CREATE TABLE IF NOT EXISTS reminders (
    id UUID PRIMARY KEY,
    user_uuid UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    message TEXT NOT NULL,
    timezone VARCHAR(64) NOT NULL,
    recurrence JSONB,
    next_run_at TIMESTAMPTZ NOT NULL,
    status VARCHAR(20) NOT NULL DEFAULT 'active',
    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    completed_at TIMESTAMPTZ,
    cancelled_at TIMESTAMPTZ,
    CONSTRAINT reminders_status_check
        CHECK (status IN ('active', 'completed', 'cancelled')),
    CONSTRAINT reminders_recurrence_check
        CHECK (recurrence IS NULL OR jsonb_typeof(recurrence) = 'object')
);

CREATE INDEX IF NOT EXISTS reminders_user_active_idx
    ON reminders (user_uuid, next_run_at)
    WHERE status = 'active';