From 77f56c5dda359eeef5ae6892088826e3a0979898 Mon Sep 17 00:00:00 2001
From: InsanusMokrassar <ovsyannikov.alexey95@gmail.com>
Date: Sun, 26 May 2024 23:35:24 +0600
Subject: [PATCH] make improvements in pagination

---
 .../pagination/PaginationResult.kt            | 24 +++++++++++---
 .../micro_utils/pagination/utils/Paginate.kt  | 31 +++++++------------
 .../pagination/utils/PaginationPaging.kt      | 26 +++++++++++++---
 3 files changed, 52 insertions(+), 29 deletions(-)

diff --git a/pagination/common/src/commonMain/kotlin/dev/inmo/micro_utils/pagination/PaginationResult.kt b/pagination/common/src/commonMain/kotlin/dev/inmo/micro_utils/pagination/PaginationResult.kt
index 28accc46693..39720d86c80 100644
--- a/pagination/common/src/commonMain/kotlin/dev/inmo/micro_utils/pagination/PaginationResult.kt
+++ b/pagination/common/src/commonMain/kotlin/dev/inmo/micro_utils/pagination/PaginationResult.kt
@@ -60,21 +60,35 @@ fun <T> emptyPaginationResult(
     0L
 )
 
+/**
+ * @return New [PaginationResult] with [data] without checking of data sizes equality
+ */
+inline fun <I, O> PaginationResult<I>.changeResultsUnchecked(
+    block: PaginationResult<I>.() -> List<O>
+): PaginationResult<O> = PaginationResult(page, size, block(), objectsNumber)
+
 /**
  * @return New [PaginationResult] with [data] without checking of data sizes equality
  */
 fun <I, O> PaginationResult<I>.changeResultsUnchecked(
     data: List<O>
-): PaginationResult<O> = PaginationResult(page, size, data, objectsNumber)
+): PaginationResult<O> = changeResultsUnchecked { data }
+/**
+ * @return New [PaginationResult] with [data] <b>with</b> checking of data sizes equality
+ */
+inline fun <I, O> PaginationResult<I>.changeResults(
+    block: PaginationResult<I>.() -> List<O>
+): PaginationResult<O> {
+    val data = block()
+    require(data.size == results.size)
+    return changeResultsUnchecked(data)
+}
 /**
  * @return New [PaginationResult] with [data] <b>with</b> checking of data sizes equality
  */
 fun <I, O> PaginationResult<I>.changeResults(
     data: List<O>
-): PaginationResult<O> {
-    require(data.size == results.size)
-    return changeResultsUnchecked(data)
-}
+): PaginationResult<O> = changeResults { data }
 
 fun <T> List<T>.createPaginationResult(
     pagination: Pagination,
diff --git a/pagination/common/src/commonMain/kotlin/dev/inmo/micro_utils/pagination/utils/Paginate.kt b/pagination/common/src/commonMain/kotlin/dev/inmo/micro_utils/pagination/utils/Paginate.kt
index ed196383a52..660635a4c8a 100644
--- a/pagination/common/src/commonMain/kotlin/dev/inmo/micro_utils/pagination/utils/Paginate.kt
+++ b/pagination/common/src/commonMain/kotlin/dev/inmo/micro_utils/pagination/utils/Paginate.kt
@@ -21,34 +21,25 @@ fun <T> Iterable<T>.paginate(with: Pagination): PaginationResult<T> {
 }
 
 fun <T> List<T>.paginate(with: Pagination): PaginationResult<T> {
-    val indices = indices
-    val firstIndex = with.firstIndex.coerceIn(indices)
-    val lastIndex = with.lastIndex.coerceIn(indices) + 1 // up to size
-    if (firstIndex > lastIndex) {
-        return emptyPaginationResult()
+    if (with.firstIndex !in indices || with.lastIndex !in indices) {
+        return emptyPaginationResult(with)
     }
-    return subList(firstIndex, lastIndex).createPaginationResult(
+    return asSequence().drop(with.firstIndex).take(with.size).toList().createPaginationResult(
         with,
         size.toLong()
     )
 }
 
 fun <T> List<T>.paginate(with: Pagination, reversed: Boolean): PaginationResult<T> {
-    val actualPagination = with.optionallyReverse(
-        size,
-        reversed
-    )
-    val indices = indices
-    val firstIndex = actualPagination.firstIndex.coerceIn(indices)
-    val lastIndex = actualPagination.lastIndex.coerceIn(indices) + 1 // up to size
-    if (firstIndex > lastIndex) {
-        return emptyPaginationResult()
+    return if (reversed) {
+        val actualPagination = with.optionallyReverse(
+            size,
+            reversed
+        )
+        paginate(actualPagination).changeResultsUnchecked { results.reversed() }
+    } else {
+        paginate(with)
     }
-
-    return subList(firstIndex, lastIndex).optionallyReverse(reversed).createPaginationResult(
-        with,
-        size.toLong()
-    )
 }
 
 fun <T> Set<T>.paginate(with: Pagination): PaginationResult<T> {
diff --git a/pagination/common/src/commonTest/kotlin/dev/inmo/micro_utils/pagination/utils/PaginationPaging.kt b/pagination/common/src/commonTest/kotlin/dev/inmo/micro_utils/pagination/utils/PaginationPaging.kt
index aef18c6948e..9dd539110ec 100644
--- a/pagination/common/src/commonTest/kotlin/dev/inmo/micro_utils/pagination/utils/PaginationPaging.kt
+++ b/pagination/common/src/commonTest/kotlin/dev/inmo/micro_utils/pagination/utils/PaginationPaging.kt
@@ -1,11 +1,9 @@
 package dev.inmo.micro_utils.pagination.utils
 
-import dev.inmo.micro_utils.pagination.FirstPagePagination
-import dev.inmo.micro_utils.pagination.firstIndex
-import dev.inmo.micro_utils.pagination.isLastPage
-import dev.inmo.micro_utils.pagination.lastIndexExclusive
+import dev.inmo.micro_utils.pagination.*
 import kotlin.test.Test
 import kotlin.test.assertEquals
+import kotlin.test.assertFalse
 import kotlin.test.assertTrue
 
 class PaginationPaging {
@@ -31,4 +29,24 @@ class PaginationPaging {
 
         assertTrue(lastPageHappened)
     }
+    @Test
+    fun testEmptyPaginateOnList() {
+        val list = listOf<Int>()
+        val startPagination = FirstPagePagination(2)
+
+        var paginationHappend = false
+        doForAllWithNextPaging(startPagination) {
+            val resultPagination = list.paginate(it)
+
+            assertEquals(resultPagination, emptyPaginationResult(it))
+
+            assertFalse(paginationHappend)
+
+            paginationHappend = true
+
+            resultPagination
+        }
+
+        assertTrue(paginationHappend)
+    }
 }