Update support lib build to generate repo XML.

Change-Id: If34e985de6af1e188f11f53c1f03e06344ca4861
diff --git a/build.gradle b/build.gradle
index 31fb405..a95df22 100644
--- a/build.gradle
+++ b/build.gradle
@@ -10,6 +10,7 @@
 }
 
 ext.supportVersion = '19.1.0'
+ext.extraVersion = 5
 ext.supportRepoOut = ''
 
 /*
@@ -29,20 +30,26 @@
 
 ext.supportRepoOut = new File(buildDir, 'support_repo')
 
-// upload anchor for subprojects.
-task mainUpload() {
-
+// Main task called by the build server.
+task(createArchive) << {
 }
 
-// main task for release
-task createArchive(type: Zip, dependsOn: mainUpload) {
+
+// upload anchor for subprojects to upload their artifacts
+// to the local repo.
+task(mainUpload) << {
+}
+
+// repository creation task
+task createRepository(type: Zip, dependsOn: mainUpload) {
     from project.ext.supportRepoOut
     destinationDir project.ext.distDir
     into 'm2repository'
-    baseName = "android-m2repository-${project.ext.supportVersion}"
+    baseName = String.format("android_m2repository_r%02d", project.ext.extraVersion)
 }
+createArchive.dependsOn createRepository
 
-// prepare repo.
+// prepare repository with older versions
 task prepareRepo(type: Copy) {
     from "$rootDir/../../prebuilts/maven_repo/android"
     into project.ext.supportRepoOut
@@ -53,6 +60,50 @@
     project.ext.supportRepoOut.mkdirs()
 }
 
+import com.google.common.io.Files
+import com.google.common.base.Charsets
+
+task(createXml) << {
+    def repoArchive = createRepository.archivePath
+    def repoArchiveName = createRepository.archiveName
+    def size = repoArchive.length()
+    def sha1 = getSha1(repoArchive)
+
+    def xml =
+"<sdk:sdk-addon xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:sdk=\"http://schemas.android.com/sdk/android/addon/6\">\n\
+  <sdk:extra>\n\
+    <sdk:revision>\n\
+      <sdk:major>${project.ext.extraVersion}</sdk:major>\n\
+    </sdk:revision>\n\
+    <sdk:vendor-display>Android</sdk:vendor-display>\n\
+    <sdk:vendor-id>android</sdk:vendor-id>\n\
+    <sdk:name-display>Local Maven repository for Support Libraries</sdk:name-display>\n\
+    <sdk:path>m2repository</sdk:path>\n\
+    <sdk:archives>\n\
+      <sdk:archive os=\"any\" arch=\"any\">\n\
+       <sdk:size>${size}</sdk:size>\n\
+       <sdk:checksum type=\"sha1\">${sha1}</sdk:checksum>\n\
+       <sdk:url>${repoArchiveName}</sdk:url>\n\
+      </sdk:archive>\n\
+    </sdk:archives>\n\
+  </sdk:extra>\n\
+</sdk:sdk-addon>"
+
+    Files.write(xml, new File(project.ext.distDir, 'repo-extras.xml'), Charsets.UTF_8)
+}
+createArchive.dependsOn createXml
+
+
+import com.google.common.hash.HashCode
+import com.google.common.hash.HashFunction
+import com.google.common.hash.Hashing
+
+def getSha1(File inputFile) {
+    HashFunction hashFunction = Hashing.sha1()
+    HashCode hashCode = hashFunction.hashString(inputFile.getAbsolutePath())
+    return hashCode.toString()
+}
+
 subprojects {
     // Change buildDir first so that all plugins pick up the new value.
     project.buildDir = project.file("$project.parent.buildDir/../$project.name/build")
@@ -71,7 +122,9 @@
         }
     }
 
+    // before the upload, make sure the repo is ready.
     release.dependsOn rootProject.tasks.prepareRepo
+    // make the mainupload depend on this one.
     mainUpload.dependsOn release
 }