adding some signing related things

app/build.gradle

@@ -2,6 +2,12 @@ apply plugin: 'com.android.application'
 apply plugin: 'kotlin-android'
 apply plugin: 'kotlin-android-extensions'
 
+def keystorePropertiesFile = rootProject.file("keystore.properties")
+def keystoreProperties = new Properties()
+if (keystorePropertiesFile.exists()) {
+    keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
+}
+
 android {
     compileSdkVersion 29
     buildToolsVersion "29.0.3"
@@ -15,13 +21,27 @@ android {
         setProperty("archivesBaseName", "dialer")
     }
 
+    signingConfigs {
+        if (keystorePropertiesFile.exists()) {
+            release {
+                keyAlias keystoreProperties['keyAlias']
+                keyPassword keystoreProperties['keyPassword']
+                storeFile file(keystoreProperties['storeFile'])
+                storePassword keystoreProperties['storePassword']
+            }
+        }
+    }
+
     buildTypes {
         debug {
             applicationIdSuffix ".debug"
         }
         release {
             minifyEnabled true
-            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+            if (keystorePropertiesFile.exists()) {
+                signingConfig signingConfigs.release
+            }
         }
     }
 

keystore.properties_sample

@@ -0,0 +1,4 @@
+storePassword=123456
+keyPassword=abcdef
+keyAlias=myAlias
+storeFile=../keystore.jks