1 files changed, 162 insertions, 0 deletions
diff --git a/lib/pleroma/helpers/media_helper.ex b/lib/pleroma/helpers/media_helper.ex
new file mode 100644
index 000000000..6b799173e
--- /dev/null
+++ b/lib/pleroma/helpers/media_helper.ex
@@ -0,0 +1,162 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Helpers.MediaHelper do
+  @moduledoc """
+  Handles common media-related operations.
+  """
+
+  alias Pleroma.HTTP
+
+  require Logger
+
+  def missing_dependencies do
+    Enum.reduce([imagemagick: "convert", ffmpeg: "ffmpeg"], [], fn {sym, executable}, acc ->
+      if Pleroma.Utils.command_available?(executable) do
+        acc
+      else
+        [sym | acc]
+      end
+    end)
+  end
+
+  def image_resize(url, options) do
+    with executable when is_binary(executable) <- System.find_executable("convert"),
+         {:ok, args} <- prepare_image_resize_args(options),
+         {:ok, env} <- HTTP.get(url, [], pool: :media),
+         {:ok, fifo_path} <- mkfifo() do
+      args = List.flatten([fifo_path, args])
+      run_fifo(fifo_path, env, executable, args)
+    else
+      nil -> {:error, {:convert, :command_not_found}}
+      {:error, _} = error -> error
+    end
+  end
+
+  defp prepare_image_resize_args(
+         %{max_width: max_width, max_height: max_height, format: "png"} = options
+       ) do
+    quality = options[:quality] || 85
+    resize = Enum.join([max_width, "x", max_height, ">"])
+
+    args = [
+      "-resize",
+      resize,
+      "-quality",
+      to_string(quality),
+      "png:-"
+    ]
+
+    {:ok, args}
+  end
+
+  defp prepare_image_resize_args(%{max_width: max_width, max_height: max_height} = options) do
+    quality = options[:quality] || 85
+    resize = Enum.join([max_width, "x", max_height, ">"])
+
+    args = [
+      "-interlace",
+      "Plane",
+      "-resize",
+      resize,
+      "-quality",
+      to_string(quality),
+      "jpg:-"
+    ]
+
+    {:ok, args}
+  end
+
+  defp prepare_image_resize_args(_), do: {:error, :missing_options}
+
+  # Note: video thumbnail is intentionally not resized (always has original dimensions)
+  def video_framegrab(url) do
+    with executable when is_binary(executable) <- System.find_executable("ffmpeg"),
+         {:ok, env} <- HTTP.get(url, [], pool: :media),
+         {:ok, fifo_path} <- mkfifo(),
+         args = [
+           "-y",
+           "-i",
+           fifo_path,
+           "-vframes",
+           "1",
+           "-f",
+           "mjpeg",
+           "-loglevel",
+           "error",
+           "-"
+         ] do
+      run_fifo(fifo_path, env, executable, args)
+    else
+      nil -> {:error, {:ffmpeg, :command_not_found}}
+      {:error, _} = error -> error
+    end
+  end
+
+  defp run_fifo(fifo_path, env, executable, args) do
+    pid =
+      Port.open({:spawn_executable, executable}, [
+        :use_stdio,
+        :stream,
+        :exit_status,
+        :binary,
+        args: args
+      ])
+
+    fifo = Port.open(to_charlist(fifo_path), [:eof, :binary, :stream, :out])
+    fix = Pleroma.Helpers.QtFastStart.fix(env.body)
+    true = Port.command(fifo, fix)
+    :erlang.port_close(fifo)
+    loop_recv(pid)
+  after
+    File.rm(fifo_path)
+  end
+
+  defp mkfifo do
+    path = Path.join(System.tmp_dir!(), "pleroma-media-preview-pipe-#{Ecto.UUID.generate()}")
+
+    case System.cmd("mkfifo", [path]) do
+      {_, 0} ->
+        spawn(fifo_guard(path))
+        {:ok, path}
+
+      {_, err} ->
+        {:error, {:fifo_failed, err}}
+    end
+  end
+
+  defp fifo_guard(path) do
+    pid = self()
+
+    fn ->
+      ref = Process.monitor(pid)
+
+      receive do
+        {:DOWN, ^ref, :process, ^pid, _} ->
+          File.rm(path)
+      end
+    end
+  end
+
+  defp loop_recv(pid) do
+    loop_recv(pid, <<>>)
+  end
+
+  defp loop_recv(pid, acc) do
+    receive do
+      {^pid, {:data, data}} ->
+        loop_recv(pid, acc <> data)
+
+      {^pid, {:exit_status, 0}} ->
+        {:ok, acc}
+
+      {^pid, {:exit_status, status}} ->
+        {:error, status}
+    after
+      5000 ->
+        :erlang.port_close(pid)
+        {:error, :timeout}
+    end
+  end
+end