adds timestamp VersionCodeScheme (#72)

* Returns the time since 1.1.2024 in seconds
* should fit in 31 bits (we need one for the sign) for about 68 years until 2092
* it’s dependency-less
* it’s monotonic (a requirement from google-side)

src/integrationTest/groovy/wooga/gradle/version/VersionPluginIntegrationSpec.groovy

@@ -114,6 +114,8 @@ class VersionPluginIntegrationSpec extends VersionIntegrationSpec {
         "versionCodeScheme"    | "releaseCount"      | VersionCodeSchemes.releaseCount      | PropertyLocation.property
         "versionCodeScheme"    | "semver"            | VersionCodeSchemes.semver            | PropertyLocation.property
         "versionCodeScheme"    | "none"              | VersionCodeSchemes.none              | PropertyLocation.property
+        "versionCodeScheme"    | "timestamp"         | VersionCodeSchemes.timestamp         | PropertyLocation.environment
+        "versionCodeScheme"    | "timestamp"         | VersionCodeSchemes.timestamp         | PropertyLocation.property
         "versionCodeOffset"    | 100                 | _                                    | PropertyLocation.environment
         "versionCodeOffset"    | 200                 | _                                    | PropertyLocation.property
         "releaseBranchPattern" | /^m.*/              | _                                    | PropertyLocation.property
@@ -179,6 +181,10 @@ class VersionPluginIntegrationSpec extends VersionIntegrationSpec {
         "versionCodeScheme"    | "setVersionCodeScheme"     | "releaseCount"                       | "String"
         "versionCodeScheme"    | "setVersionCodeScheme"     | VersionCodeSchemes.none              | "VersionCodeScheme"
         "versionCodeScheme"    | "setVersionCodeScheme"     | VersionCodeSchemes.releaseCount      | "Provider<VersionCodeScheme>"
+        "versionCodeScheme"    | "versionCodeScheme"        | "timestamp"                          | "String"
+        "versionCodeScheme"    | "versionCodeScheme"        | VersionCodeSchemes.timestamp         | "Provider<VersionCodeScheme>"
+        "versionCodeScheme"    | "versionCodeScheme.set"    | VersionCodeSchemes.timestamp         | "Provider<VersionCodeScheme>"
+
 
         "versionCodeOffset"    | "versionCodeOffset"        | 1                                    | "Integer"
         "versionCodeOffset"    | "versionCodeOffset"        | 2                                    | "Provider<Integer>"
@@ -319,4 +325,32 @@ class VersionPluginIntegrationSpec extends VersionIntegrationSpec {
         extensionName = "versionBuilder"
     }
 
+    // tests that timestamp versioncode scheme generates different versionCodes when called twice 2 seconds apart
+    def "timestamp versionCode scheme generates different versionCodes"() {
+        given: "a timestamp version scheme setting"
+        buildFile << """
+            versionBuilder {
+                versionCodeScheme = "timestamp"
+            }
+        """
+
+        def query = new PropertyQueryTaskWriter("project.versionCode", "")
+        query.write(buildFile)
+
+        when: "executing the task twice with a 2 second delay"
+
+        def version1 = query.getValue(runTasksSuccessfully(query.taskName)).toInteger()
+        // wait 2 seconds
+        Thread.sleep(2000)
+        def version2 = query.getValue(runTasksSuccessfully(query.taskName)).toInteger()
+
+        then:
+        version2 > version1
+        // sanity check, version is bigger than the difference from 1.1.2024 until the time of this test
+        version1 > 17280000
+    }
+
+
+
+
 }

src/main/groovy/wooga/gradle/version/VersionCodeSchemes.groovy

@@ -23,5 +23,6 @@ enum VersionCodeSchemes {
     semverBasic,
     semver,
     releaseCountBasic,
-    releaseCount
+    releaseCount,
+    timestamp
 }

src/main/groovy/wooga/gradle/version/internal/VersionCode.groovy

@@ -36,7 +36,8 @@ class VersionCode {
         }),
         releaseCount(VersionCodeSchemes.releaseCount, {
             GitVersionRepository git, int offset -> generateBuildNumberVersionCode(git, true) + offset
-        })
+        }),
+        timestamp(VersionCodeSchemes.timestamp, { -> generateBuildTimeVersionCode()});
 
         private final VersionCodeSchemes external
         private final Closure<Integer> generator
@@ -147,4 +148,16 @@ class VersionCode {
     static Integer generateBuildNumberVersionCode(GitVersionRepository versionRepo, Boolean countPrerelease = true) {
         return versionRepo.countReachableVersions(countPrerelease) + 1
     }
+
+    /**
+     * Returns the time since 1.1.2024 in seconds
+     * should fit in 31 bits (we need one for the sign) for about 68 years until 2092
+     * @return
+     */
+    static Integer generateBuildTimeVersionCode() {
+        def date = new Date()
+        def buildTime = date.getTime() - 1704063600000 // 1.1.2024
+        return (int)(buildTime / 1000)
+    }
+
 }