# Pleroma: A lightweight social networking server
# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only

defmodule Pleroma.Web.MastodonAPI.StatusView do
  use Pleroma.Web, :view

  require Pleroma.Constants

  alias Pleroma.Activity
  alias Pleroma.HTML
  alias Pleroma.Object
  alias Pleroma.Repo
  alias Pleroma.User
  alias Pleroma.UserRelationship
  alias Pleroma.Web.CommonAPI
  alias Pleroma.Web.CommonAPI.Utils
  alias Pleroma.Web.MastodonAPI.AccountView
  alias Pleroma.Web.MastodonAPI.PollView
  alias Pleroma.Web.MastodonAPI.StatusView
  alias Pleroma.Web.MediaProxy

  import Pleroma.Web.ActivityPub.Visibility, only: [get_visibility: 1, visible_for_user?: 2]

  # This is a naive way to do this, just spawning a process per activity
  # to fetch the preview. However it should be fine considering
  # pagination is restricted to 40 activities at a time
  defp fetch_rich_media_for_activities(activities) do
    Enum.each(activities, fn activity ->
      spawn(fn ->
        Pleroma.Web.RichMedia.Helpers.fetch_data_for_activity(activity)
      end)
    end)
  end

  # TODO: Add cached version.
  defp get_replied_to_activities([]), do: %{}

  defp get_replied_to_activities(activities) do
    activities
    |> Enum.map(fn
      %{data: %{"type" => "Create"}} = activity ->
        object = Object.normalize(activity)
        object && object.data["inReplyTo"] != "" && object.data["inReplyTo"]

      _ ->
        nil
    end)
    |> Enum.filter(& &1)
    |> Activity.create_by_object_ap_id_with_object()
    |> Repo.all()
    |> Enum.reduce(%{}, fn activity, acc ->
      object = Object.normalize(activity)
      if object, do: Map.put(acc, object.data["id"], activity), else: acc
    end)
  end

  def get_user(ap_id, fake_record_fallback \\ true) do
    cond do
      user = User.get_cached_by_ap_id(ap_id) ->
        user

      user = User.get_by_guessed_nickname(ap_id) ->
        user

      fake_record_fallback ->
        # TODO: refactor (fake records is never a good idea)
        User.error_user(ap_id)

      true ->
        nil
    end
  end

  defp get_context_id(%{data: %{"context_id" => context_id}}) when not is_nil(context_id),
    do: context_id

  defp get_context_id(%{data: %{"context" => context}}) when is_binary(context),
    do: Utils.context_to_conversation_id(context)

  defp get_context_id(_), do: nil

  defp reblogged?(activity, user) do
    object = Object.normalize(activity) || %{}
    present?(user && user.ap_id in (object.data["announcements"] || []))
  end

  def render("index.json", opts) do
    reading_user = opts[:for]

    # To do: check AdminAPIControllerTest on the reasons behind nil activities in the list
    activities = Enum.filter(opts.activities, & &1)

    # Start fetching rich media before doing anything else, so that later calls to get the cards
    # only block for timeout in the worst case, as opposed to
    # length(activities_with_links) * timeout
    fetch_rich_media_for_activities(activities)
    replied_to_activities = get_replied_to_activities(activities)

    parent_activities =
      activities
      |> Enum.filter(&(&1.data["type"] == "Announce" && &1.data["object"]))
      |> Enum.map(&Object.normalize(&1).data["id"])
      |> Activity.create_by_object_ap_id()
      |> Activity.with_preloaded_object(:left)
      |> Activity.with_preloaded_bookmark(reading_user)
      |> Activity.with_set_thread_muted_field(reading_user)
      |> Repo.all()

    relationships_opt =
      cond do
        Map.has_key?(opts, :relationships) ->
          opts[:relationships]

        is_nil(reading_user) ->
          UserRelationship.view_relationships_option(nil, [])

        true ->
          # Note: unresolved users are filtered out
          actors =
            (activities ++ parent_activities)
            |> Enum.map(&get_user(&1.data["actor"], false))
            |> Enum.filter(& &1)

          UserRelationship.view_relationships_option(reading_user, actors, subset: :source_mutes)
      end

    opts =
      opts
      |> Map.put(:replied_to_activities, replied_to_activities)
      |> Map.put(:parent_activities, parent_activities)
      |> Map.put(:relationships, relationships_opt)

    safe_render_many(activities, StatusView, "show.json", opts)
  end

  def render(
        "show.json",
        %{activity: %{data: %{"type" => "Announce", "object" => _object}} = activity} = opts
      ) do
    user = get_user(activity.data["actor"])
    created_at = Utils.to_masto_date(activity.data["published"])
    activity_object = Object.normalize(activity)

    reblogged_parent_activity =
      if opts[:parent_activities] do
        Activity.Queries.find_by_object_ap_id(
          opts[:parent_activities],
          activity_object.data["id"]
        )
      else
        Activity.create_by_object_ap_id(activity_object.data["id"])
        |> Activity.with_preloaded_bookmark(opts[:for])
        |> Activity.with_set_thread_muted_field(opts[:for])
        |> Repo.one()
      end

    reblog_rendering_opts = Map.put(opts, :activity, reblogged_parent_activity)
    reblogged = render("show.json", reblog_rendering_opts)

    favorited = opts[:for] && opts[:for].ap_id in (activity_object.data["likes"] || [])

    bookmarked = Activity.get_bookmark(reblogged_parent_activity, opts[:for]) != nil

    mentions =
      activity.recipients
      |> Enum.map(fn ap_id -> User.get_cached_by_ap_id(ap_id) end)
      |> Enum.filter(& &1)
      |> Enum.map(fn user -> AccountView.render("mention.json", %{user: user}) end)

    %{
      id: to_string(activity.id),
      uri: activity_object.data["id"],
      url: activity_object.data["id"],
      account:
        AccountView.render("show.json", %{
          user: user,
          for: opts[:for]
        }),
      in_reply_to_id: nil,
      in_reply_to_account_id: nil,
      reblog: reblogged,
      content: reblogged[:content] || "",
      created_at: created_at,
      reblogs_count: 0,
      replies_count: 0,
      favourites_count: 0,
      reblogged: reblogged?(reblogged_parent_activity, opts[:for]),
      favourited: present?(favorited),
      bookmarked: present?(bookmarked),
      muted: false,
      pinned: pinned?(activity, user),
      sensitive: false,
      spoiler_text: "",
      visibility: get_visibility(activity),
      media_attachments: reblogged[:media_attachments] || [],
      mentions: mentions,
      tags: reblogged[:tags] || [],
      application: %{
        name: "Web",
        website: nil
      },
      language: nil,
      emojis: [],
      pleroma: %{
        local: activity.local
      }
    }
  end

  def render("show.json", %{activity: %{data: %{"object" => _object}} = activity} = opts) do
    object = Object.normalize(activity)

    user = get_user(activity.data["actor"])
    user_follower_address = user.follower_address

    like_count = object.data["like_count"] || 0
    announcement_count = object.data["announcement_count"] || 0

    tags = object.data["tag"] || []
    sensitive = object.data["sensitive"] || Enum.member?(tags, "nsfw")

    tag_mentions =
      tags
      |> Enum.filter(fn tag -> is_map(tag) and tag["type"] == "Mention" end)
      |> Enum.map(fn tag -> tag["href"] end)

    mentions =
      (object.data["to"] ++ tag_mentions)
      |> Enum.uniq()
      |> Enum.map(fn
        Pleroma.Constants.as_public() -> nil
        ^user_follower_address -> nil
        ap_id -> User.get_cached_by_ap_id(ap_id)
      end)
      |> Enum.filter(& &1)
      |> Enum.map(fn user -> AccountView.render("mention.json", %{user: user}) end)

    favorited = opts[:for] && opts[:for].ap_id in (object.data["likes"] || [])

    bookmarked = Activity.get_bookmark(activity, opts[:for]) != nil

    client_posted_this_activity = opts[:for] && user.id == opts[:for].id

    expires_at =
      with true <- client_posted_this_activity,
           %Oban.Job{scheduled_at: scheduled_at} <-
             Pleroma.Workers.PurgeExpiredActivity.get_expiration(activity.id) do
        scheduled_at
      else
        _ -> nil
      end

    thread_muted? =
      cond do
        is_nil(opts[:for]) -> false
        is_boolean(activity.thread_muted?) -> activity.thread_muted?
        true -> CommonAPI.thread_muted?(opts[:for], activity)
      end

    attachment_data = object.data["attachment"] || []
    attachments = render_many(attachment_data, StatusView, "attachment.json", as: :attachment)

    created_at = Utils.to_masto_date(object.data["published"])

    reply_to = get_reply_to(activity, opts)

    reply_to_user = reply_to && get_user(reply_to.data["actor"])

    content =
      object
      |> render_content()

    content_html =
      content
      |> HTML.get_cached_scrubbed_html_for_activity(
        User.html_filter_policy(opts[:for]),
        activity,
        "mastoapi:content"
      )

    content_plaintext =
      content
      |> HTML.get_cached_stripped_html_for_activity(
        activity,
        "mastoapi:content"
      )

    summary = object.data["summary"] || ""

    card = render("card.json", Pleroma.Web.RichMedia.Helpers.fetch_data_for_activity(activity))

    url =
      if user.local do
        Pleroma.Web.Router.Helpers.o_status_url(Pleroma.Web.Endpoint, :notice, activity)
      else
        object.data["url"] || object.data["external_url"] || object.data["id"]
      end

    direct_conversation_id =
      with {_, nil} <- {:direct_conversation_id, opts[:direct_conversation_id]},
           {_, true} <- {:include_id, opts[:with_direct_conversation_id]},
           {_, %User{} = for_user} <- {:for_user, opts[:for]} do
        Activity.direct_conversation_id(activity, for_user)
      else
        {:direct_conversation_id, participation_id} when is_integer(participation_id) ->
          participation_id

        _e ->
          nil
      end

    emoji_reactions =
      with %{data: %{"reactions" => emoji_reactions}} <- object do
        Enum.map(emoji_reactions, fn
          [emoji, users] when is_list(users) ->
            build_emoji_map(emoji, users, opts[:for])

          {emoji, users} when is_list(users) ->
            build_emoji_map(emoji, users, opts[:for])

          _ ->
            nil
        end)
        |> Enum.reject(&is_nil/1)
      else
        _ -> []
      end

    # Status muted state (would do 1 request per status unless user mutes are preloaded)
    muted =
      thread_muted? ||
        UserRelationship.exists?(
          get_in(opts, [:relationships, :user_relationships]),
          :mute,
          opts[:for],
          user,
          fn for_user, user -> User.mutes?(for_user, user) end
        )

    %{
      id: to_string(activity.id),
      uri: object.data["id"],
      url: url,
      account:
        AccountView.render("show.json", %{
          user: user,
          for: opts[:for]
        }),
      in_reply_to_id: reply_to && to_string(reply_to.id),
      in_reply_to_account_id: reply_to_user && to_string(reply_to_user.id),
      reblog: nil,
      card: card,
      content: content_html,
      text: opts[:with_source] && object.data["source"],
      created_at: created_at,
      reblogs_count: announcement_count,
      replies_count: object.data["repliesCount"] || 0,
      favourites_count: like_count,
      reblogged: reblogged?(activity, opts[:for]),
      favourited: present?(favorited),
      bookmarked: present?(bookmarked),
      muted: muted,
      pinned: pinned?(activity, user),
      sensitive: sensitive,
      spoiler_text: summary,
      visibility: get_visibility(object),
      media_attachments: attachments,
      poll: render(PollView, "show.json", object: object, for: opts[:for]),
      mentions: mentions,
      tags: build_tags(tags),
      application: %{
        name: "Web",
        website: nil
      },
      language: nil,
      emojis: build_emojis(object.data["emoji"]),
      pleroma: %{
        local: activity.local,
        conversation_id: get_context_id(activity),
        in_reply_to_account_acct: reply_to_user && reply_to_user.nickname,
        content: %{"text/plain" => content_plaintext},
        spoiler_text: %{"text/plain" => summary},
        expires_at: expires_at,
        direct_conversation_id: direct_conversation_id,
        thread_muted: thread_muted?,
        emoji_reactions: emoji_reactions,
        parent_visible: visible_for_user?(reply_to, opts[:for])
      }
    }
  end

  def render("show.json", _) do
    nil
  end

  def render("card.json", %{rich_media: rich_media, page_url: page_url}) do
    page_url_data = URI.parse(page_url)

    page_url_data =
      if is_binary(rich_media["url"]) do
        URI.merge(page_url_data, URI.parse(rich_media["url"]))
      else
        page_url_data
      end

    page_url = page_url_data |> to_string

    image_url =
      if is_binary(rich_media["image"]) do
        URI.merge(page_url_data, URI.parse(rich_media["image"]))
        |> to_string
      end

    %{
      type: "link",
      provider_name: page_url_data.host,
      provider_url: page_url_data.scheme <> "://" <> page_url_data.host,
      url: page_url,
      image: image_url |> MediaProxy.url(),
      title: rich_media["title"] || "",
      description: rich_media["description"] || "",
      pleroma: %{
        opengraph: rich_media
      }
    }
  end

  def render("card.json", _), do: nil

  def render("attachment.json", %{attachment: attachment}) do
    [attachment_url | _] = attachment["url"]
    media_type = attachment_url["mediaType"] || attachment_url["mimeType"] || "image"
    href = attachment_url["href"] |> MediaProxy.url()

    type =
      cond do
        String.contains?(media_type, "image") -> "image"
        String.contains?(media_type, "video") -> "video"
        String.contains?(media_type, "audio") -> "audio"
        true -> "unknown"
      end

    <<hash_id::signed-32, _rest::binary>> = :crypto.hash(:md5, href)

    %{
      id: to_string(attachment["id"] || hash_id),
      url: href,
      remote_url: href,
      preview_url: href,
      text_url: href,
      type: type,
      description: attachment["name"],
      pleroma: %{mime_type: media_type}
    }
  end

  def render("context.json", %{activity: activity, activities: activities, user: user}) do
    %{ancestors: ancestors, descendants: descendants} =
      activities
      |> Enum.reverse()
      |> Enum.group_by(fn %{id: id} -> if id < activity.id, do: :ancestors, else: :descendants end)
      |> Map.put_new(:ancestors, [])
      |> Map.put_new(:descendants, [])

    %{
      ancestors: render("index.json", for: user, activities: ancestors, as: :activity),
      descendants: render("index.json", for: user, activities: descendants, as: :activity)
    }
  end

  def get_reply_to(activity, %{replied_to_activities: replied_to_activities}) do
    object = Object.normalize(activity)

    with nil <- replied_to_activities[object.data["inReplyTo"]] do
      # If user didn't participate in the thread
      Activity.get_in_reply_to_activity(activity)
    end
  end

  def get_reply_to(%{data: %{"object" => _object}} = activity, _) do
    object = Object.normalize(activity)

    if object.data["inReplyTo"] && object.data["inReplyTo"] != "" do
      Activity.get_create_by_object_ap_id(object.data["inReplyTo"])
    else
      nil
    end
  end

  def render_content(%{data: %{"name" => name}} = object) when not is_nil(name) and name != "" do
    url = object.data["url"] || object.data["id"]

    "<p><a href=\"#{url}\">#{name}</a></p>#{object.data["content"]}"
  end

  def render_content(object), do: object.data["content"] || ""

  @doc """
  Builds a dictionary tags.

  ## Examples

  iex> Pleroma.Web.MastodonAPI.StatusView.build_tags(["fediverse", "nextcloud"])
  [{"name": "fediverse", "url": "/tag/fediverse"},
   {"name": "nextcloud", "url": "/tag/nextcloud"}]

  """
  @spec build_tags(list(any())) :: list(map())
  def build_tags(object_tags) when is_list(object_tags) do
    object_tags
    |> Enum.filter(&is_binary/1)
    |> Enum.map(&%{name: &1, url: "/tag/#{URI.encode(&1)}"})
  end

  def build_tags(_), do: []

  @doc """
  Builds list emojis.

  Arguments: `nil` or list tuple of name and url.

  Returns list emojis.

  ## Examples

  iex> Pleroma.Web.MastodonAPI.StatusView.build_emojis([{"2hu", "corndog.png"}])
  [%{shortcode: "2hu", static_url: "corndog.png", url: "corndog.png", visible_in_picker: false}]

  """
  @spec build_emojis(nil | list(tuple())) :: list(map())
  def build_emojis(nil), do: []

  def build_emojis(emojis) do
    emojis
    |> Enum.map(fn {name, url} ->
      name = HTML.strip_tags(name)

      url =
        url
        |> HTML.strip_tags()
        |> MediaProxy.url()

      %{shortcode: name, url: url, static_url: url, visible_in_picker: false}
    end)
  end

  defp present?(nil), do: false
  defp present?(false), do: false
  defp present?(_), do: true

  defp pinned?(%Activity{id: id}, %User{pinned_activities: pinned_activities}),
    do: id in pinned_activities

  defp build_emoji_map(emoji, users, current_user) do
    %{
      name: emoji,
      count: length(users),
      me: !!(current_user && current_user.ap_id in users)
    }
  end
end