-green-700">{formatCurrency(Number(selected.amount))}</span>
              </div>
              <div className="flex justify-between items-center">
                <span className="text-gray-500">Method</span>
                <Badge variant={channelVariant[selected.channel] ?? "muted"}>{selected.channel}</Badge>
              </div>
              {(selected.referenceNumber || selected.orNumber) && (
                <div className="flex justify-between items-center">
                  <span className="text-gray-500">Reference #</span>
                  <span className="font-mono text-xs">{selected.referenceNumber ?? selected.orNumber}</span>
                </div>
              )}
              <div className="flex justify-between items-center">
                <span className="text-gray-500">Invoice</span>
                <span className="font-mono text-xs">{selected.invoice?.invoiceNumber ?? (selected.invoiceId ? selected.invoiceId.slice(0, 8) : "—")}</span>
              </div>
              <div className="flex justify-between items-center">
                <span className="text-gray-500">Payment Date</span>
                <span>{selected.paymentDate ? formatDate(selected.paymentDate) : formatDate(selected.createdAt)}</span>
              </div>
              {selected.notes && (
                <div className="flex justify-between items-start">
                  <span className="text-gray-500">Notes</span>
                  <span className="text-right max-w-[200px]">{selected.notes}</span>
                </div>
              )}
              {selected.recordedBy && (
                <div className="flex justify-between items-center">
                  <span className="text-gray-500">Recorded By</span>
                  <span>{selected.recordedBy.firstName} {selected.recordedBy.lastName}</span>
                </div>
              )}
            </div>
            <div className="flex justify-end">
              <Button variant="outline" onClick={() => setSelected(null)}>Close</Button>
            </div>
          </div>
        )}
      </Modal>
    </div>
  );
}