"use client";

import { useEffect, useMemo, useState } from "react";

import {
  ArrowUpDown,
  Clock,
  Mail,
  MapPin,
  MessageCircle,
  Package,
  Phone,
  Search,
  ShoppingBag,
  Star,
  Ticket,
  TrendingUp,
  Users,
  X,
} from "lucide-react";

import { Input } from "@/components/ui/input";
import { Sheet, SheetContent } from "@/components/ui/sheet";
import { OrderTicket } from "@/components/order-ticket/order-ticket";
import { StageBadge } from "@/components/order-ticket/stage-badge";
import { getAuthUser, ROLE_COLORS, type AuthUser } from "@/lib/auth";
import type { Order } from "@/lib/order/types";
import { useOrdersStore } from "@/stores/orders/orders-store";

interface CustomerSummary {
  mo: string;
  na: string;
  em?: string;
  ph?: string;
  cn?: string;
  totalOrders: number;
  totalSpend: number;
  avgOrder: number;
  lastOrderAt: string;
  lastOrderAmount: number;
  firstOrderAt: string;
  orders: Order[];
}

type SortKey = "na" | "totalOrders" | "totalSpend" | "lastOrderAt";

function deriveCustomers(orders: Order[]): CustomerSummary[] {
  const map = new Map<string, CustomerSummary>();
  for (const o of orders) {
    const { mo, na, em, ph, cn } = o.customer;
    if (!map.has(mo)) {
      map.set(mo, {
        mo, na, em, ph, cn,
        totalOrders: 0, totalSpend: 0, avgOrder: 0,
        lastOrderAt: o.orderedAt, lastOrderAmount: 0,
        firstOrderAt: o.orderedAt, orders: [],
      });
    }
    const c = map.get(mo)!;
    c.totalOrders += 1;
    c.totalSpend  += o.charges.total;
    if (o.orderedAt > c.lastOrderAt) { c.lastOrderAt = o.orderedAt; c.lastOrderAmount = o.charges.total; }
    if (o.orderedAt < c.firstOrderAt) c.firstOrderAt = o.orderedAt;
    c.orders.push(o);
    // Keep latest customer info
    c.na = na; c.em = em; c.ph = ph; c.cn = cn;
  }
  for (const c of map.values()) {
    c.avgOrder = c.totalOrders > 0 ? c.totalSpend / c.totalOrders : 0;
    c.orders.sort((a, b) => new Date(b.orderedAt).getTime() - new Date(a.orderedAt).getTime());
  }
  return [...map.values()];
}

export default function CustomersPage() {
  const [user, setUser] = useState<AuthUser | null>(null);
  const [search, setSearch]         = useState("");
  const [sortKey, setSortKey]       = useState<SortKey>("lastOrderAt");
  const [sortAsc, setSortAsc]       = useState(false);
  const [selected, setSelected]     = useState<CustomerSummary | null>(null);
  const [ticketOrderId, setTicketOrderId] = useState<string | null>(null);

  const orders = useOrdersStore((s) => s.orders);

  useEffect(() => { setUser(getAuthUser()); }, []);

  const customers = useMemo(() => deriveCustomers(orders), [orders]);

  const filtered = useMemo(() => {
    const q = search.toLowerCase().trim();
    return customers
      .filter((c) =>
        !q ||
        c.na.toLowerCase().includes(q) ||
        c.mo.includes(q) ||
        (c.em ?? "").toLowerCase().includes(q),
      )
      .sort((a, b) => {
        let diff = 0;
        if (sortKey === "na")           diff = a.na.localeCompare(b.na);
        else if (sortKey === "totalOrders") diff = a.totalOrders - b.totalOrders;
        else if (sortKey === "totalSpend")  diff = a.totalSpend - b.totalSpend;
        else diff = new Date(a.lastOrderAt).getTime() - new Date(b.lastOrderAt).getTime();
        return sortAsc ? diff : -diff;
      });
  }, [customers, search, sortKey, sortAsc]);

  const toggleSort = (key: SortKey) => {
    if (sortKey === key) setSortAsc((v) => !v);
    else { setSortKey(key); setSortAsc(false); }
  };

  const ticketOrder = orders.find((o) => o.id === ticketOrderId);

  const SortBtn = ({ k, label }: { k: SortKey; label: string }) => (
    <button
      type="button"
      onClick={() => toggleSort(k)}
      className="flex items-center gap-1 hover:text-foreground transition-colors"
    >
      {label}
      <ArrowUpDown className={`size-3 ${sortKey === k ? "text-primary" : "opacity-40"}`} />
    </button>
  );

  return (
    <div className="flex h-full flex-col gap-4">
      {/* Header */}
      <div className="flex items-center justify-between gap-4">
        <div>
          <h1 className="font-bold text-xl flex items-center gap-2">
            <Users className="size-5 text-blue-500" /> Customers
          </h1>
          <p className="text-muted-foreground text-sm">
            {filtered.length} of {customers.length} customer{customers.length !== 1 ? "s" : ""} · derived from orders
          </p>
        </div>
        <div className="relative max-w-xs flex-1">
          <Search className="absolute left-2.5 top-1/2 -translate-y-1/2 size-3.5 text-muted-foreground pointer-events-none" />
          <Input
            value={search}
            onChange={(e) => setSearch(e.target.value)}
            placeholder="Search name, mobile, email…"
            className="pl-8 h-8 text-sm"
          />
          {search && (
            <button type="button" onClick={() => setSearch("")} className="absolute right-2 top-1/2 -translate-y-1/2 text-muted-foreground hover:text-foreground">
              <X className="size-3.5" />
            </button>
          )}
        </div>
      </div>

      {/* Table */}
      <div className="flex-1 overflow-auto rounded-xl border bg-card">
        <table className="w-full text-sm">
          <thead className="sticky top-0 z-10 border-b bg-muted/60 backdrop-blur-sm">
            <tr className="text-[11px] uppercase tracking-wider text-muted-foreground">
              <th className="px-4 py-2.5 text-left">
                <SortBtn k="na" label="Name" />
              </th>
              <th className="px-4 py-2.5 text-left">Mobile</th>
              <th className="px-4 py-2.5 text-left">Email</th>
              <th className="px-4 py-2.5 text-right">
                <SortBtn k="totalOrders" label="Orders" />
              </th>
              <th className="px-4 py-2.5 text-right">
                <SortBtn k="totalSpend" label="Total Spend" />
              </th>
              <th className="px-4 py-2.5 text-right">Avg Order</th>
              <th className="px-4 py-2.5 text-right">
                <SortBtn k="lastOrderAt" label="Last Order" />
              </th>
            </tr>
          </thead>
          <tbody className="divide-y">
            {filtered.length === 0 && (
              <tr>
                <td colSpan={7} className="py-16 text-center text-muted-foreground">
                  <Package className="size-8 mx-auto mb-2 opacity-30" />
                  <p className="text-sm">No customers found</p>
                </td>
              </tr>
            )}
            {filtered.map((c) => (
              <tr
                key={c.mo}
                onClick={() => setSelected(c)}
                className="cursor-pointer transition-colors hover:bg-muted/30"
              >
                <td className="px-4 py-2.5">
                  <div className="flex items-center gap-2">
                    <div className="flex size-7 shrink-0 items-center justify-center rounded-full bg-primary/10 font-bold text-[11px] text-primary uppercase">
                      {c.na.charAt(0)}
                    </div>
                    <span className="font-medium">{c.na}</span>
                    {c.totalOrders >= 10 && (
                      <span title="Loyal customer">
                        <Star className="size-3 text-amber-400 fill-amber-400" />
                      </span>
                    )}
                  </div>
                </td>
                <td className="px-4 py-2.5 font-mono text-[12px] text-muted-foreground">{c.mo}</td>
                <td className="px-4 py-2.5 text-[12px] text-muted-foreground">{c.em || "—"}</td>
                <td className="px-4 py-2.5 text-right font-semibold">{c.totalOrders}</td>
                <td className="px-4 py-2.5 text-right font-semibold tabular-nums">£{c.totalSpend.toFixed(2)}</td>
                <td className="px-4 py-2.5 text-right tabular-nums text-muted-foreground">£{c.avgOrder.toFixed(2)}</td>
                <td className="px-4 py-2.5 text-right text-[12px] text-muted-foreground">
                  {new Date(c.lastOrderAt).toLocaleDateString("en-GB", { day: "2-digit", month: "short", year: "numeric" })}
                </td>
              </tr>
            ))}
          </tbody>
        </table>
      </div>

      {/* Customer detail panel */}
      <Sheet open={!!selected} onOpenChange={(open) => { if (!open) { setSelected(null); setTicketOrderId(null); } }}>
        <SheetContent side="right" className="w-[480px] max-w-[95vw] p-0 overflow-hidden flex flex-col">
          {selected && (
            <CustomerPanel
              customer={selected}
              currentUserId={user?.id}
              role={user?.role ?? "foh"}
              onOpenOrder={(id) => setTicketOrderId(id)}
              onClose={() => { setSelected(null); setTicketOrderId(null); }}
            />
          )}
        </SheetContent>
      </Sheet>

      {/* Order ticket overlay */}
      <Sheet open={!!ticketOrder} onOpenChange={(open) => { if (!open) setTicketOrderId(null); }}>
        <SheetContent side="right" className="w-[440px] max-w-[92vw] p-0 overflow-hidden flex flex-col">
          {ticketOrder && user && (
            <OrderTicket
              order={ticketOrder}
              role={user.role}
              onClose={() => setTicketOrderId(null)}
            />
          )}
        </SheetContent>
      </Sheet>
    </div>
  );
}

function CustomerPanel({
  customer,
  role,
  onOpenOrder,
  onClose,
}: {
  customer: CustomerSummary;
  currentUserId?: string;
  role: AuthUser["role"];
  onOpenOrder: (id: string) => void;
  onClose: () => void;
}) {
  const whatsappUrl = `https://wa.me/${customer.mo.replace(/\D/g, "")}`;
  const loyaltyTier =
    customer.totalOrders >= 20 ? { label: "Gold", color: "text-amber-500 bg-amber-50 border-amber-200" } :
    customer.totalOrders >= 10 ? { label: "Silver", color: "text-gray-500 bg-gray-50 border-gray-200" } :
    customer.totalOrders >= 5  ? { label: "Regular", color: "text-blue-500 bg-blue-50 border-blue-200" } :
    { label: "New", color: "text-green-600 bg-green-50 border-green-200" };

  const completedOrders = customer.orders.filter((o) => o.stage === "completed");
  const activeOrders    = customer.orders.filter((o) => o.stage !== "completed");

  return (
    <div className="flex flex-col h-full overflow-hidden">
      {/* Header */}
      <div className="flex items-start justify-between gap-3 border-b bg-gradient-to-r from-blue-50 to-background px-5 py-4 dark:from-blue-950/20">
        <div className="flex items-center gap-3">
          <div className="flex size-10 shrink-0 items-center justify-center rounded-full bg-primary/15 font-bold text-lg text-primary uppercase">
            {customer.na.charAt(0)}
          </div>
          <div>
            <h2 className="font-bold text-base">{customer.na}</h2>
            <div className="flex items-center gap-2 mt-0.5">
              <span className={`inline-flex items-center rounded border px-2 py-0.5 text-[10px] font-bold uppercase ${loyaltyTier.color}`}>
                <Star className="size-2.5 mr-1" /> {loyaltyTier.label}
              </span>
              <span className="text-[11px] text-muted-foreground">since {new Date(customer.firstOrderAt).toLocaleDateString("en-GB", { month: "short", year: "numeric" })}</span>
            </div>
          </div>
        </div>
        <button type="button" onClick={onClose} className="rounded p-1 text-muted-foreground hover:text-foreground">
          <X className="size-4" />
        </button>
      </div>

      <div className="flex-1 overflow-y-auto">
        {/* Stats strip */}
        <div className="grid grid-cols-3 divide-x border-b">
          <StatTile icon={ShoppingBag} label="Orders" value={customer.totalOrders} />
          <StatTile icon={TrendingUp} label="Total Spend" value={`£${customer.totalSpend.toFixed(2)}`} />
          <StatTile icon={Ticket} label="Avg Order" value={`£${customer.avgOrder.toFixed(2)}`} />
        </div>

        {/* Contact info */}
        <div className="border-b px-4 py-3 space-y-2">
          <p className="text-[10px] font-semibold uppercase tracking-wider text-muted-foreground">Contact</p>
          <div className="flex items-center gap-2">
            <Phone className="size-3.5 text-muted-foreground shrink-0" />
            <a href={`tel:${customer.mo}`} className="font-mono text-[13px] hover:text-primary">{customer.mo}</a>
            <a href={whatsappUrl} target="_blank" rel="noopener noreferrer"
              className="flex items-center gap-1 rounded border border-green-300 bg-green-50 px-1.5 py-0.5 text-[10px] font-medium text-green-700 hover:bg-green-100">
              <MessageCircle className="size-3" /> WA
            </a>
          </div>
          {customer.ph && (
            <div className="flex items-center gap-2">
              <Phone className="size-3.5 text-muted-foreground shrink-0" />
              <a href={`tel:${customer.ph}`} className="font-mono text-[13px] hover:text-primary">{customer.ph}</a>
              <span className="text-[10px] text-muted-foreground">landline</span>
            </div>
          )}
          {customer.em && (
            <div className="flex items-center gap-2">
              <Mail className="size-3.5 text-muted-foreground shrink-0" />
              <a href={`mailto:${customer.em}`} className="text-[13px] hover:text-primary">{customer.em}</a>
            </div>
          )}
          {customer.cn && (
            <div className="flex items-start gap-2 rounded bg-amber-50 dark:bg-amber-900/20 px-2.5 py-1.5">
              <MessageCircle className="size-3.5 text-amber-600 shrink-0 mt-0.5" />
              <p className="text-[12px] text-amber-800 dark:text-amber-300">{customer.cn}</p>
            </div>
          )}
        </div>

        {/* Last known address */}
        {(() => {
          const lastDelivery = customer.orders.find((o) => o.type === "delivery" && o.address);
          if (!lastDelivery?.address) return null;
          return (
            <div className="border-b px-4 py-3 space-y-1">
              <p className="text-[10px] font-semibold uppercase tracking-wider text-muted-foreground">Last Delivery Address</p>
              <div className="flex items-start gap-2">
                <MapPin className="size-3.5 text-muted-foreground shrink-0 mt-0.5" />
                <div>
                  <p className="text-[13px] font-medium">{lastDelivery.address.ad}</p>
                  {lastDelivery.address.an && <p className="text-[11px] text-muted-foreground">{lastDelivery.address.an}</p>}
                  {lastDelivery.address.miles && <p className="text-[11px] text-muted-foreground">{lastDelivery.address.miles} mi</p>}
                </div>
              </div>
            </div>
          );
        })()}

        {/* Active orders */}
        {activeOrders.length > 0 && (
          <div className="border-b px-4 py-3">
            <p className="mb-2 text-[10px] font-semibold uppercase tracking-wider text-muted-foreground">
              Active Orders ({activeOrders.length})
            </p>
            <div className="space-y-1.5">
              {activeOrders.map((o) => (
                <OrderRow key={o.id} order={o} onOpen={() => onOpenOrder(o.id)} />
              ))}
            </div>
          </div>
        )}

        {/* Order history */}
        <div className="px-4 py-3">
          <p className="mb-2 text-[10px] font-semibold uppercase tracking-wider text-muted-foreground">
            Order History ({completedOrders.length} completed)
          </p>
          {completedOrders.length === 0 ? (
            <p className="text-[12px] text-muted-foreground italic">No completed orders yet</p>
          ) : (
            <div className="space-y-1.5">
              {completedOrders.map((o) => (
                <OrderRow key={o.id} order={o} onOpen={() => onOpenOrder(o.id)} />
              ))}
            </div>
          )}
        </div>
      </div>
    </div>
  );
}

function OrderRow({ order, onOpen }: { order: Order; onOpen: () => void }) {
  const date = new Date(order.orderedAt).toLocaleDateString("en-GB", {
    day: "2-digit", month: "short", year: "numeric",
  });
  const time = new Date(order.orderedAt).toLocaleTimeString("en-GB", { hour: "2-digit", minute: "2-digit" });

  return (
    <button
      type="button"
      onClick={onOpen}
      className="flex w-full items-center gap-3 rounded-lg border bg-muted/20 px-3 py-2 text-left text-xs transition-colors hover:bg-muted/50 hover:border-primary/30"
    >
      <div className="flex flex-col items-start gap-0.5 flex-1 min-w-0">
        <div className="flex items-center gap-2 w-full">
          <span className="font-mono font-bold text-[11px]">{order.id}</span>
          <StageBadge stage={order.stage} type={order.type} />
          <span className="ml-auto shrink-0 font-bold tabular-nums">£{order.charges.total.toFixed(2)}</span>
        </div>
        <div className="flex items-center gap-2 text-[11px] text-muted-foreground">
          <Clock className="size-3 shrink-0" />
          <span>{date} · {time}</span>
          <span className="truncate">{order.items.map((i) => `${i.description}×${i.qty}`).join(", ")}</span>
        </div>
      </div>
    </button>
  );
}

function StatTile({ icon: Icon, label, value }: { icon: React.ElementType; label: string; value: string | number }) {
  return (
    <div className="flex flex-col items-center gap-0.5 py-3 px-2">
      <Icon className="size-4 text-muted-foreground mb-0.5" />
      <span className="font-bold text-base tabular-nums">{value}</span>
      <span className="text-[10px] text-muted-foreground uppercase tracking-wide">{label}</span>
    </div>
  );
}