import nodemailer from 'nodemailer'
import type { Config } from './config.ts'

export interface Mail {
  to: string
  subject: string
  text: string
}

export interface Mailer {
  send(mail: Mail): Promise<void>
}

export function createMailer(config: Config): Mailer {
  if (config.smtpUrl) {
    const transport = nodemailer.createTransport(config.smtpUrl)
    return { send: async (mail) => void (await transport.sendMail({ from: config.mailFrom, ...mail })) }
  }
  if (config.production) {
    console.warn('[mail] SMTP_URL is not set: emails (sign-in links, password resets, notifications) will not be sent.')
    return { send: async (mail) => console.warn(`[mail] Not sent (no SMTP): "${mail.subject}" to ${mail.to}`) }
  }
  // Development: print the email so links can be clicked from the terminal.
  return { send: async (mail) => console.log(`\n[mail] To: ${mail.to}\n[mail] Subject: ${mail.subject}\n\n${mail.text}\n`) }
}

/** Collects emails instead of sending them (tests). */
export class MemoryMailer implements Mailer {
  sent: Mail[] = []

  async send(mail: Mail) {
    this.sent.push(mail)
  }

  /** Most recent email to `to`. */
  last(to: string): Mail | undefined {
    return this.sent.findLast((mail) => mail.to === to)
  }
}