import { notFound } from "next/navigation";
import { Navbar } from "@/components/layout/Navbar";
import { Footer } from "@/components/layout/Footer";
import ClientActions from "@/app/events/[id]/ClientActions";
import { Calendar, Ticket, Paperclip, Sparkles } from "lucide-react";

export const revalidate = 60;

type OptionVariant = { id: string; name: string; price: number | null; stockLimit?: number; availableCount?: number };
type EventOption = {
  id: string;
  name: string;
  price: number;
  stockLimit?: number;
  availableCount?: number;
  isMainTicket?: boolean;
  earlyBirdTiers?: { id: string; deadline: string; price: number; stockLimit?: number }[];
  variants?: OptionVariant[];
};

type EventAttachment = { id: string; originalName: string; url: string; size: number; mimeType: string };
type Event = {
  id: string;
  title: string;
  description?: string;
  startDate: string;
  endDate: string;
  registrationDeadline?: string | null;
  goLiveAt?: string;
  price: number;
  picture?: string;
  eventOptions?: EventOption[];
  attachments?: EventAttachment[];
  requiresAuth?: boolean;
};

import { apiFetch, ApiError } from "@/lib/api";
import { ApiImage } from "@/components/shared/ApiImage";
import { formatDateTimeRange } from "@/lib/date";

// Tiered low-stock threshold: larger events use a smaller percentage.
// Math.round avoids Math.ceil inflating the threshold (e.g. ceil(1.5)=2 made
// a 10-ticket event warn at 20% when the stated threshold was 15%).
function lowStockThreshold(stockLimit: number): number {
  let pct: number;
  if (stockLimit <= 50) pct = 0.20;
  else if (stockLimit <= 200) pct = 0.15;
  else if (stockLimit <= 1000) pct = 0.10;
  else pct = 0.05;
  return Math.round(stockLimit * pct);
}

function RegisterCta({ event }: { event: Event }) {
  const now = new Date();
  const end = new Date(event.endDate);
  const deadline = event.registrationDeadline ? new Date(event.registrationDeadline) : null;
  const goLive = event.goLiveAt ? new Date(event.goLiveAt) : null;
  const notYetOpen = goLive ? now < goLive : false;
  const closed = (deadline ? now >= deadline : false) || now >= end;
  const limitedOpts = (event.eventOptions || []).filter(o => (o.stockLimit ?? 0) > 0);
  const eventSoldOut = limitedOpts.length > 0 && limitedOpts.every(o => o.availableCount !== undefined && o.availableCount <= 0);

  if (notYetOpen) {
    return (
      <button disabled className="w-full bg-gray-200 text-gray-600 px-4 py-2.5 rounded-lg cursor-not-allowed font-medium" title="Registration not yet open">
        Opens {goLive?.toLocaleString()}
      </button>
    );
  }
  if (closed) {
    return (
      <button disabled className="w-full bg-gray-200 text-gray-600 px-4 py-2.5 rounded-lg cursor-not-allowed font-medium" title="Registration closed">
        Registration closed
      </button>
    );
  }
  if (eventSoldOut) {
    return (
      <button disabled className="w-full bg-red-50 text-red-700 border border-red-200 px-4 py-2.5 rounded-lg cursor-not-allowed font-medium">
        Sold Out
      </button>
    );
  }
  return (
    <a href={`/register/${event.id}`} className="block w-full text-center bg-brand-600 text-white px-4 py-2.5 rounded-lg hover:bg-brand-700 font-medium transition-colors">
      Register
    </a>
  );
}

export default async function EventDetailPage({ params }: { params: Promise<{ id: string }> }) {
  const { id } = await params;
  let event: Event;
  try {
    event = await apiFetch<Event>(`/api/events/${id}`, { nextOptions: { next: { revalidate } } });
  } catch (e) {
    // The event endpoint 404s for missing, inactive, or not-yet-live events —
    // render the standard not-found page instead of crashing.
    if (e instanceof ApiError && e.status === 404) notFound();
    throw e;
  }

  return (
    <div className="min-h-screen flex flex-col">
      <Navbar />
      <main className="flex-1 py-8 px-4 max-w-6xl mx-auto w-full">
        <div className="grid lg:grid-cols-3 gap-8">
          <div className="lg:col-span-2 space-y-6">
            {event.picture ? (
              <ApiImage src={event.picture} alt={event.title} className="w-full aspect-video object-cover rounded-xl" />
            ) : (
              <div className="w-full aspect-video rounded-xl bg-brand-50 flex items-center justify-center">
                <Calendar className="w-12 h-12 text-brand-200" />
              </div>
            )}

            <div>
              <h1 className="text-3xl font-bold text-gray-900">{event.title}</h1>
              <p className="text-sm text-gray-500 flex items-center gap-1.5 mt-2">
                <Calendar className="w-4 h-4 shrink-0" />
                {formatDateTimeRange(event.startDate, event.endDate)}
              </p>
              <div className="mt-3">
                <ClientActions event={event} />
              </div>
            </div>

            <p className="text-gray-700 whitespace-pre-line">{event.description}</p>

            {event.attachments && event.attachments.length > 0 && (
              <div className="border rounded-xl p-5 bg-white shadow-sm">
                <div className="flex items-center gap-2 mb-3">
                  <Paperclip className="w-4 h-4 text-gray-500" />
                  <h2 className="text-base font-semibold text-gray-900">Downloads</h2>
                </div>
                <ul className="space-y-1.5">
                  {event.attachments.map((att) => (
                    <li key={att.id}>
                      <a className="text-brand-600 hover:underline text-sm" href={att.url} target="_blank" rel="noopener noreferrer">
                        {att.originalName}
                      </a>
                    </li>
                  ))}
                </ul>
              </div>
            )}

            {/* Tickets are shown in the sticky card on desktop; repeat here for mobile below the fold */}
            <div className="border rounded-xl p-5 bg-white shadow-sm lg:hidden">
              <div className="flex items-center gap-2 mb-3">
                <Ticket className="w-4 h-4 text-gray-500" />
                <h2 className="text-base font-semibold text-gray-900">Tickets</h2>
              </div>
              <TicketList event={event} />
              <div className="mt-4">
                <RegisterCta event={event} />
              </div>
            </div>
          </div>

          <div className="hidden lg:block">
            <div className="border rounded-xl p-5 bg-white shadow-sm sticky top-20">
              <div className="flex items-center gap-2 mb-3">
                <Ticket className="w-4 h-4 text-gray-500" />
                <h2 className="text-base font-semibold text-gray-900">Tickets</h2>
              </div>
              <TicketList event={event} />
              <div className="mt-4">
                <RegisterCta event={event} />
              </div>
            </div>
          </div>
        </div>
      </main>
      <Footer />
    </div>
  );
}

function TicketList({ event }: { event: Event }) {
  const options = event.eventOptions || [];
  if (options.length === 0) {
    return (
      <div className="text-center py-6">
        <Sparkles className="w-6 h-6 text-gray-300 mx-auto mb-1.5" />
        <p className="text-sm text-gray-400">Free entry — no tickets required.</p>
      </div>
    );
  }
  return (
    <div className="space-y-2">
      {options.map((opt) => {
        const hasVariants = Array.isArray(opt.variants) && opt.variants.length > 0;
        const soldOut = (opt.stockLimit ?? 0) > 0 && opt.availableCount !== undefined && opt.availableCount <= 0;
        const nearlyOut = !soldOut && (opt.stockLimit ?? 0) > 0 && opt.availableCount !== undefined && opt.availableCount <= lowStockThreshold(opt.stockLimit ?? 0);

        if (hasVariants) {
          const prices = opt.variants!.map((v) => v.price !== null && v.price !== undefined ? v.price : opt.price);
          const minPrice = Math.min(...prices);
          const maxPrice = Math.max(...prices);
          const priceLabel = minPrice === 0 && maxPrice === 0 ? "Free" : minPrice === maxPrice ? `R${minPrice.toFixed(2)}` : minPrice === 0 ? `Free – R${maxPrice.toFixed(2)}` : `From R${minPrice.toFixed(2)}`;
          return (
            <div key={opt.id} className="border rounded-lg overflow-hidden">
              <div className="flex items-center justify-between px-3 py-2 bg-gray-50 border-b">
                <span className="font-medium text-sm">{opt.name}</span>
                <div className="flex items-center gap-2">
                  <span className="text-sm text-gray-600">{priceLabel}</span>
                  {soldOut && <span className="text-xs font-medium text-red-600 bg-red-50 border border-red-200 rounded px-1.5 py-0.5">Sold out</span>}
                  {nearlyOut && !soldOut && <span className="text-xs font-medium text-orange-600 bg-orange-50 border border-orange-200 rounded px-1.5 py-0.5">{opt.availableCount} remaining</span>}
                </div>
              </div>
              <ul className="divide-y">
                {opt.variants!.slice().sort((a, b) => (a as any).order - (b as any).order).map((v) => {
                  const vPrice = v.price !== null && v.price !== undefined ? v.price : opt.price;
                  const vSoldOut = (v.stockLimit ?? 0) > 0 && v.availableCount !== undefined && v.availableCount <= 0;
                  const vNearlyOut = !vSoldOut && (v.stockLimit ?? 0) > 0 && v.availableCount !== undefined && v.availableCount <= lowStockThreshold(v.stockLimit ?? 0);
                  return (
                    <li key={v.id} className="flex items-center justify-between px-3 py-2 text-sm text-gray-700">
                      <span>{v.name}</span>
                      <div className="flex items-center gap-2">
                        <span>{vPrice === 0 ? "Free" : `R${vPrice.toFixed(2)}`}</span>
                        {vSoldOut && <span className="text-xs font-medium text-red-600 bg-red-50 border border-red-200 rounded px-1.5 py-0.5">Sold out</span>}
                        {vNearlyOut && !vSoldOut && <span className="text-xs font-medium text-orange-600 bg-orange-50 border border-orange-200 rounded px-1.5 py-0.5">{v.availableCount} remaining</span>}
                      </div>
                    </li>
                  );
                })}
              </ul>
            </div>
          );
        }

        // Early bird pricing display
        const now = new Date();
        const activeTiers = (opt.earlyBirdTiers || [])
          .filter((t) => now < new Date(t.deadline))
          .sort((a, b) => a.price - b.price);
        const displayPrice = activeTiers.length > 0 ? activeTiers[0].price : opt.price;

        return (
          <div key={opt.id} className="flex items-center justify-between border rounded-lg px-3 py-2 text-sm text-gray-700">
            <span className="font-medium">{opt.name}</span>
            <div className="flex items-center gap-2">
              {activeTiers.length > 0 ? (
                <>
                  <span className="text-brand-700 font-medium">R{displayPrice.toFixed(2)}</span>
                  <span className="text-xs text-gray-400 line-through">R{opt.price.toFixed(2)}</span>
                  <span className="text-xs text-brand-600">Early bird</span>
                </>
              ) : (
                <span>{displayPrice === 0 ? "Free" : `R${displayPrice.toFixed(2)}`}</span>
              )}
              {soldOut && <span className="text-xs font-medium text-red-600 bg-red-50 border border-red-200 rounded px-1.5 py-0.5">Sold out</span>}
              {nearlyOut && !soldOut && <span className="text-xs font-medium text-orange-600 bg-orange-50 border border-orange-200 rounded px-1.5 py-0.5">{opt.availableCount} remaining</span>}
            </div>
          </div>
        );
      })}
    </div>
  );
}