Android: Say hello to gradle!

Switching from Ant to Gradle brings lots of advantages:
 - it is way faster when rebuilding (25-50% faster than ant).
 - it enables first class Android Studio integration.
 - adding Android Extras libs (e.g. Google Play services, OBB, etc.) to
   your project is now painless.

[ChangeLog][Android] Added Gradle support to build the APK.

Change-Id: Iee492954f8ffb2c22e6ab14a8a25faf644de9a51
Reviewed-by: Daniel Teske <daniel.teske@digia.com>

src/plugins/android/androidmanager.cpp

@@ -595,4 +595,112 @@ AndroidQtSupport *AndroidManager::androidQtSupport(ProjectExplorer::Target *targ
     return 0;
 }
 
+bool AndroidManager::useGradle(ProjectExplorer::Target *target)
+{
+    if (!target)
+        return false;
+    AndroidBuildApkStep *buildApkStep
+        = AndroidGlobal::buildStep<AndroidBuildApkStep>(target->activeBuildConfiguration());
+    return buildApkStep && buildApkStep->useGradle();
+}
+
+typedef QMap<QByteArray, QByteArray> GradleProperties;
+
+static GradleProperties readGradleProperties(const QString &path)
+{
+    GradleProperties properties;
+    QFile file(path);
+    if (!file.open(QIODevice::ReadOnly))
+        return properties;
+
+    foreach (const QByteArray &line, file.readAll().split('\n')) {
+        if (line.trimmed().startsWith('#'))
+            continue;
+
+        QList<QByteArray> prop(line.split('='));
+        if (prop.size() > 1)
+            properties[prop.at(0).trimmed()] = prop.at(1).trimmed();
+    }
+    file.close();
+    return properties;
+}
+
+static bool mergeGradleProperties(const QString &path, GradleProperties properties)
+{
+    QFile::remove(path + QLatin1Char('~'));
+    QFile::rename(path, path + QLatin1Char('~'));
+    QFile file(path);
+    if (!file.open(QIODevice::Truncate | QIODevice::WriteOnly | QIODevice::Text))
+        return false;
+
+    QFile oldFile(path + QLatin1Char('~'));
+    if (oldFile.open(QIODevice::ReadOnly)) {
+        while (!oldFile.atEnd()) {
+            QByteArray line(oldFile.readLine());
+            QList<QByteArray> prop(line.split('='));
+            if (prop.size() > 1) {
+                GradleProperties::iterator it = properties.find(prop.at(0).trimmed());
+                if (it != properties.end()) {
+                    file.write(it.key() + '=' + it.value() + '\n');
+                    properties.erase(it);
+                    continue;
+                }
+            }
+            file.write(line);
+        }
+        oldFile.close();
+    } else {
+        file.write("## This file is automatically generated by QtCreator.\n"
+                   "#\n"
+                   "# This file must *NOT* be checked into Version Control Systems,\n"
+                   "# as it contains information specific to your local configuration.\n\n");
+
+    }
+
+    for (GradleProperties::const_iterator it = properties.begin(); it != properties.end(); ++it)
+        file.write(it.key() + '=' + it.value() + '\n');
+
+    file.close();
+    return true;
+}
+
+
+bool AndroidManager::updateGradleProperties(ProjectExplorer::Target *target)
+{
+    QtSupport::BaseQtVersion *version = QtSupport::QtKitInformation::qtVersion(target->kit());
+    if (!version)
+        return false;
+
+    AndroidBuildApkStep *buildApkStep
+        = AndroidGlobal::buildStep<AndroidBuildApkStep>(target->activeBuildConfiguration());
+
+    if (!buildApkStep || !buildApkStep->androidPackageSourceDir().appendPath(QLatin1String("gradlew")).toFileInfo().exists())
+        return false;
+
+    GradleProperties localProperties;
+    localProperties["sdk.dir"] = AndroidConfigurations::currentConfig().sdkLocation().toString().toLocal8Bit();
+    if (!mergeGradleProperties(buildApkStep->androidPackageSourceDir().appendPath(QLatin1String("local.properties")).toString(), localProperties))
+        return false;
+
+    QString gradlePropertiesPath = buildApkStep->androidPackageSourceDir().appendPath(QLatin1String("gradle.properties")).toString();
+    GradleProperties gradleProperties = readGradleProperties(gradlePropertiesPath);
+    gradleProperties["qt5AndroidDir"] = version->qmakeProperty("QT_INSTALL_PREFIX")
+            .append(QLatin1String("/src/android/java")).toLocal8Bit();
+    gradleProperties["buildDir"] = ".build";
+    gradleProperties["androidCompileSdkVersion"] = buildTargetSDK(target).split(QLatin1Char('-')).last().toLocal8Bit();
+    if (gradleProperties["androidBuildToolsVersion"].isEmpty()) {
+        QString maxVersion;
+        QDir buildToolsDir(AndroidConfigurations::currentConfig().sdkLocation().appendPath(QLatin1String("build-tools")).toString());
+        foreach (const QFileInfo &file, buildToolsDir.entryList(QDir::Dirs|QDir::NoDotAndDotDot)) {
+            QString ver(file.fileName());
+            if (maxVersion < ver)
+                maxVersion = ver;
+        }
+        if (maxVersion.isEmpty())
+            return false;
+        gradleProperties["androidBuildToolsVersion"] = maxVersion.toLocal8Bit();
+    }
+    return mergeGradleProperties(gradlePropertiesPath, gradleProperties);
+}
+
 } // namespace Android