CREATE TABLE IF NOT EXISTS notifications (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    user_id UUID NOT NULL REFERENCES users(id),
    channel VARCHAR(20) NOT NULL CHECK (channel IN ('push', 'sms', 'email', 'in_app')),
    title VARCHAR(200) NOT NULL,
    body TEXT NOT NULL,
    data JSONB,
    status VARCHAR(20) NOT NULL DEFAULT 'pending' CHECK (status IN ('pending', 'sent', 'failed', 'read')),
    sent_at TIMESTAMPTZ,
    read_at TIMESTAMPTZ,
    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
);

CREATE INDEX idx_notifications_user ON notifications(user_id);
CREATE INDEX idx_notifications_status ON notifications(user_id, status);