package txt import ( "fmt" "regexp" "strings" "time" ) // Go regular expression tester: https://regoio.herokuapp.com/ var DateRegexp = regexp.MustCompile("\\D\\d{4}[\\-_]\\d{2}[\\-_]\\d{2,}") var DatePathRegexp = regexp.MustCompile("\\D\\d{4}/\\d{1,2}/?\\d*") var DateTimeRegexp = regexp.MustCompile("\\D\\d{4}[\\-_]\\d{2}[\\-_]\\d{2}.{1,4}\\d{2}\\D\\d{2}\\D\\d{2,}") var DateIntRegexp = regexp.MustCompile("\\d{1,4}") var YearRegexp = regexp.MustCompile("\\d{4,5}") var IsDateRegexp = regexp.MustCompile("\\d{4}[\\-_]?\\d{2}[\\-_]?\\d{2}") var IsDateTimeRegexp = regexp.MustCompile("\\d{4}[\\-_]?\\d{2}[\\-_]?\\d{2}.{1,4}\\d{2}\\D?\\d{2}\\D?\\d{2}") var ExifDateTimeRegexp = regexp.MustCompile("((?P\\d{4})|\\D{4})\\D((?P\\d{2})|\\D{2})\\D((?P\\d{2})|\\D{2})\\D((?P\\d{2})|\\D{2})\\D((?P\\d{2})|\\D{2})\\D((?P\\d{2})|\\D{2})(?P\\D)?(?P\\d{2})?\\D?(?P\\d{2})?") var ExifDateTimeMatch = make(map[string]int) func init() { names := ExifDateTimeRegexp.SubexpNames() for i := 0; i < len(names); i++ { if name := names[i]; name != "" { ExifDateTimeMatch[name] = i } } } var ( YearMin = 1990 YearMax = time.Now().Year() + 3 ) const ( MonthMin = 1 MonthMax = 12 DayMin = 1 DayMax = 31 HourMin = 0 HourMax = 24 MinMin = 0 MinMax = 59 SecMin = 0 SecMax = 59 ) // DateTime parses a string and returns a valid Exif timestamp if possible. func DateTime(s, timeZone string) (t time.Time) { defer func() { if r := recover(); r != nil { // Panic? Return unknown time. t = time.Time{} } }() // Empty timestamp? Return unknown time. if s == "" { return time.Time{} } s = strings.TrimLeft(s, " ") // Timestamp too short or much too long? Return unknown time. if len(s) < 4 || len(s) > 50 { return time.Time{} } // Pad short timestamp with whitespace at the end. s = fmt.Sprintf("%-19s", s) // Shorten timestamp to max length. if len(s) > 25 { s = s[:25] } v := ExifDateTimeMatch m := ExifDateTimeRegexp.FindStringSubmatch(s) // Pattern doesn't match? Return unknown time. if len(m) == 0 { return time.Time{} } // Default to UTC. tz := time.UTC // Local time zone currently not supported (undefined). if timeZone == time.Local.String() { timeZone = "" } // Set time zone. loc, err := time.LoadLocation(timeZone) // Location found? if err == nil && timeZone != "" && tz != time.Local { tz = loc timeZone = tz.String() } else { timeZone = "" } // Does the timestamp contain a time zone offset? z := m[v["z"]] // Supported values, if not empty: Z, +, - zh := IntVal(m[v["zh"]], 0, 23, 0) // Hours. zm := IntVal(m[v["zm"]], 0, 59, 0) // Minutes. // Valid time zone offset found? if offset := (zh*60 + zm) * 60; offset > 0 && offset <= 86400 { // Offset timezone name example: UTC+03:30 if z == "+" { // Positive offset relative to UTC. tz = time.FixedZone(fmt.Sprintf("UTC+%02d:%02d", zh, zm), offset) } else if z == "-" { // Negative offset relative to UTC. tz = time.FixedZone(fmt.Sprintf("UTC-%02d:%02d", zh, zm), -1*offset) } } // Create rounded timestamp from parsed input values. t = time.Date( IntVal(m[v["year"]], 1, YearMax, time.Now().Year()), time.Month(IntVal(m[v["month"]], 1, 12, 1)), IntVal(m[v["day"]], 1, 31, 1), IntVal(m[v["h"]], 0, 23, 0), IntVal(m[v["m"]], 0, 59, 0), IntVal(m[v["s"]], 0, 59, 0), 0, tz).Round(time.Second) if timeZone != "" && loc != nil && loc != tz { return t.In(loc) } return t } // DateFromFilePath returns a string as time or the zero time instant in case it can not be converted. func DateFromFilePath(s string) (result time.Time) { defer func() { if r := recover(); r != nil { result = time.Time{} } }() if len(s) < 6 { return time.Time{} } if !strings.HasPrefix(s, "/") { s = "/" + s } b := []byte(s) if found := DateTimeRegexp.Find(b); len(found) > 0 { // Is it a date with time like "2020-01-30_09-57-18"? n := DateIntRegexp.FindAll(found, -1) if len(n) != 6 { return result } year := Int(string(n[0])) month := Int(string(n[1])) day := Int(string(n[2])) hour := Int(string(n[3])) min := Int(string(n[4])) sec := Int(string(n[5])) if year < YearMin || year > YearMax || month < MonthMin || month > MonthMax || day < DayMin || day > DayMax { return result } if hour < HourMin || hour > HourMax || min < MinMin || min > MinMax || sec < SecMin || sec > SecMax { return result } result = time.Date( year, time.Month(month), day, hour, min, sec, 0, time.UTC) } else if found := DateRegexp.Find(b); len(found) > 0 { // Is it a date only like "2020-01-30"? n := DateIntRegexp.FindAll(found, -1) if len(n) != 3 { return result } year := Int(string(n[0])) month := Int(string(n[1])) day := Int(string(n[2])) if year < YearMin || year > YearMax || month < MonthMin || month > MonthMax || day < DayMin || day > DayMax { return result } result = time.Date( year, time.Month(month), day, 0, 0, 0, 0, time.UTC) } else if found := DatePathRegexp.Find(b); len(found) > 0 { // Is it a date path like "2020/01/03"? n := DateIntRegexp.FindAll(found, -1) if len(n) < 2 || len(n) > 3 { return result } year := Int(string(n[0])) month := Int(string(n[1])) if year < YearMin || year > YearMax || month < MonthMin || month > MonthMax { return result } if len(n) == 2 { result = time.Date( year, time.Month(month), 1, 0, 0, 0, 0, time.UTC) } else if day := Int(string(n[2])); day >= DayMin && day <= DayMax { result = time.Date( year, time.Month(month), day, 0, 0, 0, 0, time.UTC) } } return result.UTC() } // IsTime tests if the string looks like a date and/or time. func IsTime(s string) bool { if s == "" { return false } else if m := IsDateRegexp.FindString(s); m == s { return true } else if m := IsDateTimeRegexp.FindString(s); m == s { return true } return false } // Year tries to find a matching year for a given string e.g. from a file oder directory name. func Year(s string) int { b := []byte(s) found := YearRegexp.FindAll(b, -1) for _, match := range found { year := Int(string(match)) if year > YearMin && year < YearMax { return year } } return 0 }