daterange: support relative terms

Support relative terms when writing date ranges in the search and filter
commands with the -d flag. Syntax is inspired by the notmuch search
terms.

Terms can be written with spaces or underscores for a better
readability, so both "this_week" and "this week" are allowed. Terms are
not case-sensitive.

Some terms can be prefixed with either "this" or "last" where applicable
("this" is assumed by default if omitted):

- "today", "yesterday"
- ("this"|"last") "year", "month", "week"
- all weekdays (e.g. "Tuesday", "last_wed")
- all months  (e.g. "January", "last_feb")

Note that "month" should always be spelled out to prevent a possible
ambiguity with "Monday".

Weekdays and months do not need to be written out completely, i.e.
"February..March" and "Feb..Mar" are both understood.

Relative date terms can be used with the <N (year|month|week|day)>
syntax where N is a positive integer indicating the number of time units
in the past from today. The units can be abbreviated with a single
letter, e.g. "1w 1d.." is the same as "1 week 1 day..".

More examples:
:filter -d yesterday
:filter -d last_monday..
:filter -d mon..sat
:filter -d 1y1m1w1d..
:search -d this_week "PATCH aerc"

Signed-off-by: Koni Marti <koni.marti@gmail.com>
Acked-by: Robin Jarry <robin@jarry.cc>

1 files changed, 42 insertions, 0 deletions

diff --git a/worker/lib/daterange_test.go b/worker/lib/daterange_test.go
index 983f99a0..807e7ac7 100644
--- a/worker/lib/daterange_test.go
+++ b/worker/lib/daterange_test.go
@@ -1,6 +1,7 @@
 package lib_test
 
 import (
+	"reflect"
 	"testing"
 	"time"
 
@@ -53,3 +54,44 @@ func TestParseDateRange(t *testing.T) {
 		}
 	}
 }
+
+func TestParseRelativeDate(t *testing.T) {
+	tests := []struct {
+		s    string
+		want lib.RelDate
+	}{
+		{
+			s:    "5 weeks 1 day",
+			want: lib.RelDate{Year: 0, Month: 0, Day: 5*7 + 1},
+		},
+		{
+			s:    "5_weeks 1_day",
+			want: lib.RelDate{Year: 0, Month: 0, Day: 5*7 + 1},
+		},
+		{
+			s:    "5weeks1day",
+			want: lib.RelDate{Year: 0, Month: 0, Day: 5*7 + 1},
+		},
+		{
+			s:    "5w1d",
+			want: lib.RelDate{Year: 0, Month: 0, Day: 5*7 + 1},
+		},
+		{
+			s:    "5y4m3w1d",
+			want: lib.RelDate{Year: 5, Month: 4, Day: 3*7 + 1},
+		},
+	}
+
+	for _, test := range tests {
+		da, err := lib.ParseRelativeDate(test.s)
+		if err != nil {
+			t.Errorf("ParseRelativeDate return error for %s: %v",
+				test.s, err)
+		}
+
+		if !reflect.DeepEqual(da, test.want) {
+			t.Errorf("results don't match. expected %v, got %v",
+				test.want, da)
+		}
+	}
+}