CREATE TABLE users (
    id SERIAL PRIMARY KEY,
    username VARCHAR(50) UNIQUE NOT NULL,
    email VARCHAR(255) UNIQUE NOT NULL,
    password_hash VARCHAR(255) NOT NULL,
    is_verified BOOLEAN DEFAULT FALSE,
    created_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP
);

CREATE TABLE verification_codes (
    id SERIAL PRIMARY KEY,
    user_id INT REFERENCES users(id) ON DELETE CASCADE,
    code VARCHAR(6) NOT NULL,
    expires_at TIMESTAMP WITH TIME ZONE NOT NULL,
    used BOOLEAN DEFAULT FALSE,
    created_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP
);

CREATE TABLE messages (
    id SERIAL PRIMARY KEY,
    sender_id INT REFERENCES users(id),
    receiver_id INT REFERENCES users(id),
    content TEXT NOT NULL,
    sent_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP
);