-- Multiple exact sender domains per vendor.
CREATE TABLE IF NOT EXISTS vendor_email_domains (
    domain TEXT PRIMARY KEY,
    vendor_id INTEGER NOT NULL REFERENCES vendors(id) ON DELETE CASCADE,
    created_at TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP
);

CREATE INDEX IF NOT EXISTS idx_vendor_email_domains_vendor_id
    ON vendor_email_domains(vendor_id);

INSERT INTO vendor_email_domains (domain, vendor_id)
SELECT LOWER(TRIM(domain)), id
FROM vendors
WHERE NULLIF(TRIM(domain), '') IS NOT NULL
ON CONFLICT (domain) DO NOTHING;

-- Also promote the legacy single customer domain into the existing
-- multi-domain mapping table.
INSERT INTO email_domain_customer_mappings (domain, customer_id, source)
SELECT LOWER(TRIM(email_domain)), id, 'legacy_customer_domain'
FROM customers
WHERE NULLIF(TRIM(email_domain), '') IS NOT NULL
ON CONFLICT (domain) DO NOTHING;

COMMENT ON TABLE vendor_email_domains IS
    'Exact trusted sender domains belonging to vendors; no fuzzy matching.';