sure/desktop/src/main.ts

import { invoke } from "@tauri-apps/api/core";
import { listen } from "@tauri-apps/api/event";
import { S } from "./strings";
import { serverErrorMessage } from "./status";

interface ServerEntry { url: string; label: string; }

const $ = <T extends HTMLElement>(id: string) => document.getElementById(id) as T;

// Navigate to a server's login page exactly once. connect() and the
// active-server-changed listener(s) can all request navigation for the same
// server; without this guard they fire multiple concurrent GET /sessions/new
// requests, each minting a new session + CSRF token, which race and cause
// "Can't verify CSRF token authenticity" on the POST.
function goToServer(url: string) {
  const w = window as unknown as { __sureNav?: string };
  if (w.__sureNav) return;
  w.__sureNav = url;
  // Navigate to the server root: Rails serves the dashboard if the session
  // cookie is still valid, or redirects to the login page if not — so a
  // relaunch with a live session resumes without re-logging in.
  window.location.assign(`${url}/`);
}

function fill() {
  ($("logo") as HTMLImageElement).src = new URL("./assets/logomark.svg", import.meta.url).href;
  $("title").textContent = S.title;
  $("url-label").textContent = S.serverLabel;
  ($("server-url") as HTMLInputElement).placeholder = S.urlPlaceholder;
  $("connect").textContent = S.connect;
  $("remembered-title").textContent = S.remembered;
}

function setStatus(msg: string, kind: "info" | "error" = "info") {
  const el = $("status");
  el.textContent = msg;
  el.dataset.kind = kind;
}

async function connect(rawUrl: string) {
  setStatus(S.checking, "info");
  // Remember the base check_server resolved to, not the raw input.
  let base: string | null;
  try {
    base = await invoke<string | null>("check_server", { url: rawUrl });
  } catch (e) {
    setStatus(serverErrorMessage(e), "error");
    return;
  }
  if (!base) { setStatus(S.unreachable, "error"); return; }
  try {
    const list = await invoke<ServerEntry[]>("add_server", { url: base, label: "" });
    const canonical = list.find((s) => s.url === base)?.url ?? list[0].url;
    await invoke("set_active_server", { url: canonical });
    goToServer(canonical);
  } catch (e) {
    setStatus(serverErrorMessage(e), "error");
  }
}

async function renderRemembered() {
  const servers = await invoke<ServerEntry[]>("list_servers");
  const section = $("remembered");
  const listEl = $("server-list");
  listEl.innerHTML = "";
  if (servers.length === 0) { section.classList.add("hidden"); return; }
  section.classList.remove("hidden");
  for (const s of servers) {
    const li = document.createElement("li");
    const open = document.createElement("button");
    open.className = "server-open";
    open.textContent = s.label;
    open.addEventListener("click", () => connect(s.url));
    const rm = document.createElement("button");
    rm.className = "server-remove";
    rm.textContent = S.remove;
    rm.addEventListener("click", async (e) => {
      e.stopPropagation();
      await invoke("remove_server", { url: s.url });
      renderRemembered();
    });
    li.append(open, rm);
    listEl.append(li);
  }
}

$("server-form").addEventListener("submit", (e) => {
  e.preventDefault();
  const url = ($("server-url") as HTMLInputElement).value.trim();
  if (url) connect(url);
});

// On launch, resume straight to the last server if there is one; otherwise
// show the picker.
async function boot() {
  let active: string | null = null;
  try {
    active = await invoke<string | null>("active_server");
  } catch (e) {
    // Don't let a failed read abort startup and leave a blank onboarding window.
    // eslint-disable-next-line no-console
    console.error("[sure] failed to read active server", e);
  }
  if (active) {
    goToServer(active);
    return;
  }
  fill();
  renderRemembered();
}
boot();

// Navigate when the active server changes (e.g. picked from Preferences).
listen<string>("active-server-changed", (e) => goToServer(e.payload));