Implement API actions on packs

That incldues listing them and downloading them from other instances
or from the remote url

lib/pleroma/web/emoji_api/emoji_api_controller.ex

+defmodule Pleroma.Web.EmojiAPI.EmojiAPIController do
+  use Pleroma.Web, :controller
+
+  def reload(conn, _params) do
+    Pleroma.Emoji.reload()
+
+    conn |> json("ok")
+  end
+
+  @emoji_dir_path Path.join(
+                    Pleroma.Config.get!([:instance, :static_dir]),
+                    "emoji"
+                  )
+
+  def list_packs(conn, _params) do
+    pack_infos =
+      case File.ls(@emoji_dir_path) do
+        {:error, _} ->
+          %{}
+
+        {:ok, results} ->
+          results
+          |> Enum.filter(fn file ->
+            dir_path = Path.join(@emoji_dir_path, file)
+            # Filter to only use the pack.toml packs
+            File.dir?(dir_path) and File.exists?(Path.join(dir_path, "pack.toml"))
+          end)
+          |> Enum.map(fn pack_name ->
+            pack_path = Path.join(@emoji_dir_path, pack_name)
+            pack_file = Path.join(pack_path, "pack.toml")
+
+            {pack_name, Toml.decode_file!(pack_file)}
+          end)
+          # Transform into a map of pack-name => pack-data
+          # Check if all the files are in place and can be sent
+          |> Enum.map(fn {name, pack} ->
+            pack_path = Path.join(@emoji_dir_path, name)
+
+            archive_for_sha = make_archive(name, pack, pack_path)
+            archive_sha = :crypto.hash(:sha256, archive_for_sha) |> Base.encode16()
+
+            {name,
+             pack
+             |> put_in(["pack", "can-download"], can_download?(pack, pack_path))
+             |> put_in(["pack", "download-sha256"], archive_sha)}
+          end)
+          |> Enum.into(%{})
+      end
+
+    conn |> json(pack_infos)
+  end
+
+  defp can_download?(pack, pack_path) do
+    # If the pack is set as shared, check if it can be downloaded
+    # That means that when asked, the pack can be packed and sent to the remote
+    # Otherwise, they'd have to download it from external-src
+    pack["pack"]["share-files"] and
+      Enum.all?(pack["files"], fn {_, path} ->
+        File.exists?(Path.join(pack_path, path))
+      end)
+  end
+
+  defp make_archive(name, pack, pack_dir) do
+    files =
+      ['pack.toml'] ++
+        (pack["files"] |> Enum.map(fn {_, path} -> to_charlist(path) end))
+
+    {:ok, {_, zip_result}} = :zip.zip('#{name}.zip', files, [:memory, cwd: to_charlist(pack_dir)])
+
+    zip_result
+  end
+
+  def download_shared(conn, %{"name" => name}) do
+    pack_dir = Path.join(@emoji_dir_path, name)
+    pack_toml = Path.join(pack_dir, "pack.toml")
+
+    if File.exists?(pack_toml) do
+      pack = Toml.decode_file!(pack_toml)
+
+      if can_download?(pack, pack_dir) do
+        zip_result = make_archive(name, pack, pack_dir)
+
+        conn
+        |> send_download({:binary, zip_result}, filename: "#{name}.zip")
+      else
+        {:error,
+         conn
+         |> put_status(:forbidden)
+         |> json("Pack #{name} cannot be downloaded from this instance, either pack sharing\
+           was disabled for this pack or some files are missing")}
+      end
+    else
+      {:error,
+       conn
+       |> put_status(:not_found)
+       |> json("Pack #{name} does not exist")}
+    end
+  end
+
+  def download_from(conn, %{"instance_address" => address, "pack_name" => name} = data) do
+    list_uri = "#{address}/api/pleroma/emoji/packs/list"
+
+    list = Tesla.get!(list_uri).body |> Jason.decode!()
+    full_pack = list[name]
+    pfiles = full_pack["files"]
+    pack = full_pack["pack"]
+
+    pack_info_res =
+      cond do
+        pack["share-files"] && pack["can-download"] ->
+          {:ok,
+           %{
+             sha: pack["download-sha256"],
+             uri: "#{address}/api/pleroma/emoji/packs/download_shared/#{name}"
+           }}
+
+        pack["fallback-src"] ->
+          {:ok,
+           %{
+             sha: pack["fallback-src-sha256"],
+             uri: pack["fallback-src"],
+             fallback: true
+           }}
+
+        true ->
+          {:error, "The pack was not set as shared and the is no fallback url to download from"}
+      end
+
+    case pack_info_res do
+      {:ok, %{sha: sha, uri: uri} = pinfo} ->
+        sha = Base.decode16!(sha)
+        emoji_archive = Tesla.get!(uri).body
+
+        got_sha = :crypto.hash(:sha256, emoji_archive)
+
+        if got_sha == sha do
+          local_name = data["as"] || name
+          pack_dir = Path.join(@emoji_dir_path, local_name)
+          File.mkdir_p!(pack_dir)
+
+          files =
+            ['pack.toml'] ++
+              (pfiles |> Enum.map(fn {_, path} -> to_charlist(path) end))
+
+          {:ok, _} = :zip.unzip(emoji_archive, cwd: to_charlist(pack_dir), file_list: files)
+
+          # Fallback URL might not contain a pack.toml file, if that happens - fail (for now)
+          # FIXME: there seems to be a lack of any kind of encoders besides JSON.
+          erres =
+            if pinfo[:fallback] do
+              toml_path = Path.join(pack_dir, "pack.toml")
+
+              unless File.exists?(toml_path) do
+                conn
+                |> put_status(:internal_server_error)
+                |> text("No pack.toml in falblack source")
+              end
+            end
+
+          if not is_nil(erres), do: erres, else: conn |> text("ok")
+        else
+          conn
+          |> put_status(:internal_server_error)
+          |> text("SHA256 for the pack doesn't match the one sent by the server")
+        end
+
+      {:error, e} ->
+        conn |> put_status(:internal_server_error) |> text(e)
+    end
+  end
+end

lib/pleroma/web/router.ex

@@ -207,6 +207,28 @@ defmodule Pleroma.Web.Router do
     get("/moderation_log", AdminAPIController, :list_log)
   end
 
+  scope "/api/pleroma/emoji", Pleroma.Web.EmojiAPI do
+    scope [] do
+      pipe_through([:admin_api, :oauth_write])
+
+      post("/reload", EmojiAPIController, :reload)
+    end
+
+    scope "/packs" do
+      # Modifying packs
+      pipe_through([:admin_api, :oauth_write])
+
+      post("/download_from", EmojiAPIController, :download_from)
+    end
+
+    scope "/packs" do
+      # Pack info / downloading
+      get("/list", EmojiAPIController, :list_packs)
+      get("/download_shared/:name", EmojiAPIController, :download_shared)
+      get("/sha_of_shared/:name", EmojiAPIController, :sha_of_shared)
+    end
+  end
+
   scope "/", Pleroma.Web.TwitterAPI do
     pipe_through(:pleroma_html)