Add workaround for non GMT dates (RFC822, RFC850, and RFC1123)

RFC822, RFC850, and RFC1123 are supposed to be always in GMT.

This is a workaround for the one defined in PST timezone.

reader/date/parser.go

@@ -206,8 +206,15 @@ func Parse(ds string) (t time.Time, err error) {
 		return t, errors.New("date parser: empty value")
 	}
 
-	for _, f := range dateFormats {
-		if t, err = time.Parse(f, d); err == nil {
+	for _, layout := range dateFormats {
+		switch layout {
+		case time.RFC822, time.RFC850, time.RFC1123:
+			if t, err = parseLocalTimeDates(layout, d); err == nil {
+				return
+			}
+		}
+
+		if t, err = time.Parse(layout, d); err == nil {
 			return
 		}
 	}
@@ -221,6 +228,22 @@ func Parse(ds string) (t time.Time, err error) {
 	return
 }
 
+// According to Golang documentation:
+//
+// RFC822, RFC850, and RFC1123 formats should be applied only to local times.
+// Applying them to UTC times will use "UTC" as the time zone abbreviation,
+// while strictly speaking those RFCs require the use of "GMT" in that case.
+func parseLocalTimeDates(layout, ds string) (t time.Time, err error) {
+	loc := time.UTC
+
+	// Workaround for dates that don't use GMT.
+	if strings.HasSuffix(ds, "PST") {
+		loc, _ = time.LoadLocation("America/Los_Angeles")
+	}
+
+	return time.ParseInLocation(layout, ds, loc)
+}
+
 // Replace German and French dates to English.
 func replaceNonEnglishWords(ds string) string {
 	r := strings.NewReplacer(

reader/date/parser_test.go

@@ -4,7 +4,9 @@
 
 package date // import "miniflux.app/reader/date"
 
-import "testing"
+import (
+	"testing"
+)
 
 func TestParseEmptyDate(t *testing.T) {
 	if _, err := Parse("  "); err == nil {
@@ -24,19 +26,91 @@ func TestParseAtomDate(t *testing.T) {
 		t.Fatalf(`Atom dates should be parsed correctly`)
 	}
 
-	if date.Unix() != 1513980589 {
-		t.Fatal(`Invalid date parsed`)
+	expectedTS := int64(1513980589)
+	if date.Unix() != expectedTS {
+		t.Errorf(`The Unix timestamp should be %v instead of %v`, expectedTS, date.Unix())
+	}
+
+	_, offset := date.Zone()
+	expectedOffset := 0
+	if offset != expectedOffset {
+		t.Errorf(`The offset should be %v instead of %v`, expectedOffset, offset)
 	}
 }
 
-func TestParseRSSDate(t *testing.T) {
+func TestParseRSSDateGMT(t *testing.T) {
 	date, err := Parse("Tue, 03 Jun 2003 09:39:21 GMT")
 	if err != nil {
 		t.Fatalf(`RSS dates should be parsed correctly`)
 	}
 
-	if date.Unix() != 1054633161 {
-		t.Fatal(`Invalid date parsed`)
+	expectedTS := int64(1054633161)
+	if date.Unix() != expectedTS {
+		t.Errorf(`The Unix timestamp should be %v instead of %v`, expectedTS, date.Unix())
+	}
+
+	expectedLocation := "GMT"
+	if date.Location().String() != expectedLocation {
+		t.Errorf(`The location should be %q instead of %q`, expectedLocation, date.Location())
+	}
+
+	name, offset := date.Zone()
+
+	expectedName := "GMT"
+	if name != expectedName {
+		t.Errorf(`The zone name should be %q instead of %q`, expectedName, name)
+	}
+
+	expectedOffset := 0
+	if offset != expectedOffset {
+		t.Errorf(`The offset should be %v instead of %v`, expectedOffset, offset)
+	}
+}
+
+func TestParseRSSDatePST(t *testing.T) {
+	date, err := Parse("Wed, 26 Dec 2018 10:00:54 PST")
+	if err != nil {
+		t.Fatalf(`RSS dates with PST timezone should be parsed correctly: %v`, err)
+	}
+
+	expectedTS := int64(1545847254)
+	if date.Unix() != expectedTS {
+		t.Errorf(`The Unix timestamp should be %v instead of %v`, expectedTS, date.Unix())
+	}
+
+	expectedLocation := "America/Los_Angeles"
+	if date.Location().String() != expectedLocation {
+		t.Errorf(`The location should be %q instead of %q`, expectedLocation, date.Location())
+	}
+
+	name, offset := date.Zone()
+
+	expectedName := "PST"
+	if name != expectedName {
+		t.Errorf(`The zone name should be %q instead of %q`, expectedName, name)
+	}
+
+	expectedOffset := -28800
+	if offset != expectedOffset {
+		t.Errorf(`The offset should be %v instead of %v`, expectedOffset, offset)
+	}
+}
+
+func TestParseRSSDateOffset(t *testing.T) {
+	date, err := Parse("Sun, 28 Oct 2018 13:48:00 +0100")
+	if err != nil {
+		t.Fatalf(`RSS dates with offset should be parsed correctly: %v`, err)
+	}
+
+	expectedTS := int64(1540730880)
+	if date.Unix() != expectedTS {
+		t.Errorf(`The Unix timestamp should be %v instead of %v`, expectedTS, date.Unix())
+	}
+
+	_, offset := date.Zone()
+	expectedOffset := 3600
+	if offset != expectedOffset {
+		t.Errorf(`The offset should be %v instead of %v`, expectedOffset, offset)
 	}
 }