build: Customize the logic to determine the version

The previous implementation had the problem that pre-releases always
got the revision appended. Also, the logic to remove the pre-release
identifier did not work with versioned pre-releases like "RC1".

Fix this by completely customizing the logic to determine the version:

- Releases only contain the semantic version, like "1.2.3".
- Pre-releases additionally contain the pre-release version, like
  "1.2.3-RC1".
- Commits ahead of the last release tag get the commit count and
  revision appended, like "1.2.3-RC1.001.sha.0123456".

The implementation is more verbose than before but makes it easier to
understand how the version is constructed.

Signed-off-by: Martin Nonnenmacher <[email protected]>

build.gradle.kts

@@ -36,18 +36,26 @@ semver {
     // Do not create an empty release commit when running the "releaseVersion" task.
     createReleaseCommit = false
 
+    // Use "RC" instead of "SNAPSHOT" as the default pre-release identifier.
+    defaultPreRelease = "RC"
+
     // Do not let untracked files bump the version or add a "-SNAPSHOT" suffix.
     noDirtyCheck = true
 }
 
 // Only override a default version (which usually is "unspecified"), but not a custom version.
 if (version == Project.DEFAULT_VERSION) {
-    version = semver.semVersion.takeIf { it.isPreRelease }
-        // To get rid of a build part's "+" prefix because Docker tags do not support it, use only the original "build"
-        // part as the "pre-release" part.
-        ?.toString()?.replace("${semver.defaultPreRelease}+", "")
-        // Fall back to a plain version without pre-release or build parts.
-        ?: semver.version
+    val semVersion = semver.semVersion
+
+    // Set the version based on the following rules:
+    // - If the current commit is tagged as a release (e.g., 1.2.3) or pre-release (e.g., 1.2.3-RC1), the version equals
+    //   the tag.
+    // - If the current commit is ahead of the last release or pre-release tag, the version is the tag plus the
+    //   pre-release identifier, the commit count, and the SHA. For example, "1.2.3-RC1.001.sha.0123456". Note that
+    //   semantic versions would use a "+" instead of a "." in front of the commit count, but this version is also used
+    //   as a Docker tag and Docker does not allow "+" in tags.
+    val shaLength = if (semVersion.commitCount > 0) 7 else 0
+    version = semVersion.toInfoVersionString(shaLength = shaLength).replace('+', '.')
 }
 
 logger.lifecycle("Building ORT Server version $version.")