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// Copyright 2023 Mark Lee (mlee.aus@gmail.com). All rights reserved. MIT license.import { stringify, Column } from "https://deno.land/std@0.170.0/encoding/csv.ts"import { writeAll } from "https://deno.land/std@0.171.0/streams/write_all.ts"
export interface LogOptions {  format?: 'csv' | 'json' // file extensions respectively are .csv or .txt file  disableConsoleLogging?: boolean // don't write to console  consoleOutput?: 'raw' | 'pretty'  logLabel?: string // <logLabel>.log.<instantiation-date-time>.csv|txt  maxBytes?: number // default 10mb}
enum LogLevels {  Debug = 'DEBUG',  Info = 'INFO',  Warn = 'WARN',  Error = 'ERROR'}
type SaveCallback = (file: Deno.FsFile, data: Uint8Array) => Promise<void>
export class TinyLogger {  #instantiation = getInstantiation()  #format: 'csv' | 'json'  #consoleOutput: 'raw' | 'pretty'  #logLabel: string  #path: string = Deno.cwd()  #disableConsoleLogging: boolean  #enableFileLogging = false  #encoder = new TextEncoder()  #maxBytes: number  #byteLength = 0  #logFileNumber = 0  #file!: Deno.FsFile
  #logColors: Map<string, string> = new Map(    Object.entries(      { DEBUG: 'light-blue', INFO: 'cyan', WARN: 'yellow', ERROR: 'red' }    )  )
  constructor(options?: LogOptions) {    this.#format = options?.format || 'csv'    this.#logLabel = options?.logLabel || 'log'    this.#consoleOutput = options?.consoleOutput || 'pretty'    this.#maxBytes = options?.maxBytes || 10485760    this.#disableConsoleLogging = options?.disableConsoleLogging || false    this.init()  }
  private init() {    if (this.#disableConsoleLogging && !this.#enableFileLogging) {      throw `TinyLogger Error: file logging and console logging cannot both be disabled.`    }
    if (!isAlphanumeric(this.#logLabel)) {      throw 'TinyLogger Error: loglabel contains invalid characters. Label can be alphanumeric characters only.'    }
    if (this.#logLabel !== 'log') {      this.#logLabel = `${this.#logLabel}.log`    }  }
  debug(source: string, message: string) {    const data = formatData(this.#format, LogLevels.Debug, source, message)
    if (!this.#disableConsoleLogging) {      this.logToConsole(LogLevels.Debug, source, message)    }
    if (this.#enableFileLogging) {      this.writeFile(data, this.saveCallback)    }  }
  info(source: string, message: string) {    const data = formatData(this.#format, LogLevels.Info, source, message)
    if (!this.#disableConsoleLogging) {      this.logToConsole(LogLevels.Info, source, message)    }
    if (this.#enableFileLogging) {      this.writeFile(data, this.saveCallback)    }  }
  warn(source: string, message: string) {    const data = formatData(this.#format, LogLevels.Warn, source, message)
    if (!this.#disableConsoleLogging) {      this.logToConsole(LogLevels.Warn, source, message)    }
    if (this.#enableFileLogging) {      this.writeFile(data, this.saveCallback)    }  }
  error(source: string, message: string) {    const data = formatData(this.#format, LogLevels.Error, source, message)
    if (!this.#disableConsoleLogging) {      this.logToConsole(LogLevels.Error, source, message)    }
    if (this.#enableFileLogging) {      this.writeFile(data, this.saveCallback)    }  }
  public async enableFileLogging(path?: string) {    this.#enableFileLogging = true    if (path) {      this.#path = path    }    this.#path = pathHelper(this.#path)
    await testFilePath(this.#path)    const file = `${this.#logLabel}.${this.#instantiation}.${this.#format}`    this.openFile(file)  }
  private logToConsole(    level: LogLevels,    source: string,    message: string  ) {    const time = (new Date()).toISOString()    const outputColor = this.#logColors.get(level)
    const data = JSON.stringify({      time,      [level]: source,      message    })
    switch (this.#consoleOutput) {      case 'raw':        console.log(`%c${data}`, `color: ${outputColor};`)        break
      case 'pretty':        console.log(`%c[${time}] ${level}: ${source}`, `color: ${outputColor};`)        console.log(`%c${message}\n`, `color: light-blue;`)        break    }  }
  private async saveCallback(    file: Deno.FsFile,    data: Uint8Array  ) {    await writeAll(file, data)  }
  private openFile(file: string) {    this.#file = Deno.openSync(      this.#path + file,      { read: true, write: true, create: true, append: true }    )  }
  private writeFile(data: string, saveCallback: (SaveCallback)) {    const encodedData = this.#encoder.encode(data)
    const newMessageBytes = this.#encoder.encode(data).byteLength    this.#byteLength += newMessageBytes
    if (this.#byteLength < this.#maxBytes) {      saveCallback(this.#file, encodedData)    } else {      this.#file.close()      this.#byteLength = 0      this.#logFileNumber++
      const file = `${this.#logLabel}.${this.#instantiation}_${this.#logFileNumber}.${this.#format}`      this.openFile(file)
      saveCallback(this.#file, encodedData)    }  }}
function isAlphanumeric(s: string) {  return /^[A-Za-z0-9]*$/.test(s);}
function pathHelper(path: string) {  if (path !== './') {    path = path[path.length - 1] === '/' ?      path :      path + '/'  }  return path}
function formatData(  format: 'csv' | 'json',  level: LogLevels,  source: string,  message: string) {  let data: string  const time = (new Date()).toISOString()
  switch (format) {    case 'csv': {      const columns: Column = [        'time',        'level',        'source',        'message'      ]
      data = stringify(        [{          time,          level,          source,          message        }], { columns, headers: false }      )    }      break
    case 'json': {      data = JSON.stringify({        time,        level,        source,        message      }) + '\n'    }      break  }
  return data}
async function testFilePath(path: string) {  try {    await Deno.lstat(path);  } catch (err) {    if (err instanceof Deno.errors.NotFound) {      throw `TinyLogger Error: Invalid Path '${path}'`    }    throw err;  }}
function getInstantiation() {  const dateTime = new Date()  const dtArray = dateTime.toJSON().split('T')
  const time = dtArray[1]  const timeSansMiliseconds = time.split('.')[0]  const timeForFileName = timeSansMiliseconds.replaceAll(':', '-')
  const formattedDateTime = `${dtArray[0]}T${timeForFileName}`
  return formattedDateTime}