pre-release.gradle

project.ext.getPreReleaseTag = { ->
    println "Getting git tag for pre-release version."

    def logOut = new StringBuilder(), logErr = new StringBuilder()
    def logProc = "git log -n1 --pretty='%h'".execute()
    logProc.consumeProcessOutput(logOut, logErr);
    logProc.waitForOrKill(1000)

    if (logProc.exitValue() != 0 || logErr.length() > 0) {
        throw new InvalidUserDataException("Failed to get git ref-log")
    }

    def gitLog = logOut.toString()
    println "Ref-log says: " + gitLog
    def logPattern = ~/'([a-z0-9]+)'/
    def logMatcher = logPattern.matcher(gitLog)
    if (!logMatcher.find()) {
        throw new InvalidUserDataException("Failed to find commit-ref in log!")
    }
    gitLog = logMatcher.group(1)

    def describeOut = new StringBuilder(), describeErr = new StringBuilder()
    def describeProc = "git describe --exact-match --tags $gitLog".execute()
    describeProc.consumeProcessOutput(describeOut, describeErr)
    describeProc.waitForOrKill(1000)

    if (describeProc.exitValue() != 0 || describeErr.length() > 0) {
        println "Failed to get git tag: " + describeErr.toString()
        throw new InvalidUserDataException("Current revision has no tag!")
    }
    def tagName = describeOut.toString()
    def rcPattern = ~/(\d+\.\d+\.\d+-rc\.\d+)/
    def matcher = rcPattern.matcher(tagName)
    if (!matcher.find()) {
        throw new InvalidUserDataException("Current revision is not a release candidate tag! Found: $tagName")
    }

    def tag = matcher.group(1)
    println "Found tag: " + tag
    return tag
}