import { createChat, sendUserMessage, openStream, fetchModels } from "./chatApi.svelte.js";

const STORAGE_KEY = "chatHistory";

function loadHistory() {
  try {
    return JSON.parse(localStorage.getItem(STORAGE_KEY) || "[]");
  } catch {
    return [];
  }
}

function saveHistory(list) {
  localStorage.setItem(STORAGE_KEY, JSON.stringify(list));
}

export const chatStore = (() => {
  let chatId = $state(null);
  let messages = $state([]);
  let loading = $state(false);
  let input = $state("");
  let model = $state("qwen/qwen3-235b-a22b-2507"); // default
  let models = $state([]);
  let loadingModels = $state(true);

  // public helpers
  const history = $derived(loadHistory());

  function pushHistory(id, title, msgs) {
    console.log(`push history: ${id} - ${title}`);
    const h = history.filter((c) => c.id !== id);
    h.unshift({ id, title, messages: msgs });
    saveHistory(h.slice(0, 50)); // keep last 50
  }

  async function selectChat(id) {
    if (id === chatId) return;
    chatId = id;
    const stored = loadHistory().find((c) => c.id === id);
    messages = stored?.messages || [];
    loading = true;
    loading = false;
    // Update URL with GET parameter
    const url = new URL(window.location.href);
    if (id) {
      url.searchParams.set('chat', id);
    } else {
      url.searchParams.delete('chat');
    }
    window.history.replaceState({}, "", url);
  }

  async function createAndSelect() {
    const { id } = await createChat(model);
    console.log(id);
    selectChat(id);
    return id;
  }

  async function send() {
    if (!input.trim()) return;
    if (!chatId) await createAndSelect();

    const userMsg = { id: crypto.randomUUID(), role: "user", text: input };
    messages = [...messages, userMsg];

    pushHistory(chatId, userMsg.text.slice(0, 30), messages);

    loading = true;
    const { message_id } = await sendUserMessage(chatId, input, model);
    input = "";

    let assistantMsg = { id: message_id, role: "assistant", text: "" };
    messages = [...messages, assistantMsg];

    const es = openStream(chatId, message_id);
    es.onmessage = (e) => {
      assistantMsg = { ...assistantMsg, text: assistantMsg.text + e.data };
      messages = [...messages.slice(0, -1), assistantMsg];
    };
    es.onerror = () => {
      es.close();
      loading = false;
    };
    es.addEventListener("done", (e) => {
      console.log(e);
      es.close();
      loading = false;
      pushHistory(chatId, userMsg.text.slice(0, 30), messages);
    });
  }

  async function loadModels() {
    loadingModels = true;
    models = await fetchModels();
    loadingModels = false;
    
    // Set default model if available and not already set
    if (models.length > 0 && !model) {
      model = models[0].id || models[0];
    }
  }

  function handleKey(e) {
    if (e.key === "Enter" && !e.shiftKey) {
      e.preventDefault();
      send();
    }
  }

  // initial route handling - use GET parameter instead of path
  const params = new URLSearchParams(window.location.search);
  const chatIdFromUrl = params.get('chat');
  const storedHistory = loadHistory();
  if (chatIdFromUrl && !storedHistory.find((c) => c.id === chatIdFromUrl)) {
    createAndSelect();
  } else if (chatIdFromUrl) {
    selectChat(chatIdFromUrl);
  }

  // Load models on initialization
  loadModels();

  return {
    get chatId() {
      return chatId;
    },
    get messages() {
      return messages;
    },
    get loading() {
      return loading;
    },
    get input() {
      return input;
    },
    set input(v) {
      input = v;
    },
    get model() {
      return model;
    },
    set model(v) {
      model = v;
    },
    get models() {
      return models;
    },
    get loadingModels() {
      return loadingModels;
    },
    get history() {
      return loadHistory();
    },
    selectChat,
    send,
    handleKey,
    createAndSelect,
    loadModels,
  };
})();