import json
import os

def load_json(filename):
    if not os.path.exists(filename):
        return []
    with open(filename, 'r', encoding='utf-8') as f:
        return json.load(f)

def save_json(filename, data):
    with open(filename, 'w', encoding='utf-8') as f:
        json.dump(data, f, indent=4, ensure_ascii=False)

def add_entry(filename, entry):
    data = load_json(filename)
    data.append(entry)
    save_json(filename, data)
    return entry

def update_entry(filename, entry_id, new_entry):
    data = load_json(filename)
    for i, item in enumerate(data):
        if item.get('id') == entry_id:
            data[i] = new_entry
            save_json(filename, data)
            return new_entry
    return None

def delete_entry(filename, entry_id):
    data = load_json(filename)
    new_data = [item for item in data if item.get('id') != entry_id]
    save_json(filename, new_data)
    return len(data) != len(new_data)