package tasks

import (
	"testing"
	"math/rand"
	"time"
	"os"
	"log"
)


func TestCheckTmpDir(t *testing.T) {

	//It should be able to create a random dir in /tmp
	dirName := os.TempDir()+ "/" + randString(rand.Intn(10 - 4) + 4)
	err := checkTmpDir(dirName)
	if err != nil {
		t.Fatal(err)
	}

	//checking again for this directory should return no error, as it exists
	err = checkTmpDir(dirName)
	if err != nil {
		t.Fatal(err)
	}

	err = os.Chmod(dirName,os.FileMode(int(0550)))
	if err != nil {
		t.Fatal(err)
	}
	err = checkTmpDir(dirName+"/noway")
	if err == nil {
		t.Fatal("You should not be able to write in this folder, causing an error")
	}
	err = os.Remove(dirName)
	if err != nil {
		t.Log(err)
	}

}


//HELPERS

//https://stackoverflow.com/questions/22892120/how-to-generate-a-random-string-of-a-fixed-length-in-golang
var src = rand.NewSource(time.Now().UnixNano())
const letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
const (
	letterIdxBits = 6                    // 6 bits to represent a letter index
	letterIdxMask = 1<<letterIdxBits - 1 // All 1-bits, as many as letterIdxBits
	letterIdxMax  = 63 / letterIdxBits   // # of letter indices fitting in 63 bits
)
func randString(n int) string {
	b := make([]byte, n)
	// A src.Int63() generates 63 random bits, enough for letterIdxMax characters!
	for i, cache, remain := n-1, src.Int63(), letterIdxMax; i >= 0; {
		if remain == 0 {
			cache, remain = src.Int63(), letterIdxMax
		}
		if idx := int(cache & letterIdxMask); idx < len(letterBytes) {
			b[i] = letterBytes[idx]
			i--
		}
		cache >>= letterIdxBits
		remain--
	}
	return string(b)
}