find duplicate files in the current directory

duplicates.go

package main

import (
	"crypto/md5"
	"encoding/hex"
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"os"
)

func swapColor(color string) string {
	if color == "\033[92m" {
		return "\033[93m"
	} else {
		return "\033[92m"
	}
}

func occurrences(val int64, slice []fileInfo) int {
	// count the number of times val is in slice
	count := 0
	for _, file := range slice {
		if file.size == val {
			count++
		}
	}
	return count
}

func contains(str string, arr []string) bool {
	for _, a := range arr {
		if a == str {
			return true
		}
	}
	return false
}

func hashFileMD5(filePath string) (string, error) {
	var returnMD5String string
	file, err := os.Open(filePath)
	if err != nil {
		return returnMD5String, err
	}
	defer file.Close()

	hash := md5.New()
	// io.Copy -> func Copy(dst Writer, src Reader) (written int64, err error)
	if _, err := io.Copy(hash, file); err != nil {
		return returnMD5String, err
	}
	// Get the 16 bytes hash
	hashInBytes := hash.Sum(nil)[:16]
	return hex.EncodeToString(hashInBytes), nil
}

func printColor(color, sum, file string) {
	endc := "\033[0m"
	fmt.Println(color, sum, "-", file, endc)
}

type fileInfo struct {
	name string
	size int64
	md5  string
}

func main() {
	listdir, err := ioutil.ReadDir(".")
	// would make sense to take a path as a parameter
	if err != nil {
		log.Fatal(err)
	}

	var allFiles = make([]fileInfo, 0)

	for _, file := range listdir {
		if file.IsDir() {
			continue
		} else {
			allFiles = append(allFiles, fileInfo{name: file.Name(), size: file.Size()})
		}
	}

	files := allFiles[:0]
	// populate files with items that have a unique size
	for _, file := range allFiles {
		if occurrences(file.size, allFiles) > 1 {
			files = append(files, file)
		}
	}

	for i, file := range files {
		sum, err := hashFileMD5(file.name)
		if err != nil {
			log.Fatal(err)
		}
		files[i].md5 = sum
	}

	matches := make([]string, len(files))
	i := 0
	color := "\033[92m"
	for _, file := range files {
		// matches is an array of strings. when a match is found,
		// add the md5sum to that list. At the beginning of the loop,
		// check the list to see if each sum has already been printed.
		if contains(file.md5, matches) {
			continue
		}
		matched := false
		for _, file2 := range files {
			if file.md5 == file2.md5 && file != file2 {
				printColor(color, file.md5, file2.name)
				matches[i] = file.md5
				matched = true
			}
		}

		if matched {
			printColor(color, file.md5, file.name)
			color = swapColor(color)
		}
		i++
	}
}