gradle: Use our own groovy code to compute a version from git

git worktree is not supported by androidgitversion

This makes it work with git worktrees and submodules, unlike the
plugin we used before. Unlike some other gradle plugins,
this allows us to set our own filter for tags that get included in
the version.

Thanks to Tao Pei for noticing the problem and proposing an initial fix.

Co-authored-by: tao.pei <tao.pei@xjmz.com>
Part-of: <https://gitlab.freedesktop.org/monado/monado/-/merge_requests/2204>

doc/changes/misc_features/mr.676.md

@@ -16,6 +16,7 @@
 - mr.1377
 - mr.1385
 - mr.2232
+- mr.2204
 ---
 
 More improvements to the Android port.

src/xrt/targets/openxr_android/build.gradle

@@ -1,4 +1,4 @@
-// Copyright 2020-2022, Collabora, Ltd.
+// Copyright 2020-2024, Collabora, Ltd.
 // SPDX-License-Identifier: BSL-1.0
 import groovy.xml.XmlUtil
 
@@ -8,7 +8,6 @@ plugins {
 
     id 'com.mikepenz.aboutlibraries.plugin'
 
-    id "com.gladed.androidgitversion"
     id "de.undercouch.download"
 
     // Hilt dependency injection
@@ -35,12 +34,6 @@ spotless {
     }
 }
 
-androidGitVersion {
-    tagPattern(/^v[0-9]+.*/)
-    codeFormat = 'MMNPBBBBB'
-    format = '%tag%%-count%%-gcommit%%-dirty%'
-}
-
 def parseOpenXRVersion(def fn) {
     def matches = file(fn).readLines().find {
         it.contains('XR_CURRENT_API_VERSION')
@@ -97,6 +90,60 @@ if (!(new File(project.file(project.eigenIncludeDir), "Eigen/Core")).exists()) {
     unpackEigen.enabled = false
 }
 
+// ***
+// Git version handling
+// ***
+
+// Supplied with major, minor, patch, commit count
+def versionCodeFormatPattern = "%02d%01d%01d%05d"
+
+// parsed using this regex
+def gitDescribePattern = ~/v(?<tag>(?<major>\d+)\.(?<minor>\d+)\.(?<patch>\d+))-(?<commits>\d+)-g(?<hash>[0-9a-f]+)/
+
+// Get the version code from git describe output
+def getVersionCode = { ->
+    try {
+        def stdout = new ByteArrayOutputStream()
+        exec {
+            commandLine 'git', 'describe', '--always', '--long', '--match', 'v*'
+            standardOutput = stdout
+            workingDir rootDir
+        }
+        def longOutput = stdout.toString().trim()
+        def matcher = longOutput =~ gitDescribePattern
+        if (!matcher.matches()) {
+            println "Could not find an annotated git tag matching the regex!"
+            return null
+        }
+        def codeAsString = String.format(versionCodeFormatPattern,
+            Integer.parseInt(matcher.group('major')),
+            Integer.parseInt(matcher.group('minor')),
+            Integer.parseInt(matcher.group('patch')),
+            Integer.parseInt(matcher.group('commits')))
+        return Integer.parseInt(codeAsString)
+    }
+    catch (ignored) {
+        return null;
+    }
+}
+
+// Get the version string from git describe output
+def getVersionString = { ->
+    try {
+        def stdout = new ByteArrayOutputStream()
+        exec {
+            commandLine 'git', 'describe', '--always', '--dirty', '--match', 'v*'
+            standardOutput = stdout
+            workingDir rootDir
+        }
+        return stdout.toString().trim()
+    }
+    catch (ignored) {
+        return null;
+    }
+}
+
+
 // Pass -PsharedStl=true on the gradle command line to build with the shared runtime library.
 // This has potential compatibility issues and should only be used if you're consuming another
 // library that exposes a C++ interface.
@@ -117,10 +164,11 @@ android {
         minSdkVersion project.sharedMinSdk
         targetSdkVersion project.sharedTargetSdk
 
-        versionCode androidGitVersion.code()
-        versionName androidGitVersion.name()
+        versionCode = getVersionCode()
+        versionName = getVersionString()
 
         println versionName
+        println versionCode
 
         resValue "string", "monado_lib_version", "${versionName}"