import * as expressWinston from 'express-winston'
import winston from 'winston'
const LogDNATransport = require('logdna-winston')


export const HEALTHCHECK_URL = '/zhealth'

function inDebugMode() {
  return process.env.DEBUG_LOG !== 'false';
}

// by default all logs unless ENV variable DEBUG=false is set
const logLevel = inDebugMode() ? 'debug' : 'info'

export const createLogger = (remoteAppName?: string, label?: string) : winston.Logger => {
  return winston.createLogger({
    level: logLevel,
    exitOnError: false,
    transports: getTransports(getFormat(label), remoteAppName),
    handleExceptions: true,
  })
}

// logger for use as a middleware in express
export const createWWWLogger = (remoteAppName?: string) => {
  return expressWinston.logger({
    transports: getTransports(getFormat(), remoteAppName),
    meta: true,
    requestField: inDebugMode() ? 'req' : null ,
    msg: 'HTTP {{req.method}} {{req.url}}',
    expressFormat: true,
    colorize: true,
    dynamicMeta: (req) => {
      // we remove most of the fields from the meta and keep a couple of them for debugging
      const meta: Record<string, any> = {}
      if (req) {
        meta.remoteIp = req.header('do-connecting-ip') || req.header('x-forwarded-for') || req.ip
        meta.userAgent = req.header('user-agent')
        meta.referrer = req.header('referer')
      }
      return meta
    },
    ignoreRoute: function (req, res) {
      return [HEALTHCHECK_URL].includes(req.url)
    }, // skip some log messages based on request and/or response
  })
}

function getFormat(label?: string) {
  const formats = []
  if (process.env.NODE_ENV !== 'production') {
    formats.push(winston.format.colorize())
  }
  if (label) {
    formats.push(winston.format.label({label: label, message: true}))
  }
  return winston.format.combine(...formats, winston.format.simple())
}

function getTransports(format: winston.Logform.Format, remoteAppName?: string) {
  const baseTransports = [new winston.transports.Console({format: format})]
  // ship to logDNA.com if env var is set
  if (process.env.LOGDNAKEY && remoteAppName) {
    baseTransports.push(
        new LogDNATransport({
          app: remoteAppName,
          key: process.env.LOGDNAKEY,
          level: logLevel,
          handleExceptions: true,
          exitOnError: false,
          indexMeta: true,
        })
    )
  }
  return baseTransports;
}