import { useState } from "react";
import { Check, Copy } from "lucide-react";

const ORIGIN = typeof window !== "undefined" ? window.location.origin : "https://goods.tangshasha.com";
const BASE = `${ORIGIN}/api/v1`;

function CopyBtn({ text }: { text: string }) {
  const [done, setDone] = useState(false);
  return (
    <button
      onClick={async () => {
        try {
          await navigator.clipboard.writeText(text);
          setDone(true);
          setTimeout(() => setDone(false), 1200);
        } catch {
          /* clipboard unavailable */
        }
      }}
      className="text-gray-400 hover:text-gray-600"
      title="复制"
    >
      {done ? <Check className="w-4 h-4 text-emerald-600" /> : <Copy className="w-4 h-4" />}
    </button>
  );
}

function Code({ children }: { children: string }) {
  return (
    <div className="relative group">
      <pre className="bg-gray-900 text-gray-100 text-xs rounded-md p-3 overflow-x-auto whitespace-pre">
        {children}
      </pre>
      <div className="absolute top-2 right-2 opacity-70 group-hover:opacity-100">
        <CopyBtn text={children} />
      </div>
    </div>
  );
}

function Method({ m }: { m: string }) {
  const color = m === "GET" ? "bg-sky-100 text-sky-700" : "bg-emerald-100 text-emerald-700";
  return <span className={`text-xs font-mono font-semibold rounded px-1.5 py-0.5 ${color}`}>{m}</span>;
}

type Param = { name: string; required?: boolean; desc: string };

function Endpoint({
  method,
  path,
  title,
  desc,
  params,
  example,
  response,
}: {
  method: string;
  path: string;
  title: string;
  desc: string;
  params?: Param[];
  example: string;
  response: string;
}) {
  return (
    <div className="bg-white border rounded-lg p-5">
      <div className="flex items-center gap-2 flex-wrap">
        <Method m={method} />
        <code className="text-sm text-gray-800 font-mono break-all">{path}</code>
        <span className="ml-auto" />
        <CopyBtn text={`${ORIGIN}${path}`} />
      </div>
      <div className="mt-2 font-medium text-gray-800">{title}</div>
      <p className="text-sm text-gray-500 mt-0.5">{desc}</p>

      {params && params.length > 0 && (
        <table className="mt-3 w-full text-sm">
          <thead className="text-gray-400 text-left">
            <tr>
              <th className="font-medium pr-4 pb-1">参数</th>
              <th className="font-medium pr-4 pb-1">必填</th>
              <th className="font-medium pb-1">说明</th>
            </tr>
          </thead>
          <tbody className="align-top">
            {params.map((p) => (
              <tr key={p.name}>
                <td className="pr-4 py-0.5 font-mono text-gray-700">{p.name}</td>
                <td className="pr-4 py-0.5 text-gray-500">{p.required ? "是" : "否"}</td>
                <td className="py-0.5 text-gray-600">{p.desc}</td>
              </tr>
            ))}
          </tbody>
        </table>
      )}

      <div className="mt-3 text-xs text-gray-400 mb-1">请求示例</div>
      <Code>{example}</Code>
      <div className="mt-3 text-xs text-gray-400 mb-1">返回示例</div>
      <Code>{response}</Code>
    </div>
  );
}

export default function ApiDocs() {
  return (
    <div className="space-y-5">
      <div className="bg-white border rounded-lg p-5">
        <h1 className="text-2xl font-bold text-gray-800">API 调用说明</h1>
        <p className="mt-2 text-gray-600 text-sm leading-relaxed">
          天工商品档案公共仓提供<strong>公开、只读、免鉴权</strong>的商品事实 REST API，任何人都可直接调用，
          用于按条码/名称查询商品的客观资料（品牌、品类、净含量、产地、配料、营养成分、Nutri-Score、
          厂商建议零售价快照等）。返回均为 JSON（UTF-8）。本服务不含任何购买/交易接口。
        </p>
        <div className="mt-3 text-sm text-gray-700">
          <div>
            基础地址：<code className="font-mono bg-gray-100 rounded px-1.5 py-0.5">{BASE}</code>
          </div>
          <ul className="mt-2 list-disc pl-5 text-gray-600 space-y-1">
            <li>无需 API Key / Token 即可直接 GET；带 Key 可获得更高频率上限（见下文「鉴权与限流」）。</li>
            <li>
              分页参数 <code className="font-mono">page</code>（默认 1）、
              <code className="font-mono">size</code>（默认 20，最大 100）。
            </li>
            <li>
              未找到资源返回 <code className="font-mono">404</code>，错误体形如
              <code className="font-mono">{` {"error":{"code","message","request_id"}}`}</code>。
            </li>
            <li>请合理控制调用频率；商品数据遵循各来源许可，引用时请注明天工商品档案公共仓及原始来源。</li>
          </ul>
        </div>
      </div>

      <div className="bg-white border rounded-lg p-5">
        <h2 className="text-lg font-semibold text-gray-800">鉴权与限流</h2>
        <p className="mt-2 text-gray-600 text-sm leading-relaxed">
          API 默认<strong>匿名可用</strong>：无需任何凭证即可调用，按来源 IP 计入一个较低的默认频率额度。
          如需更高额度并让用量归属到你，可在运营方申请一枚 API Key，请求时通过请求头携带：
        </p>
        <div className="mt-3">
          <Code>{`# 二选一
curl -H "X-API-Key: og_live_xxxxxxxx" ${BASE}/products/search?q=牛奶
curl -H "Authorization: Bearer og_live_xxxxxxxx" ${BASE}/products/search?q=牛奶`}</Code>
        </div>
        <p className="mt-3 text-gray-600 text-sm leading-relaxed">
          采用<strong>固定窗口</strong>限流（每分钟）。每个响应都会回写以下响应头，便于客户端自适应：
        </p>
        <table className="mt-3 w-full text-sm">
          <thead className="text-gray-400 text-left">
            <tr>
              <th className="font-medium pr-4 pb-1">响应头</th>
              <th className="font-medium pb-1">含义</th>
            </tr>
          </thead>
          <tbody className="align-top">
            <tr>
              <td className="pr-4 py-0.5 font-mono text-gray-700">X-RateLimit-Limit</td>
              <td className="py-0.5 text-gray-600">当前窗口允许的最大请求数</td>
            </tr>
            <tr>
              <td className="pr-4 py-0.5 font-mono text-gray-700">X-RateLimit-Remaining</td>
              <td className="py-0.5 text-gray-600">当前窗口剩余可用次数</td>
            </tr>
            <tr>
              <td className="pr-4 py-0.5 font-mono text-gray-700">X-RateLimit-Reset</td>
              <td className="py-0.5 text-gray-600">窗口重置的 Unix 时间戳（秒）</td>
            </tr>
            <tr>
              <td className="pr-4 py-0.5 font-mono text-gray-700">Retry-After</td>
              <td className="py-0.5 text-gray-600">超额时返回，建议等待的秒数</td>
            </tr>
          </tbody>
        </table>
        <p className="mt-3 text-gray-600 text-sm leading-relaxed">
          超过额度返回 <code className="font-mono">429 Too Many Requests</code>，错误码
          <code className="font-mono">rate_limited</code>；无效或已吊销的 Key 返回
          <code className="font-mono">401</code>，错误码 <code className="font-mono">invalid_api_key</code>。
        </p>
      </div>

      <Endpoint
        method="GET"
        path="/healthz"
        title="健康检查"
        desc="服务存活探针。"
        example={`curl ${ORIGIN}/healthz`}
        response={`{ "status": "ok" }`}
      />

      <Endpoint
        method="GET"
        path="/api/v1/products/barcode/{gtin}"
        title="按条码查询商品"
        desc="按 GTIN（条码）精确查询单个商品档案。"
        params={[{ name: "gtin", required: true, desc: "商品条码（路径参数），如 5449000000996" }]}
        example={`curl ${BASE}/products/barcode/5449000000996`}
        response={`{
  "id": "…",
  "gtin": "5449000000996",
  "name": "可口可乐 经典原味",
  "brand": "Coca-Cola",
  "category_path": "food.beverages.carbonated",
  "net_content_value": 33,
  "net_content_unit": "cl",
  "country_of_origin": "Algeria",
  "quality_score": 0.81
}`}
      />

      <Endpoint
        method="GET"
        path="/api/v1/products/search"
        title="搜索商品"
        desc="按名称做三元组（trigram）模糊搜索，可容忍错别字；支持品类/品牌/产地过滤；结果按相关度（名称相似度 × 数据质量分）排序。"
        params={[
          { name: "q", desc: "关键词（名称/条码），支持模糊匹配；留空则按质量分返回全部" },
          { name: "category", desc: "品类编码（含子树），如 food.beverages" },
          { name: "brand", desc: "品牌名（模糊匹配），如 Ferrero" },
          { name: "country", desc: "产地前缀（不区分大小写），如 China" },
          { name: "page", desc: "页码，默认 1" },
          { name: "size", desc: "每页条数，默认 20，最大 100" },
        ]}
        example={`curl "${BASE}/products/search?q=nutela&country=Italy&page=1&size=20"`}
        response={`{
  "items": [
    { "id": "…", "gtin": "3017624010701",
      "name": "Nutella", "brand": "Ferrero",
      "category_path": "food.snacks.chocolate",
      "country_of_origin": "Italy",
      "quality_score": 0.81,
      "score": 0.71 }
  ],
  "page": 1, "size": 20, "total": 1
}`}
      />

      <Endpoint
        method="GET"
        path="/api/v1/products/{id}"
        title="商品详情"
        desc="按商品 UUID 获取完整档案（含配料、营养、添加剂、图片、MSRP 等）。"
        params={[{ name: "id", required: true, desc: "商品 UUID（路径参数）" }]}
        example={`curl ${BASE}/products/{id}`}
        response={`{
  "id": "…", "name": "…", "brand": "…",
  "ingredients_text": "…",
  "nutriments": { "energy_kcal": 42, "sugars_g": 10.6 },
  "nutrition_basis": "per_100g",
  "nutri_score": "E",
  "images": [], "msrp": [],
  "quality_score": 0.81
}`}
      />

      <Endpoint
        method="GET"
        path="/api/v1/products/{id}/nutriments"
        title="商品营养成分"
        desc="仅返回该商品的营养字段。"
        params={[{ name: "id", required: true, desc: "商品 UUID（路径参数）" }]}
        example={`curl ${BASE}/products/{id}/nutriments`}
        response={`{
  "basis": "per_100g",
  "values": { "energy_kcal": 42, "sugars_g": 10.6, "salt_g": 0 }
}`}
      />

      <Endpoint
        method="GET"
        path="/api/v1/products/{id}/msrp"
        title="厂商建议零售价快照"
        desc="官方建议零售价历史快照，仅供参考，不含任何购买入口。"
        params={[{ name: "id", required: true, desc: "商品 UUID（路径参数）" }]}
        example={`curl ${BASE}/products/{id}/msrp`}
        response={`{
  "items": [
    { "amount": 3.5, "currency": "CNY", "region": "CN", "effective_date": "2025-01-01" }
  ],
  "disclaimer": "厂商建议零售价历史快照，仅供参考，不构成购买建议…"
}`}
      />

      <Endpoint
        method="GET"
        path="/api/v1/brands"
        title="品牌列表"
        desc="分页列出全部品牌。"
        params={[
          { name: "page", desc: "页码，默认 1" },
          { name: "size", desc: "每页条数，默认 20，最大 100" },
        ]}
        example={`curl "${BASE}/brands?page=1&size=20"`}
        response={`{
  "items": [ { "id": "…", "name": "Ferrero" } ],
  "page": 1, "size": 20, "total": 4
}`}
      />

      <Endpoint
        method="GET"
        path="/api/v1/categories"
        title="品类树"
        desc="返回完整品类层级（编码 + 名称）。"
        example={`curl ${BASE}/categories`}
        response={`{
  "items": [
    { "id": "…", "code": "food", "name": "食品饮料", "parent_id": null }
  ]
}`}
      />

      <Endpoint
        method="GET"
        path="/api/v1/sources/{id}"
        title="数据来源"
        desc="按 ID 查询单个数据来源（含许可、信任权重）。"
        params={[{ name: "id", required: true, desc: "来源 UUID（路径参数）" }]}
        example={`curl ${BASE}/sources/{id}`}
        response={`{
  "id": "…", "name": "openfoodfacts",
  "license": "ODbL", "trust_weight": 0.7
}`}
      />

      <div className="text-xs text-gray-400 leading-relaxed">
        数据可能存在误差或滞后，按「现状」提供，不构成医疗/购买建议。商品资料版权归各原始来源所有，
        请遵循其许可（如 OpenFoodFacts 的 ODbL）。
      </div>
    </div>
  );
}