package dns

type DomainRecordCache struct {
	domains map[string]RecordList
	fetcher Fetcher
}

type Fetcher func(domain string) (RecordList, error)

func NewDomainRecordCache(fetcher Fetcher) *DomainRecordCache {
	return &DomainRecordCache{
		fetcher: fetcher,
		domains: make(map[string]RecordList),
	}
}

func (c *DomainRecordCache) Get(domain string) (RecordList, error) {
	records, ok := c.domains[domain]
	if !ok {
		var err error
		records, err = c.fetcher(domain)
		if err != nil {
			return nil, err
		}
		c.domains[domain] = records
	}
	return records, nil
}