package com.ufund.api.ufundapi.persistence;

import java.io.IOException;

import com.ufund.api.ufundapi.model.User;


/**
 * Defines the interface for User object persistence
 * 
 * @author Team 2B Jelly Solutions
 */
public interface UserDAO {
    /**
     * Retrieves all {@linkplain User users}
     * 
     * @return An array of {@link User user} objects, may be empty
     * 
     * @throws IOException if an issue with underlying storage
     */
    User[] getUsers() throws IOException;

    /**
     * Retrieves a {@linkplain User user} with the given username
     * 
     * @param username The ID of the {@link User user} to get
     * 
     * @return a {@link User user} object with the matching username
     *         <br>
     *         null if no {@link User user} with a matching username is found
     * 
     * @throws IOException if an issue with underlying storage
     */
    User getUser(String username) throws IOException;

    /**
     * Retrieves the total count of users
     *
     * @return a {@link int amount} number of users
     *         <br>
     *
     * @throws IOException if an issue with underlying storage
     */
    int getUserCount() throws IOException;

    /**
     * Creates and saves a {@linkplain User user}
     * 
     * @param user {@linkplain User user} object to be created and saved
     *             <br>
     *             The id of the user object is automatically incremented.
     *
     * @return new {@link User user} if successful, null otherwise
     * 
     * @throws IOException if an issue with underlying storage
     */
    User addUser(User user) throws IOException;

    /**
     * Updates and saves a {@linkplain User user}
     * 
     * @param user {@link User user} object to be updated and saved
     * 
     * @return updated {@link User user} if successful, null if
     *         {@link User user} could not be found
     * 
     * @throws IOException if underlying storage cannot be accessed
     */
    User updateUser(User user) throws IOException;

    /**
     * Deletes a {@linkplain User user} with the given id
     * 
     * @param username The id of the {@link User user}
     * 
     * @return true if the {@link User user} was deleted
     *         <br>
     *         false if the user with the given id does not exist
     * 
     * @throws IOException if underlying storage cannot be accessed
     */
    boolean deleteUser(String username) throws IOException;
}