pbconfig/load.go

package config

// functions to import and export the protobuf
// data to and from config files

import (
	"errors"
	"os"
	"path/filepath"
	"strings"

	"go.wit.com/log"
	"google.golang.org/protobuf/encoding/protojson"
	"google.golang.org/protobuf/encoding/prototext"
	"google.golang.org/protobuf/proto"
)

/*
// loads a file from ~/.config/<argname>/
func Load(argname string) ([]byte, string) {
}
*/

var ErrEmpty error = log.Errorf("file was empty")

// returns:
//   - Full path to the config file. usually: ~/.config/<argname>
//   - []byte  : the contents of the file
//   - error on read
func ConfigLoad(pb proto.Message, argname string, protoname string) error {
	var fullname string
	homeDir, err := os.UserHomeDir()
	if err != nil {
		log.Warn("ConfigLoad() UserHomeDir() err", err)
		return err
	}

	fullname = filepath.Join(homeDir, ".config", argname, protoname+".text")

	if err := loadTEXT(pb, fullname); err == nil {
		return nil
	}

	if strings.HasSuffix(fullname, ".text") {
		fullname += ".json"
		if err := loadJSON(pb, fullname); err != nil {
			return err
		}
		return nil
	}

	log.Info("Config file load failed:", fullname)
	return log.Errorf("could not load config file")
}

func LoadPB(pb proto.Message, argname string, protoname string) (string, error) {
	var fullname string
	if strings.HasPrefix(argname, "/") {
		fullname = filepath.Join(argname, protoname+".pb")
	} else {
		homeDir, err := os.UserHomeDir()
		if err != nil {
			log.Warn("ConfigLoad() UserHomeDir() err", err)
			return "", err
		}

		fullname = filepath.Join(homeDir, ".config", argname, protoname+".pb")
	}

	data, err := loadFile(fullname)
	if err != nil {
		log.Warn("LoadPB()", fullname, err)
		// set pb.Filename that was attempted
		return fullname, err
	}

	// Unmarshal()
	if err = proto.Unmarshal(data, pb); err != nil {
		log.Warn("LoadPB() file", fullname)
		log.Warn("LoadPB() Unmarshal() err", err)
		return fullname, err
	}

	return fullname, nil
}

func loadTEXT(pb proto.Message, fullname string) error {
	var data []byte
	var err error
	SetFilename(pb, fullname)
	if data, err = loadFile(fullname); err != nil {
		log.Warn("config file failed to load", err)
		// set pb.Filename that was attempted
		return err
	}

	// don't even bother with Marshal()
	if data == nil {
		log.Warn("ConfigLoad() config file was empty", fullname)
		return ErrEmpty // file is empty
	}

	// Unmarshal()
	if err = prototext.Unmarshal(data, pb); err != nil {
		log.Warn("ConfigLoad() file", fullname)
		log.Warn("ConfigLoad() Unmarshal() err", err)
		return err
	}

	if fn, ok := GetFilename(pb); ok {
		if fn != fullname {
			log.Info("config.ConfigLoad() new filename:", fullname)
			SetFilename(pb, fullname)
		}
	}

	if os.Getenv("CONFIG_VERBOSE") == "true" {
		log.Infof("ConfigLoad() %s len()=%d\n", fullname, len(data))
	}
	return nil
}

// json files are backup Marshal() data in case .text Unmarshal() fails
// they always should have the ".text" filename in them
func loadJSON(pb proto.Message, fullname string) error {
	var data []byte
	var err error
	if data, err = loadFile(fullname); err != nil {
		log.Warn("config file failed to load", err)
		return err
	}

	// don't even bother with Marshal()
	if data == nil {
		log.Warn("ConfigLoad() config file was empty", fullname)
		return ErrEmpty // file is empty
	}

	// Unmarshal()
	if err = protojson.Unmarshal(data, pb); err != nil {
		log.Warn("ConfigLoad() file", fullname)
		log.Warn("ConfigLoad() Unmarshal() err", err)
		return err
	}

	if fn, ok := GetFilename(pb); ok {
		if fn != fullname {
			log.Info("config.ConfigLoad() new filename:", fullname)
			SetFilename(pb, fullname)
		}
	}

	if os.Getenv("CONFIG_VERBOSE") == "true" {
		log.Infof("ConfigLoad() %s len()=%d\n", fullname, len(data))
	}
	return nil
}

func loadFile(fullname string) ([]byte, error) {
	data, err := os.ReadFile(fullname)
	if errors.Is(err, os.ErrNotExist) {
		// if file does not exist, just return nil. this
		return nil, err
	}
	if err != nil {
		// log.Info("open config file :", err)
		return nil, err
	}
	return data, nil
}