New Email

//native

import * as wmill from "windmill-client"

/**

 * New Email

 * Emits messages received in a folder (default `inbox`) since the last poll, oldest first. The first run sets the watermark to now and emits nothing. Polls because Microsoft Graph push needs a change-notification subscription renewed every few days against a public endpoint, which belongs in a Windmill native trigger; run this as a Scheduled Poll until then. Requires Mail.Read (covered by the default Mail.ReadWrite) (a shared mailbox needs Mail.Read.Shared, not a default).

 */

export async function main(

  auth: RT.MsOutlook,

  folder: string = "inbox",

  mailbox: string | undefined

) {

  // `seen` holds the ids already emitted for the watermark second, since

  // receivedDateTime only has second precision and the filter is inclusive.

  const state: { since: string; seen: string[] } | undefined =

    await wmill.getState()

  // First run: set the watermark to now and don't emit a backlog.

  if (!state?.since) {

    await wmill.setState({

      since: new Date().toISOString().replace(/\.\d+Z$/, "Z"),

      seen: [],

    })

    return []

  }

  const base = `https://graph.microsoft.com/v1.0/${

    mailbox != null && mailbox !== ""

      ? `users/${encodeURIComponent(mailbox)}`

      : "me"

  }`

  const first = new URL(

    `${base}/mailFolders/${encodeURIComponent(folder)}/messages`

  )

  first.searchParams.append("$filter", `receivedDateTime ge ${state.since}`)

  first.searchParams.append("$orderby", "receivedDateTime asc")

  first.searchParams.append("$top", "100")

  const messages: { id: string; receivedDateTime: string }[] = []

  let next: string | undefined = first.toString()

  while (next) {

    const response = await fetch(next, {

      headers: {

        Authorization: `Bearer ${auth.token}`,

        Accept: "application/json",

      },

    })

    if (!response.ok) {

      throw new Error(`${response.status} ${await response.text()}`)

    }

    const page = (await response.json()) as {

      value: { id: string; receivedDateTime: string }[]

      "@odata.nextLink"?: string

    }

    messages.push(...page.value)

    next = page["@odata.nextLink"]

  }

  const fresh = messages.filter((m) => !state.seen.includes(m.id))

  if (fresh.length > 0) {

    const since = messages[messages.length - 1].receivedDateTime

    await wmill.setState({

      since,

      seen: messages

        .filter((m) => m.receivedDateTime === since)

        .map((m) => m.id),

    })

  }

  return fresh

}