Improve insert of suppression (pinterest#2546)

* Prevent KtlintSuppressionOutOfBoundsException Suppression if offset equals the end the line.
* Insert suppression at parent in case the target location of the suppression is a whitespace.

Closes pinterest#2514

ktlint-rule-engine/src/main/kotlin/com/pinterest/ktlint/rule/engine/api/KtlintRuleEngineSuppression.kt

@@ -1,6 +1,7 @@
 package com.pinterest.ktlint.rule.engine.api
 
 import com.pinterest.ktlint.rule.engine.core.api.RuleId
+import com.pinterest.ktlint.rule.engine.core.api.isWhiteSpace
 import com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext
 import com.pinterest.ktlint.rule.engine.internal.insertKtlintRuleSuppression
 import org.jetbrains.kotlin.com.intellij.lang.ASTNode
@@ -38,6 +39,14 @@ private fun ASTNode.findLeafElementAt(suppression: KtlintSuppression): ASTNode =
 
         is KtlintSuppressionAtOffset ->
             findLeafElementAt(suppression.offsetFromStartOf(text))
+                ?.let {
+                    if (it.isWhiteSpace()) {
+                        // A suppression can not be added at a whitespace element. Insert it at the parent instead
+                        it.treeParent
+                    } else {
+                        it
+                    }
+                }
                 ?: throw KtlintSuppressionNoElementFoundException(suppression)
     }
 
@@ -60,11 +69,22 @@ private fun KtlintSuppressionAtOffset.offsetFromStartOf(code: String): Int {
             }
 
     val codeLine = lines[line - 1]
-    if (col > codeLine.length) {
-        throw KtlintSuppressionOutOfBoundsException(this)
+    return when {
+        col == 1 && codeLine.isEmpty() -> {
+            startOffsetOfLineContainingLintError
+        }
+        col <= codeLine.length -> {
+            startOffsetOfLineContainingLintError + (col - 1)
+        }
+        col == codeLine.length + 1 -> {
+            // Offset of suppression is set at EOL of the line. This is visually correct for the reader. But the newline character was stripped
+            // from the line because the lines were split using that character.
+            startOffsetOfLineContainingLintError + col
+        }
+        else -> {
+            throw KtlintSuppressionOutOfBoundsException(this)
+        }
     }
-
-    return startOffsetOfLineContainingLintError + (col - 1)
 }
 
 public sealed class KtlintSuppressionException(

ktlint-rule-engine/src/test/kotlin/com/pinterest/ktlint/rule/engine/api/KtlintRuleEngineSuppressionKtTest.kt

@@ -4,6 +4,8 @@ import com.pinterest.ktlint.rule.engine.core.api.Rule
 import com.pinterest.ktlint.rule.engine.core.api.RuleId
 import com.pinterest.ktlint.rule.engine.core.api.RuleProvider
 import com.pinterest.ktlint.ruleset.standard.rules.CONDITION_WRAPPING_RULE_ID
+import com.pinterest.ktlint.ruleset.standard.rules.NO_CONSECUTIVE_BLANK_LINES_RULE_ID
+import com.pinterest.ktlint.ruleset.standard.rules.NO_LINE_BREAK_BEFORE_ASSIGNMENT_RULE_ID
 import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Nested
 import org.junit.jupiter.api.Test
@@ -275,6 +277,91 @@ class KtlintRuleEngineSuppressionKtTest {
         }
     }
 
+    @Test
+    fun `Given a violation with offset exactly at the EOL of a line`() {
+        val code =
+            """
+            fun foo(): String // Some comment
+                = "some-result"
+            """.trimIndent()
+        val formattedCode =
+            """
+            @Suppress("ktlint:standard:no-line-break-before-assignment")
+            fun foo(): String // Some comment
+                = "some-result"
+            """.trimIndent()
+        val actual =
+            ktLintRuleEngine
+                .insertSuppression(
+                    Code.fromSnippet(code, false),
+                    KtlintSuppressionAtOffset(1, 34, NO_LINE_BREAK_BEFORE_ASSIGNMENT_RULE_ID),
+                )
+
+        assertThat(actual).isEqualTo(formattedCode)
+    }
+
+    @Nested
+    inner class `Consecutive line suppression can not be placed at line` {
+        @Test
+        fun `Given some consecutive blank lines at top level`() {
+            val code =
+                """
+                val foo = "foo"
+
+
+                val bar = "bar"
+                """.trimIndent()
+            val formattedCode =
+                """
+                @file:Suppress("ktlint:standard:no-consecutive-blank-lines")
+
+                val foo = "foo"
+
+
+                val bar = "bar"
+                """.trimIndent()
+            val actual =
+                ktLintRuleEngine
+                    .insertSuppression(
+                        Code.fromSnippet(code, false),
+                        KtlintSuppressionAtOffset(3, 1, NO_CONSECUTIVE_BLANK_LINES_RULE_ID),
+                    )
+
+            assertThat(actual).isEqualTo(formattedCode)
+        }
+
+        @Test
+        fun `Given some consecutive blank lines inside a function`() {
+            val code =
+                """
+                fun foobar() {
+                    val foo = "foo"
+
+
+                    val bar = "bar"
+                }
+                """.trimIndent()
+            val formattedCode =
+                """
+                @Suppress("ktlint:standard:no-consecutive-blank-lines")
+                fun foobar() {
+                    val foo = "foo"
+
+
+                    val bar = "bar"
+                }
+                """.trimIndent()
+            val actual =
+                ktLintRuleEngine
+                    .insertSuppression(
+                        Code.fromSnippet(code, false),
+                        KtlintSuppressionAtOffset(3, 1, NO_CONSECUTIVE_BLANK_LINES_RULE_ID),
+                    )
+
+            assertThat(actual).isEqualTo(formattedCode)
+        }
+    }
+
     private companion object {
         val SOME_RULE_ID = RuleId("standard:some-rule-id")
     }