Add unused import inspection

closes cashapp#1161

sqldelight-compiler/src/main/kotlin/com/squareup/sqldelight/core/lang/util/TreeUtil.kt

@@ -79,6 +79,10 @@ inline fun <reified T : PsiElement> PsiElement.findChildrenOfType(): Collection<
   return PsiTreeUtil.findChildrenOfType(this, T::class.java)
 }
 
+inline fun <reified T : PsiElement> PsiElement.findChildOfType(): T? {
+  return PsiTreeUtil.findChildOfType(this, T::class.java)
+}
+
 fun PsiElement.childOfType(type: IElementType): PsiElement? {
   return node.findChildByType(type)?.psi
 }

sqldelight-idea-plugin/src/main/kotlin/com/squareup/sqldelight/intellij/inspections/UnusedImportInspection.kt

@@ -0,0 +1,54 @@
+package com.squareup.sqldelight.intellij.inspections
+
+import com.intellij.codeInsight.actions.OptimizeImportsProcessor
+import com.intellij.codeInspection.InspectionManager
+import com.intellij.codeInspection.LocalInspectionTool
+import com.intellij.codeInspection.LocalQuickFixOnPsiElement
+import com.intellij.codeInspection.ProblemDescriptor
+import com.intellij.codeInspection.ProblemHighlightType
+import com.intellij.openapi.project.Project
+import com.intellij.psi.PsiElement
+import com.intellij.psi.PsiFile
+import com.squareup.sqldelight.core.lang.psi.ImportStmtMixin
+import com.squareup.sqldelight.core.lang.util.findChildrenOfType
+import com.squareup.sqldelight.core.psi.SqlDelightJavaTypeName
+
+class UnusedImportInspection : LocalInspectionTool() {
+
+  override fun runForWholeFile(): Boolean = true
+
+  override fun checkFile(
+    file: PsiFile,
+    manager: InspectionManager,
+    isOnTheFly: Boolean
+  ): Array<ProblemDescriptor> {
+    val columnTypes = file.findChildrenOfType<SqlDelightJavaTypeName>()
+      .map { javaTypeName -> javaTypeName.text }
+
+    return file.findChildrenOfType<ImportStmtMixin>()
+      .filter { importStmtMixin -> importStmtMixin.text.findAnyOf(columnTypes) == null }
+      .map { importStmtMixin ->
+        manager.createProblemDescriptor(
+          importStmtMixin, "Unused import", isOnTheFly,
+          arrayOf(RemoveUnusedImportQuickFix(file)), ProblemHighlightType.LIKE_UNUSED_SYMBOL
+        )
+      }
+      .toTypedArray()
+  }
+
+  class RemoveUnusedImportQuickFix(file: PsiFile) : LocalQuickFixOnPsiElement(file) {
+
+    override fun getFamilyName(): String = name
+
+    override fun getText(): String = "Optimize imports"
+
+    override fun invoke(
+      project: Project,
+      file: PsiFile,
+      startElement: PsiElement,
+      endElement: PsiElement
+    ) {
+      OptimizeImportsProcessor(project, file).run()
+    }
+  }
+}

sqldelight-idea-plugin/src/main/kotlin/com/squareup/sqldelight/intellij/lang/SqlDelightImportOptimizer.kt

@@ -0,0 +1,44 @@
+package com.squareup.sqldelight.intellij.lang
+
+import com.intellij.lang.ImportOptimizer
+import com.intellij.psi.PsiDocumentManager
+import com.intellij.psi.PsiFile
+import com.intellij.psi.PsiFileFactory
+import com.squareup.sqldelight.core.lang.MigrationFile
+import com.squareup.sqldelight.core.lang.SqlDelightFile
+import com.squareup.sqldelight.core.lang.SqlDelightFileType
+import com.squareup.sqldelight.core.lang.psi.ImportStmtMixin
+import com.squareup.sqldelight.core.lang.util.findChildOfType
+import com.squareup.sqldelight.core.lang.util.findChildrenOfType
+import com.squareup.sqldelight.core.psi.SqlDelightImportStmtList
+import com.squareup.sqldelight.core.psi.SqlDelightJavaTypeName
+
+class SqlDelightImportOptimizer : ImportOptimizer {
+
+  override fun supports(file: PsiFile): Boolean = file is SqlDelightFile || file is MigrationFile
+
+  override fun processFile(file: PsiFile): Runnable = Runnable {
+    val manager = PsiDocumentManager.getInstance(file.project)
+    val document = manager.getDocument(file) ?: return@Runnable
+    manager.commitDocument(document)
+
+    val columnTypes = file.findChildrenOfType<SqlDelightJavaTypeName>()
+      .map { javaTypeName -> javaTypeName.text }
+
+    val remainingImports = file.findChildrenOfType<ImportStmtMixin>()
+      .asSequence()
+      .map { import -> import.text }
+      .filter { import -> import.findAnyOf(columnTypes) != null }
+      .sorted()
+      .joinToString("\n")
+    val factory = PsiFileFactory.getInstance(file.project)
+    val dummyFile = factory.createFileFromText(
+      "_Dummy_.${SqlDelightFileType.EXTENSION}",
+      SqlDelightFileType, remainingImports
+    )
+    val newImportList = dummyFile.findChildOfType<SqlDelightImportStmtList>()
+    if (newImportList != null) {
+      file.findChildOfType<SqlDelightImportStmtList>()?.replace(newImportList)
+    }
+  }
+}

sqldelight-idea-plugin/src/main/resources/META-INF/plugin.xml

@@ -100,10 +100,22 @@
     <lang.parserDefinition language="SqlDelightMigration"
         implementationClass="com.squareup.sqldelight.core.lang.MigrationParserDefinition"/>
 
+    <lang.importOptimizer language="SqlDelight" implementationClass="com.squareup.sqldelight.intellij.lang.SqlDelightImportOptimizer"/>
+
+    <lang.importOptimizer language="SqlDelightMigration" implementationClass="com.squareup.sqldelight.intellij.lang.SqlDelightImportOptimizer"/>
+
     <intentionAction>
       <className>com.squareup.sqldelight.intellij.intentions.ExpandColumnNamesWildcardQuickFix</className>
       <category>SQLDelight</category>
     </intentionAction>
+
+    <localInspection
+        enabledByDefault="true"
+        language="SqlDelight"
+        level="WARNING"
+        implementationClass="com.squareup.sqldelight.intellij.inspections.UnusedImportInspection"
+        displayName="Unused import inspection"
+        groupName="Declaration redundancy"/>
   </extensions>
 
   <actions>

sqldelight-idea-plugin/src/test/kotlin/com/squareup/sqldelight/intellij/inspections/UnusedImportInspectionTest.kt

@@ -0,0 +1,13 @@
+package com.squareup.sqldelight.intellij.inspections
+
+import com.intellij.codeInspection.ex.LocalInspectionToolWrapper
+import com.squareup.sqldelight.intellij.SqlDelightFixtureTestCase
+
+class UnusedImportInspectionTest : SqlDelightFixtureTestCase() {
+
+  override val fixtureDirectory: String = "inspections"
+
+  fun testUnusedImportInspection() {
+    myFixture.testInspection("", LocalInspectionToolWrapper(UnusedImportInspection()))
+  }
+}

sqldelight-idea-plugin/testData/inspections/expected.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<problems>
+  <problem>
+    <file>CreateTable.sq</file>
+    <line>1</line>
+    <description>Unused import</description>
+  </problem>
+  <problem>
+    <file>AlterTable.sqm</file>
+    <line>1</line>
+    <description>Unused import</description>
+  </problem>
+</problems>

sqldelight-idea-plugin/testData/inspections/src/AlterTable.sqm

@@ -0,0 +1,3 @@
+import java.time.OffsetDateTime;
+
+ALTER TABLE hockeyPlayer ADD COLUMN draft_year TEXT;

sqldelight-idea-plugin/testData/inspections/src/CreateTable.sq

@@ -0,0 +1,6 @@
+import java.time.OffsetDateTime;
+
+CREATE TABLE hockeyPlayer (
+  player_number INTEGER NOT NULL,
+  full_name TEXT NOT NULL
+);