tasks/cmd/tools/gensearchattributehelpers/main.go

// The MIT License
//
// Copyright (c) 2020 Temporal Technologies Inc.  All rights reserved.
//
// Copyright (c) 2020 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package main

import (
	"flag"
	"fmt"
	"io"
	"log"
	"os"
	"path"
	"reflect"
	"regexp"
	"strings"
	"text/template"

	historypb "go.temporal.io/api/history/v1"
)

type (
	eventData struct {
		AttributesTypeName string
	}

	searchAttributesHelpersData struct {
		Events []eventData
	}
)

var (
	// Is used to find attribute getters and extract the event type (match[1]).
	attributesGetterRegex = regexp.MustCompile("^Get(.+EventAttributes)$")
)

func main() {
	outPathFlag := flag.String("out", ".", "path to write generated files")
	licenseFlag := flag.String("copyright_file", "LICENSE", "path to license to copy into header")
	flag.Parse()

	licenseText := readLicenseFile(*licenseFlag)

	eventHelpersFile := path.Join(*outPathFlag, "event_gen.go")
	callWithFile(generateSearchAttributesEventHelpers, eventHelpersFile, licenseText)
}

func generateSearchAttributesEventHelpers(w io.Writer) {

	writeSearchAttributesEventHelpers(w, `
package searchattribute

import (
	commonpb "go.temporal.io/api/common/v1"
	historypb "go.temporal.io/api/history/v1"
)

func SetToEvent(event *historypb.HistoryEvent, sas *commonpb.SearchAttributes) bool {
	switch e := event.GetAttributes().(type) {
	{{- range .Events}}
	case *historypb.HistoryEvent_{{.AttributesTypeName}}:
		e.{{.AttributesTypeName}}.SearchAttributes = sas
		return true
	{{- end}}
	default:
		return false
	}
}

func GetFromEvent(event *historypb.HistoryEvent) (*commonpb.SearchAttributes, bool) {
	switch e := event.GetAttributes().(type) {
	{{- range .Events}}
	case *historypb.HistoryEvent_{{.AttributesTypeName}}:
		return e.{{.AttributesTypeName}}.GetSearchAttributes(), true
	{{- end}}
	default:
		return nil, false
	}
}
`)
}

func writeSearchAttributesEventHelpers(w io.Writer, tmpl string) {
	sahd := searchAttributesHelpersData{}

	historyEventT := reflect.TypeOf((*historypb.HistoryEvent)(nil))

	for i := 0; i < historyEventT.NumMethod(); i++ {
		attributesGetter := historyEventT.Method(i)
		matches := attributesGetterRegex.FindStringSubmatch(attributesGetter.Name)
		if len(matches) < 2 {
			continue
		}
		if attributesGetter.Type.NumOut() != 1 {
			continue
		}
		if _, found := attributesGetter.Type.Out(0).MethodByName("GetSearchAttributes"); !found {
			continue
		}

		ed := eventData{
			AttributesTypeName: matches[1],
		}
		sahd.Events = append(sahd.Events, ed)
	}

	fatalIfErr(template.Must(template.New("code").Parse(tmpl)).Execute(w, sahd))
}

func callWithFile(generator func(io.Writer), outFile string, licenseText string) {
	w, err := os.Create(outFile)
	fatalIfErr(err)
	defer func() {
		fatalIfErr(w.Close())
	}()
	_, err = fmt.Fprintf(w, "%s\n// Code generated by cmd/tools/gensearchattributehelpers. DO NOT EDIT.\n", licenseText)
	fatalIfErr(err)
	generator(w)
}

func readLicenseFile(filePath string) string {
	text, err := os.ReadFile(filePath)
	if err != nil {
		panic(err)
	}
	var lines []string
	for _, line := range strings.Split(string(text), "\n") {
		lines = append(lines, strings.TrimRight("// "+line, " "))
	}
	return strings.Join(lines, "\n") + "\n"
}

func fatalIfErr(err error) {
	if err != nil {
		//nolint:revive // calls to log.Fatal only in main() or init() functions (revive)
		log.Fatal(err)
	}
}