Flush sample (#132)

* Adding a sample flush policy for only flushing when on an unmetered connection.

* Use flush policies instead of properties.

Author: didiergarcia

samples/kotlin-android-app/src/main/java/com/segment/analytics/next/MainApplication.kt

@@ -10,6 +10,8 @@ import com.segment.analytics.next.plugins.AndroidAdvertisingIdPlugin
 import com.segment.analytics.next.plugins.AndroidRecordScreenPlugin
 import com.segment.analytics.next.plugins.PushNotificationTracking
 import com.segment.analytics.kotlin.core.platform.Plugin
+import com.segment.analytics.kotlin.core.platform.policies.CountBasedFlushPolicy
+import com.segment.analytics.kotlin.core.platform.policies.FrequencyFlushPolicy
 import com.segment.analytics.kotlin.core.utilities.*
 
 class MainApplication : Application() {
@@ -24,8 +26,12 @@ class MainApplication : Application() {
             this.collectDeviceId = true
             this.trackApplicationLifecycleEvents = true
             this.trackDeepLinks = true
-            this.flushAt = 1
-            this.flushInterval = 0
+            this.flushPolicies = listOf(
+                CountBasedFlushPolicy(3), // Flush after 3 events
+                FrequencyFlushPolicy(5000), // Flush after 5 secs
+                UnmeteredFlushPolicy(applicationContext) // Flush if network is not metered
+            )
+            this.flushPolicies = listOf(UnmeteredFlushPolicy(applicationContext))
         }
         analytics.add(AndroidRecordScreenPlugin())
         analytics.add(object : Plugin {

samples/kotlin-android-app/src/main/java/com/segment/analytics/next/UnmeteredFlushPolicy.kt

@@ -0,0 +1,50 @@
+package com.segment.analytics.next
+
+import android.content.Context
+import android.net.ConnectivityManager
+import android.net.NetworkCapabilities
+import android.os.Build
+import androidx.annotation.RequiresApi
+import androidx.core.content.ContextCompat.getSystemService
+import com.segment.analytics.kotlin.core.platform.policies.FlushPolicy
+import java.lang.ref.WeakReference
+
+/**
+ * Flush policy that checks where the Android device is connected to a metered (pay) network or an
+ * unmetered network.
+ *
+ * If the network is NOT metered this Flush policy returns true; false otherwise.
+ */
+class UnmeteredFlushPolicy(context: Context) : FlushPolicy {
+
+    lateinit var weakContext: WeakReference<Context>
+
+    init {
+        weakContext = WeakReference(context)
+    }
+
+    @RequiresApi(Build.VERSION_CODES.S)
+    override fun shouldFlush(): Boolean {
+        val context = weakContext.get()
+        var shouldFlush = false
+        context?.let {
+            val cm = getSystemService(context, ConnectivityManager::class.java) as ConnectivityManager
+
+            val nc = cm.getNetworkCapabilities(cm.activeNetwork)
+            nc?.let {
+                nc.capabilities.forEach {
+                    if (it == NetworkCapabilities.NET_CAPABILITY_NOT_METERED || it == NetworkCapabilities.NET_CAPABILITY_TEMPORARILY_NOT_METERED) {
+                        println("UMFP: YAY network is NOT metered!!")
+                        shouldFlush = true
+                    }
+                }
+
+                if (!shouldFlush) {
+                    println("UMFP: Sorry, this network was IS metered!")
+                }
+            }
+        }
+
+        return shouldFlush
+    }
+}