package aggregate

import (
	"github.com/pingcap-inc/clinic/pkg/ngm/statements/api"
	"github.com/pingcap-inc/clinic/pkg/ngm/statements/load"
)

func AggDigest() Aggregator {
	return &Digest{}
}

type Digest struct {
	digest string
}

var _ Aggregator = (*Digest)(nil)

// Add implements Aggregator
func (a *Digest) Add(record *load.StmtRecord) {
	if a.digest != "" {
		return
	}
	a.digest = record.Digest
}

// Merge implements Aggregator
func (a *Digest) Merge(agg Aggregator) {
	if agg, ok := agg.(*Digest); ok {
		if a.digest == "" {
			a.digest = agg.digest
		}
	}
}

// Output implements Aggregator
func (a *Digest) Output(model *api.Model) {
	model.Digest = a.digest
}