import { create as batshitCreate, keyResolver } from "@yornaath/batshit";
import { create } from "zustand";
import { immer } from "zustand/middleware/immer";
import { getUser } from "~/lib/api/client/user";
import type { FullUser, PartialUser, UserId } from "~/lib/api/types";

type UsersStore = {
    users: Record<UserId, PartialUser>;
    currentUserId: UserId | undefined;
    fetchUsersIfNotPresent: (userIds: UserId[]) => Promise<void>;
    addUser: (user: PartialUser) => void;
    removeUser: (userId: UserId) => void;
    setCurrentUserId: (userId: UserId) => void;
    getCurrentUser: () => FullUser | undefined;
};

const usersFetcher = batshitCreate({
    fetcher: async (userIds: UserId[]) => {
        const users = [];

        for (const userId of userIds) {
            users.push(getUser(userId));
        }

        return await Promise.all(users);
    },
    resolver: keyResolver("id"),
});

export const useUsersStore = create<UsersStore>()(
    immer((set, get) => ({
        users: {},
        currentUserId: undefined,
        fetchUsersIfNotPresent: async (userIds) => {
            const userPromises: Promise<PartialUser>[] = [];
            for (const userId of userIds) {
                const user = get().users[userId];
                if (!user) {
                    userPromises.push(usersFetcher.fetch(userId));
                }
            }

            const users = await Promise.all(userPromises);
            const activeUsers = users.filter(Boolean);

            set((state) => {
                for (const user of activeUsers) {
                    if (user?.id) state.users[user.id] = user;
                }
            });
        },
        addUser: (user) =>
            set((state) => {
                if (user.id !== get().currentUserId) state.users[user.id] = user;
                else {
                    const currentUser = get().users[user.id];
                    if (currentUser) state.users[user.id] = { ...currentUser, ...user };
                    else state.users[user.id] = user;
                }
            }),
        removeUser: (userId) =>
            set((state) => {
                delete state.users[userId];
            }),

        setCurrentUserId: (userId) =>
            set((state) => {
                state.currentUserId = userId;
            }),

        getCurrentUser: () => (get().currentUserId ? (get().users[get().currentUserId!] as FullUser) : undefined),
    })),
);