Clicking Backspace at the start of a list item: Decrease list level or exit list

richeditor-compose/src/commonMain/kotlin/com/mohamedrejeb/richeditor/model/RichTextState.kt

@@ -1478,7 +1478,7 @@ public class RichTextState internal constructor(
             else
                 it
         }
-        val paragraphFirstChildStartIndex = firstNonEmptyChildIndex ?: selection.min
+        val paragraphFirstChildStartIndex = (firstNonEmptyChildIndex ?: selection.min).coerceAtLeast(0)
 
         paragraph.type = newType
 
@@ -1864,7 +1864,26 @@ public class RichTextState internal constructor(
                     paragraphFirstChildMinIndex = minParagraphFirstChildMinIndex,
                 )
 
+                // Save the old paragraph type
+                val minParagraphOldType = minRichSpan.paragraph.type
+
+                // Set the paragraph type to DefaultParagraph
                 minRichSpan.paragraph.type = DefaultParagraph()
+
+                // Check if it's a list and handle level appropriately
+                if (
+                    maxRemoveIndex - minRemoveIndex == 1 &&
+                    minParagraphOldType is ConfigurableListLevel &&
+                    minParagraphOldType.level > 1
+                ) {
+                    // Decrease level instead of exiting list
+                    minParagraphOldType.level -= 1
+                    tempTextFieldValue = updateParagraphType(
+                        paragraph = minRichSpan.paragraph,
+                        newType = minParagraphOldType,
+                        textFieldValue = tempTextFieldValue,
+                    )
+                }
             }
         }
 
@@ -1877,8 +1896,6 @@ public class RichTextState internal constructor(
                 paragraphFirstChildMinIndex = maxParagraphFirstChildMinIndex,
             )
 
-            maxRichSpan.paragraph.type = DefaultParagraph()
-
             tempTextFieldValue = adjustOrderedListsNumbers(
                 startParagraphIndex = maxParagraphIndex + 1,
                 startNumber = 1,
@@ -2271,8 +2288,7 @@ public class RichTextState internal constructor(
                     // Ignore adding the new paragraph
                     index--
                     continue
-                } else
-                    if (
+                } else if (
                     (!config.preserveStyleOnEmptyLine || richSpan.paragraph.isEmpty()) &&
                     isSelectionAtNewRichSpan
                 ) {

richeditor-compose/src/commonTest/kotlin/com/mohamedrejeb/richeditor/model/ListBehaviorTest.kt

@@ -0,0 +1,88 @@
+package com.mohamedrejeb.richeditor.model
+
+import androidx.compose.ui.text.TextRange
+import androidx.compose.ui.text.input.TextFieldValue
+import com.mohamedrejeb.richeditor.annotation.ExperimentalRichTextApi
+import com.mohamedrejeb.richeditor.paragraph.RichParagraph
+import com.mohamedrejeb.richeditor.paragraph.type.OrderedList
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertIs
+import kotlin.test.assertIsNot
+import kotlin.test.assertTrue
+
+@OptIn(ExperimentalRichTextApi::class)
+class ListBehaviorTest {
+    @Test
+    fun testBackspaceOnEmptyListLevel1() {
+        val state = RichTextState()
+
+        // Create a list with level 1
+        state.addTextAfterSelection("1.")
+        state.addTextAfterSelection(" ")
+
+        // Verify that the list was created
+        assertIs<OrderedList>(state.richParagraphList.first().type)
+
+        // Simulate backspace at the start of empty list item
+        state.onTextFieldValueChange(TextFieldValue(
+            text = "1.",
+            selection = TextRange(2)
+        ))
+
+        // Verify that the list was exited (converted to default paragraph)
+        assertIsNot<OrderedList>(state.richParagraphList.first().type)
+    }
+
+    @Test
+    fun testBackspaceOnEmptyListLevel2() {
+        val state = RichTextState(
+            listOf(
+                RichParagraph(
+                    type = OrderedList(
+                        number = 1,
+                        initialLevel = 1,
+                    ),
+                ).also {
+                    it.children.add(
+                        RichSpan(
+                            text = "a",
+                            paragraph = it,
+                        )
+                    )
+                },
+                RichParagraph(
+                    type = OrderedList(
+                        number = 1,
+                        initialLevel = 2,
+                    ),
+                ).also {
+                    it.children.add(
+                        RichSpan(
+                            text = "",
+                            paragraph = it,
+                        )
+                    )
+                }
+            )
+        )
+
+        // Simulate backspace at the start of empty list item
+        val newText = state.annotatedString.text.dropLast(1)
+        state.onTextFieldValueChange(TextFieldValue(
+            text = newText,
+            selection = TextRange(newText.length)
+        ))
+
+        // Verify that the list level was decreased but still remains a list
+        val firstParagraphType = state.richParagraphList[0].type
+        assertIs<OrderedList>(firstParagraphType)
+        assertEquals(1, firstParagraphType.number)
+        assertEquals(1, firstParagraphType.level)
+
+        val secondParagraphType = state.richParagraphList[1].type
+        assertIs<OrderedList>(secondParagraphType)
+        assertEquals(2, secondParagraphType.number)
+        assertEquals(1, secondParagraphType.level)
+    }
+}

richeditor-compose/src/commonTest/kotlin/com/mohamedrejeb/richeditor/model/RichTextStateTest.kt

@@ -2712,10 +2712,12 @@ class RichTextStateTest {
             )
         )
 
-        richTextState.selection = TextRange(4, 14)
+        richTextState.selection = TextRange(4, 15)
         richTextState.removeSelectedText()
 
         assertEquals(2, richTextState.richParagraphList.size)
+        assertEquals("A", richTextState.richParagraphList[0].children.first().text)
+        assertEquals("D", richTextState.richParagraphList[1].children.first().text)
     }
 
     @OptIn(ExperimentalRichTextApi::class)

richeditor-compose/src/desktopTest/kotlin/com/mohamedrejeb/richeditor/model/RichTextStateKeyEventTest.kt

@@ -12,6 +12,7 @@ import androidx.compose.ui.test.ExperimentalTestApi
 import androidx.compose.ui.test.junit4.createComposeRule
 import androidx.compose.ui.test.runDesktopComposeUiTest
 import androidx.compose.ui.text.TextRange
+import com.mohamedrejeb.richeditor.annotation.ExperimentalRichTextApi
 import com.mohamedrejeb.richeditor.paragraph.RichParagraph
 import com.mohamedrejeb.richeditor.paragraph.type.OrderedList
 import com.mohamedrejeb.richeditor.ui.BasicRichTextEditor
@@ -20,7 +21,9 @@ import org.junit.Test
 import kotlin.test.assertEquals
 import kotlin.test.assertFalse
 
-@OptIn(ExperimentalTestApi::class, ExperimentalComposeUiApi::class, InternalComposeUiApi::class)
+@OptIn(ExperimentalTestApi::class, ExperimentalComposeUiApi::class, InternalComposeUiApi::class,
+    ExperimentalRichTextApi::class
+)
 class RichTextStateKeyEventTest {
     @get:Rule
     val rule = createComposeRule()