Missing files from previous commit

app/src/main/java/chat/rocket/android/util/IO.kt

+package chat.rocket.android.util
+
+import chat.rocket.common.RocketChatNetworkErrorException
+import kotlinx.coroutines.experimental.delay
+import timber.log.Timber
+
+const val DEFAULT_RETRY = 3
+
+suspend fun <T> retryIO(
+        description: String = "<missing description>",
+        times: Int = DEFAULT_RETRY,
+        initialDelay: Long = 100, // 0.1 second
+        maxDelay: Long = 1000,    // 1 second
+        factor: Double = 2.0,
+        block: suspend () -> T): T
+{
+    var currentDelay = initialDelay
+    repeat(times - 1) { currentTry ->
+        try {
+            return block()
+        } catch (e: RocketChatNetworkErrorException) {
+            Timber.d(e, "failed call($currentTry): $description")
+            e.printStackTrace()
+        }
+        delay(currentDelay)
+        currentDelay = (currentDelay * factor).toLong().coerceAtMost(maxDelay)
+    }
+    return block() // last attempt
+}
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app/src/main/java/chat/rocket/android/util/extensions/String.kt

+package chat.rocket.android.util.extensions
+
+import android.util.Patterns
+
+fun String.removeTrailingSlash(): String {
+    return if (isNotEmpty() && this[length - 1] == '/') {
+        this.replace("/+$", "")
+    } else {
+        this
+    }
+}
+
+fun String.avatarUrl(avatar: String, format: String = "jpeg") =
+    "${removeTrailingSlash()}/avatar/${avatar.removeTrailingSlash()}?format=$format"
+
+fun String.serverLogoUrl(favicon: String) = "${removeTrailingSlash()}/$favicon"
+
+fun String.casUrl(serverUrl: String, token: String) =
+    "${removeTrailingSlash()}?service=${serverUrl.removeTrailingSlash()}/_cas/$token"
+
+fun String.termsOfServiceUrl() = "${removeTrailingSlash()}/terms-of-service"
+
+fun String.privacyPolicyUrl() = "${removeTrailingSlash()}/privacy-policy"
+
+fun String.isValidUrl(): Boolean = Patterns.WEB_URL.matcher(this).matches()
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