add -use-cache parameter, use cache to improve performance (#83)

* enable batch generate

* add errgroup dep

* feat: add file cache to improve performance

* fix: remove errgroup dep

README.md

@@ -77,6 +77,8 @@ Usage of goimports-reviser:
         Set alias for versioned package names, like 'github.com/go-pg/pg/v9'. In this case import will be set as 'pg "github.com/go-pg/pg/v9"'. Optional parameter.
   -set-exit-status
     	set the exit status to 1 if a change is needed/made. Optional parameter.
+  -use-cache
+        Use cache to improve performance. Optional parameter.
 ```
 
 ## Install

go.mod

@@ -3,6 +3,7 @@ module github.com/incu6us/goimports-reviser/v3
 go 1.18
 
 require (
+	github.com/mitchellh/go-homedir v1.1.0
 	github.com/pkg/errors v0.9.1
 	github.com/stretchr/testify v1.6.1
 	golang.org/x/exp v0.0.0-20220722155223-a9213eeb770e

go.sum

@@ -6,6 +6,8 @@ github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORN
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
+github.com/mitchellh/go-homedir v1.1.0 h1:lukF9ziXFxDFPkA1vsr5zpc1XuPDn/wFntq5mG+4E0Y=
+github.com/mitchellh/go-homedir v1.1.0/go.mod h1:SfyaCUpYCn1Vlf4IUYiD9fPX4A5wJrkLzIz1N1q0pr0=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=

main.go

@@ -1,13 +1,18 @@
 package main
 
 import (
+	"crypto/md5"
+	"encoding/hex"
 	"flag"
 	"fmt"
 	"io/ioutil"
 	"log"
 	"os"
+	"path"
+	"path/filepath"
 	"strings"
 
+	"github.com/mitchellh/go-homedir"
 	"github.com/pkg/errors"
 
 	"github.com/incu6us/goimports-reviser/v3/helper"
@@ -26,6 +31,7 @@ const (
 	listDiffFileNameArg    = "list-diff"
 	setExitStatusArg       = "set-exit-status"
 	recursiveArg           = "recursive"
+	useCacheArg            = "use-cache"
 
 	// Deprecated options
 	localArg    = "local"
@@ -46,6 +52,7 @@ var (
 	listFileName              *bool
 	setExitStatus             *bool
 	isRecursive               *bool
+	isUseCache                *bool
 )
 
 var (
@@ -140,6 +147,12 @@ Optional parameter.`,
 		"Apply rules recursively if target is a directory. In case of ./... execution will be recursively applied by default. Optional parameter.",
 	)
 
+	isUseCache = flag.Bool(
+		useCacheArg,
+		false,
+		"Use cache to improve performance. Optional parameter.",
+	)
+
 	if Tag != "" {
 		shouldShowVersion = flag.Bool(
 			versionArg,
@@ -244,11 +257,68 @@ func main() {
 		return
 	}
 
-	formattedOutput, hasChange, err := reviser.NewSourceFile(originProjectName, originPath).Fix(options...)
+	originPath, err = filepath.Abs(originPath)
 	if err != nil {
 		log.Fatalf("%+v", errors.WithStack(err))
 	}
 
+	var formattedOutput []byte
+	var hasChange bool
+	if *isUseCache {
+		hash := md5.Sum([]byte(originPath))
+
+		var home string
+		if home, err = homedir.Dir(); err != nil {
+			log.Fatalf("%+v\n", errors.WithStack(err))
+		}
+		cacheDir := path.Join(home, ".cache", "goimports-reviser")
+		if err = os.MkdirAll(cacheDir, os.ModePerm); err != nil {
+			log.Fatalf("%+v\n", errors.WithStack(err))
+		}
+		cacheFile := path.Join(cacheDir, hex.EncodeToString(hash[:]))
+
+		var cacheContent, fileContent []byte
+		if cacheContent, err = ioutil.ReadFile(cacheFile); err == nil {
+			// compare file content hash
+			var fileHashHex string
+			if fileContent, err = ioutil.ReadFile(originPath); err == nil {
+				fileHash := md5.Sum(fileContent)
+				fileHashHex = hex.EncodeToString(fileHash[:])
+			}
+			if string(cacheContent) == fileHashHex {
+				// point to cache
+				return
+			}
+		}
+		formattedOutput, hasChange, err = reviser.NewSourceFile(originProjectName, originPath).Fix(options...)
+		if err != nil {
+			log.Fatalf("%+v", errors.WithStack(err))
+		}
+		fileHash := md5.Sum(formattedOutput)
+		fileHashHex := hex.EncodeToString(fileHash[:])
+		if fileInfo, err := os.Stat(cacheFile); err != nil || fileInfo.IsDir() {
+			if _, err = os.Create(cacheFile); err != nil {
+				log.Fatalf("%+v", errors.WithStack(err))
+			}
+		}
+		file, _ := os.OpenFile(cacheFile, os.O_RDWR, os.ModePerm)
+		defer file.Close()
+		if err = file.Truncate(0); err != nil {
+			log.Fatalf("%+v", errors.WithStack(err))
+		}
+		if _, err = file.Seek(0, 0); err != nil {
+			log.Fatalf("%+v", errors.WithStack(err))
+		}
+		if _, err = file.WriteString(fileHashHex); err != nil {
+			log.Fatalf("%+v", errors.WithStack(err))
+		}
+	} else {
+		formattedOutput, hasChange, err = reviser.NewSourceFile(originProjectName, originPath).Fix(options...)
+		if err != nil {
+			log.Fatalf("%+v", errors.WithStack(err))
+		}
+	}
+
 	resultPostProcess(hasChange, deprecatedMessagesCh, originPath, formattedOutput)
 }