feat: Add chaining RxJava (#2117)

Fixes: #2116

Author: anhanh11001

app/src/main/java/org/fossasia/openevent/general/about/AboutEventViewModel.kt

@@ -25,7 +25,7 @@ class AboutEventViewModel(private val eventService: EventService, private val re
     val error: LiveData<String> = mutableError
 
     fun loadEvent(id: Long) {
-        if (id.equals(-1)) {
+        if (id == -1L) {
             mutableError.value = Resource().getString(R.string.error_fetching_event_message)
             return
         }

app/src/main/java/org/fossasia/openevent/general/auth/EditProfileViewModel.kt

@@ -3,6 +3,7 @@ package org.fossasia.openevent.general.auth
 import androidx.lifecycle.LiveData
 import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.ViewModel
+import io.reactivex.Single
 import io.reactivex.disposables.CompositeDisposable
 import io.reactivex.rxkotlin.plusAssign
 import org.fossasia.openevent.general.utils.extensions.withDefaultSchedulers
@@ -35,30 +36,15 @@ class EditProfileViewModel(
     fun isLoggedIn() = authService.isLoggedIn()
 
     fun updateProfile(user: User) {
-        if (encodedImage.isNullOrEmpty()) {
-            updateUser(user)
-            return
-        }
-        compositeDisposable += authService.uploadImage(UploadImage(encodedImage))
-            .withDefaultSchedulers()
-            .doOnSubscribe {
-                mutableProgress.value = true
-            }
-            .doFinally {
-                mutableProgress.value = false
-            }
-            .subscribe({
-                updateUser(user.copy(avatarUrl = it.url))
-                mutableMessage.value = resource.getString(R.string.image_upload_success_message)
-                Timber.d("Image uploaded ${it.url}")
-            }) {
-                mutableMessage.value = resource.getString(R.string.image_upload_error_message)
-                Timber.e(it, "Error uploading user!")
-            }
-    }
+        val updateProfileObservable: Single<User> =
+            if (encodedImage.isNullOrEmpty())
+                authService.updateUser(user)
+            else
+                authService.uploadImage(UploadImage(encodedImage)).flatMap {
+                    authService.updateUser(user.copy(avatarUrl = it.url))
+                }
 
-    private fun updateUser(user: User) {
-        compositeDisposable += authService.updateUser(user)
+        compositeDisposable += updateProfileObservable
             .withDefaultSchedulers()
             .doOnSubscribe {
                 mutableProgress.value = true

app/src/main/java/org/fossasia/openevent/general/event/EventDetailsViewModel.kt

@@ -303,15 +303,15 @@ class EventDetailsViewModel(
         val range = StringBuilder()
         if (maxPrice == minPrice) {
             if (maxPrice == 0f)
-                range.append("Free")
+                range.append(resource.getString(R.string.free))
             else {
                 range.append(paymentCurrency)
                 range.append(" ")
                 range.append("%.2f".format(minPrice))
             }
         } else {
             if (minPrice == 0f)
-                range.append("Free")
+                range.append(resource.getString(R.string.free))
             else {
                 range.append(paymentCurrency)
                 range.append(" ")

app/src/main/java/org/fossasia/openevent/general/order/OrderDetailsViewModel.kt

@@ -54,31 +54,20 @@ class OrderDetailsViewModel(
     fun loadAttendeeDetails(orderId: Long) {
         if (orderId == -1L) return
 
-        compositeDisposable += orderService.getOrderById(orderId)
+        compositeDisposable += orderService
+            .getOrderById(orderId)
+            .flatMap { order ->
+                orderService.getAttendeesUnderOrder(order.identifier ?: "", order.attendees.map { it.id })
+            }
             .withDefaultSchedulers()
             .doOnSubscribe {
                 mutableProgress.value = true
-            }.subscribe({
-                loadAttendeeUnderOrder(it)
-            }, {
-                Timber.e(it, "Error fetching attendee details")
+            }.doFinally {
                 mutableProgress.value = false
-                message.value = resource.getString(R.string.error_fetching_attendee_details_message)
-            })
-    }
-
-    private fun loadAttendeeUnderOrder(order: Order) {
-        val orderIdentifier = order.identifier ?: return
-
-        compositeDisposable += orderService
-            .getAttendeesUnderOrder(orderIdentifier, order.attendees.map { it.id })
-            .withDefaultSchedulers()
-            .subscribe({
+            }.subscribe({
                 mutableAttendees.value = it
-                mutableProgress.value = false
             }, {
                 Timber.e(it, "Error fetching attendee details")
-                mutableProgress.value = false
                 message.value = resource.getString(R.string.error_fetching_attendee_details_message)
             })
     }