Add flags for loading and saving to json file

main.go

@@ -4,14 +4,30 @@ import (
 	"crypto/sha256"
 	"encoding/base64"
 	"encoding/json"
+	"flag"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"os"
 	"path/filepath"
 )
 
 func main() {
-	filesMap := newFilesMap()
+	fromFile := flag.String("from-file", "", "Load results file from <path>")
+	toFile := flag.String("to-file", "", "Save results to <path>")
+	flag.Parse()
+
+	var filesMap filesMap
+	if *fromFile != "" {
+
+		byteValue, _ := ioutil.ReadFile(*fromFile)
+
+		// we unmarshal our byteArray which contains our
+		// jsonFile's content into 'users' which we defined above
+		json.Unmarshal(byteValue, &filesMap)
+	} else {
+		filesMap = newFilesMap()
+
 		for _, path := range os.Args[1:] {
 			filepath.Walk(path, func(path string, info os.FileInfo, err error) error {
 				filesMap.Add(path, info)
@@ -19,9 +35,12 @@ func main() {
 			})
 			fmt.Println(path)
 		}
+	}
 
+	if *toFile != "" && *fromFile == "" {
 		json, _ := json.MarshalIndent(filesMap.FilesBySize, "", "  ")
-	fmt.Printf("\n\n\n%s\n\n\n", json)
+		ioutil.WriteFile(*toFile, json, 644)
+	}
 }
 
 type filesMap struct {
@@ -64,6 +83,7 @@ func (fm *filesMap) Add(path string, info os.FileInfo) error {
 		return err2
 	}
 
+	// for later files always append by hash
 	return appendByFileHash(filesByHash, fileInfo)
 }