Entries date should contains user timezone (API)

2 files changed, 122 insertions, 0 deletions

diff --git a/timezone/timezone.go b/timezone/timezone.go
new file mode 100644
index 0000000..96b7fe4
--- /dev/null
+++ b/timezone/timezone.go
@@ -0,0 +1,47 @@
+// Copyright 2018 Frédéric Guillot. All rights reserved.
+// Use of this source code is governed by the Apache 2.0
+// license that can be found in the LICENSE file.
+
+package timezone
+
+import (
+	"time"
+)
+
+// Convert converts provided date time to actual timezone.
+func Convert(tz string, t time.Time) time.Time {
+	userTimezone := getLocation(tz)
+
+	if t.Location().String() == "" {
+		// In this case, the provided date is already converted to the user timezone by Postgres,
+		// but the timezone information is not set in the time struct.
+		// We cannot use time.In() because the date will be converted a second time.
+		t = time.Date(
+			t.Year(),
+			t.Month(),
+			t.Day(),
+			t.Hour(),
+			t.Minute(),
+			t.Second(),
+			t.Nanosecond(),
+			userTimezone,
+		)
+	} else if t.Location() != userTimezone {
+		t = t.In(userTimezone)
+	}
+
+	return t
+}
+
+// Now returns the current time with the given timezone.
+func Now(tz string) time.Time {
+	return time.Now().In(getLocation(tz))
+}
+
+func getLocation(tz string) *time.Location {
+	loc, err := time.LoadLocation(tz)
+	if err != nil {
+		loc = time.Local
+	}
+	return loc
+}
diff --git a/timezone/timezone_test.go b/timezone/timezone_test.go
new file mode 100644
index 0000000..eb960f2
--- /dev/null
+++ b/timezone/timezone_test.go
@@ -0,0 +1,75 @@
+// Copyright 2018 Frédéric Guillot. All rights reserved.
+// Use of this source code is governed by the Apache 2.0
+// license that can be found in the LICENSE file.
+
+package timezone
+
+import (
+	"testing"
+	"time"
+)
+
+func TestNow(t *testing.T) {
+	tz := "Europe/Paris"
+	now := Now(tz)
+
+	if now.Location().String() != tz {
+		t.Fatalf(`Unexpected timezone, got %q instead of %q`, now.Location(), tz)
+	}
+}
+
+func TestNowWithInvalidTimezone(t *testing.T) {
+	tz := "Invalid Timezone"
+	expected := time.Local
+	now := Now(tz)
+
+	if now.Location().String() != expected.String() {
+		t.Fatalf(`Unexpected timezone, got %q instead of %q`, now.Location(), expected)
+	}
+}
+
+func TestConvertTimeWithNoTimezoneInformation(t *testing.T) {
+	tz := "Canada/Pacific"
+	input := time.Date(2018, 3, 1, 14, 2, 3, 0, time.FixedZone("", 0))
+	output := Convert(tz, input)
+
+	if output.Location().String() != tz {
+		t.Fatalf(`Unexpected timezone, got %q instead of %s`, output.Location(), tz)
+	}
+
+	hours, minutes, secs := output.Clock()
+	if hours != 14 || minutes != 2 || secs != 3 {
+		t.Fatalf(`Unexpected time, got hours=%d, minutes=%d, secs=%d`, hours, minutes, secs)
+	}
+}
+
+func TestConvertTimeWithDifferentTimezone(t *testing.T) {
+	tz := "Canada/Central"
+	input := time.Date(2018, 3, 1, 14, 2, 3, 0, time.UTC)
+	output := Convert(tz, input)
+
+	if output.Location().String() != tz {
+		t.Fatalf(`Unexpected timezone, got %q instead of %s`, output.Location(), tz)
+	}
+
+	hours, minutes, secs := output.Clock()
+	if hours != 8 || minutes != 2 || secs != 3 {
+		t.Fatalf(`Unexpected time, got hours=%d, minutes=%d, secs=%d`, hours, minutes, secs)
+	}
+}
+
+func TestConvertTimeWithIdenticalTimezone(t *testing.T) {
+	tz := "Canada/Central"
+	loc, _ := time.LoadLocation(tz)
+	input := time.Date(2018, 3, 1, 14, 2, 3, 0, loc)
+	output := Convert(tz, input)
+
+	if output.Location().String() != tz {
+		t.Fatalf(`Unexpected timezone, got %q instead of %s`, output.Location(), tz)
+	}
+
+	hours, minutes, secs := output.Clock()
+	if hours != 14 || minutes != 2 || secs != 3 {
+		t.Fatalf(`Unexpected time, got hours=%d, minutes=%d, secs=%d`, hours, minutes, secs)
+	}
+}