Introduce logLevel option

Part of #1560

src/common/TestUtils.test.ts

@@ -3,7 +3,7 @@
  * @license MIT
  */
 
-import { IBufferService, ICoreService, IOptionsService, ITerminalOptions, IPartialTerminalOptions } from 'common/services/Services';
+import { IBufferService, ICoreService, ILogService, IOptionsService, ITerminalOptions, IPartialTerminalOptions } from 'common/services/Services';
 import { IEvent, EventEmitter } from 'common/EventEmitter';
 import { clone } from 'common/Clone';
 import { DEFAULT_OPTIONS } from 'common/services/OptionsService';
@@ -36,6 +36,13 @@ export class MockCoreService implements ICoreService {
   triggerDataEvent(data: string, wasUserInput?: boolean): void {}
 }
 
+export class MockLogService implements ILogService {
+  debug(message: any, ...optionalParams: any[]): void {}
+  info(message: any, ...optionalParams: any[]): void {}
+  warn(message: any, ...optionalParams: any[]): void {}
+  error(message: any, ...optionalParams: any[]): void {}
+}
+
 export class MockOptionsService implements IOptionsService {
   options: ITerminalOptions = clone(DEFAULT_OPTIONS);
   onOptionChange: IEvent<string> = new EventEmitter<string>().event;

src/common/services/LogService.ts

@@ -0,0 +1,78 @@
+/**
+ * Copyright (c) 2019 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+import { ILogService, IOptionsService } from 'common/services/Services';
+
+interface IConsole {
+  log(message?: any, ...optionalParams: any[]): void;
+  error(message?: any, ...optionalParams: any[]): void;
+  info(message?: any, ...optionalParams: any[]): void;
+  trace(message?: any, ...optionalParams: any[]): void;
+  warn(message?: any, ...optionalParams: any[]): void;
+}
+
+// console is available on both node.js and browser contexts but the common
+// module doesn't depend on them so we need to explicitly declare it.
+declare const console: IConsole;
+
+
+export enum LogLevel {
+  Debug = 0,
+  Info = 1,
+  Warn = 2,
+  Error = 3,
+  Off = 4
+}
+
+const optionsKeyToLogLevel: { [key: string]: LogLevel } = {
+  debug: LogLevel.Debug,
+  info: LogLevel.Info,
+  warn: LogLevel.Warn,
+  error: LogLevel.Error,
+  off: LogLevel.Off
+};
+
+export class LogService implements ILogService {
+  private _logLevel!: LogLevel;
+
+  constructor(
+    private readonly _optionsService: IOptionsService
+  ) {
+    this._updateLogLevel();
+    this._optionsService.onOptionChange(key => {
+      if (key === 'logLevel') {
+        this._updateLogLevel();
+      }
+    })
+  }
+
+  private _updateLogLevel(): void {
+    this._logLevel = optionsKeyToLogLevel[this._optionsService.options.logLevel];
+  }
+
+  debug(message: any, ...optionalParams: any[]): void {
+    if (this._logLevel <= LogLevel.Debug) {
+      console.log.call(console, message, optionalParams);
+    }
+  }
+
+  info(message: any, ...optionalParams: any[]): void {
+    if (this._logLevel <= LogLevel.Info) {
+      console.info.call(console, message, optionalParams);
+    }
+  }
+
+  warn(message: any, ...optionalParams: any[]): void {
+    if (this._logLevel <= LogLevel.Warn) {
+      console.warn.call(console, message, optionalParams);
+    }
+  }
+
+  error(message: any, ...optionalParams: any[]): void {
+    if (this._logLevel <= LogLevel.Error) {
+      console.error.call(console, message, optionalParams);
+    }
+  }
+}

src/common/services/OptionsService.ts

@@ -29,6 +29,7 @@ export const DEFAULT_OPTIONS: ITerminalOptions = Object.freeze({
   fontWeightBold: 'bold',
   lineHeight: 1.0,
   letterSpacing: 0,
+  logLevel: 'info',
   scrollback: 1000,
   screenReaderMode: false,
   macOptionIsMeta: false,

src/common/services/Services.d.ts

@@ -38,6 +38,13 @@ export interface ICoreService {
     triggerDataEvent(data: string, wasUserInput?: boolean): void;
 }
 
+export interface ILogService {
+  debug(message: any, ...optionalParams: any[]): void;
+  info(message: any, ...optionalParams: any[]): void;
+  warn(message: any, ...optionalParams: any[]): void;
+  error(message: any, ...optionalParams: any[]): void;
+}
+
 export interface IOptionsService {
   readonly options: ITerminalOptions;
 
@@ -48,7 +55,7 @@ export interface IOptionsService {
 }
 
 export type FontWeight = 'normal' | 'bold' | '100' | '200' | '300' | '400' | '500' | '600' | '700' | '800' | '900';
-
+export type LogLevel = 'debug' | 'info' | 'warn' | 'error' | 'off';
 export type RendererType = 'dom' | 'canvas';
 
 export interface IPartialTerminalOptions {
@@ -66,6 +73,7 @@ export interface IPartialTerminalOptions {
   fontWeightBold?: FontWeight;
   letterSpacing?: number;
   lineHeight?: number;
+  logLevel?: LogLevel;
   macOptionIsMeta?: boolean;
   macOptionClickForcesSelection?: boolean;
   rendererType?: RendererType;
@@ -86,6 +94,7 @@ export interface ITerminalOptions {
   cols: number;
   cursorBlink: boolean;
   cursorStyle: 'block' | 'underline' | 'bar';
+  debug: boolean;
   disableStdin: boolean;
   drawBoldTextInBrightColors: boolean;
   fontSize: number;
@@ -94,6 +103,7 @@ export interface ITerminalOptions {
   fontWeightBold: FontWeight;
   letterSpacing: number;
   lineHeight: number;
+  logLevel: LogLevel;
   macOptionIsMeta: boolean;
   macOptionClickForcesSelection: boolean;
   rendererType: RendererType;
@@ -109,7 +119,6 @@ export interface ITerminalOptions {
   [key: string]: any;
   cancelEvents: boolean;
   convertEol: boolean;
-  debug: boolean;
   screenKeys: boolean;
   termName: string;
   useFlowControl: boolean;