Import/Export backend prep

internal/transfer/provider_eml.go

@@ -0,0 +1,65 @@
+// 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
+
+// EMLProvider implements import and export to/from EML file structure.
+type EMLProvider struct {
+	root string
+}
+
+// NewEMLProvider creates EMLProvider.
+func NewEMLProvider(root string) *EMLProvider {
+	return &EMLProvider{
+		root: root,
+	}
+}
+
+// ID is used for generating transfer ID by combining source and target ID.
+// We want to keep the same rules for import from or export to local files
+// no matter exact path, therefore it returns constant. The same as EML.
+func (p *EMLProvider) ID() string {
+	return "local" //nolint[goconst]
+}
+
+// Mailboxes returns all available folder names from root of EML files.
+// In case the same folder name is used more than once (for example root/a/foo
+// and root/b/foo), it's treated as the same folder.
+func (p *EMLProvider) Mailboxes(includeEmpty, includeAllMail bool) ([]Mailbox, error) {
+	var folderNames []string
+	var err error
+	if includeEmpty {
+		folderNames, err = getFolderNames(p.root)
+	} else {
+		folderNames, err = getFolderNamesWithFileSuffix(p.root, ".eml")
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	mailboxes := []Mailbox{}
+	for _, folderName := range folderNames {
+		mailboxes = append(mailboxes, Mailbox{
+			ID:          "",
+			Name:        folderName,
+			Color:       "",
+			IsExclusive: false,
+		})
+	}
+
+	return mailboxes, nil
+}