"use client";

import React, { Suspense, useEffect, useMemo, useState } from "react";
import { useAuth } from "@/hooks/useAuth";
import { apiFetch } from "@/lib/api";
import { useDismissingState } from "@/hooks/useDismissingState";
import { useRouter, useSearchParams } from "next/navigation";
import { formatDate } from "@/lib/date";
import { QrImage } from "@/components/shared/QrImage";

function EventTicketsContent() {
  const { token, user } = useAuth();
  const params = useSearchParams();
  const router = useRouter();

  const paramEventId = params.get("eventId") || "";
  const paramUserId = params.get("userId") || "";

  const [events, setEvents] = useState<any[]>([]);
  const [eventId, setEventId] = useState<string>(paramEventId);
  const [tickets, setTickets] = useState<any[]>([]);
  const [error, setError] = useDismissingState<string | null>(null);
  const [loading, setLoading] = useState(false);

  const [selectedUserId, setSelectedUserId] = useState<string>(paramUserId);
  const [selectedVariantId, setSelectedVariantId] = useState<string>("");

  const canView = useMemo(() => {
    const role = user?.role;
    return role === "admin" || role === "supervisor" || role === "staff";
  }, [user]);

  // Load events for dropdown
  useEffect(() => {
    (async () => {
      try {
        if (!token) return;
        const evs = await apiFetch<any[]>("/api/events/all", { authToken: token });
        const now = Date.now();
        const active = (evs || []).filter((ev) => {
          const t = new Date(ev.endDate).getTime();
          return !isNaN(t) && t > now;
        });
        active.sort(
            (a, b) =>
                new Date(a.startDate).getTime() - new Date(b.startDate).getTime()
        );
        setEvents(active);
        if (!paramEventId && active.length > 0) {
          setEventId(active[0].id);
          router.replace(
              `?eventId=${encodeURIComponent(active[0].id)}${
                  selectedUserId ? `&userId=${encodeURIComponent(selectedUserId)}` : ""
              }`
          );
        }
      } catch (e: any) {
        setError(e?.message || "Failed to load events");
      }
    })();
  }, [token]);

  // Sync params → state
  useEffect(() => {
    if (paramEventId && paramEventId !== eventId) setEventId(paramEventId);
    if (paramUserId && paramUserId !== selectedUserId)
      setSelectedUserId(paramUserId);
  }, [paramEventId, paramUserId]);

  // Load tickets when event changes
  useEffect(() => {
    (async () => {
      if (!token || !eventId) return;
      setLoading(true);
      setError(null);
      try {
        const list = await apiFetch<any[]>(
            `/api/tickets/event/${encodeURIComponent(eventId)}`,
            { authToken: token }
        );
        setTickets(list);
      } catch (e: any) {
        setError(e?.message || "Failed to load tickets");
      } finally {
        setLoading(false);
      }
    })();
  }, [token, eventId]);

  // Build variants list for filter (only variants present in current event's tickets)
  const variantsList = useMemo(() => {
    const map = new Map<string, string>();
    for (const t of tickets) {
      const v = t.registrationOption?.variant;
      if (v?.id) map.set(v.id, v.name);
    }
    return Array.from(map.entries())
        .map(([id, name]) => ({ id, name }))
        .sort((a, b) => a.name.localeCompare(b.name));
  }, [tickets]);

  // Build users list depending on event selection
  const usersList = useMemo(() => {
    let source = [...tickets];
    if (eventId) {
      source = source.filter((t) => String(t.eventId) === String(eventId));
    }
    const map = new Map<string, string>();
    for (const t of source) {
      const uid = t.user?.id || t.userId;
      if (!uid) continue;
      const name = t.user?.name || t.user?.email || String(uid);
      if (!map.has(String(uid))) map.set(String(uid), name);
    }
    return Array.from(map.entries())
        .map(([id, name]) => ({ id, name }))
        .sort((a, b) => a.name.localeCompare(b.name));
  }, [tickets, eventId]);

  // Filter tickets by event + user + variant
  const filteredTickets = useMemo(() => {
    let list = [...tickets];
    if (eventId) {
      list = list.filter((t) => String(t.eventId) === String(eventId));
    }
    if (selectedUserId) {
      list = list.filter(
          (t) => String(t.user?.id || t.userId) === String(selectedUserId)
      );
    }
    if (selectedVariantId) {
      list = list.filter(
          (t) => String(t.registrationOption?.variant?.id || "") === String(selectedVariantId)
      );
    }
    return list;
  }, [tickets, eventId, selectedUserId, selectedVariantId]);

  // Printing helpers
  const buildTicketHtmlCard = (t: any) => {
    const eventTitle = t.event?.title || t.eventId || "Event";
    const eventDate = t.event?.startDate ? new Date(t.event.startDate) : null;
    const optBase = t.registrationOption?.eventOption?.name || "Ticket";
    const optVariant = t.registrationOption?.variant?.name;
    const type = optVariant ? `${optBase} — ${optVariant}` : optBase;
    const qty = t.quantity || 1;
    const holder = t.user?.name || t.userId || "";
    const qrSrc = `https://api.qrserver.com/v1/create-qr-code/?size=140x140&data=${encodeURIComponent(
        t.qrCode || t.id
    )}`;
    const dateStr = eventDate ? formatDate(eventDate) : "";
    return `
      <div class="ticket">
        <div class="evt">${eventTitle}</div>
        ${dateStr ? `<div class="date">${dateStr}</div>` : ""}
        <div class="type">${type}</div>
        <div class="qty">Qty: <strong>${qty}</strong></div>
        <div class="qrwrap"><img src="${qrSrc}" alt="QR" /></div>
        <div class="meta">ID: ${t.id}</div>
        ${holder ? `<div class="meta">${holder}</div>` : ""}
      </div>
    `;
  };

  const openPrintWindow = (pagesHtml: string) => {
    const w = window.open("", "_blank");
    if (!w) return;
    w.document.write(`<!doctype html><html><head><title>Tickets</title>
      <style>
        @page { size: A4; margin: 10mm; }
        * { box-sizing: border-box; }
        body { font-family: Arial, Helvetica, sans-serif; margin: 0; padding: 0; }
        .page {
          display: grid;
          grid-template-columns: repeat(2, 1fr);
          grid-template-rows: repeat(4, 1fr);
          height: 277mm;
          gap: 6mm;
          page-break-after: always;
          break-after: page;
        }
        .page:last-child { page-break-after: avoid; break-after: avoid; }
        .ticket { border: 1px solid #000; padding: 5mm; display: flex; flex-direction: column; justify-content: space-between; overflow: hidden; }
        .evt { font-weight: bold; font-size: 14px; }
        .type { font-size: 12px; margin-top: 2mm; }
        .qty { font-size: 11px; margin-top: 1mm; }
        .date { font-size: 10px; color: #555; margin-top: 1mm; }
        .qrwrap { display: flex; justify-content: center; margin: 2mm 0; }
        .qrwrap img { width: 30mm; height: 30mm; }
        .meta { font-size: 10px; text-align: center; }
      </style>
    </head><body>
      ${pagesHtml}
      <script>
        (function(){
          function printWhenReady(){
            var imgs = Array.prototype.slice.call(document.images);
            if(imgs.length === 0){ window.print(); return; }
            var remaining = imgs.length;
            function done(){ remaining--; if(remaining <= 0){ setTimeout(function(){ window.print(); }, 100); } }
            imgs.forEach(function(img){
              if (img.complete) { done(); }
              else {
                img.addEventListener('load', done, { once: true });
                img.addEventListener('error', done, { once: true });
              }
            });
          }
          if (document.readyState === 'complete') printWhenReady();
          else window.addEventListener('load', printWhenReady);
        })();
      </script>
    </body></html>`);
    w.document.close();
    w.focus();
  };

  const printTickets = (ticketList: any[]) => {
    if (!ticketList || ticketList.length === 0) return;
    // Chunk into pages of 8 (2 columns × 4 rows per A4 sheet)
    const PAGE_SIZE = 8;
    const pages: string[] = [];
    for (let i = 0; i < ticketList.length; i += PAGE_SIZE) {
      const chunk = ticketList.slice(i, i + PAGE_SIZE);
      pages.push(`<div class="page">${chunk.map(buildTicketHtmlCard).join("")}</div>`);
    }
    openPrintWindow(pages.join(""));
  };

  return (
      <div className="max-w-6xl mx-auto w-full p-6">
        <div className="flex items-center justify-between mb-4">
          <h1 className="text-2xl font-semibold">Event Tickets</h1>
          <button
              className="px-3 py-1.5 text-sm rounded bg-gray-100 hover:bg-gray-200 text-gray-800 shadow-sm"
              onClick={() => router.push("/dashboard")}
          >
            Back
          </button>
        </div>
        <p className="text-sm text-gray-600 mb-4">
          View and print tickets for an event.
        </p>

        {!canView && (
            <div className="p-3 border rounded bg-yellow-50 text-yellow-800 text-sm mb-4">
              You need staff, supervisor, or admin access to view this page.
            </div>
        )}

        <div className="flex flex-col sm:flex-row sm:flex-wrap sm:items-center gap-2 mb-4">
          <label className="text-sm text-gray-700 shrink-0">Event</label>
          <select
              className="border rounded px-3 py-2 w-full sm:w-64 max-w-full"
              value={eventId}
              onChange={(e) => {
                const v = e.target.value;
                setEventId(v);
                setSelectedUserId("");
                router.replace(
                    `?eventId=${encodeURIComponent(v)}${
                        selectedUserId
                            ? `&userId=${encodeURIComponent(selectedUserId)}`
                            : ""
                    }`
                );
              }}
          >
            <option value="">All events</option>
            {events.map((ev) => (
                <option key={ev.id} value={ev.id}>
                  {ev.title}
                </option>
            ))}
          </select>

          <label className="text-sm text-gray-700 sm:ml-4 shrink-0">User</label>
          <select
              className="border rounded px-3 py-2 w-full sm:w-64 max-w-full"
              value={selectedUserId}
              onChange={(e) => {
                const v = e.target.value;
                setSelectedUserId(v);
                router.replace(
                    `?eventId=${encodeURIComponent(eventId || "")}${
                        v ? `&userId=${encodeURIComponent(v)}` : ""
                    }`
                );
              }}
              disabled={usersList.length === 0}
          >
            <option value="">All users</option>
            {usersList.map((u) => (
                <option key={u.id} value={u.id}>
                  {u.name}
                </option>
            ))}
          </select>

          {variantsList.length > 0 && (
              <>
                <label className="text-sm text-gray-700 sm:ml-4 shrink-0">Variant</label>
                <select
                    className="border rounded px-3 py-2 w-full sm:w-48 max-w-full"
                    value={selectedVariantId}
                    onChange={(e) => setSelectedVariantId(e.target.value)}
                >
                  <option value="">All variants</option>
                  {variantsList.map((v) => (
                      <option key={v.id} value={v.id}>{v.name}</option>
                  ))}
                </select>
              </>
          )}

          {filteredTickets.length > 0 && (
              <div className="flex gap-2">
                <button
                    onClick={() => printTickets(filteredTickets)}
                    className="px-3 py-2 border rounded"
                >
                  Print all
                </button>
                <button
                    onClick={() =>
                        printTickets(filteredTickets.filter((t) => !t.isUsed))
                    }
                    className="px-3 py-2 bg-blue-600 text-white rounded"
                >
                  Print unused
                </button>
              </div>
          )}
        </div>

        {loading && <div>Loading...</div>}
        {error && <div className="text-red-600 text-sm">{error}</div>}

        {filteredTickets.length > 0 && (
            <div className="mb-3 text-sm text-gray-700">
          <span className="mr-3">
            Total tickets: {filteredTickets.length}
          </span>
              <span className="mr-3">
            Used: {filteredTickets.filter((t) => t.isUsed).length}
          </span>
              <span>
            Unused: {filteredTickets.filter((t) => !t.isUsed).length}
          </span>
            </div>
        )}

        <div className="grid sm:grid-cols-2 lg:grid-cols-3 gap-3">
          {filteredTickets.map((t) => {
            const eventDate = t.event?.startDate
                ? new Date(t.event.startDate)
                : null;
            const optBase = t.registrationOption?.eventOption?.name || "Ticket";
            const optVariant = t.registrationOption?.variant?.name;
            const type = optVariant ? `${optBase} — ${optVariant}` : optBase;
            return (
                <div
                    key={t.id}
                    className="border rounded-xl p-3 space-y-2 bg-white shadow-sm"
                >
                  <div className="flex items-start justify-between">
                    <div className="font-medium">
                      {t.event?.title || t.eventId}
                    </div>
                    {eventDate && (
                        <span className="text-xs text-gray-500">
                    {formatDate(eventDate)}
                  </span>
                    )}
                  </div>
                  <div className="text-sm text-gray-700">{type}</div>
                  <div className="flex justify-center">
                    <QrImage value={t.qrCode || t.id} size={120} className="w-28 h-28" />
                  </div>
                  <div className="text-center text-xs text-gray-500">
                    #{String(t.id).slice(0, 8)} •{" "}
                    {t.isUsed ? "Used" : "Unused"}
                  </div>
                </div>
            );
          })}
        </div>
      </div>
  );
}

export default function EventTicketsPage() {
  return (
      <Suspense fallback={<div className="p-6">Loading...</div>}>
        <EventTicketsContent />
      </Suspense>
  );
}