package diff2

import (
	"github.com/StackExchange/dnscontrol/v4/models"
	"github.com/StackExchange/dnscontrol/v4/pkg/prettyzone"
)

type recset struct {
	Key  models.RecordKey
	Recs []*models.RecordConfig
}

func groupbyRSet(recs models.Records, origin string) []recset {

	if len(recs) == 0 {
		return nil
	}

	// Sort the NameFQDN to a consistent order. The actual sort methodology
	// doesn't matter as long as equal values are adjacent.
	// Use the PrettySort ordering so that the records are extra pretty.
	pretty := prettyzone.PrettySort(recs, origin, 0, nil)
	recs = pretty.Records

	var result []recset
	var acc []*models.RecordConfig

	// Do the first element
	prevkey := recs[0].Key()
	acc = append(acc, recs[0])

	for i := 1; i < len(recs); i++ {
		curkey := recs[i].Key()
		if prevkey == curkey { // A run of equal keys.
			acc = append(acc, recs[i])
		} else { // New key. Append old data to result and start new acc.
			result = append(result, recset{Key: prevkey, Recs: acc})
			acc = []*models.RecordConfig{recs[i]}
		}
		prevkey = curkey
	}
	result = append(result, recset{Key: prevkey, Recs: acc}) // The remainder

	return result
}