Improve countImpression functionality in native android SDK

Author: slawomirzaba

README.md

@@ -150,12 +150,15 @@ Any registered `Observer` will be called with the final authentication and subsc
 * The subscription information gets validated as well on every token refresh.
 
 ### Counting an impression
-
-To count an impression, call either the suspending function `countImpressionSuspending(context: Context)` or the compatibility function `countImpression(context: Context, callback: CountImpressionCallback)`.
-
-In both cases you'll need to supply a `Context` (i.e. an `Activity` or `Fragment`) so the login process can be started again in case the user needs to login again.
-
-For an impression to be able to be counted, a user has to be authenticated and have an active subscription applicable to your scope.
+To count an impression, call either the suspending function `countImpressionSuspending(context: Context)` or
+the compatibility function `countImpression(context: Context, callback: CountImpressionCallback)`.
+In both cases you'll need to supply a `Context` (i.e. an `Activity` or `Fragment`) so the login process can
+be started again in case the user needs to login again.
+
+These methods count impressions for billing purposes. This method must be invoked whenever a user views a piece
+of content, independently of authentication state. If the current user is authenticated the impression will automatically
+be logged as paid ad-free impression to calculate the publisher compensation. As the total amount of impressions is required
+for billing as well, this method also counts sampled impressions of non-subscribers.
 
 ```kotlin
 try {

lib/src/main/java/de/contentpass/lib/Authorizer.kt

@@ -27,7 +27,7 @@ internal interface Authorizing {
 
     fun onAuthorizationRequestResult(intent: Intent?)
 
-    suspend fun countImpression(authState: AuthState, activity: Context)
+    suspend fun countPaidImpression(authState: AuthState, activity: Context)
 }
 
 internal class Authorizer(
@@ -138,9 +138,10 @@ internal class Authorizer(
         }
     }
 
-    override suspend fun countImpression(authState: AuthState, activity: Context) {
+    override suspend fun countPaidImpression(authState: AuthState, activity: Context) {
         val impressionId = UUID.randomUUID()
-        val path = "pass/hit?pid=$propertyId&iid=$impressionId&t=pageview"
+        val publicId = propertyId.substring(0, 8)
+        val path = "pass/hit?pid=$publicId&iid=$impressionId&t=pageview"
 
         val response = fireApiRequestWithFreshTokens(path, authState, activity)
 

lib/src/main/java/de/contentpass/lib/ContentPass.kt

@@ -12,11 +12,30 @@ import com.squareup.moshi.kotlin.reflect.KotlinJsonAdapterFactory
 import kotlinx.coroutines.*
 import net.openid.appauth.AuthState
 import net.openid.appauth.AuthorizationException
+import okhttp3.Call
+import okhttp3.Callback
+import okhttp3.MediaType.Companion.toMediaType
+import okhttp3.OkHttpClient
+import okhttp3.RequestBody.Companion.toRequestBody
 import okhttp3.Request
+import okhttp3.Response
 import java.io.InputStream
+import java.io.IOException
 import java.lang.NullPointerException
 import java.util.Timer
 import java.util.TimerTask
+import java.util.UUID
+import kotlin.coroutines.suspendCoroutine
+
+const val SAMPLING_RATE = 0.05
+
+data class SampleImpressionData(
+    val ea: String,
+    val ec: String,
+    val cpabid: String,
+    val cppid: String,
+    val cpsr: Double
+)
 
 /**
  * An object that handles all communication with the contentpass servers for you.
@@ -40,6 +59,7 @@ import java.util.TimerTask
 class ContentPass internal constructor(
     private val authorizer: Authorizing,
     private val tokenStore: TokenStoring,
+    private val configuration: Configuration
 ) {
     /**
      * A collection of functions that allow you to react to changes in the [ContentPass] object.
@@ -93,7 +113,7 @@ class ContentPass internal constructor(
             configuration = grabConfiguration()
             val authorizer = Authorizer(configuration!!, context!!)
             val store = TokenStore(context!!, KeyStore(context!!))
-            return ContentPass(authorizer, store)
+            return ContentPass(authorizer, store, configuration!!)
         }
 
         private fun grabConfiguration(): Configuration? {
@@ -293,12 +313,8 @@ class ContentPass internal constructor(
      * This is the compatibility function for Java users and developers who are not yet
      * comfortable or able to use kotlin coroutines.
      *
-     * A user has to be authenticated and have an active subscription applicable to your
-     * scope for this to work.
      * This function calls the callback's onSuccess on a successful impression counting.
      * In case of an error the callback's onFailure contains an exception containing more information.
-     * If the exception is a ContentPass.CountImpressionException and the message states the http error
-     * code 404, the user most likely has no applicable subscription.
      *
      * @param context the context the authentication flow can be restarted from in case a login is necessary.
      * @param callback an object implementing the [CountImpressionCallback] interface that enables
@@ -318,17 +334,68 @@ class ContentPass internal constructor(
     /**
      * Count an impression by calling this function.
      *
-     * A user has to be authenticated and have an active subscription applicable to your
-     * scope for this to work.
      * This function simply returns on success or will throw an exception containing more information.
-     * If the exception is a ContentPass.CountImpressionException and the message states the http error
-     * code 404, the user most likely has no applicable subscription.
      *
      * @param context the context the authentication flow can be restarted from in case a login is necessary.
      */
     suspend fun countImpressionSuspending(context: Context) {
         return withContext(coroutineContext) {
-            authorizer.countImpression(authState, context)
+            if (state is State.Authenticated && (state as State.Authenticated).hasValidSubscription) {
+                authorizer.countPaidImpression(authState, context)
+            }
+
+
+            countSampledImpression()
+        }
+    }
+
+    private suspend fun countSampledImpression() {
+        val generatedSample = Math.random()
+        if (generatedSample >= SAMPLING_RATE) {
+            return
+        }
+
+        val instanceId = UUID.randomUUID().toString()
+        val publicId = configuration.propertyId.substring(0, 8)
+        val sampleImpressionData = SampleImpressionData(
+            ea = "load",
+            ec = "tcf-sampled",
+            cpabid = instanceId,
+            cppid = publicId,
+            cpsr = SAMPLING_RATE
+        )
+        val moshi = Moshi.Builder()
+            .add(KotlinJsonAdapterFactory())
+            .build()
+        val jsonAdapter = moshi.adapter(SampleImpressionData::class.java)
+        val jsonBody = jsonAdapter.toJson(sampleImpressionData)
+
+        val responseCode = postRequest("${configuration.apiUrl}/stats", jsonBody);
+        if (responseCode < 200 || responseCode >= 300) {
+            throw CountImpressionException(responseCode)
+        }
+    }
+
+
+    private suspend fun postRequest(url: String, jsonBody: String): Int {
+        val client = OkHttpClient()
+        val requestBody = jsonBody.toRequestBody("application/json; charset=UTF-8".toMediaType())
+        val request = Request.Builder()
+            .url(url)
+            .post(requestBody)
+            .header("Content-Type", "application/json; charset=UTF-8")
+            .build()
+
+        return suspendCoroutine { continuation ->
+            client.newCall(request).enqueue(object : Callback {
+                override fun onFailure(call: Call, e: IOException) {
+                    continuation.resumeWith(Result.failure(e))
+                }
+
+                override fun onResponse(call: Call, response: Response) {
+                    continuation.resumeWith(Result.success(response.code))
+                }
+            })
         }
     }
 

lib/src/test/java/de/contentpass/lib/ContentPassTests.kt

@@ -1,26 +1,53 @@
 package de.contentpass.lib
 
 import android.content.Intent
+import android.net.Uri
 import androidx.activity.ComponentActivity
 import androidx.activity.result.ActivityResult
 import androidx.activity.result.contract.ActivityResultContract
 import androidx.fragment.app.Fragment
 import io.mockk.coEvery
 import io.mockk.every
 import io.mockk.mockk
+import io.mockk.mockkStatic
 import io.mockk.verify
 import kotlinx.coroutines.runBlocking
 import net.openid.appauth.AuthState
 import org.junit.Assert.*
+import org.junit.Before
 import org.junit.Test
 import java.lang.NullPointerException
 
 class ContentPassTests {
+    private lateinit var mockUri: Uri
+    private lateinit var exampleConfiguration: Configuration
+
+    @Before
+    fun setUp() {
+        mockkStatic(Uri::class)
+
+        mockUri = mockk()
+        every { mockUri.toString() } returns "https://example.com"
+        every { mockUri.scheme } returns "https"
+        every { mockUri.host } returns "example.com"
+        every { mockUri.path } returns "/"
+        every { Uri.parse(any()) } returns mockUri
+
+
+        exampleConfiguration = Configuration(
+            2,
+            Uri.parse("https://example.com/api"),
+            Uri.parse("https://example.com/oidc"),
+            Uri.parse("https://example.com/redirect"),
+            "example"
+        )
+    }
+
     @Test
     fun `initialization without stored state results in Unauthenticated`() {
         val store = MockedTokenStore()
         assertNull(store.retrieveAuthState())
-        val contentPass = ContentPass(mockk(relaxed = true), store)
+        val contentPass = ContentPass(mockk(relaxed = true), store, exampleConfiguration)
 
         assertEquals(ContentPass.State.Unauthenticated, contentPass.state)
     }
@@ -32,7 +59,7 @@ class ContentPassTests {
         val store = MockedTokenStore()
         store.storeAuthState(state)
 
-        val contentPass = ContentPass(mockk(relaxed = true), store)
+        val contentPass = ContentPass(mockk(relaxed = true), store, exampleConfiguration)
 
         Thread.sleep(10)
 
@@ -50,7 +77,7 @@ class ContentPassTests {
             coEvery { authorizer.validateSubscription(any()) }.returns(true)
             coEvery { authorizer.authenticate(any(), any()) }.returns(state)
 
-            val contentPass = ContentPass(authorizer, mockk(relaxed = true))
+            val contentPass = ContentPass(authorizer, mockk(relaxed = true), exampleConfiguration)
             val activity: ComponentActivity = mockk(relaxed = true)
             contentPass.registerActivityResultLauncher(activity)
 
@@ -63,7 +90,7 @@ class ContentPassTests {
     @Test
     fun `calling authenticate before registerActivityResultLauncher results in NullPointerException`() =
         runBlocking {
-            val contentPass = ContentPass(mockk(relaxed = true), mockk(relaxed = true))
+            val contentPass = ContentPass(mockk(relaxed = true), mockk(relaxed = true), exampleConfiguration)
 
             try {
                 contentPass.authenticateSuspending(mockk())
@@ -77,7 +104,7 @@ class ContentPassTests {
 
     @Test
     fun `registerActivityResultLauncher for activity registers for activity result`() {
-        val contentPass = ContentPass(mockk(relaxed = true), mockk(relaxed = true))
+        val contentPass = ContentPass(mockk(relaxed = true), mockk(relaxed = true), exampleConfiguration)
         val activity: ComponentActivity = mockk(relaxed = true)
 
         contentPass.registerActivityResultLauncher(activity)
@@ -92,7 +119,7 @@ class ContentPassTests {
 
     @Test
     fun `registerActivityResultLauncher for fragment registers for activity result`() {
-        val contentPass = ContentPass(mockk(relaxed = true), mockk(relaxed = true))
+        val contentPass = ContentPass(mockk(relaxed = true), mockk(relaxed = true), exampleConfiguration)
         val fragment: Fragment = mockk(relaxed = true)
 
         contentPass.registerActivityResultLauncher(fragment)
@@ -113,7 +140,7 @@ class ContentPassTests {
         val authorizer: Authorizing = mockk()
         coEvery { authorizer.validateSubscription(any()) }.returns(true)
         coEvery { authorizer.authenticate(any(), any()) }.returns(authState)
-        val contentPass = ContentPass(authorizer, mockk(relaxed = true))
+        val contentPass = ContentPass(authorizer, mockk(relaxed = true), exampleConfiguration)
 
         contentPass.registerActivityResultLauncher(mockk<Fragment>(relaxed = true))
         contentPass.authenticateSuspending(mockk())
@@ -128,7 +155,7 @@ class ContentPassTests {
     fun `logout removes stored auth state information`() {
         val store = MockedTokenStore()
         store.storeAuthState(mockk())
-        val contentPass = ContentPass(mockk(relaxed = true), store)
+        val contentPass = ContentPass(mockk(relaxed = true), store, exampleConfiguration)
 
         assertNotNull(store.retrieveAuthState())
 
@@ -139,7 +166,7 @@ class ContentPassTests {
 
     @Test
     fun `registerObserver adds an observer that gets called on state changes`() {
-        val contentPass = ContentPass(mockk(relaxed = true), mockk(relaxed = true))
+        val contentPass = ContentPass(mockk(relaxed = true), mockk(relaxed = true), exampleConfiguration)
 
         var stateResult: ContentPass.State = ContentPass.State.Initializing
 
@@ -156,7 +183,7 @@ class ContentPassTests {
 
     @Test
     fun `unregisterObserver removes an observer`() {
-        val contentPass = ContentPass(mockk(relaxed = true), mockk(relaxed = true))
+        val contentPass = ContentPass(mockk(relaxed = true), mockk(relaxed = true), exampleConfiguration)
 
         var stateResult: ContentPass.State = ContentPass.State.Initializing
         val observer = object : ContentPass.Observer {