apskel-pos-backend/migrations/000094_add_point_payment_method.up.sql

-- Paying with EnakPoint (docs/prd-point-coin.md F9, §8, §10.5).

-- A new payment method type, next to the existing ones (edc and delivery were added to
-- the constraint outside the migrations). Every organization has exactly one method of it, made by
-- the system, which cannot be deleted or change type.
ALTER TABLE payment_methods DROP CONSTRAINT IF EXISTS payment_methods_type_check;
ALTER TABLE payment_methods ADD CONSTRAINT payment_methods_type_check
    CHECK (type IN ('cash', 'card', 'digital_wallet', 'qr', 'edc', 'delivery', 'point'));

CREATE UNIQUE INDEX uq_payment_methods_point_per_organization ON payment_methods(organization_id)
    WHERE type = 'point';

INSERT INTO payment_methods (organization_id, name, type, is_active)
SELECT id, 'EnakPoint', 'point', TRUE FROM organizations
ON CONFLICT (organization_id) WHERE type = 'point' DO NOTHING;

-- New organizations get theirs the same way they get their walk-in customer, whatever
-- code path creates them.
CREATE OR REPLACE FUNCTION create_point_payment_method()
RETURNS TRIGGER AS $$
BEGIN
    INSERT INTO payment_methods (organization_id, name, type, is_active)
    VALUES (NEW.id, 'EnakPoint', 'point', TRUE)
    ON CONFLICT (organization_id) WHERE type = 'point' DO NOTHING;
    RETURN NEW;
END;
$$ LANGUAGE plpgsql;

CREATE TRIGGER trigger_create_point_payment_method
    AFTER INSERT ON organizations
    FOR EACH ROW
    EXECUTE FUNCTION create_point_payment_method();

-- A payment made with EnakPoint records how many were used and the rupiah value of one
-- at that moment. The value is frozen so a refund returns exactly the EnakPoint used,
-- whatever the value is by then.
--
-- Written so it never evaluates to NULL: the form in the PRD, (both NULL) OR (both
-- > 0), is NULL for points_used = 1000 with point_value NULL, and a CHECK only rejects
-- FALSE, so a payment could lose its frozen value.
ALTER TABLE payments
    ADD COLUMN points_used BIGINT,
    ADD COLUMN point_value DECIMAL(10,2),
    ADD CONSTRAINT chk_payments_point_pair CHECK (
        (points_used IS NULL) = (point_value IS NULL)
        AND (points_used IS NULL OR (points_used > 0 AND point_value > 0)));