Use median to determine smart update interval (#2251)

Co-authored-by: AntsyLich <59261191+AntsyLich@users.noreply.github.com>

CHANGELOG.md

@@ -32,6 +32,7 @@ The format is a modified version of [Keep a Changelog](https://keepachangelog.co
 - Include source headers when opening failed images from reader ([@AwkwardPeak7](https://github.com/AwkwardPeak7)) ([#2004](https://github.com/mihonapp/mihon/pull/2004))
 - Added autofill support to tracker login dialog ([@AntsyLich](https://github.com/AntsyLich)) ([#2069](https://github.com/mihonapp/mihon/pull/2069))
 - Added option to hide missing chapter count ([@User826](https://github.com/User826), [@AntsyLich](https://github.com/AntsyLich)) ([#2108](https://github.com/mihonapp/mihon/pull/2108))
+- Use median to determine smart update interval, making it more resilient to long hiatuses ([@Kladki](https://github.com/Kladki)) ([#2251](https://github.com/mihonapp/mihon/pull/2251))
 
 ### Changed
 - Display all similarly named duplicates in duplicate manga dialogue ([@NarwhalHorns](https://github.com/NarwhalHorns), [@AntsyLich](https://github.com/AntsyLich)) ([#1861](https://github.com/mihonapp/mihon/pull/1861))

domain/src/main/java/tachiyomi/domain/manga/interactor/FetchInterval.kt

@@ -69,15 +69,13 @@ class FetchInterval(
         val interval = when {
             // Enough upload date from source
             uploadDates.size >= 3 -> {
-                val uploadDelta = uploadDates.last().until(uploadDates.first(), ChronoUnit.DAYS)
-                val uploadPeriod = uploadDates.indexOf(uploadDates.last())
-                uploadDelta.floorDiv(uploadPeriod).toInt()
+                val ranges = uploadDates.windowed(2).map { x -> x[1].until(x[0], ChronoUnit.DAYS) }.sorted()
+                ranges[(ranges.size - 1) / 2].toInt()
             }
             // Enough fetch date from client
             fetchDates.size >= 3 -> {
-                val fetchDelta = fetchDates.last().until(fetchDates.first(), ChronoUnit.DAYS)
-                val uploadPeriod = fetchDates.indexOf(fetchDates.last())
-                fetchDelta.floorDiv(uploadPeriod).toInt()
+                val ranges = fetchDates.windowed(2).map { x -> x[1].until(x[0], ChronoUnit.DAYS) }.sorted()
+                ranges[(ranges.size - 1) / 2].toInt()
             }
             // Default to 7 days
             else -> 7

domain/src/test/java/tachiyomi/domain/manga/interactor/FetchIntervalTest.kt

@@ -125,11 +125,11 @@ class FetchIntervalTest {
     }
 
     @Test
-    fun `returns interval of 1 day when chapters are released just below every 2 days`() {
+    fun `returns interval of 2 days when chapters are released just below every 2 days`() {
         val chapters = (1..20).map {
             chapterWithTime(chapter, (43 * it).hours)
         }
-        fetchInterval.calculateInterval(chapters, testZoneId) shouldBe 1
+        fetchInterval.calculateInterval(chapters, testZoneId) shouldBe 2
     }
 
     private fun chapterWithTime(chapter: Chapter, duration: Duration): Chapter {