3 files changed, 207 insertions, 0 deletions
diff --git a/lib/pleroma/web/metadata/opengraph.ex b/lib/pleroma/web/metadata/opengraph.ex
new file mode 100644
index 000000000..30333785e
--- /dev/null
+++ b/lib/pleroma/web/metadata/opengraph.ex
@@ -0,0 +1,154 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.Metadata.Providers.OpenGraph do
+  alias Pleroma.Web.Metadata.Providers.Provider
+  alias Pleroma.Web.Metadata
+  alias Pleroma.{HTML, Formatter, User}
+  alias Pleroma.Web.MediaProxy
+
+  @behaviour Provider
+
+  @impl Provider
+  def build_tags(%{
+        object: object,
+        url: url,
+        user: user
+      }) do
+    attachments = build_attachments(object)
+    scrubbed_content = scrub_html_and_truncate(object)
+    # Zero width space
+    content =
+      if scrubbed_content != "" and scrubbed_content != "\u200B" do
+        ": “" <> scrubbed_content <> "”"
+      else
+        ""
+      end
+
+    # Most previews only show og:title which is inconvenient. Instagram
+    # hacks this by putting the description in the title and making the
+    # description longer prefixed by how many likes and shares the post
+    # has. Here we use the descriptive nickname in the title, and expand
+    # the full account & nickname in the description. We also use the cute^Wevil
+    # smart quotes around the status text like Instagram, too.
+    [
+      {:meta,
+       [
+         property: "og:title",
+         content: "#{user.name}" <> content
+       ], []},
+      {:meta, [property: "og:url", content: url], []},
+      {:meta,
+       [
+         property: "og:description",
+         content: "#{user_name_string(user)}" <> content
+       ], []},
+      {:meta, [property: "og:type", content: "website"], []}
+    ] ++
+      if attachments == [] or Metadata.activity_nsfw?(object) do
+        [
+          {:meta, [property: "og:image", content: attachment_url(User.avatar_url(user))], []},
+          {:meta, [property: "og:image:width", content: 150], []},
+          {:meta, [property: "og:image:height", content: 150], []}
+        ]
+      else
+        attachments
+      end
+  end
+
+  @impl Provider
+  def build_tags(%{user: user}) do
+    with truncated_bio = scrub_html_and_truncate(user.bio || "") do
+      [
+        {:meta,
+         [
+           property: "og:title",
+           content: user_name_string(user)
+         ], []},
+        {:meta, [property: "og:url", content: User.profile_url(user)], []},
+        {:meta, [property: "og:description", content: truncated_bio], []},
+        {:meta, [property: "og:type", content: "website"], []},
+        {:meta, [property: "og:image", content: attachment_url(User.avatar_url(user))], []},
+        {:meta, [property: "og:image:width", content: 150], []},
+        {:meta, [property: "og:image:height", content: 150], []}
+      ]
+    end
+  end
+
+  defp build_attachments(%{data: %{"attachment" => attachments}}) do
+    Enum.reduce(attachments, [], fn attachment, acc ->
+      rendered_tags =
+        Enum.reduce(attachment["url"], [], fn url, acc ->
+          media_type =
+            Enum.find(["image", "audio", "video"], fn media_type ->
+              String.starts_with?(url["mediaType"], media_type)
+            end)
+
+          # TODO: Add additional properties to objects when we have the data available.
+          # Also, Whatsapp only wants JPEG or PNGs. It seems that if we add a second og:image
+          # object when a Video or GIF is attached it will display that in the Whatsapp Rich Preview.
+          case media_type do
+            "audio" ->
+              [
+                {:meta, [property: "og:" <> media_type, content: attachment_url(url["href"])], []}
+                | acc
+              ]
+
+            "image" ->
+              [
+                {:meta, [property: "og:" <> media_type, content: attachment_url(url["href"])],
+                 []},
+                {:meta, [property: "og:image:width", content: 150], []},
+                {:meta, [property: "og:image:height", content: 150], []}
+                | acc
+              ]
+
+            "video" ->
+              [
+                {:meta, [property: "og:" <> media_type, content: attachment_url(url["href"])], []}
+                | acc
+              ]
+
+            _ ->
+              acc
+          end
+        end)
+
+      acc ++ rendered_tags
+    end)
+  end
+
+  defp scrub_html_and_truncate(%{data: %{"content" => content}} = object) do
+    content
+    # html content comes from DB already encoded, decode first and scrub after
+    |> HtmlEntities.decode()
+    |> String.replace(~r/<br\s?\/?>/, " ")
+    |> HTML.get_cached_stripped_html_for_object(object, __MODULE__)
+    |> Formatter.demojify()
+    |> Formatter.truncate()
+  end
+
+  defp scrub_html_and_truncate(content) when is_binary(content) do
+    content
+    # html content comes from DB already encoded, decode first and scrub after
+    |> HtmlEntities.decode()
+    |> String.replace(~r/<br\s?\/?>/, " ")
+    |> HTML.strip_tags()
+    |> Formatter.demojify()
+    |> Formatter.truncate()
+  end
+
+  defp attachment_url(url) do
+    MediaProxy.url(url)
+  end
+
+  defp user_name_string(user) do
+    "#{user.name} " <>
+      if user.local do
+        "(@#{user.nickname}@#{Pleroma.Web.Endpoint.host()})"
+      else
+        "(@#{user.nickname})"
+      end
+  end
+end
diff --git a/lib/pleroma/web/metadata/provider.ex b/lib/pleroma/web/metadata/provider.ex
new file mode 100644
index 000000000..197fb2a77
--- /dev/null
+++ b/lib/pleroma/web/metadata/provider.ex
@@ -0,0 +1,7 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.Metadata.Providers.Provider do
+  @callback build_tags(map()) :: list()
+end
diff --git a/lib/pleroma/web/metadata/twitter_card.ex b/lib/pleroma/web/metadata/twitter_card.ex
new file mode 100644
index 000000000..32b979357
--- /dev/null
+++ b/lib/pleroma/web/metadata/twitter_card.ex
@@ -0,0 +1,46 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.Metadata.Providers.TwitterCard do
+  alias Pleroma.Web.Metadata.Providers.Provider
+  alias Pleroma.Web.Metadata
+
+  @behaviour Provider
+
+  @impl Provider
+  def build_tags(%{object: object}) do
+    if Metadata.activity_nsfw?(object) or object.data["attachment"] == [] do
+      build_tags(nil)
+    else
+      case find_first_acceptable_media_type(object) do
+        "image" ->
+          [{:meta, [property: "twitter:card", content: "summary_large_image"], []}]
+
+        "audio" ->
+          [{:meta, [property: "twitter:card", content: "player"], []}]
+
+        "video" ->
+          [{:meta, [property: "twitter:card", content: "player"], []}]
+
+        _ ->
+          build_tags(nil)
+      end
+    end
+  end
+
+  @impl Provider
+  def build_tags(_) do
+    [{:meta, [property: "twitter:card", content: "summary"], []}]
+  end
+
+  def find_first_acceptable_media_type(%{data: %{"attachment" => attachment}}) do
+    Enum.find_value(attachment, fn attachment ->
+      Enum.find_value(attachment["url"], fn url ->
+        Enum.find(["image", "audio", "video"], fn media_type ->
+          String.starts_with?(url["mediaType"], media_type)
+        end)
+      end)
+    end)
+  end
+end