Simplify the logic of picking up a random event from On This Day (#4938)

* Simplify the way of picking one random On this day event

* Fix lint

* Update variable name

* Add Transient to avoid being serialized

---------

Co-authored-by: Dmitry Brant <[email protected]>

Author: cooltey

app/src/main/java/org/wikipedia/feed/aggregated/AggregatedFeedContent.kt

@@ -2,6 +2,7 @@ package org.wikipedia.feed.aggregated
 
 import kotlinx.serialization.SerialName
 import kotlinx.serialization.Serializable
+import kotlinx.serialization.Transient
 import org.wikipedia.dataclient.page.PageSummary
 import org.wikipedia.feed.image.FeaturedImage
 import org.wikipedia.feed.news.NewsItem
@@ -15,4 +16,6 @@ class AggregatedFeedContent(
     @SerialName("mostread") val topRead: TopRead? = null,
     @SerialName("image") val potd: FeaturedImage? = null,
     val onthisday: List<OnThisDay.Event>? = null
-)
+) {
+    @Transient var randomOnThisDayEvent: OnThisDay.Event? = null
+}

app/src/main/java/org/wikipedia/feed/aggregated/AggregatedFeedContentClient.kt

@@ -33,10 +33,8 @@ class AggregatedFeedContentClient {
                                          outCards: MutableList<Card>) {
             for (appLangCode in WikipediaApp.instance.languageState.appLanguageCodes) {
                 if (responses.containsKey(appLangCode) && !FeedContentType.ON_THIS_DAY.langCodesDisabled.contains(appLangCode)) {
-                    responses[appLangCode]?.onthisday?.let {
-                        if (it.isNotEmpty()) {
-                            outCards.add(OnThisDayCard(it, WikiSite.forLanguageCode(appLangCode), age))
-                        }
+                    responses[appLangCode]?.randomOnThisDayEvent?.let {
+                        outCards.add(OnThisDayCard(it, WikiSite.forLanguageCode(appLangCode), age))
                     }
                 }
             }
@@ -175,6 +173,8 @@ class AggregatedFeedContentClient {
                         }
                     }
 
+                    feedContentResponse.randomOnThisDayEvent = feedContentResponse.onthisday?.random()
+
                     aggregatedClient.aggregatedResponses[langCode] = feedContentResponse
                     aggregatedClient.aggregatedResponseAge = age
                 }

app/src/main/java/org/wikipedia/feed/onthisday/OnThisDayCard.kt

@@ -9,24 +9,12 @@ import org.wikipedia.feed.view.FeedAdapter
 import org.wikipedia.util.DateUtil
 import org.wikipedia.util.L10nUtil
 import java.util.Calendar
-import java.util.Random
 import java.util.concurrent.TimeUnit
 
-class OnThisDayCard(events: List<OnThisDay.Event>, wiki: WikiSite, val age: Int) : WikiSiteCard(wiki) {
-    private val nextYear: Int
+class OnThisDayCard(val event: OnThisDay.Event, wiki: WikiSite, val age: Int) : WikiSiteCard(wiki) {
     private val date: Calendar = DateUtil.getDefaultDateFor(age)
-    private val eventShownOnCard: OnThisDay.Event
     var callback: FeedAdapter.Callback? = null
 
-    init {
-        var randomIndex = 0
-        if (events.size > 1) {
-            randomIndex = Random().nextInt(events.size - 1)
-        }
-        eventShownOnCard = events[randomIndex]
-        nextYear = events.getOrElse(randomIndex + 1) { eventShownOnCard }.year
-    }
-
     override fun type(): CardType {
         return CardType.ON_THIS_DAY
     }
@@ -48,18 +36,18 @@ class OnThisDayCard(events: List<OnThisDay.Event>, wiki: WikiSite, val age: Int)
     }
 
     fun text(): CharSequence {
-        return eventShownOnCard.text
+        return event.text
     }
 
     fun year(): Int {
-        return eventShownOnCard.year
+        return event.year
     }
 
     fun date(): Calendar {
         return date
     }
 
     fun pages(): List<PageSummary> {
-        return eventShownOnCard.pages
+        return event.pages
     }
 }