Migrate setting classes to Kotlin

src/main/java/org/nixos/idea/lsp/NixLspSettings.kt

@@ -0,0 +1,52 @@
+package org.nixos.idea.lsp
+
+import com.intellij.openapi.application.ApplicationManager
+import com.intellij.openapi.components.BaseState
+import com.intellij.openapi.components.RoamingType
+import com.intellij.openapi.components.SimplePersistentStateComponent
+import com.intellij.openapi.components.State
+import com.intellij.openapi.components.Storage
+import com.intellij.openapi.util.text.Strings
+import org.nixos.idea.settings.NixStoragePaths
+import org.nixos.idea.settings.SimplePersistentStateComponentHelper.delegate
+import java.util.ArrayDeque
+import java.util.Collections
+import java.util.Deque
+
+@State(name = "NixLspSettings", storages = [Storage(value = NixStoragePaths.TOOLS, roamingType = RoamingType.LOCAL)])
+class NixLspSettings : SimplePersistentStateComponent<NixLspSettings.State>(State()) {
+
+    class State : BaseState() {
+        var enabled by property(false)
+        var command by string()
+        var history: Deque<String> by property(ArrayDeque(), { it.isEmpty() })
+    }
+
+    var isEnabled: Boolean by delegate(State::enabled)
+    var command: String
+        get() = Strings.notNullize(state.command)
+        set(command) {
+            state.command = command
+            addToHistory(command)
+        }
+    val commandHistory: Collection<String>
+        get() = Collections.unmodifiableCollection(state.history)
+
+    private fun addToHistory(command: String) {
+        val history = state.history
+        history.remove(command)
+        history.addFirst(command)
+        while (history.size > MAX_HISTORY_SIZE) {
+            history.removeLast()
+        }
+    }
+
+    companion object {
+        private const val MAX_HISTORY_SIZE = 5
+
+        @JvmStatic
+        fun getInstance(): NixLspSettings {
+            return ApplicationManager.getApplication().getService(NixLspSettings::class.java)
+        }
+    }
+}

src/main/java/org/nixos/idea/lsp/NixLspSettingsConfigurable.kt

@@ -0,0 +1,70 @@
+package org.nixos.idea.lsp
+
+import com.intellij.openapi.options.BoundSearchableConfigurable
+import com.intellij.openapi.options.Configurable
+import com.intellij.openapi.project.ProjectManager
+import com.intellij.openapi.ui.DialogPanel
+import com.intellij.platform.lsp.api.LspServerManager
+import com.intellij.ui.RawCommandLineEditor
+import com.intellij.ui.components.JBCheckBox
+import com.intellij.ui.dsl.builder.AlignX
+import com.intellij.ui.dsl.builder.Cell
+import com.intellij.ui.dsl.builder.bindSelected
+import com.intellij.ui.dsl.builder.panel
+import com.intellij.ui.dsl.builder.selected
+import com.intellij.ui.dsl.builder.toMutableProperty
+import org.nixos.idea.lsp.ui.CommandSuggestionsPopup
+
+class NixLspSettingsConfigurable :
+    BoundSearchableConfigurable("Language Server (LSP)", "org.nixos.idea.lsp.NixLspSettingsConfigurable"),
+    Configurable.Beta {
+
+    override fun createPanel(): DialogPanel {
+        val settings = NixLspSettings.getInstance()
+        lateinit var enabledCheckBox: Cell<JBCheckBox>
+        return panel {
+            row {
+                enabledCheckBox = checkBox("Enable language server")
+                    .bindSelected(settings::isEnabled)
+            }
+            groupRowsRange("Language Server Configuration") {
+                row("Command:") {
+                    cell(RawCommandLineEditor()).applyToComponent {
+                        editorField.emptyText.setText("Command to start Language Server")
+                        editorField.accessibleContext.accessibleName = "Command to start Language Server"
+                        // TODO What about the following line?
+                        //editorField.margin = myEnabled!!.margin
+                        CommandSuggestionsPopup(
+                            this,
+                            settings.commandHistory,
+                            BUILTIN_SUGGESTIONS
+                        ).install()
+                    }.bind(
+                        RawCommandLineEditor::getText,
+                        RawCommandLineEditor::setText,
+                        settings::command.toMutableProperty()
+                    ).align(AlignX.FILL)
+                }
+            }.enabledIf(enabledCheckBox.selected)
+        }
+    }
+
+    @Suppress("UnstableApiUsage")
+    override fun apply() {
+        super.apply()
+        for (project in ProjectManager.getInstance().openProjects) {
+            LspServerManager.getInstance(project).stopAndRestartIfNeeded(NixLspServerSupportProvider::class.java)
+        }
+    }
+}
+
+private val BUILTIN_SUGGESTIONS: List<CommandSuggestionsPopup.Suggestion> = listOf(
+    CommandSuggestionsPopup.Suggestion.builtin(
+        "<html>Use <b>nil</b> from nixpkgs</html>",
+        "nix --extra-experimental-features \"nix-command flakes\" run nixpkgs#nil"
+    ),
+    CommandSuggestionsPopup.Suggestion.builtin(
+        "<html>Use <b>nixd</b> from nixpkgs</html>",
+        "nix --extra-experimental-features \"nix-command flakes\" run nixpkgs#nixd"
+    )
+)