GODT-213: Message Builder

pkg/message/build_build.go

@@ -0,0 +1,79 @@
+// Copyright (c) 2021 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 message
+
+import (
+	"sync"
+
+	"github.com/pkg/errors"
+)
+
+type buildRes struct {
+	messageID string
+	literal   []byte
+	err       error
+}
+
+func newBuildResSuccess(messageID string, literal []byte) buildRes {
+	return buildRes{
+		messageID: messageID,
+		literal:   literal,
+	}
+}
+
+func newBuildResFailure(messageID string, err error) buildRes {
+	return buildRes{
+		messageID: messageID,
+		err:       err,
+	}
+}
+
+func startBuildWorkers(buildWorkers int) (chan fetchRes, chan buildRes) {
+	buildReqCh := make(chan fetchRes)
+	buildResCh := make(chan buildRes)
+
+	go func() {
+		defer close(buildResCh)
+
+		var wg sync.WaitGroup
+
+		wg.Add(buildWorkers)
+
+		for workerID := 0; workerID < buildWorkers; workerID++ {
+			go buildWorker(buildReqCh, buildResCh, &wg)
+		}
+
+		wg.Wait()
+	}()
+
+	return buildReqCh, buildResCh
+}
+
+func buildWorker(buildReqCh <-chan fetchRes, buildResCh chan<- buildRes, wg *sync.WaitGroup) {
+	defer wg.Done()
+
+	for req := range buildReqCh {
+		if kr, err := req.api.KeyRingForAddressID(req.msg.AddressID); err != nil {
+			buildResCh <- newBuildResFailure(req.msg.ID, errors.Wrap(ErrNoSuchKeyRing, err.Error()))
+		} else if literal, err := buildRFC822(kr, req.msg, req.atts, req.opts); err != nil {
+			buildResCh <- newBuildResFailure(req.msg.ID, err)
+		} else {
+			buildResCh <- newBuildResSuccess(req.msg.ID, literal)
+		}
+	}
+}