Rider Live Plugin for using Tab for both Indentation and Completion

plugin.kts

import com.intellij.openapi.actionSystem.ActionManager
import com.intellij.openapi.actionSystem.AnAction
import com.intellij.openapi.actionSystem.AnActionEvent
import com.intellij.openapi.actionSystem.CommonDataKeys

import com.intellij.openapi.project.DumbAware

import com.intellij.codeInsight.completion.CompletionService
import com.intellij.codeInsight.completion.CompletionProgressIndicator

import liveplugin.*

class TabIndentOrCompleteAction: AnAction(), DumbAware {
    val actionManager = ActionManager.getInstance()

    fun runAction(event: AnActionEvent, name: String) {
        val dataContext = event.dataContext
        val inputEvent = event.inputEvent

        val action = actionManager.getAction(name)
        if (action != null) {
            val actionEvent = AnActionEvent.createFromAnAction(action, inputEvent, event.place, dataContext)
            action.actionPerformed(actionEvent)
        }
    }

    fun indent(event: AnActionEvent) {
        runAction(event, "AutoIndentLines")
    }

    fun emacsIndent(event: AnActionEvent) {
        runAction(event, "EmacsStyleIndent")
    }

    fun complete(event: AnActionEvent) {
        runAction(event, "CodeCompletion")
    }

    fun gotoLineStart(event: AnActionEvent) {
        runAction(event, "EditorLineStart")
    }

    fun insertTab(event: AnActionEvent) {
        runAction(event, "EditorTab")
    }

    fun escape(event: AnActionEvent) {
        runAction(event, "EditorEscape")
    }

    override fun actionPerformed(event: AnActionEvent) = {
        val editor = event.getData(CommonDataKeys.EDITOR);
        val caret = editor!!.caretModel!!.getPrimaryCaret();
        val positionStart = caret!!.visualPosition;
        val startColumn = positionStart!!.column;

        val selectionModel = editor.selectionModel
        if (selectionModel.hasSelection()) {
            // - if there is an active selection, auto indent the region and
            // then discard the active selection
            show("Indenting region...")
            indent(event)
            escape(event)
        } else {
            // - if there is no active selection we'll try to indent and complete
            // - first gotoLineStart is like pressing Home, it will move caret to the
            // beginning of the current indentation, or the start of the line otherwise
            gotoLineStart(event)

            val positionAfterLineStartAction = caret!!.visualPosition;
            val afterLineStartColumn = positionAfterLineStartAction!!.column;

            // - if gotoLineStart moved the caret to the beginning of the line, use it
            // again to move it back to the indentation
            if (afterLineStartColumn == 0) {
                gotoLineStart(event)
            }
            // - emacsIndent should indent according to the current language, or if the
            // indentation is already correct or the language is not supported then it
            // does nothing
            emacsIndent(event)

            val positionAfterIndentAction = caret!!.visualPosition;
            val afterIndentColumn = positionAfterIndentAction!!.column;

            // - if we're still at the same position after emacsIndent, then it did nothing
            // and we can try to complete
            if (afterIndentColumn == afterLineStartColumn && startColumn != 0) {
                // - to complete we move caret back where we started and then complete
                editor!!.caretModel!!.moveToVisualPosition(positionStart)
                complete(event)
            }

            // - if we're at the startColumn after the emacsIndent then I just assume it
            // is an empty line and insertTab
            if (afterIndentColumn == startColumn) {
                val completionService = CompletionService.getCompletionService()
                val completionIndicator = completionService.currentCompletion as? CompletionProgressIndicator
                if (completionIndicator == null) {
                    insertTab(event)
                    // - emacsIndent after insertTab magically fixes wrongly inserted tabs if the current
                    // file can be automatically indented, and if not then we keep the tab
                    emacsIndent(event)
                }
            }
        }
    }()
}

registerAction(id = "TabIndentOrComplete", keyStroke = "TAB", action = TabIndentOrCompleteAction())
if (!isIdeStartup) show("Enabled TabIndentOrComplete")

First time doing kotlin and anything with the jetbrains plugin api, so this probably sucks somehow. But it works well enough for myself for now.

Needs this: https://github.com/dkandalov/live-plugin

Oh, and also uses EmacsStyleIndent, so maybe just remove that if you don't want that.