package com.ufund.api.ufundapi.persistence;

import java.io.File;
import java.io.IOException;
import java.util.Map;
import java.util.TreeMap;

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

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

@Component
public class CupboardFileDAO implements CupboardDAO {

    private final Map<Integer, Need> needs; // cache
    private final ObjectMapper objectMapper;
    private int nextId;
    private final String filename;

    public CupboardFileDAO(@Value("${cupboard.file}") String filename, ObjectMapper objectMapper) throws IOException {
        this.filename = filename;
        this.objectMapper = objectMapper;
        needs = new TreeMap<>();
        load();
    }

    private synchronized int nextId() {
        int id = nextId;
        nextId++;
        return id;
    }

    /**
     * Load changes from the json file
     *
     * @throws IOException Any IO issue with the file
     */
    private void load() throws IOException {
        needs.clear();
        nextId = 0;

        Need[] needsArray = objectMapper.readValue(new File(filename), Need[].class);

        for (Need need : needsArray) {
            needs.put(need.getId(), need);
            if (need.getId() > nextId()) {
                nextId = need.getId();
            }
        }
        nextId++;
    }

    /**
     * Saves the needs to json
     *
     * @throws IOException If there was an IO issue saving the file
     */
    private void save() throws IOException {
        Need[] needArray = needs.values().toArray(Need[]::new);

        objectMapper.writeValue(new File(filename), needArray);
    }

    @Override
    public Need[] getNeeds() {
        synchronized (needs) {
            return needs.values().toArray(Need[]::new);
        }
    }

    @Override
    public Need getNeed(int id) {
        synchronized (needs) {
            return needs.getOrDefault(id, null);
        }
    }

    @Override
    public Need addNeed(Need need) throws IOException {
        synchronized (needs) {
            Need newNeed = new Need(need);
            newNeed.setID(nextId());
            needs.put(newNeed.getId(), newNeed);
            save();
            return newNeed;
        }
    }

    @Override
    public Need updateNeed(Need need) throws IOException {
        synchronized (needs) {
            if (needs.containsKey(need.getId())) {
                needs.put(need.getId(), need);
                save();
                return need;
            } else {
                return null;
            }

        }
    }

    @Override
    public boolean deleteNeed(int id) throws IOException {
        synchronized (needs) {
            if (needs.containsKey(id)) {
                needs.remove(id);
                save();
                return true;
            } else {
                return false;
            }
        }
    }
}