import { createContext, useContext, useState, useCallback } from "react";
import api from "@/utils/api.util";
import { toast } from "sonner";

const UserContext = createContext(null);

export const useUsers = () => {
  const ctx = useContext(UserContext);
  if (!ctx) throw new Error("useUsers must be used inside UserProvider");
  return ctx;
};

const PAGINATION_INIT = {
  page: 1,
  limit: 10,
  totalRecords: 0,
  totalPages: 0,
  hasPrevPage: false,
  hasNextPage: false,
};

const BASE = "/admin";

export const UserProvider = ({ children }) => {
  const [users, setUsers] = useState([]);
  const [user, setUser] = useState(null);
  const [sessions, setSessions] = useState([]);
  const [pagination, setPagination] = useState(PAGINATION_INIT);
  const [attributes, setAttributes] = useState([]);
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState(null);

  const request = useCallback(async (fn) => {
    setLoading(true);
    setError(null);
    try {
      return await fn();
    } catch (err) {
      const message = err?.response?.data?.message || err.message || "Something went wrong.";
      setError(message);
      toast.error(message);
      return null;
    } finally {
      setLoading(false);
    }
  }, []);

  // ─── GET /api/admin/users ──────────────────────────────────────────────────
  const fetchUsers = useCallback(
    ({ page = 1, limit = 10, filters = [], sort = [] } = {}) =>
      request(async () => {
        const { data } = await api.get(`${BASE}/users`, {
          params: {
            page, limit,
            filters: filters.length ? JSON.stringify(filters) : undefined,
            sort:    sort.length    ? JSON.stringify(sort)    : undefined,
          },
        });
        const final_data = data?.data;
        setUsers(final_data?.data ?? []);
        setPagination(final_data?.pagination ?? PAGINATION_INIT);
        setAttributes(final_data?.attributes ?? []);
        return data?.data;
      }),
    [request]
  );

  // ─── GET /api/admin/users/archived ────────────────────────────────────────
  const fetchArchivedUsers = useCallback(
    ({ page = 1, limit = 10, filters = [], sort = [] } = {}) =>
      request(async () => {
        const { data } = await api.get(`${BASE}/users/archived`, {
          params: {
            page, limit,
            filters: filters.length ? JSON.stringify(filters) : undefined,
            sort:    sort.length    ? JSON.stringify(sort)    : undefined,
          },
        });
        const final_data = data?.data;
        setUsers(final_data?.data ?? []);
        setPagination(final_data?.pagination ?? PAGINATION_INIT);
        setAttributes(final_data?.attributes ?? []);
        return data?.data;
      }),
    [request]
  );

  // ─── GET /api/admin/users/:id ─────────────────────────────────────────────
  const fetchUser = useCallback(
    (userId) =>
      request(async () => {
        const res = await api.get(`${BASE}/users/${userId}`);
        setUser(res.data?.data ?? null);
        return res.data;
      }),
    [request]
  );

  // ─── POST /api/admin/users/staff ──────────────────────────────────────────
  const addStaffUser = useCallback(
    (payload) =>
      request(async () => {
        const res = await api.post(`${BASE}/users/staff`, payload);
        toast.success("Staff user added successfully.");
        return res.data;
      }),
    [request]
  );

  // ─── PUT /api/admin/users/:id ─────────────────────────────────────────────
  const updateUser = useCallback(
    (userId, payload) =>
      request(async () => {
        const res = await api.put(`${BASE}/users/${userId}`, payload);
        setUsers((prev) =>
          prev.map((u) => (u.user_id === userId ? { ...u, ...res.data?.data } : u))
        );
        toast.success("User updated successfully.");
        return res.data;
      }),
    [request]
  );

  // ─── DELETE /api/admin/users/:id ──────────────────────────────────────────
  const deactivateUser = useCallback(
    (userId) =>
      request(async () => {
        const res = await api.delete(`${BASE}/users/${userId}`);
        setUsers((prev) =>
          prev.map((u) => (u.user_id === userId ? { ...u, is_active: false } : u))
        );
        toast.success("User deactivated.");
        return res.data;
      }),
    [request]
  );

  // ─── DELETE /api/admin/users/bulk ─────────────────────────────────────────
  const deactivateUsers = useCallback(
    ({ ids }) =>
      request(async () => {
        const res = await api.delete(`${BASE}/users/bulk`, { data: { ids } });
        const { deactivated_ids } = res.data?.data ?? {};
        if (deactivated_ids?.length) {
          setUsers((prev) =>
            prev.map((u) =>
              deactivated_ids.includes(u.user_id) ? { ...u, is_active: false } : u
            )
          );
          toast.success(`${deactivated_ids.length} user(s) deactivated.`);
        }
        return res.data;
      }),
    [request]
  );

  // ─── POST /api/admin/users/:id/restore ────────────────────────────────────
  const restoreUser = useCallback(
    (userId) =>
      request(async () => {
        const res = await api.post(`${BASE}/users/${userId}/restore`);
        setUsers((prev) =>
          prev.map((u) => (u.user_id === userId ? { ...u, is_active: true } : u))
        );
        toast.success("User restored.");
        return res.data;
      }),
    [request]
  );

  // ─── POST /api/admin/users/bulk/restore ───────────────────────────────────
  const restoreUsers = useCallback(
    ({ ids }) =>
      request(async () => {
        const res = await api.post(`${BASE}/users/bulk/restore`, { ids });
        const { restored_ids } = res.data?.data ?? {};
        if (restored_ids?.length) {
          setUsers((prev) =>
            prev.map((u) =>
              restored_ids.includes(u.user_id) ? { ...u, is_active: true } : u
            )
          );
          toast.success(`${restored_ids.length} user(s) restored.`);
        }
        return res.data;
      }),
    [request]
  );

  // ─── GET /api/admin/users/:id/sessions ────────────────────────────────────
  const fetchUserSessions = useCallback(
    (userId) =>
      request(async () => {
        const res = await api.get(`${BASE}/users/${userId}/sessions`);
        setSessions(res.data?.data ?? []);
        return res.data;
      }),
    [request]
  );

  // ─── DELETE /api/admin/users/:id/sessions/:sid ────────────────────────────
  const terminateSession = useCallback(
    (userId, sessionId) =>
      request(async () => {
        const res = await api.delete(`${BASE}/users/${userId}/sessions/${sessionId}`);
        setSessions((prev) =>
          prev.map((s) => (s.session_id === sessionId ? { ...s, is_active: false } : s))
        );
        toast.success("Session terminated.");
        return res.data;
      }),
    [request]
  );

  // ─── GET /api/admin/users/field-values ────────────────────────────────────
  const fetchUserFieldValues = useCallback(
    (field) =>
      request(async () => {
        const res = await api.get(`${BASE}/users/field-values`, { params: { field } });
        return res.data?.data;
      }),
    [request]
  );

  return (
    <UserContext.Provider value={{
      users, user, sessions, pagination, attributes, loading, error,
      setPagination,
      fetchUsers, fetchArchivedUsers, fetchUser,
      addStaffUser, updateUser,
      deactivateUser, deactivateUsers,
      restoreUser, restoreUsers,
      fetchUserSessions, terminateSession,
      fetchUserFieldValues,
    }}>
      {children}
    </UserContext.Provider>
  );
};