"use client";

import { useState, useEffect, type FormEvent } from "react";
import Link from "next/link";
import { SESSIONS } from "@/config/home.config";

const ageOptions = ["18-24", "25-30", "31-35", "36-40", "40+"];
const firstTimeOptions = ["是，第一次参加", "否，参加过类似活动"];

interface FormData {
  city: string;
  session: string;
  nickname: string;
  ageRange: string;
  wechatOrPhone: string;
  intro: string;
  firstTime: string;
  agreeRules: boolean;
}

function getSessionFromUrl(): string {
  if (typeof window === "undefined") return "";
  return new URLSearchParams(window.location.search).get("session") || "";
}

function getSessionInfo(sessionId: string) {
  return SESSIONS.find((s) => s.id === sessionId);
}

export default function JoinPage() {
  const [form, setForm] = useState<FormData>({
    city: "北京",
    session: "",
    nickname: "",
    ageRange: "",
    wechatOrPhone: "",
    intro: "",
    firstTime: "",
    agreeRules: false,
  });
  const [submitted, setSubmitted] = useState(false);
  const [submitting, setSubmitting] = useState(false);
  const [error, setError] = useState<string | null>(null);

  useEffect(() => {
    const sid = getSessionFromUrl();
    if (sid) setForm((prev) => ({ ...prev, session: sid }));
  }, []);

  const set = (key: keyof FormData, value: string | boolean) =>
    setForm((prev) => ({ ...prev, [key]: value }));

  const handleSubmit = async (e: FormEvent) => {
    e.preventDefault();
    setError(null);
    setSubmitting(true);
    try {
      const res = await fetch("/api/join", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({
          city: form.city,
          session: form.session,
          nickname: form.nickname,
          age_range: form.ageRange,
          wechat_or_phone: form.wechatOrPhone,
          intro: form.intro,
          first_time: form.firstTime,
          agree_rules: form.agreeRules,
        }),
      });
      const data = await res.json();
      if (!res.ok || !data?.ok) {
        throw new Error(data?.error || "提交失败，请稍后重试");
      }
      setSubmitted(true);
    } catch (err) {
      setError(err instanceof Error ? err.message : "网络错误，请重试");
    } finally {
      setSubmitting(false);
    }
  };

  const selectedSession = getSessionInfo(form.session);

  if (submitted) {
    return (
      <div className="flex min-h-screen items-center justify-center bg-[#f0f4f8] dark:bg-gray-950 px-4">
        <div className="w-full max-w-md animate-fade-in rounded-2xl bg-white dark:bg-gray-900 p-10 text-center shadow-lg border border-gray-100 dark:border-gray-800">
          <div className="mx-auto mb-5 flex h-20 w-20 items-center justify-center rounded-full bg-emerald-50 dark:bg-emerald-900/30 text-5xl">
            ✅
          </div>
          <h2 className="text-2xl font-bold text-slate-800 dark:text-slate-100">报名成功</h2>
          <p className="mt-3 text-slate-500 dark:text-slate-400">
            我们会尽快通过您留下的联系方式与您确认
          </p>
          <Link
            href="/"
            className="mt-8 inline-flex items-center gap-2 rounded-full bg-[#ff4d4f] px-8 py-3 font-semibold text-white transition-colors hover:bg-[#ff7a45]"
          >
            ← 返回首页
          </Link>
        </div>
      </div>
    );
  }

  return (
    <div className="min-h-screen bg-[#f0f4f8] dark:bg-gray-950">
      <div className="mx-auto max-w-2xl px-0 py-0 sm:px-6 sm:py-10 lg:py-14">
        <div className="overflow-hidden bg-white dark:bg-gray-900 shadow-sm sm:rounded-t-2xl">
          <div className="relative h-40 overflow-hidden bg-gradient-to-br from-sky-400 via-cyan-500 to-teal-400 sm:h-52">
            <div className="absolute inset-0 flex flex-col items-center justify-center text-white">
              <div className="text-6xl sm:text-7xl">📍</div>
              <div className="mt-2 text-sm font-medium opacity-80">
                北京周末新朋友活动
              </div>
            </div>
          </div>

          <div className="px-5 py-5 text-center sm:px-8 sm:py-7">
            <h1 className="text-xl font-bold text-slate-800 dark:text-slate-100 sm:text-2xl">
              活动报名
            </h1>
            <p className="mt-3 whitespace-pre-line text-sm leading-relaxed text-slate-400 dark:text-slate-500 sm:text-base">
              填个简单表单即可，无需注册登录
            </p>
          </div>
        </div>

        {selectedSession && (
          <div className="mt-5 rounded-2xl bg-white dark:bg-gray-900 px-5 py-4 shadow-sm border border-gray-100 dark:border-gray-800">
            <p className="text-xs text-slate-500 dark:text-slate-500 mb-1">已选场次</p>
            <p className="font-medium text-slate-800 dark:text-slate-100">{selectedSession.title}</p>
            <p className="text-sm text-slate-500 dark:text-slate-500">{selectedSession.date} {selectedSession.time} · {selectedSession.place}</p>
          </div>
        )}

        <form
          onSubmit={handleSubmit}
          className="mt-0 bg-white dark:bg-gray-900 px-5 pb-8 pt-2 shadow-sm sm:mt-5 sm:rounded-2xl sm:px-8 sm:py-8 sm:shadow-md border border-gray-100 dark:border-gray-800"
        >
          <div className="grid gap-0 sm:grid-cols-2 sm:gap-6">
            <Field label="📍 城市">
              <input
                type="text"
                placeholder="如：北京"
                value={form.city}
                onChange={(e) => set("city", e.target.value)}
                required
                className="form-input"
              />
            </Field>

            <Field label="📅 想参加的场次">
              <select
                value={form.session}
                onChange={(e) => set("session", e.target.value)}
                required
                className={`form-input appearance-none ${form.session ? "text-slate-800 dark:text-slate-100" : "text-slate-400 dark:text-slate-500"}`}
              >
                <option value="" disabled>请选择</option>
                {SESSIONS.map((s) => (
                  <option key={s.id} value={s.id}>
                    {s.title} · {s.date} {s.time}
                  </option>
                ))}
              </select>
            </Field>
          </div>

          <div className="grid gap-0 sm:grid-cols-2 sm:gap-6">
            <Field label="昵称">
              <input
                type="text"
                maxLength={40}
                placeholder="活动中使用的称呼"
                value={form.nickname}
                onChange={(e) => set("nickname", e.target.value)}
                required
                className="form-input"
              />
            </Field>

            <Field label="年龄段">
              <select
                value={form.ageRange}
                onChange={(e) => set("ageRange", e.target.value)}
                required
                className={`form-input appearance-none ${form.ageRange ? "text-slate-800 dark:text-slate-100" : "text-slate-400 dark:text-slate-500"}`}
              >
                <option value="" disabled>请选择</option>
                {ageOptions.map((o) => (
                  <option key={o} value={o}>{o}</option>
                ))}
              </select>
            </Field>
          </div>

          <div className="border-b border-slate-100 dark:border-gray-700 py-4 sm:py-5">
            <label className="mb-2 block text-base font-bold text-slate-700 dark:text-slate-300 sm:text-[17px]">
              微信号或手机号
            </label>
            <input
              type="text"
              maxLength={50}
              placeholder="用于活动联系"
              value={form.wechatOrPhone}
              onChange={(e) => set("wechatOrPhone", e.target.value)}
              required
              className="form-input"
            />
          </div>

          <div className="border-b border-slate-100 dark:border-gray-700 py-4 sm:py-5">
            <label className="mb-2 block text-base font-bold text-slate-700 dark:text-slate-300 sm:text-[17px]">
              一句话自我介绍
            </label>
            <input
              type="text"
              maxLength={140}
              placeholder="简单介绍一下自己"
              value={form.intro}
              onChange={(e) => set("intro", e.target.value)}
              required
              className="form-input"
            />
          </div>

          <div className="border-b border-slate-100 dark:border-gray-700 py-4 sm:py-5">
            <label className="mb-2 block text-base font-bold text-slate-700 dark:text-slate-300 sm:text-[17px]">
              是否第一次参加类似活动
            </label>
            <select
              value={form.firstTime}
              onChange={(e) => set("firstTime", e.target.value)}
              required
              className={`form-input appearance-none ${form.firstTime ? "text-slate-800 dark:text-slate-100" : "text-slate-400 dark:text-slate-500"}`}
            >
              <option value="" disabled>请选择</option>
              {firstTimeOptions.map((o) => (
                <option key={o} value={o}>{o}</option>
              ))}
            </select>
          </div>

          <div className="py-4 sm:py-5">
            <label className="flex items-start gap-3 cursor-pointer">
              <input
                type="checkbox"
                checked={form.agreeRules}
                onChange={(e) => set("agreeRules", e.target.checked)}
                required
                className="mt-1 rounded border-gray-300 text-[#ff4d4f] focus:ring-[#ff4d4f]"
              />
              <span className="text-sm text-slate-600 dark:text-slate-400">
                我已阅读并同意活动规则（公开场地、尊重边界、如有不适可随时离开）
              </span>
            </label>
          </div>

          <div className="mt-8 sm:mt-10">
            {error && (
              <p className="mb-4 rounded-lg bg-red-50 dark:bg-red-900/30 px-4 py-3 text-center text-sm text-red-600 dark:text-red-400">
                {error}
              </p>
            )}
            <button
              type="submit"
              disabled={submitting}
              className="w-full rounded-full bg-[#ff4d4f] py-3.5 text-lg font-semibold text-white shadow-md transition-all hover:bg-[#ff3333] active:scale-[0.98] disabled:cursor-not-allowed disabled:opacity-70 sm:py-4"
            >
              {submitting ? "提交中…" : "提交报名"}
            </button>
          </div>
        </form>

        <div className="mt-6 text-center">
          <Link href="/" className="text-sm text-slate-400 dark:text-slate-500 transition-colors hover:text-[#ff4d4f]">
            ← 返回首页
          </Link>
        </div>
      </div>
    </div>
  );
}

function Field({
  label,
  children,
}: {
  label: string;
  children: React.ReactNode;
}) {
  return (
    <div className="relative flex items-center gap-3 py-3.5 sm:flex-col sm:items-stretch sm:gap-0 sm:py-4 border-b border-slate-100 dark:border-gray-700 sm:border-b-0">
      <label className="w-[90px] shrink-0 text-[15px] font-bold text-slate-700 dark:text-slate-300 sm:mb-2 sm:w-auto sm:text-[17px]">
        {label}
      </label>
      <div className="relative min-w-0 flex-1">{children}</div>
    </div>
  );
}