fetch fallback host if needed (#83)

sdk/src/main/java/com/apphud/sdk/ApphudInternal+Fallback.kt

@@ -2,8 +2,10 @@ package com.apphud.sdk
 
 import android.content.Context
 import android.content.SharedPreferences
+import com.apphud.sdk.client.ApiClient
 import com.apphud.sdk.domain.ApphudUser
 import com.apphud.sdk.domain.FallbackJsonObject
+import com.apphud.sdk.managers.RequestManager
 import com.apphud.sdk.mappers.PaywallsMapper
 import com.apphud.sdk.parser.GsonParser
 import com.apphud.sdk.parser.Parser
@@ -14,16 +16,57 @@ import com.google.gson.reflect.TypeToken
 import kotlinx.coroutines.launch
 import okhttp3.Request
 import java.io.IOException
+import java.net.MalformedURLException
+import java.net.URL
+
+internal fun String.withRemovedScheme(): String {
+    return replace("https://", "")
+}
 
 private val gson = GsonBuilder().serializeNulls().create()
 private val parser: Parser = GsonParser(gson)
 private val paywallsMapper = PaywallsMapper(parser)
-
-internal fun ApphudInternal.processFallbackError(request: Request) {
+internal var fallbackHost: String? = null
+internal var processedFallbackData = false
+internal fun ApphudInternal.processFallbackError(request: Request, isTimeout: Boolean) {
     if ((request.url.encodedPath.endsWith("/customers") ||
-        request.url.encodedPath.endsWith("/subscriptions"))
-        && !fallbackMode) {
-        processFallbackData()
+        request.url.encodedPath.endsWith("/subscriptions") ||
+                request.url.encodedPath.endsWith("/products"))
+        && !processedFallbackData) {
+
+        if (fallbackHost?.withRemovedScheme() == request.url.host) {
+            processFallbackData()
+        } else {
+            coroutineScope.launch {
+                tryFallbackHost()
+                if (fallbackHost == null) {
+                    processFallbackData()
+                }
+            }
+        }
+    }
+}
+
+internal fun tryFallbackHost() {
+    val host = RequestManager.fetchFallbackHost()
+    host?.let {
+        if (isValidUrl(it)) {
+            fallbackHost = it
+            ApphudInternal.fallbackMode = true
+            ApiClient.host = fallbackHost!!
+            ApphudLog.logE("Fallback to host $fallbackHost")
+            ApphudInternal.isRegisteringUser = false
+            ApphudInternal.refreshPaywallsIfNeeded()
+        }
+    }
+}
+
+fun isValidUrl(urlString: String): Boolean {
+    return try {
+        URL(urlString)
+        true
+    } catch (e: MalformedURLException) {
+        false
     }
 }
 
@@ -38,6 +81,8 @@ private fun ApphudInternal.processFallbackData() {
             ApphudLog.log("Fallback: user created: $userId")
         }
 
+        processedFallbackData = true
+
         // read paywalls from cache
         var ids = paywalls.map { it.products?.map { it.productId } ?: listOf() }.flatten()
         if (ids.isEmpty()) {
@@ -87,6 +132,7 @@ private fun getJsonDataFromAsset(
 
 internal fun ApphudInternal.disableFallback() {
     fallbackMode = false
+    processedFallbackData = false
     ApphudLog.log("Fallback: DISABLED")
     coroutineScope.launch(errorHandler) {
         if (productGroups.isEmpty()) { // if fallback raised on start, there no product groups, so reload products and details

sdk/src/main/java/com/apphud/sdk/client/ApiClient.kt

@@ -1,6 +1,6 @@
 package com.apphud.sdk.client
 
 object ApiClient {
-    var host = "https://api.apphud.com"
+    var host = "https://gateway.apphud.com"
     var readTimeout: Long = 10L
 }

sdk/src/main/java/com/apphud/sdk/managers/HttpRetryInterceptor.kt

@@ -4,7 +4,12 @@ import com.apphud.sdk.ApphudInternal
 import com.apphud.sdk.ApphudInternal.FALLBACK_ERRORS
 import com.apphud.sdk.ApphudInternal.fallbackMode
 import com.apphud.sdk.ApphudLog
+import com.apphud.sdk.ApphudUtils
+import com.apphud.sdk.fallbackHost
 import com.apphud.sdk.processFallbackError
+import com.apphud.sdk.tryFallbackHost
+import com.apphud.sdk.withRemovedScheme
+import kotlinx.coroutines.launch
 import okhttp3.Interceptor
 import okhttp3.Request
 import okhttp3.Response
@@ -48,22 +53,22 @@ class HttpRetryInterceptor : Interceptor {
                     }
 
                     if (response.code in FALLBACK_ERRORS) {
-                        ApphudInternal.processFallbackError(request)
+                        ApphudInternal.processFallbackError(request, isTimeout = false)
                         if (ApphudInternal.fallbackMode) {
                             tryCount = MAX_COUNT
                         }
                     }
 
                     ApphudLog.logE(
-                        "Request (${request.url.encodedPath}) failed with code (${response.code}). Will retry in ${STEP / 1000} seconds ($tryCount).",
+                        "Request (${request.url}) failed with code (${response.code}). Will retry in ${STEP / 1000} seconds ($tryCount).",
                     )
 
                     Thread.sleep(STEP)
                 }
             } catch (e: SocketTimeoutException) {
-                ApphudInternal.processFallbackError(request)
+                ApphudInternal.processFallbackError(request, isTimeout = true)
                 ApphudLog.logE(
-                    "Request (${request.url.encodedPath}) failed with SocketTimeoutException. Will retry in ${STEP / 1000} seconds ($tryCount).",
+                    "Request (${request.url}) failed with SocketTimeoutException. Will retry in ${STEP / 1000} seconds ($tryCount).",
                 )
                 if (ApphudInternal.fallbackMode) {
                     throw e
@@ -72,9 +77,14 @@ class HttpRetryInterceptor : Interceptor {
             } catch (e: UnknownHostException) {
                 // do not retry when no internet connection issue
                 tryCount = MAX_COUNT
+                if (ApphudUtils.isOnline(ApphudInternal.context)) {
+                    ApphudInternal.coroutineScope.launch {
+                        tryFallbackHost()
+                    }
+                }
             } catch (e: Exception) {
                 ApphudLog.logE(
-                    "Request (${request.url.encodedPath}) failed with Exception. Will retry in ${STEP / 1000} seconds ($tryCount).",
+                    "Request (${request.url}) failed with Exception. Will retry in ${STEP / 1000} seconds ($tryCount).",
                 )
                 Thread.sleep(STEP)
             } finally {
@@ -83,6 +93,12 @@ class HttpRetryInterceptor : Interceptor {
                 if (!isSuccess && tryCount < MAX_COUNT && !(response?.code in 401..403)) {
 //                    response?.close()
                 }
+
+                if (fallbackHost != null && fallbackHost?.withRemovedScheme() != request.url.host) {
+                    // invalid host, need to abort these requests
+                    tryCount = MAX_COUNT
+                    throw UnknownHostException("APPHUD_HOST_CHANGED")
+                }
             }
         }
         if (!isSuccess) {

sdk/src/main/java/com/apphud/sdk/managers/RequestManager.kt

@@ -217,7 +217,7 @@ object RequestManager {
                 completionHandler(null, ApphudError(message))
             }
         } catch (e: SocketTimeoutException) {
-            ApphudInternal.processFallbackError(request)
+            ApphudInternal.processFallbackError(request, isTimeout = true)
             val message = e.message ?: "Undefined error"
             completionHandler(null, ApphudError(message, null, APPHUD_ERROR_TIMEOUT))
         } catch (e: IOException) {
@@ -399,7 +399,7 @@ object RequestManager {
                     completionHandler(null, ApphudError("Registration failed"))
                 }
             } catch (e: SocketTimeoutException) {
-                ApphudInternal.processFallbackError(request)
+                ApphudInternal.processFallbackError(request, isTimeout = true)
                 val message = e.message ?: "Registration failed"
                 completionHandler(null, ApphudError(message, null, APPHUD_ERROR_TIMEOUT))
             } catch (ex: UnknownHostException) {
@@ -657,6 +657,26 @@ object RequestManager {
         }
     }
 
+    fun fetchFallbackHost(): String? {
+        val url = "https://apphud.blob.core.windows.net/apphud-gateway/fallback.txt"
+        val client = OkHttpClient()
+
+        // Build the request
+        val request = Request.Builder()
+            .url(url)
+            .build()
+
+        // Execute the request
+        val response = client.newCall(request).execute()
+
+        // Return the response body as a string if the request was successful
+        return if (response.isSuccessful) {
+            response.body?.string()
+        } else {
+            null
+        }
+    }
+
     fun grantPromotional(
         daysCount: Int,
         productId: String?,