time_series.go

package search

import (
	"bytes"
	"context"
	"encoding/json"
	"io/ioutil"
	"net/http"
	"reflect"
	"strings"
	"time"

	opensearchapi "github.com/opensearch-project/opensearch-go/opensearchapi"
	"gitlab.com/uafrica/go-utils/errors"
	"gitlab.com/uafrica/go-utils/logger"
	"gitlab.com/uafrica/go-utils/reflection"
)

const TimeFormat = "2006-01-02T15:04:05+07:00"

//embed this into your log struct
type TimeSeriesHeader struct {
	StartTime  time.Time `json:"@timestamp"`
	EndTime    time.Time `json:"@end_time"`
	DurationMs int64     `json:"@duration_ms"`
}

type TimeSeries interface {
	Write(StartTime time.Time, EndTime time.Time, data interface{}) error
	Search(query Query, limit int64) (docs interface{}, totalCount int, err error)
}

type timeSeries struct {
	w            *writer
	name         string
	dataType     reflect.Type
	settings     Settings
	mappings     Mappings
	jsonSettings []byte
	jsonMappings []byte
	createdDates map[string]bool

	searchResponseBodyType reflect.Type
}

//purpose:
//	create a time series to write e.g. api logs
//parameters:
//	name must be the openSearch index name prefix without the date, e.g. "uafrica-v3-api-logs"
//		the actual indices in openSearch will be called "<indexName>-<ccyymmdd>" e.g. "uafrica-v3-api-logs-20210102"
//	tmpl must be your log data struct consisting of public fields as:
//		Xxx string `json:"<name>" search:"keyword|text|long|date"`	(can later add more types)
//		Xxx time.Time `json:"<name>"`								assumes type "date" for opensearch
//		Xxx int `json:"<name>"`										assumes type "long" for opensearch, specify keyword if required
func (w *writer) TimeSeries(name string, tmpl interface{}) (TimeSeries, error) {
	if !indexNameRegex.MatchString(name) {
		return nil, errors.Errorf("invalid index_name:\"%s\"", name)
	}

	//if already created, just return
	if existingTimeSeries, ok := w.timeSeriesByName[name]; ok {
		return existingTimeSeries, nil
	}

	structType := reflect.TypeOf(tmpl)
	if tmpl == nil || structType.Kind() != reflect.Struct {
		return nil, errors.Errorf("%T is not a struct", tmpl)
	}
	if structType.NumField() < 1 || !structType.Field(0).Anonymous || structType.Field(0).Type != reflect.TypeOf(TimeSeriesHeader{}) {
		return nil, errors.Errorf("%T does not start with anonymous TimeSeriesHeader", tmpl)