do refactoring

Author: hikaru7719

kadai2/miyahara/converter/TestData/jpg/testData.jpg

@@ -0,0 +1,139 @@
+package converter
+
+import (
+	"errors"
+	"fmt"
+	"image"
+	"image/jpeg"
+	"image/png"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// Converter Convert jpg to png or png to jpg.
+// In represent a input file type.
+// Out represent a output file type.
+// Directory represent a target directory.
+type Converter struct {
+	in        string
+	out       string
+	directory string
+}
+
+// FileSet is Set of input file name and output file name.
+type FileSet struct {
+	inputFileName  string
+	outputFileName string
+}
+
+// New return a new Converter.
+func New(in, out, directory string) *Converter {
+	return &Converter{in: in, out: out, directory: directory}
+}
+
+// Run execute image convert function.
+func (c Converter) Run() int {
+	var err error
+	fileSetSlice, err := c.dirWalk()
+	if err != nil {
+		fmt.Println(err)
+		return 1
+	}
+	err = c.convert(fileSetSlice)
+	if err != nil {
+		fmt.Println(err)
+		return 1
+	}
+	return 0
+}
+
+// dirWalk returns file set of input file name and output file in target directory.
+func (c Converter) dirWalk() ([]FileSet, error) {
+	fileSetSlice := make([]FileSet, 0, 50)
+	err := filepath.Walk(c.directory, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		if filepath.Ext(info.Name()) == ("." + c.in) {
+			inputFileName := path
+			outputFileName := c.outputFilePath(inputFileName)
+			fileSet := FileSet{inputFileName: inputFileName, outputFileName: outputFileName}
+			fmt.Println(inputFileName, outputFileName)
+			fileSetSlice = append(fileSetSlice, fileSet)
+		}
+		return nil
+	})
+
+	if err != nil {
+		return nil, err
+	}
+
+	return fileSetSlice, nil
+}
+
+// convert calls execute function every file set.
+func (c Converter) convert(fileSetSlice []FileSet) error {
+	var err error
+
+	for _, fileSet := range fileSetSlice {
+		err = c.execute(fileSet)
+		if err != nil {
+			break
+		}
+	}
+
+	return err
+}
+
+// execute function open file and calls encode function.
+func (c Converter) execute(fileset FileSet) error {
+	var err error
+
+	inputFile, err := os.Open(fileset.inputFileName)
+	defer inputFile.Close()
+	if err != nil {
+		return err
+	}
+
+	outputFile, err := os.Create(fileset.outputFileName)
+	defer outputFile.Close()
+	if err != nil {
+		return err
+	}
+
+	img, _, err := image.Decode(inputFile)
+	if err != nil {
+		return err
+	}
+
+	err = c.encode(outputFile, img)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// encode returns error by encode function.
+// if output type is not support, Encode returns error.
+func (c Converter) encode(file *os.File, image image.Image) error {
+	switch c.out {
+	case "jpg", "jpeg":
+		err := jpeg.Encode(file, image, &jpeg.Options{Quality: 80})
+		return err
+	case "png":
+		err := png.Encode(file, image)
+		return err
+	default:
+		return errors.New("invalid output type")
+	}
+}
+
+// outputFilePath returns output file path to correspond input file path.
+func (c Converter) outputFilePath(inputFileName string) string {
+	stringSlice := strings.Split(inputFileName, ".")
+	outputFileName := stringSlice[0] + "." + c.out
+	return outputFileName
+}