import { EventName, EventInput } from './dto/shared.dto'

if (typeof Buffer === 'undefined') global.Buffer = require('buffer').Buffer

const DEFAULT_METRICS_URL = 'https://affinity-metrics.dev.affinity-project.org'

let fetch: any

if (!fetch) {
  fetch = require('node-fetch')
}

const keccak256 = require('keccak256')

class Metrics {
  _linksDescriptionByEventName(eventName: string) {
    switch (eventName) {
      case EventName.BLOOM_VAULT_READ:
      case EventName.BLOOM_VAULT_WRITE:
        return { linkDescription: 'apiKey', secondaryLinkDescription: 'numberOfVCs'  }
      case EventName.USER_ONBOARDED:
        return { linkDescription: 'apiKey' }

      case EventName.VC_VERIFIED:
        return { linkDescription: 'holderDid' }

      case EventName.VC_VERIFIED_PER_PARTY:
        return { linkDescription: 'verifierDid', secondaryLinkDescription: 'vcId' }

      case EventName.VP_VERIFIED:
      case EventName.VP_VERIFIED_JWT:
        return { linkDescription: 'holderDid' }

      case EventName.VC_SAVED:
      case EventName.VC_ISSUE_INITIATED:
      case EventName.SHARED_MESSAGE_CREATED:
        return { linkDescription: 'vcId', secondaryLinkDescription: 'issuerId' }

      case EventName.VC_SIGNED:
        return { linkDescription: 'holderDid', secondaryLinkDescription: 'VcId' }

      case EventName.VP_SIGNED:
      case EventName.VP_SIGNED_JWT:
        return { linkDescription: 'holderDid', secondaryLinkDescription: 'VpId' }

      case EventName.VC_REVOKED:
        return { linkDescription: 'issuerDid' }

      case EventName.DID_CREATED:
      case EventName.DID_UPDATED:
        return { linkDescription: 'did' }

      default:
        // a safe guard
        return { linkDescription: 'not implemented' }
    }
  }

  _prepareEventParams(event: EventInput) {
    // TODO: To check event's `link` and `secondaryLink` values if those are and should be DIDs
    // const regexDID = /^did:[\w|\d]{2,}:[\w|\d|:|;|\-|=]{10,}/
    const { link } = event
    const linkBuffer = Buffer.from(link)
    const hashedLinkBuffer = keccak256(linkBuffer)

    const { name } = event
    const { linkDescription, secondaryLinkDescription } = this._linksDescriptionByEventName(name)

    return Object.assign({}, event, {
      link: hashedLinkBuffer.toString('hex'),
      linkDescription,
      ...(secondaryLinkDescription ? { secondaryLinkDescription } : {})
    })
  }

  async send(
    eventInput: any,
    apiKeyHash: string,
    metricsUrl?: string,
    topic: string = 'createEvent',
  ): Promise<any> {
    try {
      metricsUrl = metricsUrl || DEFAULT_METRICS_URL

      const url = `${metricsUrl}/api/v1/events/${topic}`

      let event
      if (topic === 'createEvent') {
        event = this._prepareEventParams(eventInput)
      } else {
        event = eventInput
      }

      const body = JSON.stringify(event, null, 2)
      const headers = {
        Accept:         'application/json',
        'Content-Type': 'application/json',
        'Api-Key':      apiKeyHash
      }
      const response = await fetch(url, { method: 'POST', headers, body })
      const result = await response.json()

      if (response.status.toString().startsWith('2')) {
        return result
      } else {
        throw new Error(result)
      }
    } catch (error) {
      //TODO: error handler and reporter
      return { error }
    }
  }
}

export const metrics = new Metrics()