// Static-Space shim: answer the playground's own /api/* and /sample routes
// in the browser by calling the Socrata APIs directly (they send
// Access-Control-Allow-Origin: *). This keeps index.html identical to the
// FastAPI-served version — only the transport changes.
(function () {
  const DOMAIN = "data.cityofnewyork.us";
  const ID_RE = /^[a-z0-9]{4}-[a-z0-9]{4}$/;
  const MAX_LIMIT = 1000;

  const SAMPLES = [
    {
      title: "311 complaints by borough, 2026",
      tool: "query_dataset",
      args: {
        dataset_id: "erm2-nwe9",
        select: "borough, count(*) as n",
        where: "created_date > '2026-01-01T00:00:00'",
        group: "borough",
        order: "n DESC",
      },
    },
    { title: "Search the catalog for squirrels", tool: "search_datasets", args: { query: "squirrel census" } },
    {
      title: "Top complaint types this year",
      tool: "profile_column",
      args: { dataset_id: "erm2-nwe9", column: "complaint_type", top: 10 },
    },
    { title: "Schema of the 2015 Street Tree Census", tool: "get_schema", args: { dataset_id: "uvpi-gqnh" } },
  ];

  const ok = (body) => new Response(JSON.stringify(body), { status: 200, headers: { "Content-Type": "application/json" } });
  const fail = (status, detail) => new Response(JSON.stringify({ detail }), { status, headers: { "Content-Type": "application/json" } });

  function checkId(id) {
    if (!ID_RE.test((id || "").trim().toLowerCase()))
      throw { status: 422, detail: `invalid dataset id '${id}': expected the Socrata 4x4 form, e.g. 'erm2-nwe9'` };
    return id.trim().toLowerCase();
  }
  const clamp = (v, dflt) => Math.max(1, Math.min(parseInt(v || dflt, 10) || dflt, MAX_LIMIT));

  async function upstream(url) {
    const res = await fetch(url);
    if (!res.ok) {
      let detail = "";
      try { detail = (await res.json()).message || ""; } catch (e) { /* not json */ }
      if (res.status === 404) throw { status: 502, detail: "not found — check the dataset id and domain" };
      if (res.status === 400) throw { status: 502, detail: `the API rejected the query (${detail || "bad request"}) — check your SoQL syntax` };
      throw { status: 502, detail: `HTTP ${res.status} from Socrata: ${detail}` };
    }
    return res.json();
  }

  async function route(path, params) {
    if (path === "/sample") {
      const i = parseInt(params.get("index") || "0", 10) || 0;
      return SAMPLES[((i % SAMPLES.length) + SAMPLES.length) % SAMPLES.length];
    }
    if (path === "/api/search") {
      const data = await upstream(
        "https://api.us.socrata.com/api/catalog/v1?domains=" + DOMAIN +
        "&only=dataset&q=" + encodeURIComponent(params.get("q") || "") +
        "&limit=" + clamp(params.get("limit"), 10)
      );
      return (data.results || []).map((r) => ({
        id: r.resource.id,
        name: r.resource.name,
        description: (r.resource.description || "").slice(0, 500),
        updated: r.resource.data_updated_at,
        domain: DOMAIN,
      }));
    }
    if (path.startsWith("/api/schema/")) {
      const id = checkId(path.split("/").pop());
      const data = await upstream(`https://${DOMAIN}/api/views/${id}.json`);
      return {
        id,
        domain: DOMAIN,
        name: data.name,
        description: (data.description || "").slice(0, 1000),
        columns: (data.columns || [])
          .filter((c) => !String(c.fieldName || "").startsWith(":"))
          .map((c) => ({ field_name: c.fieldName, type: c.dataTypeName, description: (c.description || "").slice(0, 300) })),
      };
    }
    if (path === "/api/query" || path === "/api/profile") {
      const id = checkId(params.get("dataset_id"));
      const q = new URLSearchParams();
      if (path === "/api/profile") {
        const col = params.get("column") || "";
        q.set("$select", `${col}, count(*) as count`);
        q.set("$group", col);
        q.set("$order", "count DESC");
        q.set("$limit", clamp(params.get("top"), 20));
      } else {
        for (const [key, dollar] of [["select", "$select"], ["where", "$where"], ["group", "$group"], ["order", "$order"]])
          if (params.get(key)) q.set(dollar, params.get(key));
        q.set("$limit", clamp(params.get("limit"), 50));
        if (+params.get("offset")) q.set("$offset", +params.get("offset"));
      }
      return upstream(`https://${DOMAIN}/resource/${id}.json?` + q.toString());
    }
    throw { status: 404, detail: "unknown route " + path };
  }

  const realFetch = window.fetch.bind(window);
  window.fetch = async function (input, init) {
    const url = typeof input === "string" ? input : input.url;
    if (url.startsWith("/api/") || url.startsWith("/sample")) {
      const u = new URL(url, location.origin);
      try {
        return ok(await route(u.pathname, u.searchParams));
      } catch (e) {
        return fail(e.status || 502, e.detail || String(e));
      }
    }
    return realFetch(input, init);
  };
})();