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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.import { getLevelByName, getLevelName, LogLevels } from "./levels.ts";import type { LevelName } from "./levels.ts";import type { BaseHandler } from "./handlers.ts";
// deno-lint-ignore no-explicit-anyexport type GenericFunction = (...args: any[]) => any;
export interface LogRecordOptions {  msg: string;  args: unknown[];  level: number;  loggerName: string;}
/** * An object that encapsulates provided message and arguments as well some * metadata that can be later used when formatting a message. */export class LogRecord {  readonly msg: string;  #args: unknown[];  #datetime: Date;  readonly level: number;  readonly levelName: string;  readonly loggerName: string;
  constructor(options: LogRecordOptions) {    this.msg = options.msg;    this.#args = [...options.args];    this.level = options.level;    this.loggerName = options.loggerName;    this.#datetime = new Date();    this.levelName = getLevelName(options.level);  }  get args(): unknown[] {    return [...this.#args];  }  get datetime(): Date {    return new Date(this.#datetime.getTime());  }}
export interface LoggerOptions {  handlers?: BaseHandler[];}
export class Logger {  #level: LogLevels;  #handlers: BaseHandler[];  readonly #loggerName: string;
  constructor(    loggerName: string,    levelName: LevelName,    options: LoggerOptions = {},  ) {    this.#loggerName = loggerName;    this.#level = getLevelByName(levelName);    this.#handlers = options.handlers || [];  }
  get level(): LogLevels {    return this.#level;  }  set level(level: LogLevels) {    this.#level = level;  }
  get levelName(): LevelName {    return getLevelName(this.#level);  }  set levelName(levelName: LevelName) {    this.#level = getLevelByName(levelName);  }
  get loggerName(): string {    return this.#loggerName;  }
  set handlers(hndls: BaseHandler[]) {    this.#handlers = hndls;  }  get handlers(): BaseHandler[] {    return this.#handlers;  }
  /** If the level of the logger is greater than the level to log, then nothing   * is logged, otherwise a log record is passed to each log handler.  `msg` data   * passed in is returned.  If a function is passed in, it is only evaluated   * if the msg will be logged and the return value will be the result of the   * function, not the function itself, unless the function isn't called, in which   * case undefined is returned.  All types are coerced to strings for logging.   */  #_log<T>(    level: number,    msg: (T extends GenericFunction ? never : T) | (() => T),    ...args: unknown[]  ): T | undefined {    if (this.level > level) {      return msg instanceof Function ? undefined : msg;    }
    let fnResult: T | undefined;    let logMessage: string;    if (msg instanceof Function) {      fnResult = msg();      logMessage = this.asString(fnResult);    } else {      logMessage = this.asString(msg);    }    const record: LogRecord = new LogRecord({      msg: logMessage,      args: args,      level: level,      loggerName: this.loggerName,    });
    this.#handlers.forEach((handler) => {      handler.handle(record);    });
    return msg instanceof Function ? fnResult : msg;  }
  asString(data: unknown): string {    if (typeof data === "string") {      return data;    } else if (      data === null ||      typeof data === "number" ||      typeof data === "bigint" ||      typeof data === "boolean" ||      typeof data === "undefined" ||      typeof data === "symbol"    ) {      return String(data);    } else if (data instanceof Error) {      return data.stack!;    } else if (typeof data === "object") {      return JSON.stringify(data);    }    return "undefined";  }
  debug<T>(msg: () => T, ...args: unknown[]): T | undefined;  debug<T>(msg: T extends GenericFunction ? never : T, ...args: unknown[]): T;  debug<T>(    msg: (T extends GenericFunction ? never : T) | (() => T),    ...args: unknown[]  ): T | undefined {    return this.#_log(LogLevels.DEBUG, msg, ...args);  }
  info<T>(msg: () => T, ...args: unknown[]): T | undefined;  info<T>(msg: T extends GenericFunction ? never : T, ...args: unknown[]): T;  info<T>(    msg: (T extends GenericFunction ? never : T) | (() => T),    ...args: unknown[]  ): T | undefined {    return this.#_log(LogLevels.INFO, msg, ...args);  }
  warning<T>(msg: () => T, ...args: unknown[]): T | undefined;  warning<T>(msg: T extends GenericFunction ? never : T, ...args: unknown[]): T;  warning<T>(    msg: (T extends GenericFunction ? never : T) | (() => T),    ...args: unknown[]  ): T | undefined {    return this.#_log(LogLevels.WARNING, msg, ...args);  }
  error<T>(msg: () => T, ...args: unknown[]): T | undefined;  error<T>(msg: T extends GenericFunction ? never : T, ...args: unknown[]): T;  error<T>(    msg: (T extends GenericFunction ? never : T) | (() => T),    ...args: unknown[]  ): T | undefined {    return this.#_log(LogLevels.ERROR, msg, ...args);  }
  critical<T>(msg: () => T, ...args: unknown[]): T | undefined;  critical<T>(    msg: T extends GenericFunction ? never : T,    ...args: unknown[]  ): T;  critical<T>(    msg: (T extends GenericFunction ? never : T) | (() => T),    ...args: unknown[]  ): T | undefined {    return this.#_log(LogLevels.CRITICAL, msg, ...args);  }}