Add server reachability check before loading WebView

app/src/main/java/com/immichframe/immichframe/Helpers.kt

@@ -10,8 +10,10 @@ import retrofit2.Call
 import retrofit2.http.GET
 import androidx.core.graphics.scale
 import okhttp3.OkHttpClient
+import okhttp3.Request
 import retrofit2.Retrofit
 import retrofit2.converter.gson.GsonConverterFactory
+import java.util.concurrent.TimeUnit
 
 object Helpers {
     fun textSizeMultiplier(context: Context, currentSizeSp: Float, multiplier: Float): Float {
@@ -184,4 +186,23 @@ object Helpers {
             .addConverterFactory(GsonConverterFactory.create()).build()
     }
 
+    private val reachabilityClient = OkHttpClient.Builder()
+        .connectTimeout(5, TimeUnit.SECONDS)
+        .readTimeout(5, TimeUnit.SECONDS)
+        .build()
+
+    fun isServerReachable(url: String): Boolean {
+        return try {
+            val request = Request.Builder()
+                .url(url)
+                .head()
+                .build()
+            reachabilityClient.newCall(request).execute().use {
+                true // any HTTP response = reachable
+            }
+        } catch (e: Exception) {
+            false
+        }
+    }
+
 }

app/src/main/java/com/immichframe/immichframe/MainActivity.kt

@@ -43,6 +43,7 @@ import java.text.SimpleDateFormat
 import java.util.Calendar
 import java.util.Locale
 import kotlinx.coroutines.*
+import androidx.lifecycle.lifecycleScope
 import androidx.core.graphics.toColorInt
 import androidx.core.graphics.drawable.toDrawable
 import androidx.core.net.toUri
@@ -588,7 +589,7 @@ class MainActivity : AppCompatActivity() {
             webView.settings.javaScriptEnabled = true
             webView.settings.cacheMode = WebSettings.LOAD_NO_CACHE
             webView.settings.domStorageEnabled = true
-            webView.loadUrl(savedUrl)
+            loadWebViewWithRetry(savedUrl)
         } else {
             retrofit = Helpers.createRetrofit(savedUrl, authSecret)
             apiService = retrofit!!.create(Helpers.ApiService::class.java)
@@ -856,4 +857,37 @@ class MainActivity : AppCompatActivity() {
         rcpServer.stop()
         handler.removeCallbacksAndMessages(null)
     }
+
+    private fun loadWebViewWithRetry(
+        url: String,
+        attempt: Int = 1,
+        maxAttempts: Int = 36
+    ) {
+        lifecycleScope.launch {
+            val reachable = withContext(Dispatchers.IO) {
+                Helpers.isServerReachable(url)
+            }
+
+            if (reachable) {
+                webView.loadUrl(url)
+            } else if (attempt <= maxAttempts) {
+                Toast.makeText(
+                    this@MainActivity,
+                    "Connecting to server... Attempt $attempt of $maxAttempts",
+                    Toast.LENGTH_SHORT
+                ).show()
+
+                delay(5_000)
+                loadWebViewWithRetry(url, attempt + 1, maxAttempts)
+            } else {
+                Toast.makeText(
+                    this@MainActivity,
+                    "Could not connect to server after $maxAttempts attempts",
+                    Toast.LENGTH_LONG
+                ).show()
+
+                webView.loadUrl(url)
+            }
+        }
+    }
 }

app/src/main/java/com/immichframe/immichframe/ScreenSaverService.kt

@@ -27,6 +27,9 @@ import android.widget.Toast
 import androidx.preference.PreferenceManager
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.delay
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 import retrofit2.Call
@@ -41,6 +44,7 @@ import androidx.core.graphics.drawable.toDrawable
 import androidx.core.net.toUri
 
 class ScreenSaverService : DreamService() {
+    private var webViewRetryScope: CoroutineScope? = null
     private var wakeLock: PowerManager.WakeLock? = null
     private lateinit var webView: WebView
     private lateinit var imageView1: ImageView
@@ -83,6 +87,7 @@ class ScreenSaverService : DreamService() {
     @SuppressLint("ClickableViewAccessibility")
     override fun onDreamingStarted() {
         super.onDreamingStarted()
+        webViewRetryScope = CoroutineScope(Dispatchers.Main + Job())
         isFullscreen = true
         isInteractive = true
         setContentView(R.layout.screen_saver_view)
@@ -105,6 +110,8 @@ class ScreenSaverService : DreamService() {
 
     override fun onDreamingStopped() {
         super.onDreamingStopped()
+        webViewRetryScope?.cancel()
+        webViewRetryScope = null
         stopImageTimer()
         releaseWakeLock()
         handler.removeCallbacksAndMessages(null)
@@ -518,7 +525,7 @@ class ScreenSaverService : DreamService() {
             webView.settings.javaScriptEnabled = true
             webView.settings.cacheMode = WebSettings.LOAD_NO_CACHE
             webView.settings.domStorageEnabled = true
-            webView.loadUrl(savedUrl)
+            loadWebViewWithRetry(savedUrl)
         } else {
             retrofit = Helpers.createRetrofit(savedUrl, authSecret)
             apiService = retrofit!!.create(Helpers.ApiService::class.java)
@@ -613,4 +620,37 @@ class ScreenSaverService : DreamService() {
         }
         wakeLock = null
     }
+
+    private fun loadWebViewWithRetry(
+        url: String,
+        attempt: Int = 1,
+        maxAttempts: Int = 36
+    ) {
+        webViewRetryScope?.launch {
+            val reachable = withContext(Dispatchers.IO) {
+                Helpers.isServerReachable(url)
+            }
+
+            if (reachable) {
+                webView.loadUrl(url)
+            } else if (attempt <= maxAttempts) {
+                Toast.makeText(
+                    this@ScreenSaverService,
+                    "Connecting to server... Attempt $attempt of $maxAttempts",
+                    Toast.LENGTH_SHORT
+                ).show()
+
+                delay(5_000)
+                loadWebViewWithRetry(url, attempt + 1, maxAttempts)
+            } else {
+                Toast.makeText(
+                    this@ScreenSaverService,
+                    "Could not connect to server after $maxAttempts attempts",
+                    Toast.LENGTH_LONG
+                ).show()
+
+                webView.loadUrl(url)
+            }
+        }
+    }
 }