Make inspection lenses clickable and show popup with intentions

src/main/kotlin/com/chylex/intellij/inspectionlens/editor/lens/EditorLensInlay.kt

@@ -36,7 +36,9 @@ internal value class EditorLensInlay(private val inlay: Inlay<LensRenderer>) {
 				.disableSoftWrapping(true)
 				.priority(priority)
 			
-			return editor.inlayModel.addAfterLineEndElement(offset, properties, renderer)?.let(::EditorLensInlay)
+			return editor.inlayModel.addAfterLineEndElement(offset, properties, renderer)
+				?.also(renderer::setInlay)
+				?.let(::EditorLensInlay)
 		}
 		
 		/**

src/main/kotlin/com/chylex/intellij/inspectionlens/editor/lens/IntentionsPopup.kt

@@ -0,0 +1,40 @@
+package com.chylex.intellij.inspectionlens.editor.lens
+
+import com.intellij.codeInsight.daemon.impl.IntentionsUI
+import com.intellij.codeInsight.hint.HintManager
+import com.intellij.codeInsight.intention.impl.ShowIntentionActionsHandler
+import com.intellij.lang.LangBundle
+import com.intellij.openapi.editor.Editor
+import com.intellij.openapi.editor.ScrollType
+import com.intellij.openapi.project.Project
+import com.intellij.psi.PsiDocumentManager
+import com.intellij.psi.PsiFile
+import com.intellij.psi.util.PsiUtilBase
+
+internal object IntentionsPopup {
+	fun showAt(editor: Editor, offset: Int) {
+		editor.caretModel.moveToOffset(offset)
+		editor.scrollingModel.scrollToCaret(ScrollType.MAKE_VISIBLE)
+		
+		if (!tryShowPopup(editor)) {
+			HintManager.getInstance().showInformationHint(editor, LangBundle.message("hint.text.no.context.actions.available.at.this.location"));
+		}
+	}
+	
+	private fun tryShowPopup(editor: Editor): Boolean {
+		val project = editor.project ?: return false
+		val file = PsiUtilBase.getPsiFileInEditor(editor, project) ?: return false
+		
+		PsiDocumentManager.getInstance(project).commitAllDocuments()
+		IntentionsUI.getInstance(project).hide()
+		
+		HANDLER.showIntentionHint(project, editor, file, showFeedbackOnEmptyMenu = true)
+		return true
+	}
+	
+	private val HANDLER = object : ShowIntentionActionsHandler() {
+		public override fun showIntentionHint(project: Project, editor: Editor, file: PsiFile, showFeedbackOnEmptyMenu: Boolean) {
+			super.showIntentionHint(project, editor, file, showFeedbackOnEmptyMenu)
+		}
+	}
+}

src/main/kotlin/com/chylex/intellij/inspectionlens/editor/lens/LensRenderer.kt

@@ -3,43 +3,136 @@ package com.chylex.intellij.inspectionlens.editor.lens
 import com.chylex.intellij.inspectionlens.settings.LensSettingsState
 import com.intellij.codeInsight.daemon.impl.HighlightInfo
 import com.intellij.codeInsight.daemon.impl.HintRenderer
+import com.intellij.codeInsight.hints.presentation.InputHandler
 import com.intellij.openapi.editor.Editor
 import com.intellij.openapi.editor.Inlay
+import com.intellij.openapi.editor.colors.EditorFontType
+import com.intellij.openapi.editor.ex.EditorEx
+import com.intellij.openapi.editor.impl.EditorImpl
 import com.intellij.openapi.editor.markup.TextAttributes
 import com.intellij.openapi.util.text.StringUtil
+import com.intellij.ui.paint.EffectPainter
+import java.awt.Cursor
 import java.awt.Graphics
+import java.awt.Graphics2D
+import java.awt.Point
 import java.awt.Rectangle
+import java.awt.event.MouseEvent
+import javax.swing.SwingUtilities
 
 /**
  * Renders the text of an inspection lens.
  */
-class LensRenderer(info: HighlightInfo, settings: LensSettingsState) : HintRenderer(null) {
+class LensRenderer(private var info: HighlightInfo, settings: LensSettingsState) : HintRenderer(null), InputHandler {
 	private val useEditorFont = settings.useEditorFont
-	private lateinit var severity: LensSeverity
+	private lateinit var inlay: Inlay<*>
+	private lateinit var attributes: LensSeverityTextAttributes
+	private var hovered = false
 	
 	init {
 		setPropertiesFrom(info)
 	}
 	
+	fun setInlay(inlay: Inlay<*>) {
+		check(!this::inlay.isInitialized) { "Inlay already set" }
+		this.inlay = inlay
+	}
+	
 	fun setPropertiesFrom(info: HighlightInfo) {
+		this.info = info
+		
 		text = getValidDescriptionText(info.description)
-		severity = LensSeverity.from(info.severity)
+		attributes = LensSeverity.from(info.severity).textAttributes
 	}
 	
 	override fun paint(inlay: Inlay<*>, g: Graphics, r: Rectangle, textAttributes: TextAttributes) {
 		fixBaselineForTextRendering(r)
 		super.paint(inlay, g, r, textAttributes)
+		
+		if (hovered) {
+			paintHoverEffect(inlay, g, r)
+		}
+	}
+	
+	private fun paintHoverEffect(inlay: Inlay<*>, g: Graphics, r: Rectangle) {
+		val editor = inlay.editor
+		if (editor !is EditorImpl) {
+			return
+		}
+		
+		val font = editor.colorsScheme.getFont(EditorFontType.PLAIN)
+		val x = r.x + TEXT_HORIZONTAL_PADDING
+		val y = r.y + editor.ascent + 1
+		val w = inlay.widthInPixels - UNDERLINE_WIDTH_REDUCTION
+		val h = editor.descent
+		
+		g.color = attributes.foregroundColor
+		EffectPainter.LINE_UNDERSCORE.paint(g as Graphics2D, x, y, w, h, font)
 	}
 	
 	override fun getTextAttributes(editor: Editor): TextAttributes {
-		return severity.textAttributes
+		return attributes
 	}
 	
 	override fun useEditorFont(): Boolean {
 		return useEditorFont
 	}
 	
+	override fun mouseMoved(event: MouseEvent, translated: Point) {
+		setHovered(isHoveringText(translated))
+	}
+	
+	override fun mouseExited() {
+		setHovered(false)
+	}
+	
+	private fun setHovered(hovered: Boolean) {
+		if (this.hovered == hovered) {
+			return
+		}
+		
+		this.hovered = hovered
+		
+		val editor = inlay.editor
+		if (editor is EditorEx) {
+			val cursor = if (hovered) Cursor.getPredefinedCursor(Cursor.HAND_CURSOR) else null
+			editor.setCustomCursor(this::class.java, cursor)
+		}
+		
+		inlay.repaint()
+	}
+	
+	override fun mousePressed(event: MouseEvent, translated: Point) {
+		if (!SwingUtilities.isLeftMouseButton(event) || !isHoveringText(translated)) {
+			return
+		}
+		
+		event.consume()
+		IntentionsPopup.showAt(inlay.editor, info.actualStartOffset)
+	}
+	
+	private fun isHoveringText(point: Point): Boolean {
+		return point.x >= HOVER_PADDING_LEFT
+			&& point.y >= 4
+			&& point.x < inlay.widthInPixels - HOVER_PADDING_RIGHT
+			&& point.y < inlay.heightInPixels - 1
+	}
+	
 	private companion object {
+		/**
+		 * [HintRenderer.paintHint] renders padding around text, but not around effects.
+		 */
+		private const val TEXT_HORIZONTAL_PADDING = 7
+		
+		/**
+		 * The last character is always a period, which does not take up the full width, so the underline and the hover region are shrunk by an additional pixel.
+		 */
+		private const val EXTRA_RIGHT_SIDE_PADDING = 1
+		
+		private const val UNDERLINE_WIDTH_REDUCTION = (TEXT_HORIZONTAL_PADDING * 2) + EXTRA_RIGHT_SIDE_PADDING
+		private const val HOVER_PADDING_LEFT = TEXT_HORIZONTAL_PADDING - 2
+		private const val HOVER_PADDING_RIGHT = HOVER_PADDING_LEFT + EXTRA_RIGHT_SIDE_PADDING
+		
 		private fun getValidDescriptionText(text: String?): String {
 			return if (text.isNullOrBlank()) " " else addMissingPeriod(unescapeHtmlEntities(text))
 		}