Mini plugin for IntelliJ to show keyboard shortcuts similar to Presentation Assistant (to be used via LivePlugin)

plugin.kts

import com.intellij.ide.ui.UISettings
import com.intellij.openapi.Disposable
import com.intellij.openapi.actionSystem.ActionManager
import com.intellij.openapi.actionSystem.AnAction
import com.intellij.openapi.actionSystem.AnActionEvent
import com.intellij.openapi.actionSystem.IdeActions
import com.intellij.openapi.actionSystem.ex.AnActionListener
import com.intellij.openapi.application.ApplicationManager
import com.intellij.openapi.project.Project
import com.intellij.openapi.ui.popup.Balloon
import com.intellij.openapi.ui.popup.JBPopupFactory
import com.intellij.platform.ide.impl.presentationAssistant.getWinKeyText
import com.intellij.platform.ide.impl.presentationAssistant.getWinModifiersText
import com.intellij.ui.BalloonImpl
import com.intellij.ui.JBColor
import com.intellij.ui.awt.RelativePoint
import liveplugin.currentEditor
import liveplugin.show
import java.awt.Point
import java.awt.event.KeyEvent
import javax.swing.KeyStroke

// See https://gist.github.com/dkandalov/54839566c1de9e6012c93bcb87309306

// Not using built-in Presentation Assistant because:
// - it shows shortcuts from the keymap, not the actual shortcuts
// - it shows shortcuts for actions which were not invoked via keyboard
// - there is no way exclude shortcuts, e.g. up/down in project tree view
// - there is no way include shortcuts, e.g. text editor navigation
// - displayed text cannot be customised, e.g. remove "Move Caret " prefix

ShortcutsPresenter(NotificationBalloon(pluginDisposable), pluginDisposable).init()

class ShortcutsPresenter(
    private val notificationBalloon: NotificationBalloon,
    private val parentDisposable: Disposable,
    private val showActionId: Boolean = false
) {
    private val actionManager = ActionManager.getInstance()!!

    fun init() = apply {
        ApplicationManager.getApplication().messageBus.connect(parentDisposable)
            .subscribe(AnActionListener.TOPIC, object : AnActionListener {
                override fun beforeActionPerformed(action: AnAction, event: AnActionEvent) {
                    val project = event.project ?: return
                    val lastKeyStroke = (event.inputEvent as? KeyEvent)?.let(KeyStroke::getKeyStrokeForEvent) ?: return
                    val actionId = actionManager.getId(action)
                    val actionDescription = event.presentation.text
                        ?.replace("Move Caret to ", "")
                        ?.replace("Move Caret ", "")
                        ?.replace(" in Text Component", "")
                    if (actionId in excludedActions || actionDescription == null) return

                    if (showActionId) show(actionId)
                    notificationBalloon.showShortcut(lastKeyStroke.toPresentableString(), actionDescription, project)
                }
            })
    }

    // Not using: MacKeymapUtil.getKeyStrokeText(this, "+", false)
    // because Windows key rendering (e.g. "Meta+F12") is easier to read.
    private fun KeyStroke.toPresentableString() =
        listOfNotNull(if (modifiers > 0) getWinModifiersText(modifiers) else null, getWinKeyText(keyCode))
            .filter { it.isNotEmpty() }
            .joinToString("+")
            .trim()
            .replace("Meta", "Cmd")

    private val movingActions = setOf(
//        "EditorLeft", "EditorRight", "EditorDown", "EditorUp",
//        "EditorLineStart", "EditorLineEnd", "EditorPageUp", "EditorPageDown",
//        "EditorPreviousWord", "EditorNextWord",
//        "EditorScrollUp", "EditorScrollDown",
//        "EditorTextStart", "EditorTextEnd",
//        "EditorDownWithSelection", "EditorUpWithSelection",
//        "EditorRightWithSelection", "EditorLeftWithSelection",
//        "EditorLineStartWithSelection", "EditorLineEndWithSelection",
//        "EditorPageDownWithSelection", "EditorPageUpWithSelection",
//        "EditorNextWordWithSelection", "EditorPreviousWordWithSelection",
//        "ijkl.MoveCaretLeftWithSelectionAction",
        "Tree-selectNext", "Tree-selectPrevious", "Tree-selectParent", "Tree-selectChild",
        "List-selectNextColumn", "List-selectPreviousColumn",
        "NavBar-selectLeft", "NavBar-selectRight", "NavBar-selectDown", "NavBar-selectUp",
    )

    private val editorActions = setOf(
        IdeActions.ACTION_EDITOR_BACKSPACE,
        IdeActions.ACTION_EDITOR_ENTER,
        IdeActions.ACTION_EDITOR_NEXT_TEMPLATE_VARIABLE,
        "\$Undo", "\$Redo",
//        "EditorCut", "EditorCopy", "EditorPaste",
//        "EditorDelete",
//        "EditorEscape",
        "EditorChooseLookupItem"
    )

    private val otherActions = setOf(
        "CloseFirstNotification", "CloseAllNotifications",
        "Remove Top Editor Component",
        "Toggle refactorings counter",
        "Increment refactorings counter",
        "Decrement refactorings counter",
        "NextWindow",
//        "ActivateProjectToolWindow",
//        "ActivateVersionControlToolWindow",
//        "ActivateRunToolWindow",
    )

    private val excludedActions = movingActions + editorActions + otherActions
}

class NotificationBalloon(private val parentDisposable: Disposable) {
    private var balloon1: Balloon? = null
    private var balloon2: Balloon? = null
    private var balloonText: String? = null

    fun showShortcut(keyStroke: String, actionDescription: String, project: Project) {
        val text = "$keyStroke - $actionDescription"
        if (balloon1 == null || balloon1!!.wasFadedOut()) {
            balloon1 = createBalloon(actionDescription).showIn(project)
            balloon2 = createBalloon(keyStroke).showIn(project, balloon1)
            balloonText = text
        } else if (balloonText == text) {
            return
        } else {
            balloon1!!.hide()
            balloon2!!.hide()
            balloon1 = createBalloon(actionDescription).showIn(project)
            balloon2 = createBalloon(keyStroke).showIn(project, balloon1)
            balloonText = text
        }
    }

    private val blue4 = JBColor.namedColor("ColorPalette.Blue4")
    private val backgroundColor = JBColor.background()
    private val borderColor = JBColor.gray
    private val fontSize = 24

    private fun createBalloon(text: String) =
        JBPopupFactory.getInstance()
            .createHtmlTextBalloonBuilder(
                /* htmlContent = */ "<span style='font-size: ${fontSize}pt; font-weight:bold'>$text</span>",
                /* icon = */ null,
                /* fillColor = */ backgroundColor,
                /* listener = */ null
            )
            .setBorderColor(borderColor)
            .setFadeoutTime(3000)
            .setAnimationCycle(50)
            .setCloseButtonEnabled(false)
            .setHideOnClickOutside(false)
            .setDisposable(parentDisposable)
            .setHideOnFrameResize(false)
            .setHideOnKeyOutside(false)
            .setBlockClicksThroughBalloon(true)
            .setHideOnAction(false)
            .setShowCallout(false)
            .setCornerRadius(15)
            .createBalloon()

    private fun Balloon.showIn(project: Project, relativeToBalloon: Balloon? = null) = apply {
        if (relativeToBalloon == null) {
            val component = project.currentEditor?.component ?: return@apply
            val point = Point(component.width - preferredSize.width / 2, 100)
            show(RelativePoint(component, point), Balloon.Position.atLeft)
        } else {
            val component = (relativeToBalloon as BalloonImpl).component ?: return@apply
            val gap = if (UISettings.getInstance().presentationMode) 60 else 40
            val point = Point(-preferredSize.width / 2 + gap, component.height / 2)
            show(RelativePoint(component, point), Balloon.Position.atLeft)
        }
    }
}