Add github-based automatic versioning (#42)

This applies to the shadowjar and adds the PhotonVersion class

.gitignore

@@ -124,3 +124,4 @@ New client/photon-client/*
 photon-server/build
 photon-server/photon-vision
 photon-server/src/main/resources/web
+photon-server/src/main/java/org/photonvision/PhotonVersion.java

photon-server/build.gradle

@@ -6,10 +6,12 @@ plugins {
     id "jacoco"
 }
 
+apply from: 'versioningHelper.gradle'
+
 mainClassName = 'org.photonvision.Main'
 
 group 'org.photonvision'
-version '2020.6.1'
+version getCurrentVersion()
 
 sourceCompatibility = 11
 
@@ -129,6 +131,8 @@ spotless {
     java {
         target "src/*/java/org/**/*.java"
         licenseHeaderFile "$rootDir/LicenseHeader.txt"
+
+        targetExclude("src/main/java/org/photonvision/PhotonVersion.java")
     }
 }
 

photon-server/versioningHelper.gradle

@@ -0,0 +1,26 @@
+gradle.allprojects {
+    ext.getCurrentVersion = { ->
+        def stdout = new ByteArrayOutputStream()
+        exec {
+            commandLine 'git', 'describe', '--tags'
+            standardOutput = stdout
+        }
+        return stdout.toString().trim().toLowerCase()
+    }
+}
+
+task writeCurrentVersionJava {
+    File versionFile = new File("src/main/java/org/photonvision/PhotonVersion.java")
+    versionFile.delete()
+    versionFile << "package org.photonvision;\n" +
+            "\n" +
+            "/*\n" +
+            " * Autogenerated file! Do not manually edit this file. This version is regenerated\n" +
+            " * any time the publish task is run, or when this file is deleted.\n" +
+            " */\n\n" +
+            "public class PhotonVersion {\n" +
+            String.format("    public static final String versionString = \"%s\";\n", getCurrentVersion()) +
+            "}"
+}
+
+build.dependsOn writeCurrentVersionJava