helpers.go

package codetainer

import (
	"crypto/md5"
	"io"
	"os"
	"regexp"
	"strings"
	"time"
)

const (
	// Email regex
	Email string = "^(((([a-zA-Z]|\\d|[!#\\$%&'\\*\\+\\-\\/=\\?\\^_`{\\|}~]|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])+(\\.([a-zA-Z]|\\d|[!#\\$%&'\\*\\+\\-\\/=\\?\\^_`{\\|}~]|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])+)*)|((\\x22)((((\\x20|\\x09)*(\\x0d\\x0a))?(\\x20|\\x09)+)?(([\\x01-\\x08\\x0b\\x0c\\x0e-\\x1f\\x7f]|\\x21|[\\x23-\\x5b]|[\\x5d-\\x7e]|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])|(\\([\\x01-\\x09\\x0b\\x0c\\x0d-\\x7f]|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}]))))*(((\\x20|\\x09)*(\\x0d\\x0a))?(\\x20|\\x09)+)?(\\x22)))@((([a-zA-Z]|\\d|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])|(([a-zA-Z]|\\d|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])([a-zA-Z]|\\d|-|\\.|_|~|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])*([a-zA-Z]|\\d|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])))\\.)+(([a-zA-Z]|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])|(([a-zA-Z]|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])([a-zA-Z]|\\d|-|\\.|_|~|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])*([a-zA-Z]|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])))\\.?$"
)

var (
	rxEmail = regexp.MustCompile(Email)
)

func fileExists(filePath string) bool {

	_, err := os.Stat(filePath)

	if err != nil && os.IsNotExist(err) {
		return false
	}

	return true
}

func ComputeMd5(filePath string) ([]byte, error) {
	var result []byte
	file, err := os.Open(filePath)
	if err != nil {
		return result, err
	}
	defer file.Close()

	hash := md5.New()
	if _, err := io.Copy(hash, file); err != nil {
		return result, err
	}

	return hash.Sum(result), nil
}

// IsEmail checks a string to validate
// its a proper email address
func IsEmail(str string) bool {
	// TODO uppercase letters are not supported
	low := strings.ToLower(str)
	return rxEmail.MatchString(low)
}

// IsExist checks whether a file or directory exists.
// It returns false when the file or directory does not exist.
func IsExist(path string) bool {
	_, err := os.Stat(path)
	return err == nil || os.IsExist(err)
}

var datePatterns = []string{
	// year
	"Y", "2006", // A full numeric representation of a year, 4 digits   Examples: 1999 or 2003
	"y", "06", //A two digit representation of a year   Examples: 99 or 03

	// month
	"m", "01", // Numeric representation of a month, with leading zeros 01 through 12
	"n", "1", // Numeric representation of a month, without leading zeros   1 through 12
	"M", "Jan", // A short textual representation of a month, three letters Jan through Dec
	"F", "January", // A full textual representation of a month, such as January or March   January through December

	// day
	"d", "02", // Day of the month, 2 digits with leading zeros 01 to 31
	"j", "2", // Day of the month without leading zeros 1 to 31

	// week
	"D", "Mon", // A textual representation of a day, three letters Mon through Sun
	"l", "Monday", // A full textual representation of the day of the week  Sunday through Saturday

	// time
	"g", "3", // 12-hour format of an hour without leading zeros    1 through 12
	"G", "15", // 24-hour format of an hour without leading zeros   0 through 23
	"h", "03", // 12-hour format of an hour with leading zeros  01 through 12
	"H", "15", // 24-hour format of an hour with leading zeros  00 through 23

	"a", "pm", // Lowercase Ante meridiem and Post meridiem am or pm
	"A", "PM", // Uppercase Ante meridiem and Post meridiem AM or PM

	"i", "04", // Minutes with leading zeros    00 to 59
	"s", "05", // Seconds, with leading zeros   00 through 59

	// time zone
	"T", "MST",
	"P", "-07:00",
	"O", "-0700",

	// RFC 2822
	"r", time.RFC1123Z,
}

func DateFormat(t time.Time, format string) string {
	replacer := strings.NewReplacer(datePatterns...)
	format = replacer.Replace(format)
	return t.Format(format)
}