import { Injectable, OnModuleInit } from '@nestjs/common'
import { MailDataRequired, MailService as SendgridLibMailService } from '@sendgrid/mail'
import { debug, Debugger } from 'debug'
import { get, isEmpty, isNil } from 'lodash'
import { nanoid } from 'nanoid'

import { SendgridConfig } from '../../typings/global'

import { MailService, MailerSendOptions } from './mail.service'

export const SENDGRID_DISABLED_MESSAGE = 'Message has not be sent: SendGrid is disabled!'

type SendOptions = MailerSendOptions & {
  templateId: string
  from: string
  sender: string
}

@Injectable()
export class SendgridMailService extends MailService implements OnModuleInit {
  private debug: Debugger = debug(`http:${this.constructor.name}`)
  private _settings: SendgridConfig
  private _sendgridLibMailService: SendgridLibMailService

  onModuleInit(): void {
    this._settings = globalThis.secret.sendgrid_settings as SendgridConfig
    this._sendgridLibMailService = new SendgridLibMailService()
    this._sendgridLibMailService.setApiKey(this._settings.key)
  }

  get enabled(): boolean {
    return this._settings.enabled
  }

  async send(options: MailerSendOptions): Promise<any> {
    try {
      const args = this.extract(options)

      return await this.sendMessage(args)
    } catch (error) {
      const bodyErrors = get(error, 'response.body.errors', null)?.reduce(
        (previous: string, current: { message: string }) =>
          `${previous}${!isEmpty(previous) ? ` | ${current.message}` : current.message}`,
        '',
      )

      throw new Error(`Error sending mail to '${JSON.stringify(options)}': ${bodyErrors || error.message}`)
    }
  }

  private async sendMessage({
    to,
    substitutions,
    dynamicTemplateData,
    templateId,
    from,
    sendAt,
    attachments,
  }: SendOptions): Promise<any> {
    if (!this.enabled) {
      return this.disabledMessage(SENDGRID_DISABLED_MESSAGE)
    }

    const args: MailDataRequired = {
      dynamicTemplateData,
      substitutions,
      templateId,
      from,
      to,
    }

    if (attachments)
      args.attachments = attachments.map(attachment => ({
        content: Buffer.isBuffer(attachment.content) ? attachment.content.toString('base64') : attachment.content,
        filename: attachment.filename,
        type: attachment.type,
        disposition: 'attachment',
      }))

    if (!isNil(sendAt)) args.sendAt = Math.round(+sendAt / 1000)

    const id = nanoid()

    this.debug.extend('request')(JSON.stringify({ id, type: 'publish_sns', body: { ...args } }))

    const response = this._sendgridLibMailService.send(args)

    this.debug.extend('response')(JSON.stringify({ id, response }))

    return response
  }

  private extract = (options: MailerSendOptions): SendOptions => {
    const { to, substitutions, dynamicTemplateData, templateId } = options
    const { sender } = this._settings

    return {
      to,
      substitutions,
      sender,
      from: sender,
      templateId,
      dynamicTemplateData,
      sendAt: options.sendAt,
      attachments: options.attachments,
    }
  }

  private disabledMessage = (result: string): { result: string } => {
    return {
      result,
    }
  }
}