Add in-app sponsor support

app/build.gradle

@@ -113,6 +113,8 @@ dependencies {
     }
     implementation 'com.google.guava:guava:32.1.2-android'
     playImplementation 'com.google.android.play:app-update-ktx:2.1.0'
+    playImplementation "com.android.billingclient:billing:6.1.0"
+    playImplementation "com.android.billingclient:billing-ktx:6.1.0"
 }
 
 if (getProps("APPCENTER_TOKEN") != "") {

app/src/main/java/io/nekohasekai/sfa/ui/main/SettingsFragment.kt

@@ -103,6 +103,11 @@ class SettingsFragment : Fragment() {
         binding.openDebugButton.setOnClickListener {
             startActivity(Intent(requireContext(), DebugActivity::class.java))
         }
+        binding.startSponserButton.setOnClickListener {
+            Vendor.startSponsor(requireActivity()) {
+                activity.launchCustomTab("https://sekai.icu/sponsor/")
+            }
+        }
         lifecycleScope.launch(Dispatchers.IO) {
             reloadSettings()
         }

app/src/main/java/io/nekohasekai/sfa/vendor/VendorInterface.kt

@@ -5,5 +5,5 @@ import android.app.Activity
 interface VendorInterface {
     fun checkUpdateAvailable(): Boolean
     fun checkUpdate(activity: Activity, byUser: Boolean)
-
+    fun startSponsor(activity: Activity, fallback: () -> Unit)
 }

app/src/main/res/layout/fragment_settings.xml

@@ -348,6 +348,53 @@
 
         </com.google.android.material.card.MaterialCardView>
 
+        <com.google.android.material.card.MaterialCardView
+            style="?attr/materialCardViewElevatedStyle"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="16dp">
+
+            <LinearLayout
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:orientation="vertical"
+                android:paddingStart="16dp"
+                android:paddingTop="16dp"
+                android:paddingEnd="16dp"
+                android:paddingBottom="8dp">
+
+                <TextView
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="@string/sponsor"
+                    android:textAppearance="?attr/textAppearanceTitleLarge">
+
+                </TextView>
+
+                <TextView
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:layout_marginTop="8dp"
+                    android:text="@string/sponsor_message" />
+
+                <LinearLayout
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:gravity="center_vertical|end"
+                    android:orientation="horizontal">
+
+                    <Button
+                        android:id="@+id/startSponserButton"
+                        style="@style/Widget.Material3.Button.TextButton"
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:text="@string/action_start" />
+
+                </LinearLayout>
+
+            </LinearLayout>
+
+        </com.google.android.material.card.MaterialCardView>
 
     </LinearLayout>
 

app/src/main/res/values/strings.xml

@@ -140,6 +140,10 @@
     <string name="vpn_app_type_other">Other</string>
     <string name="vpn_core_type_unknown">Unknown</string>
     <string name="no_updates_available">No updates available</string>
-
+    <string name="sponsor">Sponsor</string>
+    <string name="sponsor_play">Sponsor via Play Store</string>
+    <string name="sponsor_message">If I\'ve defended your modern life, please consider sponsoring me.</string>
+    <string name="other_methods">Other methods</string>
+    <string name="action_start">Start</string>
 
 </resources>

app/src/other/java/io/nekohasekai/sfa/vendor/Vendor.kt

@@ -11,5 +11,8 @@ object Vendor : VendorInterface {
     override fun checkUpdate(activity: Activity, byUser: Boolean) {
     }
 
+    override fun startSponsor(activity: Activity, fallback: () -> Unit) {
+        fallback()
+    }
 
 }

app/src/play/java/io/nekohasekai/sfa/vendor/Vendor.kt

@@ -1,15 +1,30 @@
 package io.nekohasekai.sfa.vendor
 
 import android.app.Activity
+import android.app.ProgressDialog
 import android.content.Context
 import android.util.Log
+import com.android.billingclient.api.BillingClient
+import com.android.billingclient.api.BillingClientStateListener
+import com.android.billingclient.api.BillingFlowParams
+import com.android.billingclient.api.BillingResult
+import com.android.billingclient.api.ProductDetails
+import com.android.billingclient.api.QueryProductDetailsParams
+import com.android.billingclient.api.queryProductDetails
 import com.google.android.material.dialog.MaterialAlertDialogBuilder
 import com.google.android.play.core.appupdate.AppUpdateManagerFactory
 import com.google.android.play.core.appupdate.AppUpdateOptions
 import com.google.android.play.core.install.model.AppUpdateType
 import com.google.android.play.core.install.model.InstallStatus
 import com.google.android.play.core.install.model.UpdateAvailability
+import io.nekohasekai.sfa.Application
 import io.nekohasekai.sfa.R
+import io.nekohasekai.sfa.ktx.errorDialogBuilder
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.GlobalScope
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+import java.util.concurrent.atomic.AtomicInteger
 
 object Vendor : VendorInterface {
 
@@ -69,6 +84,112 @@ object Vendor : VendorInterface {
         }
     }
 
+    private lateinit var billingClient: BillingClient
+    override fun startSponsor(activity: Activity, fallback: () -> Unit) {
+        if (!::billingClient.isInitialized) {
+            billingClient = BillingClient.newBuilder(Application.application)
+                .setListener { _, _ ->
+                }
+                .enablePendingPurchases()
+                .build()
+        }
+        val dialog = ProgressDialog(activity)
+        dialog.setMessage(activity.getString(R.string.loading))
+        dialog.show()
+        billingClient.startConnection(object : BillingClientStateListener {
+            override fun onBillingSetupFinished(result: BillingResult) {
+                dialog.dismiss()
+                if (result.responseCode == BillingClient.BillingResponseCode.OK) {
+                    GlobalScope.launch(Dispatchers.IO) {
+                        runCatching {
+                            startSponsor0(activity, fallback)
+                        }.onFailure { exception ->
+                            withContext(Dispatchers.Main) {
+                                activity.errorDialogBuilder(exception).show()
+                            }
+                        }
+                    }
+                } else {
+                    GlobalScope.launch(Dispatchers.Main) {
+                        activity.errorDialogBuilder(result.toString()).show()
+                    }
+                }
+            }
+
+            override fun onBillingServiceDisconnected() {
+            }
+        })
+    }
+
+    private suspend fun startSponsor0(activity: Activity, fallback: () -> Unit) {
+        val params = QueryProductDetailsParams.newBuilder()
+            .setProductList(
+                listOf(
+                    QueryProductDetailsParams.Product.newBuilder()
+                        .setProductId("sponsor_circle_1")
+                        .setProductType(BillingClient.ProductType.SUBS)
+                        .build(),
+                    QueryProductDetailsParams.Product.newBuilder()
+                        .setProductId("sponsor_circle_10")
+                        .setProductType(BillingClient.ProductType.SUBS)
+                        .build(),
+                    QueryProductDetailsParams.Product.newBuilder()
+                        .setProductId("sponsor_circle_100")
+                        .setProductType(BillingClient.ProductType.SUBS)
+                        .build(),
+                )
+            ).build()
+        val (result, products) = billingClient.queryProductDetails(params)
+        if (result.responseCode != BillingClient.BillingResponseCode.OK) {
+            error(result.toString())
+        }
+        if (products.isNullOrEmpty()) {
+            withContext(Dispatchers.Main) {
+                fallback()
+            }
+            return
+        }
+        val selecting = products.sortedBy { it.productId.substringAfterLast("_").toInt() }
+        val selected = AtomicInteger(0)
+        withContext(Dispatchers.Main) {
+            MaterialAlertDialogBuilder(activity)
+                .setTitle(R.string.sponsor_play)
+                .setSingleChoiceItems(
+                    selecting.map { it.title.removeSuffix(" (sing-box)") }.toMutableList().also {
+                        it.add(activity.getString(R.string.other_methods))
+                    }.toTypedArray(),
+                    0
+                ) { _, which ->
+                    selected.set(which)
+                }
+                .setNeutralButton(android.R.string.cancel, null)
+                .setPositiveButton(R.string.action_start) { _, _ ->
+                    if (selected.get() == selecting.size) {
+                        fallback()
+                        return@setPositiveButton
+                    }
+                    startSponsor1(activity, selecting[selected.get()])
+                }
+                .show()
+        }
+    }
+
+    private fun startSponsor1(activity: Activity, product: ProductDetails) {
+        val paramsList = listOf(
+            BillingFlowParams.ProductDetailsParams.newBuilder()
+                .setProductDetails(product)
+                .setOfferToken(product.subscriptionOfferDetails!![0].offerToken)
+                .build()
+        )
+        val flowParams = BillingFlowParams.newBuilder()
+            .setProductDetailsParamsList(paramsList)
+            .build()
+        val result = billingClient.launchBillingFlow(activity, flowParams)
+        if (result.responseCode != BillingClient.BillingResponseCode.OK) {
+            activity.errorDialogBuilder(result.toString()).show()
+        }
+    }
+
     private fun Context.showNoUpdatesDialog() {
         MaterialAlertDialogBuilder(this)
             .setTitle(io.nekohasekai.sfa.R.string.check_update)