// Parse chat ID from GET parameter
export function getChatIdFromUrl() {
  const params = new URLSearchParams(window.location.search);
  return params.get('chat');
}

// Update URL with GET parameter
export function updateUrlWithChatId(chatId) {
  const url = new URL(window.location.href);
  if (chatId) {
    url.searchParams.set('chat', chatId);
  } else {
    url.searchParams.delete('chat');
  }
  window.history.replaceState({}, "", url);
}

// which chat is on screen right now
export let activeChatId = $state(null);

export function switchChat(chatId) {
  activeChatId = chatId;
  updateUrlWithChatId(chatId);
}

export function newChat() {
  const id = "chat_" + crypto.randomUUID();
  switchChat(id);
  return id;
}

// restore last opened chat (or create first one)
(() => {
  const ids = JSON.parse(localStorage.getItem("chat_ids") || "[]");
  const urlChatId = getChatIdFromUrl();
  
  if (urlChatId) {
    switchChat(urlChatId);
  } else if (ids.length) {
    switchChat(ids[0]);
  } else {
    newChat();
  }
})();