Add first wc in go!

Co-authored-by: Nicolas Hahn <nicolas@stonespring.org>

go/src/wc.go

@@ -0,0 +1,84 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"path/filepath"
+	"sort"
+)
+
+type LineCount struct {
+	filename string
+	count int
+	err error
+}
+
+func linesInFile(filename string) *LineCount {
+	dat, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return &LineCount{filename, -1, err}
+	}
+	count := 0
+	for _, b := range dat {
+		if b == '\n' {
+			count += 1
+		}
+	}
+	return &LineCount{filename, count, nil}
+}
+
+func getFilesInDir(path string) ([]string, error) {
+	itemsInDir, err := ioutil.ReadDir(path)
+	if err != nil {
+		return nil, err
+	}
+	files := make([]string, 0)
+	for _, f := range itemsInDir {
+		if f.Mode().IsRegular() {
+			files = append(files, filepath.Join(path, f.Name()))
+		}
+	}
+	return files, nil
+}
+
+func check(err error) {
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func main() {
+	args := os.Args[1:]
+	dirPath := "./"
+	if len(args) != 0 {
+		dirPath = args[0]
+	}
+	files, err := getFilesInDir(dirPath)
+	check(err)
+	ch := make(chan *LineCount, len(files))
+	lineCounts := make([]*LineCount, len(files))
+	for _, filename := range files {
+		go func(filename string) {
+			ch <- linesInFile(filename)
+		}(filename)
+	}
+	totalCount := 0
+	for i, _ := range files {
+		lineCount := <-ch
+		if (*lineCount).err == nil {
+			totalCount += (*lineCount).count
+		}
+		lineCounts[i] = lineCount
+	}
+	sort.Slice(lineCounts, func(i, j int) bool {
+		return (*lineCounts[i]).count > (*lineCounts[j]).count
+	})
+	for _, lineCount := range lineCounts {
+		count := (*lineCount).count
+		filename := (*lineCount).filename
+		fmt.Printf("%10v %s\n", count, filename)
+	}
+	fmt.Printf("%10v [TOTAL]\n", totalCount)
+}