Import/Export backend prep

internal/transfer/utils.go

@@ -0,0 +1,141 @@
+// 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 (
+	"bufio"
+	"bytes"
+	"io/ioutil"
+	"net/mail"
+	"net/textproto"
+	"path/filepath"
+	"sort"
+	"strings"
+
+	"github.com/pkg/errors"
+)
+
+// getFolderNames collects all folder names under `root`.
+// Folder names will be without a path.
+func getFolderNames(root string) ([]string, error) {
+	return getFolderNamesWithFileSuffix(root, "")
+}
+
+// getFolderNamesWithFileSuffix collects all folder names under `root`, which
+// contains some file with a give `fileSuffix`. Names will be without a path.
+func getFolderNamesWithFileSuffix(root, fileSuffix string) ([]string, error) {
+	folders := []string{}
+
+	files, err := ioutil.ReadDir(root)
+	if err != nil {
+		return nil, err
+	}
+
+	hasFileWithSuffix := fileSuffix == ""
+	for _, file := range files {
+		if file.IsDir() {
+			subfolders, err := getFolderNamesWithFileSuffix(filepath.Join(root, file.Name()), fileSuffix)
+			if err != nil {
+				return nil, err
+			}
+			for _, subfolder := range subfolders {
+				match := false
+				for _, folder := range folders {
+					if folder == subfolder {
+						match = true
+						break
+					}
+				}
+				if !match {
+					folders = append(folders, subfolder)
+				}
+			}
+		} else if fileSuffix == "" || strings.HasSuffix(file.Name(), fileSuffix) {
+			hasFileWithSuffix = true
+		}
+	}
+
+	if hasFileWithSuffix {
+		folders = append(folders, filepath.Base(root))
+	}
+
+	sort.Strings(folders)
+	return folders, nil
+}
+
+// getFilePathsWithSuffix collects all file names with `suffix` under `root`.
+// File names will be with relative path based to `root`.
+func getFilePathsWithSuffix(root, suffix string) ([]string, error) {
+	fileNames, err := getFilePathsWithSuffixInner("", root, suffix)
+	if err != nil {
+		return nil, err
+	}
+	sort.Strings(fileNames)
+	return fileNames, err
+}
+
+func getFilePathsWithSuffixInner(prefix, root, suffix string) ([]string, error) {
+	fileNames := []string{}
+
+	files, err := ioutil.ReadDir(root)
+	if err != nil {
+		return nil, err
+	}
+
+	for _, file := range files {
+		if !file.IsDir() {
+			if strings.HasSuffix(file.Name(), suffix) {
+				fileNames = append(fileNames, filepath.Join(prefix, file.Name()))
+			}
+		} else {
+			subfolderFileNames, err := getFilePathsWithSuffixInner(
+				filepath.Join(prefix, file.Name()),
+				filepath.Join(root, file.Name()),
+				suffix,
+			)
+			if err != nil {
+				return nil, err
+			}
+			fileNames = append(fileNames, subfolderFileNames...)
+		}
+	}
+
+	return fileNames, nil
+}
+
+// getMessageTime returns time of the message specified in the message header.
+func getMessageTime(body []byte) (int64, error) {
+	mailHeader, err := getMessageHeader(body)
+	if err != nil {
+		return 0, err
+	}
+	if t, err := mailHeader.Date(); err == nil && !t.IsZero() {
+		return t.Unix(), nil
+	}
+	return 0, nil
+}
+
+// getMessageHeader returns headers of the message body.
+func getMessageHeader(body []byte) (mail.Header, error) {
+	tpr := textproto.NewReader(bufio.NewReader(bytes.NewBuffer(body)))
+	header, err := tpr.ReadMIMEHeader()
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to read headers")
+	}
+	return mail.Header(header), nil
+}