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// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.const { open, openSync, close, renameSync, statSync } = Deno;type File = Deno.File;type Writer = Deno.Writer;type OpenOptions = Deno.OpenOptions;import { getLevelByName, LevelName, LogLevels } from "./levels.ts";import { LogRecord } from "./logger.ts";import { red, yellow, blue, bold } from "../fmt/colors.ts";import { existsSync, exists } from "../fs/exists.ts";
const DEFAULT_FORMATTER = "{levelName} {msg}";type FormatterFunction = (logRecord: LogRecord) => string;type LogMode = "a" | "w" | "x";
interface HandlerOptions {  formatter?: string | FormatterFunction;}
export class BaseHandler {  level: number;  levelName: LevelName;  formatter: string | FormatterFunction;
  constructor(levelName: LevelName, 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 LogLevels.INFO:        msg = blue(msg);        break;      case LogLevels.WARNING:        msg = yellow(msg);        break;      case LogLevels.ERROR:        msg = red(msg);        break;      case LogLevels.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;  #encoder = new TextEncoder();
  abstract log(msg: string): void;}
interface FileHandlerOptions extends HandlerOptions {  filename: string;  mode?: LogMode;}
export class FileHandler extends WriterHandler {  protected _file!: File;  protected _filename: string;  protected _mode: LogMode;  protected _openOptions: OpenOptions;  #encoder = new TextEncoder();
  constructor(levelName: LevelName, options: FileHandlerOptions) {    super(levelName, options);    this._filename = options.filename;    // default to append mode, write only    this._mode = options.mode ? options.mode : "a";    this._openOptions = {      createNew: this._mode === "x",      create: this._mode !== "x",      append: this._mode === "a",      truncate: this._mode !== "a",      write: true,    };  }
  async setup(): Promise<void> {    this._file = await open(this._filename, this._openOptions);    this._writer = this._file;  }
  log(msg: string): void {    Deno.writeSync(this._file.rid, this.#encoder.encode(msg + "\n"));  }
  destroy(): Promise<void> {    this._file.close();    return Promise.resolve();  }}
interface RotatingFileHandlerOptions extends FileHandlerOptions {  maxBytes: number;  maxBackupCount: number;}
export class RotatingFileHandler extends FileHandler {  #maxBytes: number;  #maxBackupCount: number;
  constructor(levelName: LevelName, options: RotatingFileHandlerOptions) {    super(levelName, options);    this.#maxBytes = options.maxBytes;    this.#maxBackupCount = options.maxBackupCount;  }
  async setup(): Promise<void> {    if (this.#maxBytes < 1) {      throw new Error("maxBytes cannot be less than 1");    }    if (this.#maxBackupCount < 1) {      throw new Error("maxBackupCount cannot be less than 1");    }    await super.setup();
    if (this._mode === "w") {      // Remove old backups too as it doesn't make sense to start with a clean      // log file, but old backups      for (let i = 1; i <= this.#maxBackupCount; i++) {        if (await exists(this._filename + "." + i)) {          await Deno.remove(this._filename + "." + i);        }      }    } else if (this._mode === "x") {      // Throw if any backups also exist      for (let i = 1; i <= this.#maxBackupCount; i++) {        if (await exists(this._filename + "." + i)) {          Deno.close(this._file.rid);          throw new Deno.errors.AlreadyExists(            "Backup log file " + this._filename + "." + i + " already exists"          );        }      }    }  }
  handle(logRecord: LogRecord): void {    if (this.level > logRecord.level) return;
    const msg = this.format(logRecord);    const currentFileSize = statSync(this._filename).size;    if (currentFileSize + msg.length > this.#maxBytes) {      this.rotateLogFiles();    }
    return this.log(msg);  }
  rotateLogFiles(): void {    close(this._file.rid);
    for (let i = this.#maxBackupCount - 1; i >= 0; i--) {      const source = this._filename + (i === 0 ? "" : "." + i);      const dest = this._filename + "." + (i + 1);
      if (existsSync(source)) {        renameSync(source, dest);      }    }
    this._file = openSync(this._filename, this._openOptions);    this._writer = this._file;  }}