import { createContext, ReactNode, useCallback, useContext, useEffect, useState } from "react";
import * as api from "./api";
import { HTTPError } from "./api";
import type { User } from "./types";

interface AuthCtx {
  user: User | null;
  loading: boolean;
  login: (username: string, password: string) => Promise<void>;
  register: (username: string, password: string, displayName: string) => Promise<void>;
  logout: () => Promise<void>;
  setUser: (u: User | null) => void;
}

const Ctx = createContext<AuthCtx | null>(null);

export function AuthProvider({ children }: { children: ReactNode }) {
  const [user, setUser] = useState<User | null>(null);
  const [loading, setLoading] = useState(true);

  useEffect(() => {
    api
      .getMe()
      .then(setUser)
      .catch((e) => {
        if (!(e instanceof HTTPError) || e.status !== 401) {
          console.warn("getMe failed", e);
        }
      })
      .finally(() => setLoading(false));
  }, []);

  const login = useCallback(async (username: string, password: string) => {
    const u = await api.login(username, password);
    setUser(u);
  }, []);

  const register = useCallback(async (username: string, password: string, displayName: string) => {
    await api.register(username, password, displayName);
    const u = await api.login(username, password);
    setUser(u);
  }, []);

  const logout = useCallback(async () => {
    await api.logout();
    setUser(null);
  }, []);

  return <Ctx.Provider value={{ user, loading, login, register, logout, setUser }}>{children}</Ctx.Provider>;
}

export function useAuth(): AuthCtx {
  const v = useContext(Ctx);
  if (!v) throw new Error("useAuth: missing AuthProvider");
  return v;
}