-- Пользователи
CREATE TABLE users (
    user_id SERIAL PRIMARY KEY,
    username VARCHAR(255) UNIQUE NOT NULL,
    email VARCHAR(255) UNIQUE NOT NULL,
    password VARCHAR(255) NOT NULL,
    full_name VARCHAR(255),
    date_joined TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

-- Посты
CREATE TABLE posts (
    post_id SERIAL PRIMARY KEY,
    user_id INT REFERENCES users(user_id),
    content TEXT NOT NULL,
    post_date TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

-- Комментарии
CREATE TABLE comments (
    comment_id SERIAL PRIMARY KEY,
    user_id INT REFERENCES users(user_id),
    post_id INT REFERENCES posts(post_id),
    content TEXT NOT NULL,
    comment_date TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

-- Лайки
CREATE TABLE likes (
    like_id SERIAL PRIMARY KEY,
    user_id INT REFERENCES users(user_id),
    post_id INT REFERENCES posts(post_id),
    comment_id INT REFERENCES comments(comment_id),
    like_date TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

-- Друзья
CREATE TABLE friends (
    friendship_id SERIAL PRIMARY KEY,
    user1_id INT REFERENCES users(user_id),
    user2_id INT REFERENCES users(user_id),
    friendship_date TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);