fs: allow --min-age/--max-age to take a date as well as a duration

Fixes #4211

docs/content/filtering.md

@@ -429,6 +429,13 @@ seconds or with a suffix of:
 For example `--max-age 2d` means no files older than 2 days will be
 transferred.
 
+This can also be an absolute time in one of these formats
+
+- RFC3339 - eg "2006-01-02T15:04:05Z07:00"
+- ISO8601 Date and time, local timezone - "2006-01-02T15:04:05"
+- ISO8601 Date and time, local timezone - "2006-01-02 15:04:05"
+- ISO8601 Date - "2006-01-02" (YYYY-MM-DD)
+
 ### `--min-age` - Don't transfer any file younger than this ###
 
 This option controls the minimum age of files to transfer.  Give in

fs/parseduration.go

@@ -48,20 +48,10 @@ var ageSuffixes = []struct {
 	{Suffix: "", Multiplier: time.Second},
 }
 
-// ParseDuration parses a duration string. Accept ms|s|m|h|d|w|M|y suffixes. Defaults to second if not provided
-func ParseDuration(age string) (time.Duration, error) {
+// parse the age as suffixed ages
+func parseDurationSuffixes(age string) (time.Duration, error) {
 	var period float64
 
-	if age == "off" {
-		return time.Duration(DurationOff), nil
-	}
-
-	// Attempt to parse as a time.Duration first
-	d, err := time.ParseDuration(age)
-	if err == nil {
-		return d, nil
-	}
-
 	for _, ageSuffix := range ageSuffixes {
 		if strings.HasSuffix(age, ageSuffix.Suffix) {
 			numberString := age[:len(age)-len(ageSuffix.Suffix)]
@@ -78,6 +68,51 @@ func ParseDuration(age string) (time.Duration, error) {
 	return time.Duration(period), nil
 }
 
+// time formats to try parsing ages as - in order
+var timeFormats = []string{
+	time.RFC3339,
+	"2006-01-02T15:04:05",
+	"2006-01-02 15:04:05",
+	"2006-01-02",
+}
+
+// parse the age as time before the epoch in various date formats
+func parseDurationDates(age string, epoch time.Time) (t time.Duration, err error) {
+	var instant time.Time
+	for _, timeFormat := range timeFormats {
+		instant, err = time.Parse(timeFormat, age)
+		if err == nil {
+			return epoch.Sub(instant), nil
+		}
+	}
+	return t, err
+}
+
+// ParseDuration parses a duration string. Accept ms|s|m|h|d|w|M|y suffixes. Defaults to second if not provided
+func ParseDuration(age string) (d time.Duration, err error) {
+	if age == "off" {
+		return time.Duration(DurationOff), nil
+	}
+
+	// Attempt to parse as a time.Duration first
+	d, err = time.ParseDuration(age)
+	if err == nil {
+		return d, nil
+	}
+
+	d, err = parseDurationSuffixes(age)
+	if err == nil {
+		return d, nil
+	}
+
+	d, err = parseDurationDates(age, time.Now())
+	if err == nil {
+		return d, nil
+	}
+
+	return d, err
+}
+
 // ReadableString parses d into a human readable duration.
 // Based on https://github.com/hako/durafmt
 func (d Duration) ReadableString() string {

fs/parseduration_test.go

@@ -2,6 +2,7 @@ package fs
 
 import (
 	"fmt"
+	"strings"
 	"testing"
 	"time"
 
@@ -36,6 +37,10 @@ func TestParseDuration(t *testing.T) {
 		{"1x", 0, true},
 		{"off", time.Duration(DurationOff), false},
 		{"1h2m3s", time.Hour + 2*time.Minute + 3*time.Second, false},
+		{"2001-02-03", time.Since(time.Date(2001, 2, 3, 0, 0, 0, 0, time.Local)), false},
+		{"2001-02-03 10:11:12", time.Since(time.Date(2001, 2, 3, 10, 11, 12, 0, time.Local)), false},
+		{"2001-02-03T10:11:12", time.Since(time.Date(2001, 2, 3, 10, 11, 12, 0, time.Local)), false},
+		{"2001-02-03T10:11:12.123Z", time.Since(time.Date(2001, 2, 3, 10, 11, 12, 123, time.UTC)), false},
 	} {
 		duration, err := ParseDuration(test.in)
 		if test.err {
@@ -43,7 +48,12 @@ func TestParseDuration(t *testing.T) {
 		} else {
 			require.NoError(t, err)
 		}
-		assert.Equal(t, test.want, duration)
+		if strings.HasPrefix(test.in, "2001-") {
+			ok := duration > test.want-time.Second && duration < test.want+time.Second
+			assert.True(t, ok, test.in)
+		} else {
+			assert.Equal(t, test.want, duration)
+		}
 	}
 }