"use client";
export const dynamic = "force-dynamic";

import { useState } from "react";
import { useQuery } from "@tanstack/react-query";
import { BarChart, Bar, XAxis, YAxis, Tooltip, ResponsiveContainer, PieChart, Pie, Cell, LineChart, Line, CartesianGrid, Legend } from "recharts";
import { RefreshCw, TrendingUp, Users, AlertTriangle, DollarSign, Download } from "lucide-react";
import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/Card";
import { Button } from "@/components/ui/Button";
import { Badge } from "@/components/ui/Badge";
import { Table, TableHead, TableBody, TableRow, Th, Td, EmptyState } from "@/components/ui/Table";
import { formatCurrency, formatDate } from "@/lib/utils";
import api from "@/lib/api";

const COLORS = ["#0891B2", "#059669", "#F59E0B", "#EF4444", "#8B5CF6", "#EC4899"];

type Tab = "overview" | "collections" | "tickets";

function KpiCard({ title, value, sub, icon: Icon, color }: { title: string; value: string; sub?: string; icon: any; color: string }) {
  return (
    <Card>
      <CardContent className="pt-5">
        <div className="flex items-start justify-between">
          <div>
            <p className="text-sm text-gray-500">{title}</p>
            <p className="text-2xl font-bold text-gray-900 mt-1">{value}</p>
            {sub && <p className="text-xs text-gray-400 mt-0.5">{sub}</p>}
          </div>
          <div className="w-10 h-10 rounded-xl flex items-center justify-center" style={{ backgroundColor: color + "20" }}>
            <Icon size={20} style={{ color }} />
          </div>
        </div>
      </CardContent>
    </Card>
  );
}

function downloadCSV(data: any[], filename: string) {
  if (!data.length) return;
  const headers = Object.keys(data[0]);
  const rows = data.map(row => headers.map(h => JSON.stringify(row[h] ?? "")).join(","));
  const csv = [headers.join(","), ...rows].join("\n");
  const blob = new Blob([csv], { type: "text/csv" });
  const url = URL.createObjectURL(blob);
  const a = document.createElement("a");
  a.href = url; a.download = filename; a.click();
  URL.revokeObjectURL(url);
}

export default function ReportsPage() {
  const today = new Date();
  const firstOfMonth = new Date(today.getFullYear(), today.getMonth(), 1).toISOString().split("T")[0];
  const [tab, setTab] = useState<Tab>("overview");
  const [from, setFrom] = useState(firstOfMonth);
  const [to, setTo] = useState(today.toISOString().split("T")[0]);

  // Overview data
  const { data: collection = [], isLoading: collLoading, refetch: refetchAll } = useQuery({
    queryKey: ["reports-collection", from, to],
    queryFn: async () => {
      const res = await api.get(`/api/v1/reports/collection?from=${from}&to=${to}`);
      return res.data as Array<{ collector: string; totalAmount: number; paymentCount: number }>;
    },
  });

  const { data: aging = [] } = useQuery({
    queryKey: ["reports-aging"],
    queryFn: async () => {
      const res = await api.get("/api/v1/reports/aging");
      return res.data as Array<{ bucket: string; invoiceCount: number; totalAmount: number }>;
    },
  });

  const { data: subscribers = [] } = useQuery({
    queryKey: ["reports-subscribers"],
    queryFn: async () => {
      const res = await api.get("/api/v1/reports/subscribers");
      return res.data as Array<{ status: string; count: number; area?: string; plan?: string }>;
    },
  });

  const { data: revenue = [] } = useQuery({
    queryKey: ["reports-revenue"],
    queryFn: async () => {
      const res = await api.get("/api/v1/reports/revenue");
      return (res.data as Array<{ month: string; revenue: number; totalInvoiced: number }>)
        .filter(r => r.revenue > 0 || r.totalInvoiced > 0).slice(-12);
    },
  });

  // Collections tab data
  const { data: paymentsData } = useQuery({
    queryKey: ["reports-payments", from, to],
    queryFn: async () => {
      const res = await api.get(`/api/v1/payments?page=1&limit=100`);
      return (res.data as any)?.data ?? [];
    },
    enabled: tab === "collections",
  });

  // Tickets tab data
  const { data: ticketsData } = useQuery({
    queryKey: ["reports-tickets"],
    queryFn: async () => {
      const [open, resolved, all] = await Promise.all([
        api.get("/api/v1/tickets?status=OPEN&limit=100"),
        api.get("/api/v1/tickets?status=RESOLVED&limit=100"),
        api.get("/api/v1/tickets?limit=50"),
      ]);
      return {
        open: (open.data as any)?.meta?.total ?? (open.data as any)?.data?.length ?? 0,
        resolved: (resolved.data as any)?.meta?.total ?? (resolved.data as any)?.data?.length ?? 0,
        list: (all.data as any)?.data ?? [],
        total: (all.data as any)?.meta?.total ?? 0,
      };
    },
    enabled: tab === "tickets",
  });

  // Derived KPIs
  const totalCollected = collection.reduce((s, c) => s + Number(c.totalAmount), 0);
  const totalPayments = collection.reduce((s, c) => s + c.paymentCount, 0);
  const totalOutstanding = aging.reduce((s, a) => s + Number(a.totalAmount), 0);
  const overdueCount = aging.reduce((s, a) => s + a.invoiceCount, 0);
  const subByStatus = subscribers.filter(s => !s.area && !s.plan);
  const activeCount = subByStatus.find(s => s.status === "ACTIVE")?.count ?? 0;
  const pendingCount = subByStatus.find(s => s.status === "PENDING")?.count ?? 0;
  const suspendedCount = subByStatus.find(s => s.status === "SUSPENDED")?.count ?? 0;
  const totalSubs = subByStatus.reduce((s, x) => s + x.count, 0);
  const subByArea = subscribers.filter(s => !!s.area);
  const agingRisk: Record<string, string> = { "0-30": "text-yellow-600", "31-60": "text-orange-600", "61-90": "text-red-500", "90+": "text-red-700" };

  const payments: any[] = paymentsData ?? [];

  return (
    <div className="space-y-6">
      <div className="flex items-center justify-between flex-wrap gap-3">
        <div>
          <h1 className="text-2xl font-bold text-gray-900">Reports</h1>
          <p className="text-sm text-gray-500">Financial and operational analytics</p>
        </div>
        <div className="flex items-center gap-2">
          <div className="flex items-center gap-2 text-sm">
            <label className="text-gray-500">From</label>
            <input type="date" value={from} onChange={e => setFrom(e.target.value)}
              className="border rounded-lg px-3 py-1.5 text-sm focus:outline-none focus:ring-2 focus:ring-blue-500" />
            <label className="text-gray-500">To</label>
            <input type="date" value={to} onChange={e => setTo(e.target.value)}
              className="border rounded-lg px-3 py-1.5 text-sm focus:outline-none focus:ring-2 focus:ring-blue-500" />
          </div>
          <Button onClick={() => refetchAll()} variant="outline" size="sm"><RefreshCw size={14} className="mr-1" />Refresh</Button>
        </div>
      </div>

      {/* Tabs */}
      <div className="flex border-b border-gray-200">
        {(["overview", "collections", "tickets"] as Tab[]).map(t => (
          <button key={t} onClick={() => setTab(t)}
            className={`px-5 py-2.5 text-sm font-medium border-b-2 capitalize transition-colors ${
              tab === t ? "border-blue-600 text-blue-600" : "border-transparent text-gray-500 hover:text-gray-700"
            }`}>
            {t}
          </button>
        ))}
      </div>

      {/* Overview Tab */}
      {tab === "overview" && (
        <div className="space-y-6">
          <div className="grid grid-cols-2 lg:grid-cols-4 gap-4">
            <KpiCard title="Total Collected" value={formatCurrency(totalCollected)} sub={`${totalPayments} payments`} icon={DollarSign} color="#059669" />
            <KpiCard title="Active Subscribers" value={String(activeCount)} sub={`${pendingCount} pending · ${suspendedCount} suspended`} icon={Users} color="#0891B2" />
            <KpiCard title="Outstanding Balance" value={formatCurrency(totalOutstanding)} sub={`${overdueCount} overdue invoices`} icon={AlertTriangle} color="#EF4444" />
            <KpiCard title="Total Subscribers" value={String(totalSubs)} sub="across all statuses" icon={TrendingUp} color="#8B5CF6" />
          </div>

          <div className="grid grid-cols-1 lg:grid-cols-2 gap-6">
            <Card>
              <CardHeader><CardTitle>Collection by Collector</CardTitle></CardHeader>
              <CardContent>
                {collLoading ? <div className="h-40 animate-pulse bg-gray-100 rounded" /> :
                  collection.length === 0 ? <p className="text-sm text-gray-400 py-6 text-center">No collection data for this period</p> : (
                    <>
                      <div className="space-y-2 mb-4">
                        {collection.map((c, i) => (
                          <div key={i} className="flex items-center justify-between py-2 border-b last:border-0">
                            <div><p className="text-sm font-medium text-gray-800">{c.collector}</p><p className="text-xs text-gray-400">{c.paymentCount} payments</p></div>
                            <div className="text-right"><p className="text-sm font-bold text-green-700">{formatCurrency(c.totalAmount)}</p></div>
                          </div>
                        ))}
                        <div className="flex justify-between pt-1 font-semibold text-sm"><span>Total</span><span className="text-green-700">{formatCurrency(totalCollected)}</span></div>
                      </div>
                      <ResponsiveContainer width="100%" height={160}>
                        <BarChart data={collection}><XAxis dataKey="collector" tick={{ fontSize: 11 }} /><YAxis tick={{ fontSize: 11 }} tickFormatter={v => `₱${(v/1000).toFixed(0)}k`} /><Tooltip formatter={(v: any) => formatCurrency(Number(v))} /><Bar dataKey="totalAmount" fill="#0891B2" radius={[4,4,0,0]} /></BarChart>
                      </ResponsiveContainer>
                    </>
                  )
                }
              </CardContent>
            </Card>
            <Card>
              <CardHeader><CardTitle>Accounts Receivable Aging</CardTitle></CardHeader>
              <CardContent>
                <div className="space-y-3">
                  {aging.map((a) => (
                    <div key={a.bucket} className="flex items-center justify-between p-3 rounded-lg bg-gray-50">
                      <div><p className={`text-sm font-semibold ${agingRisk[a.bucket] ?? "text-gray-700"}`}>{a.bucket} days</p><p className="text-xs text-gray-400">{a.invoiceCount} invoices</p></div>
                      <p className={`text-base font-bold ${a.totalAmount > 0 ? agingRisk[a.bucket] ?? "text-gray-800" : "text-gray-400"}`}>{formatCurrency(a.totalAmount)}</p>
                    </div>
                  ))}
                  <div className="flex justify-between px-3 py-2 bg-red-50 rounded-lg font-semibold text-sm"><span className="text-red-700">Total Outstanding</span><span className="text-red-700">{formatCurrency(totalOutstanding)}</span></div>
                </div>
              </CardContent>
            </Card>
          </div>

          {revenue.length > 0 && (
            <Card>
              <CardHeader><CardTitle>Revenue Trend (Monthly)</CardTitle></CardHeader>
              <CardContent>
                <ResponsiveContainer width="100%" height={220}>
                  <LineChart data={revenue} margin={{ top: 5, right: 20, left: 0, bottom: 5 }}>
                    <CartesianGrid strokeDasharray="3 3" stroke="#F1F5F9" />
                    <XAxis dataKey="month" tick={{ fontSize: 11 }} /><YAxis tick={{ fontSize: 11 }} tickFormatter={v => `₱${(v/1000).toFixed(0)}k`} />
                    <Tooltip formatter={(v: any) => formatCurrency(Number(v))} /><Legend />
                    <Line type="monotone" dataKey="revenue" stroke="#059669" strokeWidth={2} dot={false} name="Collected" />
                    <Line type="monotone" dataKey="totalInvoiced" stroke="#0891B2" strokeWidth={2} dot={false} name="Invoiced" strokeDasharray="4 2" />
                  </LineChart>
                </ResponsiveContainer>
              </CardContent>
            </Card>
          )}

          <div className="grid grid-cols-1 lg:grid-cols-2 gap-6">
            <Card>
              <CardHeader><CardTitle>Subscribers by Status</CardTitle></CardHeader>
              <CardContent>
                {subByStatus.length === 0 ? <p className="text-sm text-gray-400 py-4 text-center">No subscriber data</p> : (
                  <div className="flex gap-6 items-center">
                    <ResponsiveContainer width="50%" height={160}>
                      <PieChart><Pie data={subByStatus} dataKey="count" nameKey="status" cx="50%" cy="50%" outerRadius={60}>{subByStatus.map((_, i) => <Cell key={i} fill={COLORS[i % COLORS.length]} />)}</Pie><Tooltip /></PieChart>
                    </ResponsiveContainer>
                    <div className="space-y-2">
                      {subByStatus.map((s, i) => (<div key={s.status} className="flex items-center gap-2"><div className="w-3 h-3 rounded-full" style={{ backgroundColor: COLORS[i % COLORS.length] }} /><span className="text-sm text-gray-700">{s.status}</span><span className="text-sm font-bold ml-auto">{s.count}</span></div>))}
                      <div className="border-t pt-1 flex justify-between text-sm font-semibold"><span>Total</span><span>{totalSubs}</span></div>
                    </div>
                  </div>
                )}
              </CardContent>
            </Card>
            {subByArea.length > 0 && (
              <Card>
                <CardHeader><CardTitle>Active Subscribers by Area</CardTitle></CardHeader>
                <CardContent>
                  <div className="space-y-2">
                    {subByArea.map(a => (
                      <div key={a.area} className="flex items-center justify-between py-2 border-b last:border-0">
                        <span className="text-sm font-medium">{a.area}</span>
                        <div className="flex items-center gap-2"><div className="w-20 bg-gray-100 rounded-full h-2"><div className="h-2 rounded-full bg-blue-500" style={{ width: `${Math.min(100, (a.count / (activeCount || 1)) * 100)}%` }} /></div><span className="text-sm font-bold w-6 text-right">{a.count}</span></div>
                      </div>
                    ))}
                  </div>
                </CardContent>
              </Card>
            )}
          </div>
        </div>
      )}

      {/* Collections Tab */}
      {tab === "collections" && (
        <div className="space-y-4">
          <div className="flex items-center justify-between">
            <h2 className="text-lg font-semibold text-gray-800">Payment Collections</h2>
            <Button size="sm" variant="outline" onClick={() => downloadCSV(payments.map(p => ({
              Date: p.paymentDate ?? p.createdAt,
              Client: p.client ? `${p.client.firstName} ${p.client.lastName}` : "",
              Amount: p.amount, Channel: p.channel, Reference: p.referenceNumber ?? "", Notes: p.notes ?? "",
            })), `collections-${from}-${to}.csv`)}>
              <Download size={14} className="mr-1" /> Export CSV
            </Button>
          </div>
          <Card>
            <CardContent className="p-0">
              <Table>
                <TableHead>
                  <TableRow><Th>Date</Th><Th>Client</Th><Th>Amount</Th><Th>Channel</Th><Th>Reference</Th><Th>Notes</Th></TableRow>
                </TableHead>
                <TableBody>
                  {payments.length === 0 ? <EmptyState message="No payments found" /> :
                    payments.map((p: any) => (
                      <TableRow key={p.id}>
                        <Td className="text-xs text-gray-500">{formatDate(p.paymentDate ?? p.createdAt)}</Td>
                        <Td className="font-medium">{p.client ? `${p.client.firstName} ${p.client.lastName}` : "—"}</Td>
                        <Td className="text-green-700 font-medium">{formatCurrency(Number(p.amount))}</Td>
                        <Td><Badge variant="muted">{p.channel}</Badge></Td>
                        <Td className="text-xs text-gray-400">{p.referenceNumber ?? "—"}</Td>
                        <Td className="text-xs text-gray-400 max-w-[120px] truncate">{p.notes ?? "—"}</Td>
                      </TableRow>
                    ))
                  }
                </TableBody>
              </Table>
            </CardContent>
          </Card>
        </div>
      )}

      {/* Tickets Tab */}
      {tab === "tickets" && (
        <div className="space-y-4">
          {ticketsData && (
            <>
              <div className="grid grid-cols-3 gap-4">
                <Card><CardContent className="pt-5 text-center"><p className="text-3xl font-bold text-yellow-600">{ticketsData.open}</p><p className="text-sm text-gray-500 mt-1">Open</p></CardContent></Card>
                <Card><CardContent className="pt-5 text-center"><p className="text-3xl font-bold text-green-600">{ticketsData.resolved}</p><p className="text-sm text-gray-500 mt-1">Resolved</p></CardContent></Card>
                <Card><CardContent className="pt-5 text-center"><p className="text-3xl font-bold text-blue-600">{ticketsData.total}</p><p className="text-sm text-gray-500 mt-1">Total</p></CardContent></Card>
              </div>
              <Card>
                <CardHeader><CardTitle>Recent Tickets</CardTitle></CardHeader>
                <CardContent className="p-0">
                  <Table>
                    <TableHead>
                      <TableRow><Th>Subject</Th><Th>Client</Th><Th>Type</Th><Th>Priority</Th><Th>Status</Th><Th>Created</Th></TableRow>
                    </TableHead>
                    <TableBody>
                      {ticketsData.list.length === 0 ? <EmptyState message="No tickets found" /> :
                        ticketsData.list.map((t: any) => (
                          <TableRow key={t.id}>
                            <Td className="font-medium max-w-[180px] truncate">{t.subject}</Td>
                            <Td>{t.client ? `${t.client.firstName} ${t.client.lastName}` : "—"}</Td>
                            <Td><Badge variant="muted">{t.type}</Badge></Td>
                            <Td><Badge variant={t.priority === "HIGH" ? "warning" : "muted"}>{t.priority}</Badge></Td>
                            <Td><Badge variant={t.status === "RESOLVED" ? "success" : t.status === "OPEN" ? "warning" : "muted"}>{t.status}</Badge></Td>
                            <Td className="text-xs text-gray-400">{formatDate(t.createdAt)}</Td>
                          </TableRow>
                        ))
                      }
                    </TableBody>
                  </Table>
                </CardContent>
              </Card>
            </>
          )}
        </div>
      )}
    </div>
  );
}