/* eslint-disable no-console */
import type { Transporter } from 'nodemailer'
import type SMTPConnection from 'nodemailer/lib/smtp-connection'
import type { EmailAdapter } from 'payload'

import nodemailer from 'nodemailer'
import { InvalidConfiguration } from 'payload'

export type NodemailerAdapterArgs = {
  defaultFromAddress: string
  defaultFromName: string
  skipVerify?: boolean
  transport?: Transporter
  transportOptions?: SMTPConnection.Options
}

type NodemailerAdapter = EmailAdapter<unknown>

/**
 * Creates an email adapter using nodemailer
 *
 * If no email configuration is provided, an ethereal email test account is returned
 */
export const nodemailerAdapter = async (
  args?: NodemailerAdapterArgs,
): Promise<NodemailerAdapter> => {
  const { defaultFromAddress, defaultFromName, transport } = await buildEmail(args)

  const adapter: NodemailerAdapter = () => ({
    name: 'nodemailer',
    defaultFromAddress,
    defaultFromName,
    sendEmail: async (message) => {
      return await transport.sendMail({
        from: `${defaultFromName} <${defaultFromAddress}>`,
        ...message,
      })
    },
  })
  return adapter
}

async function buildEmail(emailConfig?: NodemailerAdapterArgs): Promise<{
  defaultFromAddress: string
  defaultFromName: string
  transport: Transporter
}> {
  if (!emailConfig) {
    const transport = await createMockAccount(emailConfig)
    if (!transport) {
      throw new InvalidConfiguration('Unable to create Nodemailer test account.')
    }

    return {
      defaultFromAddress: 'info@payloadcms.com',
      defaultFromName: 'Payload',
      transport,
    }
  }

  // Create or extract transport
  let transport: Transporter
  if ('transport' in emailConfig && emailConfig.transport) {
    ;({ transport } = emailConfig)
  } else if ('transportOptions' in emailConfig && emailConfig.transportOptions) {
    transport = nodemailer.createTransport(emailConfig.transportOptions)
  } else {
    transport = await createMockAccount(emailConfig)
  }

  if (!emailConfig.skipVerify) {
    await verifyTransport(transport)
  }

  return {
    defaultFromAddress: emailConfig.defaultFromAddress,
    defaultFromName: emailConfig.defaultFromName,
    transport,
  }
}

async function verifyTransport(transport: Transporter) {
  try {
    await transport.verify()
  } catch (err: unknown) {
    console.error({ err, msg: 'Error verifying Nodemailer transport.' })
  }
}

/**
 * Use ethereal.email to create a mock email account
 */
async function createMockAccount(emailConfig?: NodemailerAdapterArgs) {
  try {
    const etherealAccount = await nodemailer.createTestAccount()

    const smtpOptions = {
      ...(emailConfig || {}),
      auth: {
        pass: etherealAccount.pass,
        user: etherealAccount.user,
      },
      fromAddress: emailConfig?.defaultFromAddress,
      fromName: emailConfig?.defaultFromName,
      host: 'smtp.ethereal.email',
      port: 587,
      secure: false,
    }
    const transport = nodemailer.createTransport(smtpOptions)
    const { pass, user, web } = etherealAccount

    console.info('E-mail configured with ethereal.email test account. ')
    console.info(`Log into mock email provider at ${web}`)
    console.info(`Mock email account username: ${user}`)
    console.info(`Mock email account password: ${pass}`)
    return transport
  } catch (err: unknown) {
    if (err instanceof Error) {
      console.error({ err, msg: 'There was a problem setting up the mock email handler' })
      throw new InvalidConfiguration(
        `Unable to create Nodemailer test account. Error: ${err.message}`,
      )
    }
    throw new InvalidConfiguration('Unable to create Nodemailer test account.')
  }
}