"use client";

import { useCallback, useEffect, useState } from "react";
import { Card, Spinner } from "@heroui/react";
import {
  Thunderbolt,
  PlugConnection,
  CreditCard,
  ChartColumn,
  TagDollar,
  Person,
} from "@gravity-ui/icons";
import { useSession } from "@/lib/auth-client";
import { api, type Stats, type UserStats, type Transaction, type ChargePoint } from "@/lib/api";

// ── Helpers ────────────────────────────────────────────────────────────────

function timeAgo(dateStr: string | null | undefined): string {
  if (!dateStr) return "—";
  const ms = Date.now() - new Date(dateStr).getTime();
  if (ms < 60_000) return "刚刚";
  if (ms < 3_600_000) return `${Math.floor(ms / 60_000)} 分钟前`;
  if (ms < 86_400_000) return `${Math.floor(ms / 3_600_000)} 小时前`;
  return new Date(dateStr).toLocaleDateString("zh-CN", { month: "short", day: "numeric" });
}

function cpOnline(cp: ChargePoint): boolean {
  if (!cp.lastHeartbeatAt) return false;
  return Date.now() - new Date(cp.lastHeartbeatAt).getTime() < 120_000;
}

// ── StatCard ───────────────────────────────────────────────────────────────

type CardColor = "accent" | "success" | "warning" | "default";

const colorStyles: Record<CardColor, { border: string; bg: string; icon: string }> = {
  accent: { border: "border-accent", bg: "bg-accent/10", icon: "text-accent" },
  success: { border: "border-success", bg: "bg-success/10", icon: "text-success" },
  warning: { border: "border-warning", bg: "bg-warning/10", icon: "text-warning" },
  default: { border: "border-border", bg: "bg-default", icon: "text-muted" },
};

function StatusDot({ color }: { color: "success" | "warning" | "muted" }) {
  const cls =
    color === "success" ? "bg-success" : color === "warning" ? "bg-warning" : "bg-muted/40";
  return <span className={`inline-block h-1.5 w-1.5 shrink-0 rounded-full ${cls}`} />;
}

function StatCard({
  title,
  value,
  footer,
  icon: Icon,
  color = "default",
}: {
  title: string;
  value: string | number;
  footer?: React.ReactNode;
  icon?: React.ComponentType<{ className?: string }>;
  color?: CardColor;
}) {
  const s = colorStyles[color];
  return (
    <Card className={`border-t-2 ${s.border}`}>
      <Card.Content className="flex flex-col gap-3">
        <div className="flex items-start justify-between gap-2">
          <p className="text-sm text-muted">{title}</p>
          {Icon && (
            <div className={`flex size-9 shrink-0 items-center justify-center rounded-xl ${s.bg}`}>
              <Icon className={`size-4.5 ${s.icon}`} />
            </div>
          )}
        </div>
        <p className="text-3xl font-bold tabular-nums leading-none text-foreground">{value}</p>
        {footer && (
          <div className="flex flex-wrap items-center gap-x-1.5 gap-y-1 text-xs text-muted">
            {footer}
          </div>
        )}
      </Card.Content>
    </Card>
  );
}

// ── Panel wrapper ──────────────────────────────────────────────────────────

function Panel({ title, children }: { title: string; children: React.ReactNode }) {
  return (
    <div className="rounded-xl border border-border bg-surface-secondary">
      <div className="border-b border-border px-5 py-3.5">
        <p className="text-sm font-semibold text-foreground">{title}</p>
      </div>
      {children}
    </div>
  );
}

// ── RecentTransactions ────────────────────────────────────────────────────

function RecentTransactions({ txns }: { txns: Transaction[] }) {
  if (txns.length === 0) {
    return <div className="py-8 text-center text-sm text-muted">暂无充电记录</div>;
  }
  return (
    <ul className="divide-y divide-border">
      {txns.map((tx) => {
        const active = !tx.stopTimestamp;
        const kwh =
          tx.energyWh != null ? (tx.energyWh / 1000).toFixed(2) : active ? "充电中…" : "—";
        const amount =
          tx.chargeAmount != null && tx.chargeAmount > 0
            ? `¥${(tx.chargeAmount / 100).toFixed(2)}`
            : active
              ? "—"
              : "免费";
        return (
          <li key={tx.id} className="flex items-center gap-3 px-5 py-3">
            <span
              className={`flex size-7 shrink-0 items-center justify-center rounded-full ${active ? "bg-warning-soft" : "bg-success/10"}`}
            >
              <Thunderbolt
                className={`size-3.5 ${active ? "text-warning" : "text-success"}`}
              />
            </span>
            <div className="min-w-0 flex-1">
              <p className="truncate text-sm font-medium text-foreground">
                {tx.chargePointIdentifier ?? "—"}
                {tx.connectorNumber != null && (
                  <span className="ml-1 text-xs text-muted">#{tx.connectorNumber}</span>
                )}
              </p>
              <p className="text-xs text-muted">{tx.idTag}</p>
            </div>
            <div className="shrink-0 text-right">
              <p className="text-sm font-medium tabular-nums text-foreground">{kwh}</p>
              <p className="text-xs text-muted">{amount}</p>
            </div>
            <div className="w-16 shrink-0 text-right">
              <p className="text-xs text-muted">{timeAgo(tx.startTimestamp)}</p>
            </div>
          </li>
        );
      })}
    </ul>
  );
}

// ── ChargePointStatus ─────────────────────────────────────────────────────

function ChargePointStatus({ cps }: { cps: ChargePoint[] }) {
  if (cps.length === 0) {
    return <div className="py-8 text-center text-sm text-muted">暂无充电桩</div>;
  }
  return (
    <ul className="divide-y divide-border">
      {cps.map((cp) => {
        const online = cpOnline(cp);
        const chargingCount = cp.connectors.filter((c) => c.status === "Charging").length;
        const availableCount = cp.connectors.filter((c) => c.status === "Available").length;
        return (
          <li key={cp.id} className="flex items-center gap-3 px-5 py-3">
            <span
              className={`mt-0.5 h-2 w-2 shrink-0 rounded-full ${online ? "bg-success" : "bg-muted/40"}`}
            />
            <div className="min-w-0 flex-1">
              <p className="truncate font-mono text-sm font-medium text-foreground">
                {cp.chargePointIdentifier}
              </p>
              <p className="text-xs text-muted">
                {cp.chargePointModel ?? cp.chargePointVendor ?? "未知型号"}
              </p>
            </div>
            <div className="shrink-0 text-right">
              {chargingCount > 0 && (
                <p className="text-xs font-medium text-warning">{chargingCount} 充电中</p>
              )}
              <p className="text-xs text-muted">
                {online ? `${availableCount} 可用` : "离线"}
              </p>
            </div>
          </li>
        );
      })}
    </ul>
  );
}

// ── Page ───────────────────────────────────────────────────────────────────

export default function DashboardPage() {
  const { data: sessionData, isPending } = useSession();
  const isAdmin = sessionData?.user?.role === "admin";

  const [adminStats, setAdminStats] = useState<Stats | null>(null);
  const [userStats, setUserStats] = useState<UserStats | null>(null);
  const [recentTxns, setRecentTxns] = useState<Transaction[]>([]);
  const [chargePoints, setChargePoints] = useState<ChargePoint[]>([]);
  const [loading, setLoading] = useState(false);

  const load = useCallback(async () => {
    if (isPending) return;
    setLoading(true);
    try {
      const [statsData, txnsData, cpsData] = await Promise.all([
        api.stats.get(),
        api.transactions.list({ limit: 6 }),
        isAdmin ? api.chargePoints.list() : Promise.resolve(null),
      ]);
      if ("totalChargePoints" in statsData) {
        setAdminStats(statsData as Stats);
      } else {
        setUserStats(statsData as UserStats);
      }
      setRecentTxns(txnsData.data);
      if (cpsData) setChargePoints(cpsData);
    } catch {}
    finally {
      setLoading(false);
    }
  }, [isPending, isAdmin]);

  useEffect(() => { void load(); }, [load]);

  if (isPending || loading) {
    return (
      <div className="space-y-6">
        <div>
          <h1 className="text-xl font-semibold text-foreground">概览</h1>
          <p className="mt-0.5 text-sm text-muted">加载中…</p>
        </div>
        <div className="flex justify-center py-16">
          <Spinner />
        </div>
      </div>
    );
  }

  // ── Admin view ────────────────────────────────────────────────────────────

  if (isAdmin) {
    const s = adminStats;
    const todayKwh = s ? (s.todayEnergyWh / 1000).toFixed(1) : "—";
    const todayRevenue = s ? `¥${(s.todayRevenue / 100).toFixed(2)}` : "—";
    const offlineCount = (s?.totalChargePoints ?? 0) - (s?.onlineChargePoints ?? 0);

    return (
      <div className="space-y-6">
        <div>
          <h1 className="text-xl font-semibold text-foreground">概览</h1>
          <p className="mt-0.5 text-sm text-muted">实时运营状态</p>
        </div>

        {/* Today's live metrics */}
        <div className="grid grid-cols-2 gap-4 lg:grid-cols-4">
          <StatCard
            title="今日充电次数"
            value={s?.todayTransactions ?? "—"}
            icon={ChartColumn}
            color="accent"
            footer={<span>当日 00:00 起累计</span>}
          />
          <StatCard
            title="今日充电量"
            value={`${todayKwh} kWh`}
            icon={Thunderbolt}
            color="accent"
            footer={<span>当日累计输出电能</span>}
          />
          <StatCard
            title="今日营收"
            value={todayRevenue}
            icon={TagDollar}
            color="success"
            footer={<span>已完成订单金额合计</span>}
          />
          <StatCard
            title="活跃充电"
            value={s?.activeTransactions ?? "—"}
            icon={Thunderbolt}
            color={s?.activeTransactions ? "warning" : "default"}
            footer={
              <>
                <StatusDot color={s?.activeTransactions ? "success" : "muted"} />
                <span className={s?.activeTransactions ? "font-medium text-success" : ""}>
                  {s?.activeTransactions ? "充电进行中" : "当前空闲"}
                </span>
              </>
            }
          />
        </div>

        {/* Infrastructure metrics */}
        <div className="grid grid-cols-3 gap-4">
          <StatCard
            title="充电桩总数"
            value={s?.totalChargePoints ?? "—"}
            icon={PlugConnection}
            color="default"
            footer={
              <>
                <StatusDot color="success" />
                <span className="font-medium text-success">
                  {s?.onlineChargePoints ?? 0} 在线
                </span>
                <span className="text-border">·</span>
                <span>{offlineCount} 离线</span>
              </>
            }
          />
          <StatCard
            title="储值卡总数"
            value={s?.totalIdTags ?? "—"}
            icon={CreditCard}
            color="default"
            footer={<span>已注册卡片总量</span>}
          />
          <StatCard
            title="注册用户"
            value={s?.totalUsers ?? "—"}
            icon={Person}
            color="default"
            footer={<span>系统用户总数</span>}
          />
        </div>

        {/* Detail panels */}
        <div className="grid grid-cols-1 gap-4 lg:grid-cols-5">
          <div className="lg:col-span-2">
            <Panel title="充电桩状态">
              <ChargePointStatus cps={chargePoints} />
            </Panel>
          </div>
          <div className="lg:col-span-3">
            <Panel title="最近充电会话">
              <RecentTransactions txns={recentTxns} />
            </Panel>
          </div>
        </div>
      </div>
    );
  }

  // ── User view ─────────────────────────────────────────────────────────────

  const s = userStats;
  const totalYuan = s ? (s.totalBalance / 100).toFixed(2) : "—";
  const todayKwh = s ? (s.todayEnergyWh / 1000).toFixed(2) : "—";

  return (
    <div className="space-y-6">
      <div>
        <h1 className="text-xl font-semibold text-foreground">概览</h1>
        <p className="mt-0.5 text-sm text-muted">
          {sessionData?.user?.name ?? sessionData?.user?.email} 的账户概览
        </p>
      </div>

      <div className="grid grid-cols-2 gap-4 lg:grid-cols-4">
        <StatCard
          title="我的储值卡"
          value={s?.totalIdTags ?? "—"}
          icon={CreditCard}
          color="accent"
          footer={<span>已绑定的储值卡数量</span>}
        />
        <StatCard
          title="账户总余额"
          value={`¥${totalYuan}`}
          icon={TagDollar}
          color="success"
          footer={<span>所有储值卡余额合计</span>}
        />
        <StatCard
          title="今日充电量"
          value={`${todayKwh} kWh`}
          icon={Thunderbolt}
          color={s?.todayEnergyWh ? "warning" : "default"}
          footer={
            <>
              <StatusDot color={s?.activeTransactions ? "success" : "muted"} />
              <span className={s?.activeTransactions ? "font-medium text-success" : ""}>
                {s?.activeTransactions ? "充电中" : "当前空闲"}
              </span>
            </>
          }
        />
        <StatCard
          title="累计充电次数"
          value={s?.totalTransactions ?? "—"}
          icon={ChartColumn}
          color="default"
          footer={<span>今日 {s?.todayTransactions ?? 0} 次</span>}
        />
      </div>

      <Panel title="最近充电记录">
        <RecentTransactions txns={recentTxns} />
      </Panel>
    </div>
  );
}