import type { Context, Hono } from 'hono'

const registry = new WeakMap<Hono<any, any>, Sender>()

/** Transactional email sender shared by authentication and route groups. */
export type Sender = {
  /** Console URL embedded in email links. Defaults to the hosted console. */
  consoleUrl?: string | undefined
  /** Sender address for transactional emails. */
  from: string
  /** Sends one message. */
  send: (message: Message) => Promise<unknown>
}

/** One transactional email message. */
export type Message = {
  /** Sender address. */
  from: string
  /** HTML body. */
  html?: string | undefined
  /** Subject line. */
  subject: string
  /** Plain-text body. */
  text: string
  /** Recipient address. */
  to: string
}

/** Hono environment variables for transactional email delivery. */
export type Variables = {
  /** Transactional email sender; undefined when dispatch is disabled. */
  email: Sender | undefined
}

/** Attaches a legacy group-level sender for `App.create` to collect on mount. */
export function attach<const app extends Hono<any, any>>(
  app: app,
  sender: Sender | undefined,
): app {
  if (sender) registry.set(app, sender)
  return app
}

/** Returns the app's transactional email sender, when configured. */
export function get<environment extends { Variables: Variables }>(
  c: Context<environment>,
): Sender | undefined {
  return c.get('email')
}

/** Returns a group-level sender attached for backward compatibility. */
export function read(app: Hono<any, any>): Sender | undefined {
  return registry.get(app)
}