bun-activitypub/src/outbox.ts

import { idsFromValue } from "./activitypub"
import * as db from "./db";
import { ACTOR } from "./env"
import { fetchObject, send } from "./request";

export default async function outbox(activity:any):Promise<Response> {
  const date = new Date()
  const id = `${date.getTime().toString(16)}`
  console.log('outbox', id, activity)

  // https://www.w3.org/TR/activitypub/#object-without-create
  if(!activity.actor && !(activity.object || activity.target || activity.result || activity.origin || activity.instrument)) {
    const object = activity
    activity = {
      "@context": "https://www.w3.org/ns/activitystreams",
      type: "Create",
      actor: ACTOR,
      object
    }
    const { to, bto, cc, bcc, audience } = object
    if(to) activity.to = to
    if(bto) activity.bto = bto
    if(cc) activity.cc = cc
    if(bcc) activity.bcc = bcc
    if(audience) activity.audience = audience
  }

  activity.id = `${ACTOR}/outbox/${id}`
  if(!activity.published) activity.published = date.toISOString()

  if(activity.type === 'Create' && activity.object && Object(activity.object) === activity.object) {
    // When a Create activity is posted, the actor of the activity SHOULD be copied onto the object's attributedTo field.
    activity.object.attributedTo = activity.actor
    if(!activity.object.published) activity.object.published = activity.published
  }

  // get the main recipients ([...new Set()] is to dedupe)
  const recipientList = [...new Set([...idsFromValue(activity.to), ...idsFromValue(activity.cc), ...idsFromValue(activity.audience)])]
  // add in the blind recipients 
  const finalRecipientList = [...new Set([...recipientList, ...idsFromValue(activity.bto), ...idsFromValue(activity.bcc)])]
  // remove the blind recipients from the activity
  delete activity.bto
  delete activity.bcc

  // now that has been taken care of, it's time to update our local data, depending on the contents of the activity
  switch(activity.type) {
    case "Accept": await accept(activity, id); break;
    case "Follow": await follow(activity, id); break;
    case "Like": await like(activity, id); break;
    case "Dislike": await dislike(activity, id); break;
    case "Annouce": await announce(activity, id); break;
    case "Create": await create(activity, id); break;
    case "Undo": await undo(activity); break;
    case "Delete": await deletePost(activity); break;
    // TODO: case "Anncounce": return await share(activity)
  }
  // save the activity data for the outbox
  await db.createOutboxActivity(activity, id)

  // send to the appropriate recipients
  finalRecipientList.forEach((to) => {
    if (to.startsWith(ACTOR + "/followers")) db.listFollowers().then(followers => followers.forEach(f => send(ACTOR, f.actor, activity)))
    else if (to === "https://www.w3.org/ns/activitystreams#Public") return // there's nothing to "send" to here
    else if (to) send(ACTOR, to, activity)
  })

  return new Response("", { status: 201, headers: { location: activity.id } })
}

async function create(activity:any, id:string) {
  activity.object.id = activity.object.url = `${ACTOR}/post/${id}`
  await db.createPost(activity.object, id)
  return true
}

async function accept(activity:any, id:string) {
  return true
}

async function follow(activity:any, id:string) {
  await db.createFollowing(activity.object , id)
  return true
}

async function like(activity:any, id:string) {
  if(typeof activity.object === 'string'){
    await db.createLiked(activity.object, id)
    activity.object = await fetchObject(ACTOR, activity.object)
  }
  else {
    const liked = await idsFromValue(activity.object)
    liked.forEach(l => db.createLiked(l, id))
  }
  await db.createPost(activity, id)
  return true
}

async function dislike(activity:any, id:string) {
  if(typeof activity.object === 'string'){
    await db.createDisliked(activity.object, id)
    activity.object = await fetchObject(ACTOR, activity.object)
  }
  else {
    const disliked = await idsFromValue(activity.object)
    disliked.forEach(l => db.createDisliked(l, id))
  }
  await db.createPost(activity, id)
  return true
}

async function announce(activity:any, id:string) {
  if(typeof activity.object === 'string'){
    await db.createShared(activity.object, id)
    activity.object = await fetchObject(ACTOR, activity.object)
  }
  else {
    const shared = await idsFromValue(activity.object)
    shared.forEach(l => db.createShared(l, id))
  }
  await db.createPost(activity, id)
  return true
}

// async function share(activity:any) {
//   let object = activity.object
//   if(typeof object === 'string') {
//     try{
//       object = await fetchObject(object)
//     }
//     catch { }
//   }
//   db.createShared(object)
//   return true
// }

async function undo(activity:any) {
  const id = await idsFromValue(activity.object).at(0)
  if (!id) return true
  const match = id.match(/\/([0-9a-f]+)\/?$/)
  const local_id = match ? match[1] : id
  console.log('undo', local_id)
  try{
    const existing = await db.getOutboxActivity(local_id)

    switch(activity.object.type) {
      case "Follow": await db.deleteFollowing(existing.object); break;
      case "Like":  idsFromValue(existing.object).forEach(async id => await db.deleteLiked(id)); await db.deletePost(local_id); break;
      case "Dislike":  idsFromValue(existing.object).forEach(async id => await db.deleteDisliked(id)); await db.deletePost(local_id); break;
      case "Announce":  idsFromValue(existing.object).forEach(async id => await db.deleteShared(id)); await db.deletePost(local_id); break;
      
    }
  }
  catch {
    return false
  }
  
  return true
}

async function deletePost(activity:any) {
  const id = await idsFromValue(activity.object).at(0)
  if(!id) return false
  const post = await db.getPostByURL(id)
  if(!post) return false
  await db.deletePost(post.local_id)
  return true
}