package promremotewrite

import (
	"net/http"

	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/common"
	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/remotewrite"
	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompb"
	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
	parser "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/promremotewrite"
	"github.com/VictoriaMetrics/VictoriaMetrics/lib/writeconcurrencylimiter"
	"github.com/VictoriaMetrics/metrics"
)

var (
	rowsInserted  = metrics.NewCounter(`vmagent_rows_inserted_total{type="promremotewrite"}`)
	rowsPerInsert = metrics.NewHistogram(`vmagent_rows_per_insert{type="promremotewrite"}`)
)

// InsertHandler processes remote write for prometheus.
func InsertHandler(req *http.Request) error {
	return writeconcurrencylimiter.Do(func() error {
		return parser.ParseStream(req, insertRows)
	})
}

func insertRows(timeseries []prompb.TimeSeries) error {
	ctx := common.GetPushCtx()
	defer common.PutPushCtx(ctx)

	rowsTotal := 0
	tssDst := ctx.WriteRequest.Timeseries[:0]
	labels := ctx.Labels[:0]
	samples := ctx.Samples[:0]
	for i := range timeseries {
		ts := &timeseries[i]
		labelsLen := len(labels)
		for i := range ts.Labels {
			label := &ts.Labels[i]
			labels = append(labels, prompbmarshal.Label{
				Name:  bytesutil.ToUnsafeString(label.Name),
				Value: bytesutil.ToUnsafeString(label.Value),
			})
		}
		samplesLen := len(samples)
		for i := range ts.Samples {
			sample := &ts.Samples[i]
			samples = append(samples, prompbmarshal.Sample{
				Value:     sample.Value,
				Timestamp: sample.Timestamp,
			})
		}
		tssDst = append(tssDst, prompbmarshal.TimeSeries{
			Labels:  labels[labelsLen:],
			Samples: samples[samplesLen:],
		})
		rowsTotal += len(ts.Samples)
	}
	ctx.WriteRequest.Timeseries = tssDst
	ctx.Labels = labels
	ctx.Samples = samples
	remotewrite.Push(&ctx.WriteRequest)
	rowsInserted.Add(rowsTotal)
	rowsPerInsert.Update(float64(rowsTotal))
	return nil
}