/** Read-only view of the Core SSH sessions (permission `session.read`). */
import { call } from "../transport";
import type { SessionStatus } from "../types";

export function displayName(session: SessionStatus): string {
  return (session.adhoc ? session.label : `${session.label} — ${session.username}@${session.host}`)
    + (session.slot ? ` · T${session.slot}` : "")
    + (session.jump?.length ? ` ⇢ ${session.jump[0].host}` : "");
}

export function reconcile(previousId: string, list: readonly SessionStatus[]): { id: string; reason: "keep" | "gone" | "auto" | "choose" } {
  const connected = list.filter((session) => session.state === "connected");
  if (previousId) return connected.some((session) => session.sessionId === previousId)
    ? { id: previousId, reason: "keep" } : { id: "", reason: "gone" };
  return connected.length === 1 ? { id: connected[0].sessionId, reason: "auto" } : { id: "", reason: "choose" };
}

let askedFor = "";

/**
 * Several connections and none chosen: asks once which one the module should use.
 * Asks again only when the set of connections changes; closing the dialog leaves the menu as it is.
 */
export function offerChoice(select: HTMLSelectElement, list: readonly SessionStatus[], title: string): void {
  const connected = list.filter((session) => session.state === "connected");
  const key = connected.map((session) => session.sessionId).sort().join("|");
  if (connected.length < 2 || select.value || key === askedFor || document.querySelector("dialog[open]")) return;
  askedFor = key;
  const dialog = document.createElement("dialog");
  dialog.style.cssText = "min-width:340px;max-width:560px;padding:18px;border:1px solid rgba(151,183,218,.25);border-radius:12px;color:#edf6ff;background:#0c1a2a";
  const heading = document.createElement("div");
  heading.textContent = title;
  heading.style.cssText = "margin-bottom:12px;font-size:14px;font-weight:600";
  dialog.append(heading);
  for (const session of connected) {
    const button = document.createElement("button");
    button.type = "button";
    button.textContent = displayName(session);
    button.style.cssText = "display:block;width:100%;margin-top:6px;padding:10px 12px;border:1px solid rgba(151,183,218,.25);border-radius:8px;color:inherit;background:rgba(255,255,255,.04);text-align:start;font:inherit;cursor:pointer";
    button.addEventListener("click", () => {
      dialog.close();
      if (!select.value && [...select.options].some((option) => option.value === session.sessionId)) {
        select.value = session.sessionId;
        select.dispatchEvent(new Event("change", { bubbles: true }));
      }
    });
    dialog.append(button);
  }
  dialog.addEventListener("close", () => dialog.remove());
  document.body.append(dialog);
  dialog.showModal();
}

export const sessions = Object.freeze({
  list: () => call<SessionStatus[]>("module_sessions_list", "plugin:sessions:list"),
  displayName,
  reconcile,
  offerChoice
});