//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//

import Foundation
import LanguageServerProtocol
import SKCore

/// The state of a `ToolchainLanguageServer`
public enum LanguageServerState {
  /// The language server is running with semantic functionality enabled
  case connected
  /// The language server server has crashed and we are waiting for it to relaunch
  case connectionInterrupted
  /// The language server has relaunched but semantic functionality is currently disabled
  case semanticFunctionalityDisabled
}

/// A `LanguageServer` that exists within the context of the current process.
public protocol ToolchainLanguageServer: AnyObject {

  // MARK: - Creation

  init?(
    client: LocalConnection,
    toolchain: Toolchain,
    clientCapabilities: ClientCapabilities?,
    options: SourceKitServer.Options,
    workspace: Workspace,
    reopenDocuments: @escaping (ToolchainLanguageServer) -> Void
  ) throws

  /// Returns `true` if this instance of the language server can handle opening documents in `workspace`.
  /// If this returns `false`, a new language server will be started for `workspace`.
  func canHandle(workspace: Workspace) -> Bool

  // MARK: - Lifetime

  func initializeSync(_ initialize: InitializeRequest) throws -> InitializeResult
  func clientInitialized(_ initialized: InitializedNotification)
  /// `callback` will be called when the server has finished shutting down.
  func shutdown(callback: @escaping () -> Void)

  /// Add a handler that is called whenever the state of the language server changes.
  func addStateChangeHandler(handler: @escaping (_ oldState: LanguageServerState, _ newState: LanguageServerState) -> Void)

  // MARK: - Text synchronization

  /// Sent to open up a document on the Language Server.
  /// This may be called before or after a corresponding
  /// `documentUpdatedBuildSettings` call for the same document.
  func openDocument(_ note: DidOpenTextDocumentNotification)

  /// Sent to close a document on the Language Server.
  func closeDocument(_ note: DidCloseTextDocumentNotification)
  func changeDocument(_ note: DidChangeTextDocumentNotification)
  func willSaveDocument(_ note: WillSaveTextDocumentNotification)
  func didSaveDocument(_ note: DidSaveTextDocumentNotification)

  // MARK: - Build System Integration

  /// Sent when the `BuildSystem` has resolved build settings, such as for the intial build settings
  /// or when the settings have changed (e.g. modified build system files). This may be sent before
  /// the respective `DocumentURI` has been opened.
  func documentUpdatedBuildSettings(_ uri: DocumentURI, change: FileBuildSettingsChange)

  /// Sent when the `BuildSystem` has detected that dependencies of the given file have changed
  /// (e.g. header files, swiftmodule files, other compiler input files).
  func documentDependenciesUpdated(_ uri: DocumentURI)

  // MARK: - Text Document

  func completion(_ req: Request<CompletionRequest>)
  func hover(_ req: Request<HoverRequest>)
  func symbolInfo(_ request: Request<SymbolInfoRequest>)

  /// Returns true if the `ToolchainLanguageServer` will take ownership of the request.
  func definition(_ request: Request<DefinitionRequest>) -> Bool

  func documentSymbolHighlight(_ req: Request<DocumentHighlightRequest>)
  func foldingRange(_ req: Request<FoldingRangeRequest>)
  func documentSymbol(_ req: Request<DocumentSymbolRequest>)
  func documentColor(_ req: Request<DocumentColorRequest>)
  func documentSemanticTokens(_ req: Request<DocumentSemanticTokensRequest>)
  func documentSemanticTokensDelta(_ req: Request<DocumentSemanticTokensDeltaRequest>)
  func documentSemanticTokensRange(_ req: Request<DocumentSemanticTokensRangeRequest>)
  func colorPresentation(_ req: Request<ColorPresentationRequest>)
  func codeAction(_ req: Request<CodeActionRequest>)
  func inlayHint(_ req: Request<InlayHintRequest>)

  // MARK: - Other

  func executeCommand(_ req: Request<ExecuteCommandRequest>)

  /// Crash the language server. Should be used for crash recovery testing only.
  func _crash()
}