"use client";

import { useState } from "react";
import { useQuery } from "@tanstack/react-query";
import { RefreshCw } from "lucide-react";
import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/Card";
import { Button } from "@/components/ui/Button";
import { AccountingNav } from "@/components/accounting/AccountingNav";
import { formatCurrency } from "@/lib/utils";
import api from "@/lib/api";
import type {
  TrialBalanceLine,
  ProfitLossReport,
  BalanceSheetReport,
  CashFlowReport,
} from "@/types/index";

type ReportTab = "trial-balance" | "profit-loss" | "balance-sheet" | "cash-flow";

const TABS: { key: ReportTab; label: string }[] = [
  { key: "trial-balance", label: "Trial Balance" },
  { key: "profit-loss", label: "Profit & Loss" },
  { key: "balance-sheet", label: "Balance Sheet" },
  { key: "cash-flow", label: "Cash Flow" },
];

// ─── Trial Balance ─────────────────────────────────────────────────────────────

function TrialBalance({ dateFrom, dateTo }: { dateFrom: string; dateTo: string }) {
  const { data, isLoading } = useQuery<TrialBalanceLine[]>({
    queryKey: ["report-trial-balance", dateFrom, dateTo],
    queryFn: async () => {
      const res = await api.get(`/api/v1/reports/trial-balance?dateFrom=${dateFrom}&dateTo=${dateTo}`);
      const d = res.data;
      if (Array.isArray(d)) return d;
      return (d as { data?: TrialBalanceLine[] }).data ?? d as TrialBalanceLine[];
    },
  });

  const lines = data ?? [];
  const totalDebit = lines.reduce((s, l) => s + Number(l.debit), 0);
  const totalCredit = lines.reduce((s, l) => s + Number(l.credit), 0);

  if (isLoading) return <div className="h-64 animate-pulse bg-gray-100 rounded-xl" />;

  return (
    <Card>
      <CardHeader><CardTitle>Trial Balance</CardTitle></CardHeader>
      <CardContent className="p-0">
        {lines.length === 0 ? (
          <p className="text-sm text-gray-400 py-8 text-center">No data for this period</p>
        ) : (
          <table className="w-full text-sm">
            <thead className="bg-gray-50 border-b">
              <tr>
                <th className="text-left px-4 py-2.5 text-xs font-medium text-gray-500">Code</th>
                <th className="text-left px-4 py-2.5 text-xs font-medium text-gray-500">Account</th>
                <th className="text-right px-4 py-2.5 text-xs font-medium text-gray-500">Debit</th>
                <th className="text-right px-4 py-2.5 text-xs font-medium text-gray-500">Credit</th>
                <th className="text-right px-4 py-2.5 text-xs font-medium text-gray-500">Balance</th>
              </tr>
            </thead>
            <tbody>
              {lines.map((l, i) => (
                <tr key={i} className="border-t hover:bg-gray-50">
                  <td className="px-4 py-2.5 font-mono text-xs text-gray-500">{l.code}</td>
                  <td className="px-4 py-2.5 font-medium">{l.name}</td>
                  <td className="px-4 py-2.5 text-right font-mono text-sm">
                    {Number(l.debit) > 0 ? formatCurrency(Number(l.debit)) : "—"}
                  </td>
                  <td className="px-4 py-2.5 text-right font-mono text-sm">
                    {Number(l.credit) > 0 ? formatCurrency(Number(l.credit)) : "—"}
                  </td>
                  <td className={`px-4 py-2.5 text-right font-mono text-sm font-semibold ${Number(l.balance) < 0 ? "text-red-600" : "text-gray-800"}`}>
                    {formatCurrency(Math.abs(Number(l.balance)))}
                    {Number(l.balance) < 0 && " Cr"}
                  </td>
                </tr>
              ))}
            </tbody>
            <tfoot className="border-t bg-gray-50 font-semibold">
              <tr>
                <td colSpan={2} className="px-4 py-2.5 text-sm">Totals</td>
                <td className="px-4 py-2.5 text-right font-mono text-sm">{formatCurrency(totalDebit)}</td>
                <td className="px-4 py-2.5 text-right font-mono text-sm">{formatCurrency(totalCredit)}</td>
                <td className="px-4 py-2.5 text-right">
                  {Math.abs(totalDebit - totalCredit) < 0.01 ? (
                    <span className="text-green-600 text-xs">✓ Balanced</span>
                  ) : (
                    <span className="text-red-500 text-xs">Off by {formatCurrency(Math.abs(totalDebit - totalCredit))}</span>
                  )}
                </td>
              </tr>
            </tfoot>
          </table>
        )}
      </CardContent>
    </Card>
  );
}

// ─── P&L ──────────────────────────────────────────────────────────────────────

function ProfitLoss({ dateFrom, dateTo }: { dateFrom: string; dateTo: string }) {
  const { data, isLoading } = useQuery<ProfitLossReport>({
    queryKey: ["report-profit-loss", dateFrom, dateTo],
    queryFn: async () => {
      const res = await api.get(`/api/v1/reports/profit-loss?dateFrom=${dateFrom}&dateTo=${dateTo}`);
      return res.data as ProfitLossReport;
    },
  });

  if (isLoading) return <div className="h-64 animate-pulse bg-gray-100 rounded-xl" />;
  if (!data) return <p className="text-sm text-gray-400 py-8 text-center">No data for this period</p>;

  const netIncome = Number(data.netIncome ?? (Number(data.totalRevenue) - Number(data.totalExpenses)));

  return (
    <Card>
      <CardHeader><CardTitle>Profit &amp; Loss Statement</CardTitle></CardHeader>
      <CardContent>
        <div className="space-y-6">
          {/* Revenue */}
          <div>
            <h3 className="text-sm font-semibold text-gray-700 mb-2 uppercase tracking-wide">Revenue</h3>
            <div className="space-y-1">
              {(data.revenue ?? []).map((r, i) => (
                <div key={i} className="flex justify-between text-sm py-1 border-b border-gray-50">
                  <span className="text-gray-700">{r.name}</span>
                  <span className="font-mono font-medium">{formatCurrency(Number(r.amount))}</span>
                </div>
              ))}
              <div className="flex justify-between text-sm font-bold py-1 border-t">
                <span>Total Revenue</span>
                <span className="text-green-700">{formatCurrency(Number(data.totalRevenue))}</span>
              </div>
            </div>
          </div>

          {/* Expenses */}
          <div>
            <h3 className="text-sm font-semibold text-gray-700 mb-2 uppercase tracking-wide">Expenses</h3>
            <div className="space-y-1">
              {(data.expenses ?? []).map((e, i) => (
                <div key={i} className="flex justify-between text-sm py-1 border-b border-gray-50">
                  <span className="text-gray-700">{e.name}</span>
                  <span className="font-mono font-medium">{formatCurrency(Number(e.amount))}</span>
                </div>
              ))}
              <div className="flex justify-between text-sm font-bold py-1 border-t">
                <span>Total Expenses</span>
                <span className="text-red-600">{formatCurrency(Number(data.totalExpenses))}</span>
              </div>
            </div>
          </div>

          {/* Net Income */}
          <div className={`flex justify-between text-base font-bold p-3 rounded-lg ${netIncome >= 0 ? "bg-green-50 text-green-800" : "bg-red-50 text-red-800"}`}>
            <span>Net Income</span>
            <span>{formatCurrency(netIncome)}</span>
          </div>
        </div>
      </CardContent>
    </Card>
  );
}

// ─── Balance Sheet ─────────────────────────────────────────────────────────────

function BalanceSheet({ asOf }: { asOf: string }) {
  const { data, isLoading } = useQuery<BalanceSheetReport>({
    queryKey: ["report-balance-sheet", asOf],
    queryFn: async () => {
      const res = await api.get(`/api/v1/reports/balance-sheet?asOf=${asOf}`);
      return res.data as BalanceSheetReport;
    },
  });

  if (isLoading) return <div className="h-64 animate-pulse bg-gray-100 rounded-xl" />;
  if (!data) return <p className="text-sm text-gray-400 py-8 text-center">No data</p>;

  function Section({ title, items, total, color }: { title: string; items: Array<{ name: string; amount: number }>; total: number; color: string }) {
    return (
      <div>
        <h3 className="text-sm font-semibold text-gray-700 mb-2 uppercase tracking-wide">{title}</h3>
        <div className="space-y-1">
          {items.map((item, i) => (
            <div key={i} className="flex justify-between text-sm py-1 border-b border-gray-50">
              <span className="text-gray-700">{item.name}</span>
              <span className="font-mono">{formatCurrency(Number(item.amount))}</span>
            </div>
          ))}
          <div className={`flex justify-between text-sm font-bold py-1 border-t ${color}`}>
            <span>Total {title}</span>
            <span>{formatCurrency(Number(total))}</span>
          </div>
        </div>
      </div>
    );
  }

  return (
    <Card>
      <CardHeader><CardTitle>Balance Sheet</CardTitle></CardHeader>
      <CardContent>
        <div className="grid grid-cols-1 md:grid-cols-2 gap-8">
          <Section title="Assets" items={data.assets ?? []} total={data.totalAssets} color="text-blue-700" />
          <div className="space-y-6">
            <Section title="Liabilities" items={data.liabilities ?? []} total={data.totalLiabilities} color="text-red-600" />
            <Section title="Equity" items={data.equity ?? []} total={data.totalEquity} color="text-purple-700" />
          </div>
        </div>
        <div className="mt-6 p-3 rounded-lg bg-gray-50 flex justify-between text-sm font-bold">
          <span>Total Liabilities + Equity</span>
          <span>{formatCurrency(Number(data.totalLiabilities) + Number(data.totalEquity))}</span>
        </div>
      </CardContent>
    </Card>
  );
}

// ─── Cash Flow ─────────────────────────────────────────────────────────────────

function CashFlow({ dateFrom, dateTo }: { dateFrom: string; dateTo: string }) {
  const { data, isLoading } = useQuery<CashFlowReport>({
    queryKey: ["report-cash-flow", dateFrom, dateTo],
    queryFn: async () => {
      const res = await api.get(`/api/v1/reports/cash-flow?dateFrom=${dateFrom}&dateTo=${dateTo}`);
      return res.data as CashFlowReport;
    },
  });

  if (isLoading) return <div className="h-64 animate-pulse bg-gray-100 rounded-xl" />;
  if (!data) return <p className="text-sm text-gray-400 py-8 text-center">No data for this period</p>;

  function CashSection({ title, items, net }: { title: string; items: Array<{ name: string; amount: number }>; net: number }) {
    return (
      <div>
        <h3 className="text-sm font-semibold text-gray-700 mb-2 uppercase tracking-wide">{title}</h3>
        <div className="space-y-1">
          {items.map((item, i) => (
            <div key={i} className="flex justify-between text-sm py-1 border-b border-gray-50">
              <span className="text-gray-700">{item.name}</span>
              <span className={`font-mono ${Number(item.amount) < 0 ? "text-red-600" : ""}`}>
                {formatCurrency(Number(item.amount))}
              </span>
            </div>
          ))}
          <div className="flex justify-between text-sm font-bold py-1 border-t">
            <span>Net {title}</span>
            <span className={Number(net) >= 0 ? "text-green-700" : "text-red-600"}>
              {formatCurrency(Number(net))}
            </span>
          </div>
        </div>
      </div>
    );
  }

  return (
    <Card>
      <CardHeader><CardTitle>Cash Flow Statement</CardTitle></CardHeader>
      <CardContent>
        <div className="space-y-6">
          <CashSection title="Operating Activities" items={data.operating ?? []} net={data.netOperating} />
          <CashSection title="Investing Activities" items={data.investing ?? []} net={data.netInvesting} />
          <CashSection title="Financing Activities" items={data.financing ?? []} net={data.netFinancing} />
          <div className={`flex justify-between text-base font-bold p-3 rounded-lg ${Number(data.netCashFlow) >= 0 ? "bg-green-50 text-green-800" : "bg-red-50 text-red-800"}`}>
            <span>Net Cash Flow</span>
            <span>{formatCurrency(Number(data.netCashFlow))}</span>
          </div>
        </div>
      </CardContent>
    </Card>
  );
}

// ─── Main Page ─────────────────────────────────────────────────────────────────

export default function AccountingReportsPage() {
  const today = new Date().toISOString().split("T")[0];
  const firstOfYear = `${new Date().getFullYear()}-01-01`;

  const [activeTab, setActiveTab] = useState<ReportTab>("trial-balance");
  const [dateFrom, setDateFrom] = useState(firstOfYear);
  const [dateTo, setDateTo] = useState(today);
  const [asOf, setAsOf] = useState(today);

  return (
    <div className="space-y-4">
      <div className="flex items-start justify-between flex-wrap gap-3">
        <div>
          <h1 className="text-2xl font-bold text-gray-900">Accounting</h1>
          <p className="text-sm text-gray-500">Financial statements and accounting reports</p>
        </div>
        {activeTab !== "balance-sheet" ? (
          <div className="flex items-center gap-2 text-sm">
            <label className="text-gray-500">From</label>
            <input type="date" value={dateFrom} onChange={(e) => setDateFrom(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={dateTo} onChange={(e) => setDateTo(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>
        ) : (
          <div className="flex items-center gap-2 text-sm">
            <label className="text-gray-500">As of</label>
            <input type="date" value={asOf} onChange={(e) => setAsOf(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>
        )}
      </div>

      <AccountingNav />

      {/* Report tabs */}
      <div className="flex gap-1 flex-wrap">
        {TABS.map(({ key, label }) => (
          <button
            key={key}
            onClick={() => setActiveTab(key)}
            className={`px-4 py-2 rounded-lg text-sm font-medium transition-colors ${
              activeTab === key
                ? "bg-blue-100 text-blue-700"
                : "text-gray-500 hover:bg-gray-100 hover:text-gray-700"
            }`}
          >
            {label}
          </button>
        ))}
      </div>

      {activeTab === "trial-balance" && <TrialBalance dateFrom={dateFrom} dateTo={dateTo} />}
      {activeTab === "profit-loss" && <ProfitLoss dateFrom={dateFrom} dateTo={dateTo} />}
      {activeTab === "balance-sheet" && <BalanceSheet asOf={asOf} />}
      {activeTab === "cash-flow" && <CashFlow dateFrom={dateFrom} dateTo={dateTo} />}
    </div>
  );
}