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// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.const { open } = Deno;type File = Deno.File;type Writer = Deno.Writer;import { getLevelByName, LogLevel } from "./levels.ts";import { LogRecord } from "./logger.ts";import { red, yellow, blue, bold } from "../fmt/colors.ts";
const DEFAULT_FORMATTER = "{levelName} {msg}";type FormatterFunction = (logRecord: LogRecord) => string;
interface HandlerOptions {  formatter?: string | FormatterFunction;}
export class BaseHandler {  level: number;  levelName: string;  formatter: string | FormatterFunction;
  constructor(levelName: string, options: HandlerOptions = {}) {    this.level = getLevelByName(levelName);    this.levelName = levelName;
    this.formatter = options.formatter || DEFAULT_FORMATTER;  }
  handle(logRecord: LogRecord): void {    if (this.level > logRecord.level) return;
    const msg = this.format(logRecord);    return this.log(msg);  }
  format(logRecord: LogRecord): string {    if (this.formatter instanceof Function) {      return this.formatter(logRecord);    }
    return this.formatter.replace(/{(\S+)}/g, (match, p1): string => {      const value = logRecord[p1 as keyof LogRecord];
      // do not interpolate missing values      if (!value) {        return match;      }
      return String(value);    });  }
  log(_msg: string): void {}  async setup(): Promise<void> {}  async destroy(): Promise<void> {}}
export class ConsoleHandler extends BaseHandler {  format(logRecord: LogRecord): string {    let msg = super.format(logRecord);
    switch (logRecord.level) {      case LogLevel.INFO:        msg = blue(msg);        break;      case LogLevel.WARNING:        msg = yellow(msg);        break;      case LogLevel.ERROR:        msg = red(msg);        break;      case LogLevel.CRITICAL:        msg = bold(red(msg));        break;      default:        break;    }
    return msg;  }
  log(msg: string): void {    console.log(msg);  }}
export abstract class WriterHandler extends BaseHandler {  protected _writer!: Writer;  private _encoder = new TextEncoder();
  log(msg: string): void {    this._writer.write(this._encoder.encode(msg + "\n"));  }}
interface FileHandlerOptions extends HandlerOptions {  filename: string;}
export class FileHandler extends WriterHandler {  private _file!: File;  private _filename: string;
  constructor(levelName: string, options: FileHandlerOptions) {    super(levelName, options);    this._filename = options.filename;  }
  async setup(): Promise<void> {    // open file in append mode - write only    this._file = await open(this._filename, "a");    this._writer = this._file;  }
  async destroy(): Promise<void> {    await this._file.close();  }}