utility: Added function to parse timestamps.

utility.go

@@ -3,6 +3,9 @@ package exif
 import (
     "fmt"
     "bytes"
+    "strings"
+    "strconv"
+    "time"
 
     "github.com/dsoprea/go-logging"
 )
@@ -63,3 +66,51 @@ func DumpBytesClauseToString(data []byte) string {
 
     return b.String()
 }
+
+func ParseExifFullTimestamp(fullTimestampPhrase string) (timestamp time.Time, err error) {
+    defer func() {
+        if state := recover(); state != nil {
+            err = log.Wrap(state.(error))
+        }
+    }()
+
+    parts := strings.Split(fullTimestampPhrase, " ")
+    datestampValue, timestampValue := parts[0], parts[1]
+
+    dateParts := strings.Split(datestampValue, ":")
+
+    year, err := strconv.ParseUint(dateParts[0], 10, 16)
+    if err != nil {
+        log.Panicf("could not parse year")
+    }
+
+    month, err := strconv.ParseUint(dateParts[1], 10, 8)
+    if err != nil {
+        log.Panicf("could not parse month")
+    }
+
+    day, err := strconv.ParseUint(dateParts[2], 10, 8)
+    if err != nil {
+        log.Panicf("could not parse day")
+    }
+
+    timeParts := strings.Split(timestampValue, ":")
+
+    hour, err := strconv.ParseUint(timeParts[0], 10, 8)
+    if err != nil {
+        log.Panicf("could not parse hour")
+    }
+
+    minute, err := strconv.ParseUint(timeParts[1], 10, 8)
+    if err != nil {
+        log.Panicf("could not parse minute")
+    }
+
+    second, err := strconv.ParseUint(timeParts[2], 10, 8)
+    if err != nil {
+        log.Panicf("could not parse second")
+    }
+
+    timestamp = time.Date(int(year), time.Month(month), int(day), int(hour), int(minute), int(second), 0, time.UTC)
+    return timestamp, nil
+}

utility_test.go

@@ -1,10 +1,11 @@
 package exif
 
 import (
+    "io/ioutil"
+
     "testing"
     "os"
-
-    "io/ioutil"
+    "time"
 
     "github.com/dsoprea/go-logging"
 )
@@ -72,3 +73,15 @@ func TestDumpBytesClauseToString(t *testing.T) {
         t.Fatalf("result not expected")
     }
 }
+
+func TestParseExifFullTimestamp(t *testing.T) {
+    timestamp, err := ParseExifFullTimestamp("2018:11:30 13:01:49")
+    log.PanicIf(err)
+
+    actual := timestamp.Format(time.RFC3339)
+    expected := "2018-11-30T13:01:49Z"
+
+    if actual != expected {
+        t.Fatalf("time not formatted correctly: [%s] != [%s]", actual, expected)
+    }
+}