/**
 * Shared page chrome for all MesmerTools HuggingFace Spaces.
 *
 * `createSpace()` builds the header, hero, a card with a <form> + output slot,
 * a status area (errors + the rate-limit cross-sell banner), and the footer
 * "more free tools" strip (the SEO backlinks). A tool space only has to fill
 * the returned `form` and `output` elements and wire its submit handler.
 */

import { SITE, ENDPOINTS, TOOL_CATALOG, siteUrl } from "./config.js";
import { RateLimitError } from "./api-client.js";

/** Tiny hyperscript helper. `props` supports className, text, html, on*, attrs, dataset, style. */
export function el(tag, props = {}, ...children) {
  const node = document.createElement(tag);
  for (const [key, value] of Object.entries(props || {})) {
    if (value == null) continue;
    if (key === "className") node.className = value;
    else if (key === "text") node.textContent = value;
    else if (key === "html") node.innerHTML = value;
    else if (key === "dataset") Object.assign(node.dataset, value);
    else if (key === "style" && typeof value === "object") Object.assign(node.style, value);
    else if (key.startsWith("on") && typeof value === "function") {
      node.addEventListener(key.slice(2).toLowerCase(), value);
    } else node.setAttribute(key, value);
  }
  for (const child of children.flat()) {
    if (child == null || child === false) continue;
    node.appendChild(typeof child === "string" ? document.createTextNode(child) : child);
  }
  return node;
}

function header() {
  return el("header", { className: "ms-header" },
    el("a", { className: "ms-brand", href: SITE.origin, target: "_blank", rel: "noopener" },
      el("span", { className: "ms-brand-mark", text: "M" }),
      el("span", { className: "ms-brand-name", text: SITE.name }),
    ),
    el("a", { className: "ms-header-link", href: SITE.origin, target: "_blank", rel: "noopener",
      html: "All tools <span aria-hidden=\"true\">↗</span>" }),
  );
}

function crossSell(toolKey) {
  const items = TOOL_CATALOG.filter((t) => t.key !== toolKey);
  return el("footer", { className: "ms-footer" },
    el("p", { className: "ms-footer-title", text: "More free tools on MesmerTools" }),
    el("div", { className: "ms-grid" },
      ...items.map((t) =>
        el("a", { className: "ms-tool-card", href: siteUrl(t.path), target: "_blank", rel: "noopener" },
          el("span", { className: "ms-tool-emoji", text: t.emoji }),
          el("span", { className: "ms-tool-text" },
            el("span", { className: "ms-tool-name", text: t.name }),
            el("span", { className: "ms-tool-desc", text: t.desc }),
          ),
        ),
      ),
    ),
    el("p", { className: "ms-powered" },
      "Powered by ",
      el("a", { href: SITE.origin, target: "_blank", rel: "noopener", text: "mesmer.tools" }),
      " — runs on the public MesmerTools API.",
    ),
  );
}

/**
 * @param {object} opts
 * @param {string} opts.toolKey   key in ENDPOINTS / TOOL_CATALOG (also excluded from the strip)
 * @param {string} opts.emoji
 * @param {string} opts.title
 * @param {string} opts.subtitle
 * @param {string} [opts.intro]   optional longer paragraph under the subtitle
 * @returns {{form: HTMLFormElement, output: HTMLElement, setLoading: Function,
 *            showError: Function, showRateLimit: Function, clearStatus: Function,
 *            clearOutput: Function, limitNote: string}}
 */
export function createSpace(opts) {
  const { toolKey, emoji, title, subtitle, intro } = opts;
  const endpoint = ENDPOINTS[toolKey] || {};
  const limit = endpoint.freeLimitPerHour;
  const limitNote = limit
    ? `${limit} free requests/hour per user · higher limits on mesmer.tools`
    : `Free · backed by mesmer.tools`;

  const root = document.getElementById("app") || document.body;

  const status = el("div", { className: "ms-status", role: "status", "aria-live": "polite" });
  const form = el("form", { className: "ms-form" });
  const output = el("div", { className: "ms-output" });

  const hero = el("section", { className: "ms-hero" },
    el("div", { className: "ms-hero-emoji", text: emoji }),
    el("h1", { className: "ms-title", text: title }),
    el("p", { className: "ms-subtitle", text: subtitle }),
    intro ? el("p", { className: "ms-intro", text: intro }) : null,
    el("p", { className: "ms-limit-note", text: limitNote }),
  );

  const card = el("section", { className: "ms-card" }, form, status, output);
  const main = el("main", { className: "ms-main" }, hero, card);

  root.appendChild(header());
  root.appendChild(main);
  root.appendChild(crossSell(toolKey));

  function clearStatus() {
    status.replaceChildren();
  }

  function showRateLimit() {
    const full = siteUrl(endpoint.fullToolPath || "/");
    const msg = limit
      ? `You've used your ${limit} free requests this hour. Each visitor gets their own quota — `
      : `You've hit a temporary limit — `;
    clearStatus();
    status.appendChild(
      el("div", { className: "ms-banner ms-banner-limit" },
        el("strong", { text: "Free limit reached. " }),
        msg,
        el("a", { className: "ms-banner-cta", href: full, target: "_blank", rel: "noopener",
          text: "use the full tool on mesmer.tools →" }),
      ),
    );
  }

  /** Renders a RateLimitError as the cross-sell banner; anything else as an error. */
  function showError(err) {
    if (err instanceof RateLimitError || (err && err.isRateLimit)) {
      showRateLimit();
      return;
    }
    const text = typeof err === "string" ? err : (err && err.message) || "Something went wrong.";
    clearStatus();
    status.appendChild(el("div", { className: "ms-banner ms-banner-error", text }));
  }

  function setLoading(isLoading, label) {
    card.classList.toggle("is-loading", !!isLoading);
    if (isLoading) {
      clearStatus();
      status.appendChild(
        el("div", { className: "ms-banner ms-banner-loading" },
          el("span", { className: "ms-spinner", "aria-hidden": "true" }),
          el("span", { text: label || "Working…" }),
        ),
      );
    } else {
      clearStatus();
    }
  }

  function clearOutput() {
    output.replaceChildren();
  }

  return { form, output, status, setLoading, showError, showRateLimit, clearStatus, clearOutput, limitNote };
}

/** Standalone footer for non-tool spaces (e.g. the benchmark) that build their own body. */
export function mountChrome(toolKey) {
  const root = document.getElementById("app") || document.body;
  root.prepend(header());
  root.appendChild(crossSell(toolKey));
}