import { useState } from "react";
import { Search, PlusCircle, Code2, ScanBarcode, ShieldCheck, ArrowRight } from "lucide-react";
import { api } from "../api";
import type { ProductSummary } from "../types";

const EXAMPLES = ["可乐", "Nutella", "牛奶", "5449000000996"];

const FEATURES = [
  {
    icon: Search,
    title: "客观可查",
    desc: "按名称或条码检索商品的成分、营养、规格等官方事实。",
  },
  {
    icon: ShieldCheck,
    title: "可溯源",
    desc: "每条资料标注数据来源与质量分，公开透明、人人可核。",
  },
  {
    icon: Code2,
    title: "开放 API",
    desc: "免鉴权只读 REST 接口，开发者可直接接入商品档案。",
  },
];

export default function Home({
  onOpen,
  onContribute,
}: {
  onOpen: (id: string) => void;
  onContribute: () => void;
}) {
  const [q, setQ] = useState("");
  const [items, setItems] = useState<ProductSummary[]>([]);
  const [total, setTotal] = useState(0);
  const [searched, setSearched] = useState(false);
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState("");

  async function run(term?: string, e?: React.FormEvent) {
    e?.preventDefault();
    const keyword = (term ?? q).trim();
    if (term !== undefined) setQ(term);
    setLoading(true);
    setError("");
    try {
      const res = await api.search(keyword, 1, 30);
      setItems(res.items);
      setTotal(res.total);
      setSearched(true);
    } catch (err) {
      setError(err instanceof Error ? err.message : "搜索失败");
    } finally {
      setLoading(false);
    }
  }

  return (
    <div className="animate-fade-up">
      <section className="relative overflow-hidden rounded-3xl border border-gray-100 bg-gradient-to-b from-white to-brand-50/40 px-6 py-14 text-center shadow-card">
        <div
          aria-hidden
          className="pointer-events-none absolute -top-24 left-1/2 h-72 w-[42rem] -translate-x-1/2 rounded-full bg-brand-200/30 blur-3xl"
        />
        <div className="relative">
          <span className="inline-flex items-center gap-1.5 rounded-full border border-brand-200 bg-white/70 px-3 py-1 text-xs font-medium text-brand-700">
            <ShieldCheck className="w-3.5 h-3.5" /> 公益 · 开放 · 可溯源
          </span>
          <h1 className="mt-5 text-4xl sm:text-5xl font-extrabold tracking-tight text-gray-900">
            天<span className="bg-gradient-to-r from-brand-600 to-emerald-500 bg-clip-text text-transparent">工</span>
          </h1>
          <p className="mx-auto mt-3 max-w-xl text-gray-500">
            输入商品名称或条码，检索客观、可溯源的商品资料。人人可查，人人可贡献。
          </p>

          <form onSubmit={(e) => run(undefined, e)} className="mx-auto mt-7 flex max-w-2xl gap-2">
            <div className="flex flex-1 items-center gap-2 rounded-xl border border-gray-200 bg-white px-3.5 shadow-sm transition focus-within:border-brand-400 focus-within:ring-4 focus-within:ring-brand-500/10">
              <Search className="h-5 w-5 shrink-0 text-gray-400" />
              <input
                autoFocus
                value={q}
                onChange={(e) => setQ(e.target.value)}
                placeholder="例如：可乐、Nutella、5449000000996"
                className="flex-1 bg-transparent py-3.5 outline-none"
              />
            </div>
            <button type="submit" disabled={loading} className="btn-primary px-7">
              {loading ? "检索中…" : "检索"}
            </button>
          </form>

          <div className="mt-4 flex flex-wrap items-center justify-center gap-2">
            <span className="text-xs text-gray-400">试试：</span>
            {EXAMPLES.map((ex) => (
              <button key={ex} type="button" className="chip" onClick={() => run(ex)}>
                <ScanBarcode className="w-3 h-3" /> {ex}
              </button>
            ))}
          </div>
        </div>
      </section>

      {error && (
        <div className="mx-auto mt-6 max-w-2xl rounded-xl bg-red-50 px-4 py-2.5 text-sm text-red-700">
          {error}
        </div>
      )}

      {searched ? (
        <div className="mt-8">
          <div className="mb-3 text-sm text-gray-500">
            共 <span className="font-semibold text-gray-700">{total}</span> 条结果
            {q ? `（关键词：${q}）` : ""}
          </div>
          {items.length === 0 ? (
            <div className="card p-10 text-center text-gray-500">
              <p>没有找到相关商品。</p>
              <button
                onClick={onContribute}
                className="mt-3 inline-flex items-center gap-1.5 font-medium text-brand-700 hover:underline"
              >
                <PlusCircle className="w-4 h-4" /> 你知道这个商品？去贡献档案
              </button>
            </div>
          ) : (
            <ul className="card divide-y divide-gray-100 overflow-hidden">
              {items.map((p) => (
                <li key={p.id}>
                  <button
                    onClick={() => onOpen(p.id)}
                    className="group flex w-full items-center justify-between gap-4 px-4 py-3.5 text-left transition hover:bg-brand-50/50"
                  >
                    <div className="min-w-0">
                      <div className="truncate font-medium text-gray-800 group-hover:text-brand-700">
                        {p.name}
                      </div>
                      <div className="mt-0.5 text-xs text-gray-500">
                        {p.brand || "未知品牌"}
                        {p.gtin ? ` · ${p.gtin}` : ""}
                      </div>
                    </div>
                    <div className="flex shrink-0 items-center gap-3">
                      <span className="text-right text-xs text-gray-400">
                        <span className="block">{p.category_path || ""}</span>
                        {p.country_of_origin ? (
                          <span className="block">产地：{p.country_of_origin}</span>
                        ) : null}
                      </span>
                      <ArrowRight className="h-4 w-4 text-gray-300 transition group-hover:translate-x-0.5 group-hover:text-brand-500" />
                    </div>
                  </button>
                </li>
              ))}
            </ul>
          )}
        </div>
      ) : (
        <div className="mt-8 grid gap-4 sm:grid-cols-3">
          {FEATURES.map(({ icon: Icon, title, desc }) => (
            <div key={title} className="card p-5 transition hover:shadow-card-hover">
              <span className="grid h-10 w-10 place-items-center rounded-xl bg-brand-50 text-brand-600">
                <Icon className="h-5 w-5" />
              </span>
              <h3 className="mt-3 font-semibold text-gray-800">{title}</h3>
              <p className="mt-1 text-sm leading-relaxed text-gray-500">{desc}</p>
            </div>
          ))}
        </div>
      )}
    </div>
  );
}
