feat: custom address/date parser based on rfc5322 abnf

pkg/message/rfc5322/obs_zone.go

@@ -0,0 +1,82 @@
+// Copyright (c) 2020 Proton Technologies AG
+//
+// This file is part of ProtonMail Bridge.
+//
+// ProtonMail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// ProtonMail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with ProtonMail Bridge.  If not, see <https://www.gnu.org/licenses/>.
+
+package rfc5322
+
+import (
+	"errors"
+	"strings"
+	"time"
+
+	"github.com/ProtonMail/proton-bridge/pkg/message/rfc5322/parser"
+	"github.com/sirupsen/logrus"
+)
+
+type obsZone struct {
+	location *time.Location
+}
+
+func (w *walker) EnterObsZone(ctx *parser.ObsZoneContext) {
+	logrus.WithField("text", ctx.GetText()).Trace("Entering obsZone")
+
+	loc := time.UTC
+
+	switch strings.ToLower(ctx.GetText()) {
+	case "ut":
+		loc = time.FixedZone(ctx.GetText(), 0)
+	case "utc":
+		loc = time.FixedZone(ctx.GetText(), 0)
+	case "gmt":
+		loc = time.FixedZone(ctx.GetText(), 0)
+	case "est":
+		loc = time.FixedZone(ctx.GetText(), -5*60*60)
+	case "edt":
+		loc = time.FixedZone(ctx.GetText(), -4*60*60)
+	case "cst":
+		loc = time.FixedZone(ctx.GetText(), -6*60*60)
+	case "cdt":
+		loc = time.FixedZone(ctx.GetText(), -5*60*60)
+	case "mst":
+		loc = time.FixedZone(ctx.GetText(), -7*60*60)
+	case "mdt":
+		loc = time.FixedZone(ctx.GetText(), -6*60*60)
+	case "pst":
+		loc = time.FixedZone(ctx.GetText(), -8*60*60)
+	case "pdt":
+		loc = time.FixedZone(ctx.GetText(), -7*60*60)
+	default:
+		w.err = errors.New("bad timezone")
+	}
+
+	w.enter(&obsZone{
+		location: loc,
+	})
+}
+
+func (w *walker) ExitObsZone(ctx *parser.ObsZoneContext) {
+	logrus.WithField("text", ctx.GetText()).Trace("Exiting obsZone")
+
+	type withObsZone interface {
+		withObsZone(*obsZone)
+	}
+
+	res := w.exit().(*obsZone)
+
+	if parent, ok := w.parent().(withObsZone); ok {
+		parent.withObsZone(res)
+	}
+}