import { writable, derived, get } from 'svelte/store';
import { auth as authApi, setup as setupApi, features as featuresApi } from './api.js';

// ── Auth store ────────────────────────────────────────────────────────────────

function createAuthStore() {
  const { subscribe, set, update } = writable({
    user: null,
    token: null,
    refreshToken: null,
    loading: true,
    initialized: false,
  });

  return {
    subscribe,

    async init() {
      if (typeof localStorage === 'undefined') {
        update(s => ({ ...s, loading: false, initialized: true }));
        return;
      }
      const token = localStorage.getItem('mac_token');
      const refreshToken = localStorage.getItem('mac_refresh');
      if (!token) {
        update(s => ({ ...s, loading: false, initialized: true }));
        return;
      }
      try {
        const user = await authApi.me();
        update(s => ({ ...s, user, token, refreshToken, loading: false, initialized: true }));
      } catch {
        localStorage.removeItem('mac_token');
        localStorage.removeItem('mac_refresh');
        update(s => ({ ...s, loading: false, initialized: true }));
      }
    },

    async login(identifier, password) {
      const data = await authApi.login(identifier, password);
      localStorage.setItem('mac_token', data.access_token);
      if (data.refresh_token) localStorage.setItem('mac_refresh', data.refresh_token);
      update(s => ({ ...s, user: data.user, token: data.access_token, refreshToken: data.refresh_token }));
      return data;
    },

    async logout() {
      const rt = localStorage.getItem('mac_refresh');
      try { if (rt) await authApi.logout(); } catch {}
      localStorage.removeItem('mac_token');
      localStorage.removeItem('mac_refresh');
      set({ user: null, token: null, refreshToken: null, loading: false, initialized: true });
    },

    setUser(user) {
      update(s => ({ ...s, user }));
    },
  };
}

export const authStore = createAuthStore();
export const user = derived(authStore, $a => $a.user);
export const isAdmin = derived(authStore, $a => $a.user?.role === 'admin');
export const isFacultyOrAdmin = derived(authStore, $a => ['faculty', 'admin'].includes($a.user?.role));
export const isLoggedIn = derived(authStore, $a => !!$a.user);

// ── Setup store ───────────────────────────────────────────────────────────────

export const setupStore = writable({ is_first_run: null, checked: false });

export async function checkSetup() {
  try {
    const data = await setupApi.status();
    setupStore.set({ ...data, checked: true });
    return data;
  } catch {
    setupStore.set({ is_first_run: false, checked: true });
  }
}

// ── Feature flags store ───────────────────────────────────────────────────────

export const featureStore = writable({ flags: {}, roles: {}, loaded: false });

export async function loadFeatures() {
  try {
    const data = await featuresApi.status();
    featureStore.set({ ...data, loaded: true });
  } catch {
    featureStore.set({ flags: {}, roles: {}, loaded: true });
  }
}

export function hasFeature(key) {
  return derived(featureStore, $f => !!$f.flags[key]);
}

// ── UI state ──────────────────────────────────────────────────────────────────

export const sidebarOpen = writable(true);
export const theme = writable('light');

// ── Loading state ─────────────────────────────────────────────────────────────
export const globalLoading = writable(false);
export const loadingMessage = writable('');
export const locale = writable('en');

export const toast = writable(null);

let toastTimer = null;
export function showToast(message, type = 'info', duration = 4000) {
  if (toastTimer) clearTimeout(toastTimer);
  toast.set({ message, type, id: Date.now() });
  toastTimer = setTimeout(() => toast.set(null), duration);
}

// ── Chat store ────────────────────────────────────────────────────────────────

export const chatStore = writable({
  conversations: [], // [{ id, title, messages: [{role, content, model, ts}] }]
  activeId: null,
  streaming: false,
});

export function newConversation() {
  const id = crypto.randomUUID();
  chatStore.update(s => ({
    ...s,
    conversations: [{ id, title: 'New Chat', messages: [] }, ...s.conversations],
    activeId: id,
  }));
  return id;
}

export function appendMessage(convId, message) {
  chatStore.update(s => ({
    ...s,
    conversations: s.conversations.map(c =>
      c.id === convId
        ? { ...c, messages: [...c.messages, message],
            title: c.title === 'New Chat' && message.role === 'user'
              ? message.content.slice(0, 40) + (message.content.length > 40 ? '…' : '')
              : c.title }
        : c
    ),
  }));
}

export function updateLastMessage(convId, patch) {
  chatStore.update(s => ({
    ...s,
    conversations: s.conversations.map(c =>
      c.id === convId
        ? { ...c, messages: c.messages.map((m, i) =>
            i === c.messages.length - 1 ? { ...m, ...patch } : m) }
        : c
    ),
  }));
}