import { createContext, useCallback, useContext, useEffect, useMemo, useState } from "react";
import { api } from "./api";

export type SystemSettings = {
  system_name: string;
  logo_url: string | null;
};

const DEFAULT: SystemSettings = {
  system_name: "考试阅卷系统",
  logo_url: null,
};

const SystemSettingsContext = createContext<{
  settings: SystemSettings;
  logoCacheKey: number;
  refresh: () => Promise<void>;
}>({ settings: DEFAULT, logoCacheKey: 0, refresh: async () => {} });

export function SystemSettingsProvider({ children }: { children: React.ReactNode }) {
  const [settings, setSettings] = useState<SystemSettings>(DEFAULT);
  const [logoCacheKey, setLogoCacheKey] = useState(0);

  const refresh = useCallback(async () => {
    try {
      const { data } = await api.get<SystemSettings>("/api/settings");
      setSettings(data);
      setLogoCacheKey((k) => k + 1);
      document.title = data.system_name;
    } catch {
      setSettings(DEFAULT);
    }
  }, []);

  useEffect(() => {
    refresh();
  }, [refresh]);

  const value = useMemo(() => ({ settings, logoCacheKey, refresh }), [settings, logoCacheKey, refresh]);

  return <SystemSettingsContext.Provider value={value}>{children}</SystemSettingsContext.Provider>;
}

export function useSystemSettings() {
  return useContext(SystemSettingsContext);
}

export function logoSrc(logoUrl: string | null, cacheBust?: number) {
  if (!logoUrl) return null;
  const q = cacheBust ? `?t=${cacheBust}` : "";
  return `${logoUrl}${q}`;
}