Localize time.Format

Fixes #8797

2 files changed, 238 insertions, 0 deletions

diff --git a/common/htime/time.go b/common/htime/time.go
new file mode 100644
index 000000000..cd294b3a2
--- /dev/null
+++ b/common/htime/time.go
@@ -0,0 +1,127 @@
+// Copyright 2021 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package htime
+
+import (
+	"strings"
+	"time"
+
+	"github.com/go-playground/locales"
+)
+
+var (
+	longDayNames = []string{
+		"Sunday",
+		"Monday",
+		"Tuesday",
+		"Wednesday",
+		"Thursday",
+		"Friday",
+		"Saturday",
+	}
+
+	shortDayNames = []string{
+		"Sun",
+		"Mon",
+		"Tue",
+		"Wed",
+		"Thu",
+		"Fri",
+		"Sat",
+	}
+
+	shortMonthNames = []string{
+		"Jan",
+		"Feb",
+		"Mar",
+		"Apr",
+		"May",
+		"Jun",
+		"Jul",
+		"Aug",
+		"Sep",
+		"Oct",
+		"Nov",
+		"Dec",
+	}
+
+	longMonthNames = []string{
+		"January",
+		"February",
+		"March",
+		"April",
+		"May",
+		"June",
+		"July",
+		"August",
+		"September",
+		"October",
+		"November",
+		"December",
+	}
+)
+
+func NewTimeFormatter(ltr locales.Translator) TimeFormatter {
+	if ltr == nil {
+		panic("must provide a locales.Translator")
+	}
+	return TimeFormatter{
+		ltr: ltr,
+	}
+}
+
+// TimeFormatter is locale aware.
+type TimeFormatter struct {
+	ltr locales.Translator
+}
+
+func (f TimeFormatter) Format(t time.Time, layout string) string {
+	if layout == "" {
+		return ""
+	}
+
+	if layout[0] == ':' {
+		// It may be one of Hugo's custom layouts.
+		switch strings.ToLower(layout[1:]) {
+		case "date_full":
+			return f.ltr.FmtDateFull(t)
+		case "date_long":
+			return f.ltr.FmtDateLong(t)
+		case "date_medium":
+			return f.ltr.FmtDateMedium(t)
+		case "date_short":
+			return f.ltr.FmtDateShort(t)
+		case "time_full":
+			return f.ltr.FmtTimeFull(t)
+		case "time_long":
+			return f.ltr.FmtTimeLong(t)
+		case "time_medium":
+			return f.ltr.FmtTimeMedium(t)
+		case "time_short":
+			return f.ltr.FmtTimeShort(t)
+		}
+	}
+
+	s := t.Format(layout)
+
+	monthIdx := t.Month() - 1 // Month() starts at 1.
+	dayIdx := t.Weekday()
+
+	s = strings.ReplaceAll(s, longMonthNames[monthIdx], f.ltr.MonthWide(t.Month()))
+	s = strings.ReplaceAll(s, shortMonthNames[monthIdx], f.ltr.MonthAbbreviated(t.Month()))
+	s = strings.ReplaceAll(s, longDayNames[dayIdx], f.ltr.WeekdayWide(t.Weekday()))
+	s = strings.ReplaceAll(s, shortDayNames[dayIdx], f.ltr.WeekdayAbbreviated(t.Weekday()))
+
+	return s
+}
diff --git a/common/htime/time_test.go b/common/htime/time_test.go
new file mode 100644
index 000000000..383027755
--- /dev/null
+++ b/common/htime/time_test.go
@@ -0,0 +1,111 @@
+// Copyright 2021 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package htime
+
+import (
+	"testing"
+	"time"
+
+	translators "github.com/bep/gotranslators"
+	qt "github.com/frankban/quicktest"
+)
+
+func TestTimeFormatter(t *testing.T) {
+	c := qt.New(t)
+
+	june06, _ := time.Parse("2006-Jan-02", "2018-Jun-06")
+	june06 = june06.Add(7777 * time.Second)
+
+	c.Run("Norsk nynorsk", func(c *qt.C) {
+		f := NewTimeFormatter(translators.Get("nn"))
+
+		c.Assert(f.Format(june06, "Monday Jan 2 2006"), qt.Equals, "onsdag juni 6 2018")
+		c.Assert(f.Format(june06, "Mon January 2 2006"), qt.Equals, "on. juni 6 2018")
+		c.Assert(f.Format(june06, "Mon Mon"), qt.Equals, "on. on.")
+	})
+
+	c.Run("Custom layouts Norsk nynorsk", func(c *qt.C) {
+		f := NewTimeFormatter(translators.Get("nn"))
+
+		c.Assert(f.Format(june06, ":date_full"), qt.Equals, "onsdag 6. juni 2018")
+		c.Assert(f.Format(june06, ":date_long"), qt.Equals, "6. juni 2018")
+		c.Assert(f.Format(june06, ":date_medium"), qt.Equals, "6. juni 2018")
+		c.Assert(f.Format(june06, ":date_short"), qt.Equals, "06.06.2018")
+
+		c.Assert(f.Format(june06, ":time_full"), qt.Equals, "kl. 02:09:37 UTC")
+		c.Assert(f.Format(june06, ":time_long"), qt.Equals, "02:09:37 UTC")
+		c.Assert(f.Format(june06, ":time_medium"), qt.Equals, "02:09:37")
+		c.Assert(f.Format(june06, ":time_short"), qt.Equals, "02:09")
+
+	})
+
+	c.Run("Custom layouts English", func(c *qt.C) {
+		f := NewTimeFormatter(translators.Get("en"))
+
+		c.Assert(f.Format(june06, ":date_full"), qt.Equals, "Wednesday, June 6, 2018")
+		c.Assert(f.Format(june06, ":date_long"), qt.Equals, "June 6, 2018")
+		c.Assert(f.Format(june06, ":date_medium"), qt.Equals, "Jun 6, 2018")
+		c.Assert(f.Format(june06, ":date_short"), qt.Equals, "6/6/18")
+
+		c.Assert(f.Format(june06, ":time_full"), qt.Equals, "2:09:37 am UTC")
+		c.Assert(f.Format(june06, ":time_long"), qt.Equals, "2:09:37 am UTC")
+		c.Assert(f.Format(june06, ":time_medium"), qt.Equals, "2:09:37 am")
+		c.Assert(f.Format(june06, ":time_short"), qt.Equals, "2:09 am")
+
+	})
+
+	c.Run("English", func(c *qt.C) {
+		f := NewTimeFormatter(translators.Get("en"))
+
+		c.Assert(f.Format(june06, "Monday Jan 2 2006"), qt.Equals, "Wednesday Jun 6 2018")
+		c.Assert(f.Format(june06, "Mon January 2 2006"), qt.Equals, "Wed June 6 2018")
+		c.Assert(f.Format(june06, "Mon Mon"), qt.Equals, "Wed Wed")
+	})
+
+}
+
+func BenchmarkTimeFormatter(b *testing.B) {
+	june06, _ := time.Parse("2006-Jan-02", "2018-Jun-06")
+
+	b.Run("Native", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			got := june06.Format("Monday Jan 2 2006")
+			if got != "Wednesday Jun 6 2018" {
+				b.Fatalf("invalid format, got %q", got)
+			}
+		}
+	})
+
+	b.Run("Localized", func(b *testing.B) {
+		f := NewTimeFormatter(translators.Get("nn"))
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			got := f.Format(june06, "Monday Jan 2 2006")
+			if got != "onsdag juni 6 2018" {
+				b.Fatalf("invalid format, got %q", got)
+			}
+		}
+	})
+
+	b.Run("Localized Custom", func(b *testing.B) {
+		f := NewTimeFormatter(translators.Get("nn"))
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			got := f.Format(june06, ":date_medium")
+			if got != "6. juni 2018" {
+				b.Fatalf("invalid format, got %q", got)
+			}
+		}
+	})
+}