Get Message

//native

/**

 * Get Message

 * Get a Gmail message by ID. With the default `full` format the decoded plain-text body is added as `body_text` (falling back to the HTML body when there is no plain-text part).

 */

export async function main(

  auth: RT.Gmail,

  message_id: string,

  format: "full" | "metadata" | "minimal" | "raw" = "full"

) {

  const url = new URL(

    `https://gmail.googleapis.com/gmail/v1/users/me/messages/${message_id}`

  )

  url.searchParams.append("format", format)

  const response = await fetch(url, {

    headers: {

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

      Accept: "application/json",

    },

  })

  if (!response.ok) {

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

  }

  const message = await response.json()

  if (message.payload) {

    message.body_text =

      findBody(message.payload, "text/plain") ??

      findBody(message.payload, "text/html")

  }

  return message

}

type Part = { mimeType: string; body?: { data?: string }; parts?: Part[] }

function findBody(part: Part, mimeType: string): string | undefined {

  if (part.mimeType === mimeType && part.body?.data) {

    const b64 = part.body.data.replace(/-/g, "+").replace(/_/g, "/")

    return new TextDecoder().decode(

      Uint8Array.from(atob(b64), (c) => c.charCodeAt(0))

    )

  }

  for (const p of part.parts ?? []) {

    const found = findBody(p, mimeType)

    if (found !== undefined) return found

  }

}