package com.ufund.api.ufundapi.persistence;

import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Objects;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.ufund.api.ufundapi.model.User;

@Component
public class UserFileDAO implements UserDAO {

    private final Map<String, User> users; // cache
    private final ObjectMapper objectMapper;
    private final String filename;

    public UserFileDAO(@Value("${users.file}") String filename, ObjectMapper objectMapper) throws IOException {
        this.filename = filename;
        this.objectMapper = objectMapper;
        users = new HashMap<>();
        load(); // load the users from the file
    }

    /**
     * Load changes from the json file
     *
     * @throws IOException Any IO issue with the file
     */
    private void load() throws IOException {
        users.clear();

        User[] usersArray = objectMapper.readValue(new File(filename), User[].class);

        for (User user : usersArray) {
            users.put(user.getUsername(), user);
        }
    }

    /**
     * Saves the needs to json
     *
     * @throws IOException If there was an IO issue saving the file
     */
    private void save() throws IOException {
        objectMapper.writeValue(new File(filename), users.values());
    }

    @Override
    public User[] getUsers() {
        synchronized (users) {
            return users.values().toArray(User[]::new);
        }
    }

    @Override
    public int getUserCount() {
        synchronized (users) {
            return users.size();
        }
    }

    @Override
    public User getUser(String username) {
        synchronized (users) {
            return users.getOrDefault(username, null);
        }
    }

    @Override
    public User addUser(User user) throws IOException {
        synchronized (users) {
            var res = users.putIfAbsent(user.getUsername(), user);
            save();
            if (res == null) {
                return user;
            }
            return res;
        }
    }

    @Override
    public User updateUser(User user) throws IOException {
        synchronized (users) {
            if (users.containsKey(user.getUsername())) {
                var old = users.put(user.getUsername(), user);
                user.copyPassword(Objects.requireNonNull(old));
                save();
                return user;
            } else {
                return null;
            }
        }
    }

    @Override
    public boolean deleteUser(String username) throws IOException {
        synchronized (users) {
            if (users.containsKey(username)) {
                users.remove(username);
                save();
                return true;
            } else {
                return false;
            }
        }
    }

}