import Transport from 'winston-transport'
import fetch from 'node-fetch'

import { DataDogTransportOptions } from './types'

interface QueryParams {
  hostname?: string
  service?: string
  ddsource: string
  ddtags?: string
}

interface Log {
  dd?: { [key: string]: string }
}

class DataDogTransport extends Transport {
  private ddsource = 'nodejs'

  constructor(private options: DataDogTransportOptions) {
    super({ level: options.level, format: options.format })
  }

  get name() {
    return 'datadog'
  }

  async log(log: Log, callback: () => void) {
    setImmediate(() => {
      this.emit('logged', log)
    })

    const queryParams = this._getQueryParams(log)

    const url = this._getUrl(queryParams)

    try {
      await fetch(url, {
        method: 'POST',
        headers: {
          'content-type': 'application/json',
        },
        body: JSON.stringify(log),
      })
    } catch (err) {
    } finally {
      callback()
    }
  }

  _getQueryParams(log: Log) {
    const queryParams: QueryParams = {
      hostname: this.options.hostname,
      service: this.options.service,
      ddsource: this.ddsource,
      ddtags: this._getDDTags(log),
    }

    return queryParams
  }

  _getUrl(queryParams: QueryParams) {
    const url = new URL(this.options.apiKey, this.options.intakeUrl)

    Object.keys(queryParams).forEach((param) => {
      const value = queryParams[param as keyof QueryParams]

      if (value == undefined || !value.length) return

      url.searchParams.append(param, value)
    })

    return url.toString()
  }

  _getDDTags(log: Log) {
    let tags = this.options.ddtags || ''

    const addTag = (key: string, value: string) =>
      (tags += (tags.length ? ',' : '') + `${key}:${value}`)

    if (log.dd?.trace_id) addTag('trace_id', log.dd.trace_id)
    if (log.dd?.span_id) addTag('span_id', log.dd.span_id)
    if (this.options.storefrontVersion) addTag('version', this.options.storefrontVersion)
    if (this.options.siteState) addTag('site_state', this.options.siteState)

    return tags
  }
}

export { DataDogTransport }