// Shared helpers for Canon's pages. No build step, no dependencies.

/** Create an element: h("button", { class: "btn", onclick }, "Save") */
export function h(tag, attrs = {}, ...children) {
  const el = document.createElement(tag);
  let value;
  for (const [k, v] of Object.entries(attrs || {})) {
    if (v === false || v == null) continue;
    if (k === "value") value = v;
    else if (k.startsWith("on") && typeof v === "function") el.addEventListener(k.slice(2), v);
    else if (k === "class") el.className = v;
    else if (k === "style" && typeof v === "object") Object.assign(el.style, v);
    else if (k in el && typeof v !== "string") el[k] = v;
    else el.setAttribute(k, v === true ? "" : v);
  }
  append(el, children);
  // Set after children so <select> options exist.
  if (value !== undefined) el.value = value;
  return el;
}

function append(el, children) {
  for (const c of children.flat(Infinity)) {
    if (c == null || c === false) continue;
    el.append(c instanceof Node ? c : document.createTextNode(String(c)));
  }
}

const SVG = "http://www.w3.org/2000/svg";

export function icon(name) {
  const svg = document.createElementNS(SVG, "svg");
  svg.setAttribute("class", "icon");
  svg.setAttribute("aria-hidden", "true");
  const use = document.createElementNS(SVG, "use");
  use.setAttribute("href", `/static/img/icons.svg#${name}`);
  svg.append(use);
  return svg;
}

export function readBoot() {
  const el = document.getElementById("boot");
  return el ? JSON.parse(el.textContent) : {};
}

export class APIError extends Error {
  constructor(message, status, body) {
    super(message);
    this.status = status;
    this.body = body;
  }
}

/** Call the admin JSON API. Throws APIError with a human message. */
export async function api(method, path, body) {
  const opts = { method, headers: { "X-Canon": "1" }, credentials: "same-origin" };
  if (body instanceof FormData) {
    opts.body = body;
  } else if (body !== undefined) {
    opts.headers["Content-Type"] = "application/json";
    opts.body = JSON.stringify(body);
  }
  let res;
  try {
    res = await fetch(path, opts);
  } catch {
    throw new APIError("Can't reach the server. Check your connection.", 0);
  }
  if (res.status === 204) return null;
  const data = await res.json().catch(() => ({}));
  if (res.status === 401) {
    location.href = "/login?next=" + encodeURIComponent(location.pathname);
  }
  if (!res.ok) throw new APIError(data.error || `Request failed (${res.status})`, res.status, data);
  return data;
}

let toastBox;
export function toast(message, { error = false, timeout = 3200 } = {}) {
  if (!toastBox) {
    toastBox = h("div", { class: "toasts", role: "status", "aria-live": "polite" });
    document.body.append(toastBox);
  }
  const t = h("div", { class: "toast" + (error ? " toast--error" : "") }, icon(error ? "alert" : "check"), message);
  toastBox.append(t);
  setTimeout(() => {
    t.classList.add("is-leaving");
    setTimeout(() => t.remove(), 250);
  }, error ? Math.max(timeout, 5000) : timeout);
}

/** Open a modal dialog. Returns the <dialog>; it removes itself on close. */
export function openDialog(content, { className = "", onClose } = {}) {
  const dlg = h("dialog", { class: className }, content);
  dlg.addEventListener("click", (e) => {
    // Clicking the backdrop (outside the box) closes.
    if (e.target !== dlg) return;
    const r = dlg.getBoundingClientRect();
    const inside = e.clientX >= r.left && e.clientX <= r.right && e.clientY >= r.top && e.clientY <= r.bottom;
    if (!inside) dlg.close();
  });
  dlg.addEventListener("close", () => {
    onClose?.();
    dlg.remove();
  });
  document.body.append(dlg);
  dlg.showModal();
  return dlg;
}

export function dialogHead(title, dlg) {
  return h("div", { class: "dialog-head" },
    h("h2", {}, title),
    h("button", { type: "button", class: "icon-btn", "aria-label": "Close", onclick: () => dlg().close() }, icon("x")),
  );
}

/** Ask a yes/no question. Resolves true when confirmed. */
export function confirmDialog({ title, message, confirm = "Confirm", danger = false }) {
  return new Promise((resolve) => {
    let ok = false;
    let dlg;
    const content = h("form", { method: "dialog" },
      dialogHead(title, () => dlg),
      h("div", { class: "dialog-body" }, h("p", { class: "muted" }, message)),
      h("div", { class: "dialog-foot" },
        h("button", { type: "button", class: "btn", onclick: () => dlg.close() }, "Cancel"),
        h("button", {
          type: "submit",
          class: "btn " + (danger ? "btn--danger btn--solid" : "btn--primary"),
          onclick: () => { ok = true; },
        }, confirm),
      ),
    );
    dlg = openDialog(content, { onClose: () => resolve(ok) });
    dlg.style.maxWidth = "440px";
  });
}

export function debounce(fn, ms) {
  let t;
  return (...args) => {
    clearTimeout(t);
    t = setTimeout(() => fn(...args), ms);
  };
}

export function busy(button, on) {
  button.disabled = on;
  button.setAttribute("aria-busy", on ? "true" : "false");
}

export const fmt = new Intl.NumberFormat();

export function storageGet(key) {
  try { return localStorage.getItem(key); } catch { return null; }
}
export function storageSet(key, val) {
  try { localStorage.setItem(key, val); } catch { /* private mode */ }
}

// Close <details class="menu"> dropdowns when clicking elsewhere or picking an item.
document.addEventListener("click", (e) => {
  for (const d of document.querySelectorAll("details.menu[open]")) {
    if (!d.contains(e.target) || e.target.closest(".menu-pop a")) d.open = false;
  }
});