We build too many walls and not enough bridges

pkg/updates/compare_versions.go

@@ -0,0 +1,102 @@
+// 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 updates
+
+import (
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+var nonVersionChars = regexp.MustCompile(`([^0-9.]+)`) //nolint[gochecknoglobals]
+
+// sanitizeVersion returns only numbers and periods.
+func sanitizeVersion(version string) string {
+	return nonVersionChars.ReplaceAllString(version, "")
+}
+
+// Result can be false positive, but must not be false negative.
+// Assuming
+//  * dot separated integers format e.g. "A.B.C.…" where A,B,C,… are integers
+//  * `1.1` == `1.1.0` (i.e. first is not newer)
+//  * `1.1.1` > `1.1` (i.e. first is newer)
+func isFirstVersionNewer(first, second string) (firstIsNewer bool, err error) {
+	first = sanitizeVersion(first)
+	second = sanitizeVersion(second)
+
+	firstIsNewer, err = false, nil
+	if first == second {
+		return
+	}
+
+	firstIsNewer = true
+	var firstArr, secondArr []int
+	if firstArr, err = versionStrToInts(first); err != nil {
+		return
+	}
+	if secondArr, err = versionStrToInts(second); err != nil {
+		return
+	}
+
+	verLength := max(len(firstArr), len(secondArr))
+	firstArr = appendZeros(firstArr, verLength)
+	secondArr = appendZeros(secondArr, verLength)
+
+	for i := 0; i < verLength; i++ {
+		if firstArr[i] == secondArr[i] {
+			continue
+		}
+		return firstArr[i] > secondArr[i], nil
+	}
+	return false, nil
+}
+
+func versionStrToInts(version string) (intArr []int, err error) {
+	strArr := strings.Split(version, ".")
+	intArr = make([]int, len(strArr))
+	for index, item := range strArr {
+		if item == "" {
+			intArr[index] = 0
+			continue
+		}
+		intArr[index], err = strconv.Atoi(item)
+		if err != nil {
+			return
+		}
+	}
+	return
+}
+
+func appendZeros(ints []int, newsize int) []int {
+	size := len(ints)
+	if size >= newsize {
+		return ints
+	}
+	zeros := make([]int, newsize-size)
+	return append(ints, zeros...)
+}
+
+func max(ints ...int) (max int) {
+	max = ints[0]
+	for _, a := range ints {
+		if max < a {
+			max = a
+		}
+	}
+	return
+}