improvements on the x/jsonx/iso8601 time format

x/jsonx/iso8601.go

@@ -1,18 +1,34 @@
 package jsonx
 
 import (
+	"database/sql/driver"
+	"errors"
 	"fmt"
 	"strconv"
 	"strings"
 	"time"
 )
 
+var fixedEastUTCLocations = make(map[int]*time.Location)
+
+func registerFixedEastUTCLocation(name string, secondsFromUTC int) {
+	loc := time.FixedZone(name, secondsFromUTC)
+	fixedEastUTCLocations[secondsFromUTC] = loc
+}
+
+func init() {
+	registerFixedEastUTCLocation("EEST", 3*60*60) // + 3 hours.
+}
+
 const (
 	// ISO8601Layout holds the time layout for the the javascript iso time.
 	// Read more at: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/toISOString.
 	ISO8601Layout = "2006-01-02T15:04:05"
 	// ISO8601ZLayout same as ISO8601Layout but with the timezone suffix.
 	ISO8601ZLayout = "2006-01-02T15:04:05Z"
+	// ISO8601ZUTCOffsetLayout ISO 8601 format, with full time and zone with UTC offset.
+	// Example: 2022-08-10T03:21:00.000000+03:00.
+	ISO8601ZUTCOffsetLayout = "2006-01-02T15:04:05.999999Z07:00"
 )
 
 // ISO8601 describes a time compatible with javascript time format.
@@ -29,7 +45,28 @@ func ParseISO8601(s string) (ISO8601, error) {
 		err error
 	)
 
-	if s[len(s)-1] == 'Z' {
+	if idx := strings.LastIndexFunc(s, startUTCOffsetIndexFunc); idx > 20 /* should have some distance, e.g. 26 */ {
+		length := parseSignedOffset(s[idx:])
+
+		if idx+1 > idx+length || len(s) <= idx+length+1 {
+			return ISO8601{}, fmt.Errorf("ISO8601: invalid timezone format: %s", s[idx:])
+		}
+
+		offsetText := s[idx+1 : idx+length]
+		offset, parseErr := strconv.Atoi(offsetText)
+		if parseErr != nil {
+			return ISO8601{}, err
+		}
+
+		// E.g. offset of +0300 is returned as 10800 which is - (3 * 60 * 60).
+		secondsEastUTC := offset * 60 * 60
+
+		if loc, ok := fixedEastUTCLocations[secondsEastUTC]; ok { // Specific (fixed) zone.
+			tt, err = time.ParseInLocation(ISO8601ZUTCOffsetLayout, s, loc)
+		} else { // Local or UTC.
+			tt, err = time.Parse(ISO8601ZUTCOffsetLayout, s)
+		}
+	} else if s[len(s)-1] == 'Z' {
 		tt, err = time.Parse(ISO8601ZLayout, s)
 	} else {
 		tt, err = time.Parse(ISO8601Layout, s)
@@ -39,7 +76,7 @@ func ParseISO8601(s string) (ISO8601, error) {
 		return ISO8601{}, err
 	}
 
-	return ISO8601(tt.UTC()), nil
+	return ISO8601(tt), nil
 }
 
 // UnmarshalJSON parses the "b" into ISO8601 time.
@@ -90,6 +127,11 @@ func (t ISO8601) String() string {
 	return tt.Format(ISO8601Layout)
 }
 
+// Value returns the database value of time.Time.
+func (t ISO8601) Value() (driver.Value, error) {
+	return time.Time(t), nil
+}
+
 // Scan completes the sql driver.Scanner interface.
 func (t *ISO8601) Scan(src interface{}) error {
 	switch v := src.(type) {
@@ -104,6 +146,8 @@ func (t *ISO8601) Scan(src interface{}) error {
 			return err
 		}
 		*t = tt
+	case []byte:
+		return t.Scan(string(v))
 	case nil:
 		*t = ISO8601(time.Time{})
 	default:
@@ -112,3 +156,54 @@ func (t *ISO8601) Scan(src interface{}) error {
 
 	return nil
 }
+
+// parseSignedOffset parses a signed timezone offset (e.g. "+03" or "-04").
+// The function checks for a signed number in the range -23 through +23 excluding zero.
+// Returns length of the found offset string or 0 otherwise.
+//
+// Language internal function.
+func parseSignedOffset(value string) int {
+	sign := value[0]
+	if sign != '-' && sign != '+' {
+		return 0
+	}
+	x, rem, err := leadingInt(value[1:])
+
+	// fail if nothing consumed by leadingInt
+	if err != nil || value[1:] == rem {
+		return 0
+	}
+	if x > 23 {
+		return 0
+	}
+	return len(value) - len(rem)
+}
+
+var errLeadingInt = errors.New("ISO8601: time: bad [0-9]*") // never printed.
+
+// leadingInt consumes the leading [0-9]* from s.
+//
+// Language internal function.
+func leadingInt(s string) (x uint64, rem string, err error) {
+	i := 0
+	for ; i < len(s); i++ {
+		c := s[i]
+		if c < '0' || c > '9' {
+			break
+		}
+		if x > 1<<63/10 {
+			// overflow
+			return 0, "", errLeadingInt
+		}
+		x = x*10 + uint64(c) - '0'
+		if x > 1<<63 {
+			// overflow
+			return 0, "", errLeadingInt
+		}
+	}
+	return x, s[i:], nil
+}
+
+func startUTCOffsetIndexFunc(char rune) bool {
+	return char == '+' || char == '-'
+}