nulla/lib/nulla/activitypub.ex

defmodule Nulla.ActivityPub do
  @spec context() :: list()
  defp context do
    [
      "https://www.w3.org/ns/activitystreams",
      "https://w3id.org/security/v1",
      Jason.OrderedObject.new(
        manuallyApprovesFollowers: "as:manuallyApprovesFollowers",
        toot: "http://joinmastodon.org/ns#",
        featured: %{"@id" => "toot:featured", "@type" => "@id"},
        featuredTags: %{"@id" => "toot:featuredTags", "@type" => "@id"},
        alsoKnownAs: %{"@id" => "as:alsoKnownAs", "@type" => "@id"},
        movedTo: %{"@id" => "as:movedTo", "@type" => "@id"},
        schema: "http://schema.org#",
        PropertyValue: "schema:PropertyValue",
        value: "schema:value",
        discoverable: "toot:discoverable",
        suspended: "toot:suspended",
        memorial: "toot:memorial",
        indexable: "toot:indexable",
        attributionDomains: %{"@id" => "toot:attributionDomains", "@type" => "@id"},
        Hashtag: "as:Hashtag",
        vcard: "http://www.w3.org/2006/vcard/ns#"
      )
    ]
  end

  @spec user(String.t(), Nulla.Models.User.t()) :: Jason.OrderedObject.t()
  def user(domain, user) do
    Jason.OrderedObject.new(
      "@context": context(),
      id: "https://#{domain}/@#{user.username}",
      type: "Person",
      following: "https://#{domain}/@#{user.username}/following",
      followers: "https://#{domain}/@#{user.username}/followers",
      inbox: "https://#{domain}/@#{user.username}/inbox",
      outbox: "https://#{domain}/@#{user.username}/outbox",
      featured: "https://#{domain}/@#{user.username}/collections/featured",
      preferredUsername: user.username,
      name: user.realname,
      summary: user.bio,
      url: "https://#{domain}/@#{user.username}",
      manuallyApprovesFollowers: user.follow_approval,
      discoverable: user.is_discoverable,
      indexable: user.is_indexable,
      published: DateTime.to_iso8601(user.inserted_at),
      memorial: user.is_memorial,
      publicKey:
        Jason.OrderedObject.new(
          id: "https://#{domain}/@#{user.username}#main-key",
          owner: "https://#{domain}/@#{user.username}",
          publicKeyPem: user.public_key
        ),
      tag:
        Enum.map(user.tags, fn tag ->
          Jason.OrderedObject.new(
            type: "Hashtag",
            href: "https://#{domain}/tags/#{tag}",
            name: "##{tag}"
          )
        end),
      attachment:
        Enum.map(user.fields, fn {name, value} ->
          Jason.OrderedObject.new(
            type: "PropertyValue",
            name: name,
            value: value
          )
        end),
      endpoints: Jason.OrderedObject.new(sharedInbox: "https://#{domain}/inbox"),
      icon:
        Jason.OrderedObject.new(
          type: "Image",
          mediaType: MIME.from_path(user.avatar),
          url: "https://#{domain}/files/#{user.avatar}"
        ),
      image:
        Jason.OrderedObject.new(
          type: "Image",
          mediaType: MIME.from_path(user.banner),
          url: "https://#{domain}/files/#{user.banner}"
        ),
      "vcard:bday": user.birthday,
      "vcard:Address": user.location
    )
  end

  @spec note(String.t(), Nulla.Models.Note.t()) :: Jason.OrderedObject.t()
  def note(domain, note) do
    attachment =
      case note.media_attachments do
        [] ->
          []

        attachments ->
          [
            attachment:
              Enum.map(attachments, fn att ->
                Jason.OrderedObject.new(
                  type: "Document",
                  mediaType: att.mime_type,
                  url: "https://#{domain}/files/#{att.file}"
                )
              end)
          ]
      end

    Jason.OrderedObject.new(
      "@context": [
        "https://www.w3.org/ns/activitystreams",
        Jason.OrderedObject.new(sensitive: "as:sensitive")
      ],
      id: "https://#{domain}/@#{note.user.username}/#{note.id}",
      type: "Note",
      summary: nil,
      inReplyTo: nil,
      published: note.inserted_at,
      url: "https://#{domain}/@#{note.user.username}/#{note.id}",
      attributedTo: "https://#{domain}/@#{note.user.username}",
      to: [
        "https://www.w3.org/ns/activitystreams#Public"
      ],
      cc: [
        "https://#{domain}/@#{note.user.username}/followers"
      ],
      sensetive: false,
      content: note.content,
      contentMap: Jason.OrderedObject.new("#{note.language}": note.content),
      attachment: attachment
    )
  end

  @spec activity(String.t(), Nulla.Models.Activity.t()) :: Jason.OrderedObject.t()
  def activity(domain, activity) do
    Jason.OrderedObject.new(
      "@context": "https://www.w3.org/ns/activitystreams",
      id: "https://#{domain}/activities/#{activity.id}",
      type: activity.type,
      actor: activity.actor,
      object: activity.object,
      to: activity.to
    )
  end

  @spec following(String.t(), Nulla.Models.User.t(), Integer.t()) :: Jason.OrderedObject.t()
  def following(domain, user, total) do
    Jason.OrderedObject.new(
      "@context": "https://www.w3.org/ns/activitystreams",
      id: "https://#{domain}/@#{user.username}/following",
      type: "OrderedCollection",
      totalItems: total,
      first: "https://#{domain}/@#{user.username}/following?page=1"
    )
  end

  @spec following(
          String.t(),
          Nulla.Models.User.t(),
          Integer.t(),
          List.t(),
          Integer.t(),
          Integer.t()
        ) :: Jason.OrderedObject.t()
  def following(domain, user, total, following_list, page, offset)
      when is_integer(page) and page > 0 do
    data = [
      "@context": "https://www.w3.org/ns/activitystreams",
      id: "https://#{domain}/@#{user.username}/following?page=#{page}",
      type: "OrderedCollectionPage",
      totalItems: total,
      next: "https://#{domain}/@#{user.username}/following?page=#{page + 1}",
      prev: "https://#{domain}/@#{user.username}/following?page=#{page - 1}",
      partOf: "https://#{domain}/@#{user.username}/following",
      orderedItems: following_list
    ]

    data =
      if page <= 1 do
        Keyword.delete(data, :prev)
      else
        data
      end

    data =
      if page * offset > total do
        data
        |> Keyword.delete(:next)
        |> Keyword.delete(:prev)
      else
        data
      end

    Jason.OrderedObject.new(data)
  end

  @spec followers(String.t(), Nulla.Models.User.t(), Integer.t()) :: Jason.OrderedObject.t()
  def followers(domain, user, total) do
    Jason.OrderedObject.new(
      "@context": "https://www.w3.org/ns/activitystreams",
      id: "https://#{domain}/@#{user.username}/followers",
      type: "OrderedCollection",
      totalItems: total,
      first: "https://#{domain}/@#{user.username}/followers?page=1"
    )
  end

  @spec followers(
          String.t(),
          Nulla.Models.User.t(),
          Integer.t(),
          List.t(),
          Integer.t(),
          Integer.t()
        ) :: Jason.OrderedObject.t()
  def followers(domain, user, total, followers_list, page, offset)
      when is_integer(page) and page > 0 do
    data = [
      "@context": "https://www.w3.org/ns/activitystreams",
      id: "https://#{domain}/@#{user.username}/followers?page=#{page}",
      type: "OrderedCollectionPage",
      totalItems: total,
      next: "https://#{domain}/@#{user.username}/followers?page=#{page + 1}",
      prev: "https://#{domain}/@#{user.username}/followers?page=#{page - 1}",
      partOf: "https://#{domain}/@#{user.username}/followers",
      orderedItems: followers_list
    ]

    data =
      if page <= 1 do
        Keyword.delete(data, :prev)
      else
        data
      end

    data =
      if page * offset > total do
        data
        |> Keyword.delete(:next)
        |> Keyword.delete(:prev)
      else
        data
      end

    Jason.OrderedObject.new(data)
  end
end