feat: custom address/date parser based on rfc5322 abnf

pkg/message/rfc5322/month.go

@@ -0,0 +1,84 @@
+// 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 month struct {
+	value time.Month
+}
+
+func (w *walker) EnterMonth(ctx *parser.MonthContext) {
+	logrus.WithField("text", ctx.GetText()).Trace("Entering month")
+
+	var m time.Month
+
+	switch strings.ToLower(ctx.GetText()) {
+	case "jan":
+		m = time.January
+	case "feb":
+		m = time.February
+	case "mar":
+		m = time.March
+	case "apr":
+		m = time.April
+	case "may":
+		m = time.May
+	case "jun":
+		m = time.June
+	case "jul":
+		m = time.July
+	case "aug":
+		m = time.August
+	case "sep":
+		m = time.September
+	case "oct":
+		m = time.October
+	case "nov":
+		m = time.November
+	case "dec":
+		m = time.December
+	default:
+		w.err = errors.New("no such month")
+	}
+
+	w.enter(&month{
+		value: m,
+	})
+}
+
+func (w *walker) ExitMonth(ctx *parser.MonthContext) {
+	logrus.WithField("text", ctx.GetText()).Trace("Exiting month")
+
+	type withMonth interface {
+		withMonth(*month)
+	}
+
+	res := w.exit().(*month)
+
+	if parent, ok := w.parent().(withMonth); ok {
+		parent.withMonth(res)
+	}
+}