Import/Export backend prep

internal/transfer/provider_eml_source.go

@@ -0,0 +1,135 @@
+// 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 transfer
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+
+	"github.com/pkg/errors"
+)
+
+// TransferTo exports messages based on rules to channel.
+func (p *EMLProvider) TransferTo(rules transferRules, progress *Progress, ch chan<- Message) {
+	log.Info("Started transfer from EML to channel")
+	defer log.Info("Finished transfer from EML to channel")
+
+	filePathsPerFolder, err := p.getFilePathsPerFolder(rules)
+	if err != nil {
+		progress.fatal(err)
+		return
+	}
+
+	// This list is not filtered by time but instead going throgh each file
+	// twice or keeping all in memory we will tell rough estimation which
+	// will be updated during processing each file.
+	for folderName, filePaths := range filePathsPerFolder {
+		if progress.shouldStop() {
+			break
+		}
+
+		progress.updateCount(folderName, uint(len(filePaths)))
+	}
+
+	for folderName, filePaths := range filePathsPerFolder {
+		// No error guaranteed by getFilePathsPerFolder.
+		rule, _ := rules.getRuleBySourceMailboxName(folderName)
+		log.WithField("rule", rule).Debug("Processing rule")
+		p.exportMessages(rule, filePaths, progress, ch)
+	}
+}
+
+func (p *EMLProvider) getFilePathsPerFolder(rules transferRules) (map[string][]string, error) {
+	filePaths, err := getFilePathsWithSuffix(p.root, ".eml")
+	if err != nil {
+		return nil, err
+	}
+
+	filePathsMap := map[string][]string{}
+	for _, filePath := range filePaths {
+		folder := filepath.Base(filepath.Dir(filepath.Join(p.root, filePath)))
+		_, err := rules.getRuleBySourceMailboxName(folder)
+		if err != nil {
+			log.WithField("msg", filePath).Trace("Message skipped due to folder name")
+			continue
+		}
+
+		filePathsMap[folder] = append(filePathsMap[folder], filePath)
+	}
+
+	return filePathsMap, nil
+}
+
+func (p *EMLProvider) exportMessages(rule *Rule, filePaths []string, progress *Progress, ch chan<- Message) {
+	count := uint(len(filePaths))
+
+	for _, filePath := range filePaths {
+		if progress.shouldStop() {
+			break
+		}
+
+		msg, err := p.exportMessage(rule, filePath)
+
+		// Read and check time in body only if the rule specifies it
+		// to not waste energy.
+		if err == nil && rule.HasTimeLimit() {
+			msgTime, msgTimeErr := getMessageTime(msg.Body)
+			if msgTimeErr != nil {
+				err = msgTimeErr
+			} else if !rule.isTimeInRange(msgTime) {
+				log.WithField("msg", filePath).Debug("Message skipped due to time")
+
+				count--
+				progress.updateCount(rule.SourceMailbox.Name, count)
+				continue
+			}
+		}
+
+		// addMessage is called after time check to not report message
+		// which should not be exported but any error from reading body
+		// or parsing time is reported as an error.
+		progress.addMessage(filePath, rule)
+		progress.messageExported(filePath, msg.Body, err)
+		if err == nil {
+			ch <- msg
+		}
+	}
+}
+
+func (p *EMLProvider) exportMessage(rule *Rule, filePath string) (Message, error) {
+	fullFilePath := filepath.Clean(filepath.Join(p.root, filePath))
+	file, err := os.Open(fullFilePath) //nolint[gosec]
+	if err != nil {
+		return Message{}, errors.Wrap(err, "failed to open message")
+	}
+	defer file.Close() //nolint[errcheck]
+
+	body, err := ioutil.ReadAll(file)
+	if err != nil {
+		return Message{}, errors.Wrap(err, "failed to read message")
+	}
+
+	return Message{
+		ID:      filePath,
+		Unread:  false,
+		Body:    body,
+		Source:  rule.SourceMailbox,
+		Targets: rule.TargetMailboxes,
+	}, nil
+}