bun-activitypub/src/admin.ts

import { idsFromValue } from "./activitypub"
import { getFollowing, getOutboxActivity, listLiked } from "./db"
import { ACTOR, ADMIN_PASSWORD, ADMIN_USERNAME, BASE_URL } from "./env"
import outbox from "./outbox"
import { fetchObject } from "./request"

export default (req: Request): Response | Promise<Response> | undefined => {
  const url = new URL(req.url)

  if(!url.pathname.startsWith('/admin')) return undefined
  url.pathname = url.pathname.substring(6)
  
  if(ADMIN_USERNAME && ADMIN_PASSWORD && !checkAuth(req.headers)) return new Response("", { status: 401 })

  let match
  if(req.method === "GET" && (match = url.pathname.match(/^\/test\/?$/i))) return new Response("", { status: 204 })
  else if(req.method == "POST" && (match = url.pathname.match(/^\/create\/?$/i))) return create(req)
  else if(req.method == "POST" && (match = url.pathname.match(/^\/follow\/([^\/]+)\/?$/i))) return follow(req, match[1])
  else if(req.method == "DELETE" && (match = url.pathname.match(/^\/follow\/([^\/]+)\/?$/i))) return unfollow(req, match[1])
  else if(req.method == "POST" && (match = url.pathname.match(/^\/like\/(.+)\/?$/i))) return like(req, match[1])
  else if(req.method == "DELETE" && (match = url.pathname.match(/^\/like\/(.+)\/?$/i))) return unlike(req, match[1])

  console.log(`Couldn't match admin path ${req.method} "${url.pathname}"`)
  
  return undefined
}

const checkAuth = (headers: Headers): Boolean => {
  // check the basic auth header
  const auth = headers.get("Authorization")
  const split = auth?.split("")
  if(!split || split.length != 2 || split[0] !== "Basic") return false
  const decoded = atob(split[1])
  const [username, password] = decoded.split(":")
  return username === ADMIN_USERNAME && password === ADMIN_PASSWORD
}

// create an activity
const create = async (req:Request):Promise<Response> => {
  const body = await req.json()

  // create the object, merging in supplied data
  const date = new Date()
  const object = {
    attributedTo: ACTOR,
    published: date.toISOString(),
    to: ["https://www.w3.org/ns/activitystreams#Public"],
    cc: [`${ACTOR}/followers`],
    ...body.object
  }

  const activity = {
    "@context": "https://www.w3.org/ns/activitystreams",
    type: "Create",
    published: date.toISOString(),
    actor: ACTOR,
    to: ["https://www.w3.org/ns/activitystreams#Public"],
    cc: [`${ACTOR}/followers`],
    ...body,
    object: { ...object }
  }

  return await outbox(activity)
}

const follow = async (req:Request, handle:string):Promise<Response> => {
  // send the follow request to the supplied actor
  return await outbox({
    "@context": "https://www.w3.org/ns/activitystreams",
    type: "Follow",
    actor: ACTOR,
    object: handle,
    to: [handle, "https://www.w3.org/ns/activitystreams#Public"]
  })
}

const unfollow = async (req:Request, handle:string):Promise<Response> => {
  // check to see if we are already following. If not, just return success
  const existing = await getFollowing(handle)
  if (!existing) return new Response("", { status: 204 })
  const activity = await getOutboxActivity(existing.id)
  // outbox will also take care of the deletion
  return await outbox({
    "@context": "https://www.w3.org/ns/activitystreams",
    type: "Undo",
    actor: ACTOR,
    object: activity,
    to: activity.to
  })
}

const like = async (req:Request, object_url:string):Promise<Response> => {
  const object = await (await fetchObject(ACTOR, object_url)).json()

  return await outbox({
    "@context": "https://www.w3.org/ns/activitystreams",
    type: "Like",
    actor: ACTOR,
    object: object,
    to: [...idsFromValue(object.attributedTo), "https://www.w3.org/ns/activitystreams#Public"]
  })
}

const unlike = async (req:Request, object_id:string):Promise<Response> => {
  // check to see if we are already following. If not, just return success
  const liked = await listLiked()
  let existing = liked.find(o => o.object_id === object_id)
  if (!existing){
    const object = await (await fetchObject(ACTOR, object_id)).json()
    idsFromValue(object).forEach(id => {
      const e = liked.find(o => o.object_id === id)
      if(e) existing = e
    })
  }
  if (!existing) return new Response("No like found to delete", { status: 204 })
  const activity = await getOutboxActivity(existing.id)
  // outbox will also take care of the deletion
  return await outbox({
    "@context": "https://www.w3.org/ns/activitystreams",
    type: "Undo",
    actor: ACTOR,
    object: activity,
    to: activity.to
  })
}