import { Injectable, NestInterceptor, ExecutionContext, CallHandler } from '@nestjs/common'
import { Response } from 'express'
import { debug, Debugger } from 'debug'
import { isEmpty, omit } from 'lodash'
import { Observable } from 'rxjs'
import { catchError, tap } from 'rxjs/operators'
import * as fastRedact from 'fast-redact'

const HEADERS_OMITTED = ['accept-encoding', 'connection', 'content-length']
const ERROR_PROPERTIES_OMITTED = ['response', 'status']
const REDACT_PROPERTY_PATHS = ['input.credentials.password', '*.password']

@Injectable()
export class LoggingInterceptor implements NestInterceptor {
  logger: Debugger
  redacter: fastRedact.redactFn

  constructor() {
    this.logger = debug('request')
    this.redacter = fastRedact({
      paths: REDACT_PROPERTY_PATHS,
    })
  }

  intercept(context: ExecutionContext, next: CallHandler): Observable<any> {
    const ctx = context.switchToHttp()
    const req = ctx.getRequest()
    const res = ctx.getResponse()

    this.logger.extend('path')(req.path)

    if (req.headers) this.logger.extend('headers')(JSON.stringify(omit(req.headers, ...HEADERS_OMITTED)))
    if (req.body) this.logger.extend('body')(this.redacter(req.body))
    if (req.params && !isEmpty(req.params)) this.logger.extend('params')(JSON.stringify(req.params))

    return next.handle().pipe(
      tap(data => this.logResponse(data, res)),
      catchError(error => this.logError(error)),
    )
  }

  private logResponse(data: any, res: Response): void {
    const responseLogger = this.logger.extend('response')

    if (data) responseLogger.extend('body')(this.redacter(data))

    responseLogger.extend('status_code')(res.statusCode)
  }

  private logError(error: Error | any): any {
    if (!error) throw error

    const errorLogger = this.logger.extend('error')

    errorLogger.extend('message')(this.redacter(omit(error, ...ERROR_PROPERTIES_OMITTED)))

    errorLogger.extend('status_code')(error.status || 500)

    throw error
  }
}