rwImageInfo.go

package lib

import (
	"io/ioutil"
	"log"
	"os"

	jsoniter "github.com/json-iterator/go"
)

var json = jsoniter.ConfigCompatibleWithStandardLibrary

// ImageInfoChan - channel to send signal to write current state of imageInfo map into file
var ImageInfoChan = make(chan bool, 1000)

// WriteImageInfoToFile function writes current state of imageInfo map into file
func WriteImageInfoToFile(imageInfoChan chan bool) {
	for {
		_, ok := <-imageInfoChan
		if !ok {
			log.Println("ImageInfoChan closed:: writing to file storage is corrupted")
			return
		}

		ImageInfo.Lock()
		tempJSONByte, marshalErr := json.Marshal(ImageInfo.AlbumMap)
		ImageInfo.Unlock()
		if marshalErr != nil {
			log.Println("Error in marshalling ImageInfo: ", marshalErr)
		}

		fileWriteErr := ioutil.WriteFile("image-db/image-info.json", tempJSONByte, 0755)
		if fileWriteErr != nil {
			log.Println("Cannot write into image-info.json: ", fileWriteErr)
		}
	}
}

// ReadImageInfoFromFile function reads the image info on start of the application
func ReadImageInfoFromFile() {
	permErr := os.Chmod("image-db", 0777)
	if permErr != nil {
		log.Println("Error in setting folder permission: ", permErr)
	}

	_, statErr := os.Stat("image-db/image-info.json")
	if os.IsNotExist(statErr) {
		ImageInfoChan <- true
		log.Println("Writing initial database file")
	} else {
		byteFile, readErr := ioutil.ReadFile("image-db/image-info.json")
		if readErr != nil {
			panic(readErr)
		}

		ImageInfo.Lock()
		jsonbinderr := json.Unmarshal(byteFile, &ImageInfo.AlbumMap)
		ImageInfo.Unlock()
		if jsonbinderr != nil {
			panic(jsonbinderr)
		}
		log.Println("Reading existing database file")
	}
}