"use client";

import { useState } from "react";
import { MapPin, Clock, ArrowRight } from "lucide-react";
import Link from "next/link";
import { AddToCalendarButton } from "@/components/public/AddToCalendarDialog";
import { formatMeetupCivilDate } from "@/lib/meetupEventTime";

// Initial number of meetups shown before "Load more". Mobile is enforced via
// CSS (3) so there's no SSR/viewport mismatch; desktop shows up to 6.
const INITIAL_MOBILE = 3;
const INITIAL_DESKTOP = 6;

interface MeetupData {
  id?: string;
  title: string;
  date: string;
  time?: string;
  location?: string;
  link?: string;
  description?: string;
  organizer?: { name: string; slug?: string };
}

interface MeetupsSectionProps {
  meetups: MeetupData[];
}

export function MeetupsSection({ meetups }: MeetupsSectionProps) {
  // Number of extra batches revealed via "Load more". Each batch adds 3 on
  // mobile and 6 on desktop, so visible counts are 3*(pages+1) / 6*(pages+1).
  const [pages, setPages] = useState(0);

  const mobileVisible = INITIAL_MOBILE * (pages + 1);
  const desktopVisible = INITIAL_DESKTOP * (pages + 1);

  // Visibility per card. Enforced with CSS so the server-rendered markup matches
  // both viewports (desktopVisible >= mobileVisible, so "mobile-only" never occurs).
  const cardVisibilityClass = (i: number) => {
    if (i < mobileVisible) return "flex";
    if (i < desktopVisible) return "hidden md:flex";
    return "hidden";
  };

  // Show the button only when content is still hidden at the given breakpoint.
  let loadMoreClass = "hidden";
  if (meetups.length > desktopVisible) loadMoreClass = "flex";
  else if (meetups.length > mobileVisible) loadMoreClass = "flex md:hidden";

  return (
    <section className="py-24 px-8 border-t border-zinc-800/50">
      <div className="max-w-6xl mx-auto">
        <div className="flex justify-between items-end mb-12">
          <div>
            <p className="uppercase tracking-[0.2em] text-primary mb-2 font-semibold text-xs">
              Mark your calendar
            </p>
            <h2 className="text-3xl font-black tracking-tight">Upcoming Meetups</h2>
          </div>
          <div className="hidden md:flex items-center gap-4">
            <AddToCalendarButton />
            <Link
              href="/events"
              className="flex items-center gap-2 text-sm text-primary font-semibold hover:gap-3 transition-all"
            >
              All events <ArrowRight size={16} />
            </Link>
          </div>
        </div>

        {meetups.length === 0 ? (
          <div className="border border-zinc-800 rounded-xl px-8 py-12 text-center">
            <p className="text-on-surface-variant text-sm">
              No upcoming meetups scheduled. Check back soon.
            </p>
          </div>
        ) : (
          <div className="grid grid-cols-1 md:grid-cols-2 lg:grid-cols-3 gap-5">
            {meetups.map((meetup, i) => {
              const civil = formatMeetupCivilDate(meetup.date);
              const month = civil?.monthShort ?? "—";
              const day = civil?.day ?? "--";
              const full = civil?.full ?? "";
              const href = meetup.id ? `/events/${meetup.id}` : "#upcoming-meetups";

              return (
                <Link
                  key={meetup.id ?? i}
                  href={href}
                  className={`group ${cardVisibilityClass(i)} flex-col bg-zinc-900 border border-zinc-800 rounded-xl p-6 hover:border-zinc-700 hover:-translate-y-0.5 hover:shadow-xl transition-all duration-200`}
                >
                  <div className="flex items-start gap-4 mb-4">
                    <div className="bg-zinc-800 rounded-lg px-3 py-2 text-center shrink-0 min-w-[52px]">
                      <span className="block text-[10px] font-bold uppercase text-primary tracking-wider leading-none mb-0.5">
                        {month}
                      </span>
                      <span className="block text-2xl font-black leading-none">{day}</span>
                    </div>
                    <div className="min-w-0">
                      <h3 className="font-bold text-base leading-snug group-hover:text-primary transition-colors">
                        {meetup.title}
                      </h3>
                      <p className="text-on-surface-variant/60 text-xs mt-1">{full}</p>
                    </div>
                  </div>

                  {meetup.description && (
                    <p className="text-on-surface-variant text-sm leading-relaxed mb-4 flex-1 line-clamp-2">
                      {meetup.description}
                    </p>
                  )}

                  <p className="text-[11px] text-on-surface-variant/50 font-medium uppercase tracking-wide mb-2">
                    Organized by{" "}
                    <span className="text-on-surface-variant/70 normal-case tracking-normal">
                      {meetup.organizer?.name || "Belgian Bitcoin Embassy"}
                    </span>
                  </p>

                  <div className="flex flex-col gap-1.5 mt-auto pt-4 border-t border-zinc-800/60">
                    {meetup.location && (
                      <p className="flex items-center gap-1.5 text-xs text-on-surface-variant/60">
                        <MapPin size={12} className="shrink-0 text-primary/60" />
                        {meetup.location}
                      </p>
                    )}
                    {meetup.time && (
                      <p className="flex items-center gap-1.5 text-xs text-on-surface-variant/60">
                        <Clock size={12} className="shrink-0 text-primary/60" />
                        {meetup.time}
                      </p>
                    )}
                  </div>

                  <span className="flex items-center gap-1.5 text-primary text-xs font-semibold mt-4 group-hover:gap-2.5 transition-all">
                    View Details <ArrowRight size={12} />
                  </span>
                </Link>
              );
            })}
          </div>
        )}

        <div className={`${loadMoreClass} justify-center mt-10`}>
          <button
            type="button"
            onClick={() => setPages((p) => p + 1)}
            className="flex items-center gap-2 rounded-lg border border-zinc-700 px-6 py-2.5 text-sm font-semibold text-on-surface hover:border-primary hover:text-primary transition-colors"
          >
            Load more
          </button>
        </div>

        <div className="md:hidden flex flex-col items-center gap-3 mt-8">
          <Link
            href="/events"
            className="flex items-center gap-2 text-primary font-semibold text-sm"
          >
            All events <ArrowRight size={16} />
          </Link>
          <AddToCalendarButton />
        </div>
      </div>
    </section>
  );
}