- base presenter helper method for all presenters that need to passt…

…hrough a view requirement of a field to the repository object. Every time the object gets updated the transform code will get executed and the resulting data passed to the view to update (#63)

bisqapps/shared/presentation/src/commonMain/kotlin/network/bisq/mobile/presentation/BasePresenter.kt

@@ -5,6 +5,11 @@ import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.cancel
+import kotlinx.coroutines.flow.SharingStarted
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.stateIn
+import network.bisq.mobile.domain.data.model.BaseModel
 
 /**
  * Presenter for any type of view.
@@ -96,5 +101,33 @@ abstract class BasePresenter(private val rootPresenter: MainPresenter?) {
         this.dependants!!.remove(child)
     }
 
+    /**
+     * Pass through function that allows you to link the requested type the view is asking for in its view presenter interface
+     * with the field in the domain model of the repository.
+     *
+     * @param M base model from where to extract the requested type T
+     * @param T the requested view type T
+     * @param repositoryFlow
+     * @param transform the transformation function from the
+     * @param initialValue
+     * @param scope defaults to Coroutine.Main (view thread)
+     * @param started defaults to Lazy loading
+     */
+    protected fun <M: BaseModel, T> stateFlowFromRepository(
+        repositoryFlow: StateFlow<M?>,
+        transform: (M?) -> T,
+        initialValue: T,
+        scope: CoroutineScope = CoroutineScope(Dispatchers.Main),
+        started: SharingStarted = SharingStarted.Lazily
+    ): StateFlow<T> {
+        return repositoryFlow
+            .map { transform(it) }
+            .stateIn(
+                scope = scope,
+                started = started,
+                initialValue = initialValue
+            )
+    }
+
     private fun isRoot() = rootPresenter == null
 }

bisqapps/shared/presentation/src/commonMain/kotlin/network/bisq/mobile/presentation/MainPresenter.kt

@@ -21,14 +21,12 @@ open class MainPresenter(private val greetingRepository: GreetingRepository<Gree
     private val _isContentVisible = MutableStateFlow(false)
     override val isContentVisible: StateFlow<Boolean> = _isContentVisible
 
-    // TODO remove we don't need all the gretting example stuff anymore - but this code to passthrough should be a helper for presentation
-    private val _greetingText: StateFlow<String> = greetingRepository.data
-        .map { it?.greet() ?: "" } // Transform Greeting to String, we don't want the null
-        .stateIn(
-            scope = CoroutineScope(Dispatchers.Main), // Use an appropriate CoroutineScope for lifecycle control
-            started = SharingStarted.Lazily,
-            initialValue = "Welcome!"
-        )
+    // passthrough example
+    private val _greetingText: StateFlow<String> = stateFlowFromRepository(
+        repositoryFlow = greetingRepository.data,
+        transform = { it?.greet() ?: "" },
+        initialValue = "Welcome!"
+    )
 
     override val greetingText: StateFlow<String> = _greetingText