"use client";

import {
  createContext,
  useCallback,
  useContext,
  useEffect,
  useMemo,
  useState,
} from "react";
import { getMe, getTenant, refreshAuth } from "@/lib/meshkee";
import { BUSINESS_URL, CUSTOMER_URL, TOKEN_KEYS } from "@/lib/config";
import { displayName, isWebsiteAdmin } from "@/lib/format";
import type { MeshkeeUser } from "@/lib/types";

type AuthContextValue = {
  user: MeshkeeUser | null;
  loading: boolean;
  isAdmin: boolean;
  label: string;
  customerUrl: string;
  businessUrl: string;
  profileUrl: string;
  loginUrl: string;
  logout: () => void;
  refresh: () => Promise<void>;
};

const AuthContext = createContext<AuthContextValue | null>(null);

function readToken(key: string) {
  try {
    return localStorage.getItem(key);
  } catch {
    return null;
  }
}

function writeTokens(access?: string | null, refresh?: string | null) {
  try {
    if (access) localStorage.setItem(TOKEN_KEYS.access, access);
    else localStorage.removeItem(TOKEN_KEYS.access);
    if (refresh) localStorage.setItem(TOKEN_KEYS.refresh, refresh);
    else localStorage.removeItem(TOKEN_KEYS.refresh);
  } catch {
    /* ignore */
  }
}

function captureTokensFromUrl() {
  if (typeof window === "undefined") return;
  const url = new URL(window.location.href);
  const hash = new URLSearchParams(url.hash.replace(/^#/, ""));
  const access =
    url.searchParams.get("accessToken") ||
    url.searchParams.get("token") ||
    hash.get("accessToken") ||
    hash.get("token");
  const refresh =
    url.searchParams.get("refreshToken") || hash.get("refreshToken");

  if (!access && !refresh) return;

  writeTokens(access, refresh);
  url.searchParams.delete("accessToken");
  url.searchParams.delete("refreshToken");
  url.searchParams.delete("token");
  url.hash = "";
  window.history.replaceState({}, "", `${url.pathname}${url.search}`);
}

export function AuthProvider({ children }: { children: React.ReactNode }) {
  const [user, setUser] = useState<MeshkeeUser | null>(null);
  const [loading, setLoading] = useState(true);
  const [businessId, setBusinessId] = useState<string | number | null>(null);

  const loginUrl = useMemo(() => {
    const returnTo =
      typeof window !== "undefined"
        ? window.location.origin
        : "https://www.plift.ir";
    return `${CUSTOMER_URL}?redirect=${encodeURIComponent(returnTo)}`;
  }, []);

  const refresh = useCallback(async () => {
    captureTokensFromUrl();
    const access = readToken(TOKEN_KEYS.access);
    const refreshToken = readToken(TOKEN_KEYS.refresh);

    if (!access && !refreshToken) {
      setUser(null);
      setLoading(false);
      return;
    }

    try {
      let token = access;
      if (!token && refreshToken) {
        const refreshed = await refreshAuth(refreshToken);
        writeTokens(refreshed.accessToken, refreshed.refreshToken);
        token = refreshed.accessToken;
        if (refreshed.user) {
          setUser(refreshed.user);
          setLoading(false);
          return;
        }
      }
      if (!token) {
        setUser(null);
        return;
      }
      const me = await getMe(token);
      setUser(me);
    } catch {
      if (refreshToken) {
        try {
          const refreshed = await refreshAuth(refreshToken);
          writeTokens(refreshed.accessToken, refreshed.refreshToken);
          const me = refreshed.user || (await getMe(refreshed.accessToken));
          setUser(me);
          return;
        } catch {
          writeTokens(null, null);
          setUser(null);
        }
      } else {
        writeTokens(null, null);
        setUser(null);
      }
    } finally {
      setLoading(false);
    }
  }, []);

  useEffect(() => {
    let cancelled = false;
    (async () => {
      try {
        const tenant = await getTenant();
        if (!cancelled) setBusinessId(tenant.id);
      } catch {
        /* ignore */
      }
      if (!cancelled) await refresh();
    })();
    return () => {
      cancelled = true;
    };
  }, [refresh]);

  const logout = useCallback(() => {
    writeTokens(null, null);
    setUser(null);
  }, []);

  const value: AuthContextValue = {
    user,
    loading,
    isAdmin: user ? isWebsiteAdmin(user, businessId) : false,
    label: user ? `${displayName(user)} عزیز` : "",
    customerUrl: CUSTOMER_URL,
    businessUrl: BUSINESS_URL,
    profileUrl: `${CUSTOMER_URL}/profile`,
    loginUrl,
    logout,
    refresh,
  };

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

export function useAuth() {
  const ctx = useContext(AuthContext);
  if (!ctx) throw new Error("useAuth must be used within AuthProvider");
  return ctx;
}