defmodule Pleroma.Web.EmojiAPI.EmojiAPIController do
  use Pleroma.Web, :controller

  require Logger

  def reload(conn, _params) do
    Pleroma.Emoji.reload()

    conn |> text("ok")
  end

  @emoji_dir_path Path.join(
                    Pleroma.Config.get!([:instance, :static_dir]),
                    "emoji"
                  )

  @cache_seconds_per_file Pleroma.Config.get!([:emoji, :shared_pack_cache_seconds_per_file])

  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.json packs
            File.dir?(dir_path) and File.exists?(Path.join(dir_path, "pack.json"))
          end)
          |> Enum.map(fn pack_name ->
            pack_path = Path.join(@emoji_dir_path, pack_name)
            pack_file = Path.join(pack_path, "pack.json")

            {pack_name, Jason.decode!(File.read!(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)

            if can_download?(pack, pack_path) do
              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"], true)
               |> put_in(["pack", "download-sha256"], archive_sha)}
            else
              {name,
               pack
               |> put_in(["pack", "can-download"], false)}
            end
          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 create_archive_and_cache(name, pack, pack_dir, md5) do
    files =
      ['pack.json'] ++
        (pack["files"] |> Enum.map(fn {_, path} -> to_charlist(path) end))

    {:ok, {_, zip_result}} = :zip.zip('#{name}.zip', files, [:memory, cwd: to_charlist(pack_dir)])

    cache_ms = :timer.seconds(@cache_seconds_per_file * Enum.count(files))

    Cachex.put!(
      :emoji_packs_cache,
      name,
      # if pack.json MD5 changes, the cache is not valid anymore
      %{pack_json_md5: md5, pack_data: zip_result},
      # Add a minute to cache time for every file in the pack
      ttl: cache_ms
    )

    Logger.debug("Create an archive for the '#{name}' emoji pack, \
keeping it in cache for #{div(cache_ms, 1000)}s")

    zip_result
  end

  defp make_archive(name, pack, pack_dir) do
    # Having a different pack.json md5 invalidates cache
    pack_file_md5 = :crypto.hash(:md5, File.read!(Path.join(pack_dir, "pack.json")))

    maybe_cached_pack = Cachex.get!(:emoji_packs_cache, name)

    zip_result =
      if is_nil(maybe_cached_pack) do
        create_archive_and_cache(name, pack, pack_dir, pack_file_md5)
      else
        if maybe_cached_pack[:pack_file_md5] == pack_file_md5 do
          Logger.debug("Using cache for the '#{name}' shared emoji pack")

          maybe_cached_pack[:pack_data]
        else
          create_archive_and_cache(name, pack, pack_dir, pack_file_md5)
        end
      end

    zip_result
  end

  def download_shared(conn, %{"name" => name}) do
    pack_dir = Path.join(@emoji_dir_path, name)
    pack_file = Path.join(pack_dir, "pack.json")

    if File.exists?(pack_file) do
      pack = Jason.decode!(File.read!(pack_file))

      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)
         |> text("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)
       |> text("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 there is no fallback src 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)

          # Fallback cannot contain a pack.json file
          files =
            unless(pinfo[:fallback], do: ['pack.json'], else: []) ++
              (pfiles |> Enum.map(fn {_, path} -> to_charlist(path) end))

          {:ok, _} = :zip.unzip(emoji_archive, cwd: to_charlist(pack_dir), file_list: files)

          # Fallback can't contain a pack.json file, since that would cause the fallback-src-sha256
          # in it to depend on itself
          if pinfo[:fallback] do
            pack_file_path = Path.join(pack_dir, "pack.json")

            File.write!(pack_file_path, Jason.encode!(full_pack, pretty: true))
          end

          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

  def delete(conn, %{"name" => name}) do
    pack_dir = Path.join(@emoji_dir_path, name)

    case File.rm_rf(pack_dir) do
      {:ok, _} ->
        conn |> text("ok")

      {:error, _} ->
        conn |> put_status(:internal_server_error) |> text("Couldn't delete the pack #{name}")
    end
  end

  def update_metadata(conn, %{"pack_name" => name, "new_data" => new_data}) do
    pack_dir = Path.join(@emoji_dir_path, name)
    pack_file_p = Path.join(pack_dir, "pack.json")

    full_pack = Jason.decode!(File.read!(pack_file_p))

    # The new fallback-src is in the new data and it's not the same as it was in the old data
    should_update_fb_sha =
      not is_nil(new_data["fallback-src"]) and
        new_data["fallback-src"] != full_pack["pack"]["fallback-src"]

    new_data =
      if should_update_fb_sha do
        pack_arch = Tesla.get!(new_data["fallback-src"]).body

        {:ok, flist} = :zip.unzip(pack_arch, [:memory])

        # Check if all files from the pack.json are in the archive
        has_all_files =
          Enum.all?(full_pack["files"], fn {_, from_manifest} ->
            Enum.find(flist, fn {from_archive, _} ->
              to_string(from_archive) == from_manifest
            end)
          end)

        unless has_all_files do
          {:error,
           conn
           |> put_status(:bad_request)
           |> text("The fallback archive does not have all files specified in pack.json")}
        else
          fallback_sha = :crypto.hash(:sha256, pack_arch) |> Base.encode16()

          {:ok, new_data |> Map.put("fallback-src-sha256", fallback_sha)}
        end
      else
        {:ok, new_data}
      end

    case new_data do
      {:ok, new_data} ->
        full_pack = Map.put(full_pack, "pack", new_data)
        File.write!(pack_file_p, Jason.encode!(full_pack, pretty: true))

        # Send new data back with fallback sha filled
        conn |> json(new_data)

      {:error, e} ->
        e
    end
  end

  def update_file(
        conn,
        %{"pack_name" => pack_name, "action" => action, "shortcode" => shortcode} = params
      ) do
    pack_dir = Path.join(@emoji_dir_path, pack_name)
    pack_file_p = Path.join(pack_dir, "pack.json")

    full_pack = Jason.decode!(File.read!(pack_file_p))

    res =
      case action do
        "add" ->
          unless Map.has_key?(full_pack["files"], shortcode) do
            with %{"file" => %Plug.Upload{filename: filename, path: upload_path}} <- params do
              # If there was a file name provided with the request, use it, otherwise just use the
              # uploaded file name
              filename =
                if Map.has_key?(params, "filename") do
                  params["filename"]
                else
                  filename
                end

              file_path = Path.join(pack_dir, filename)

              # If the name contains directories, create them
              if String.contains?(file_path, "/") do
                File.mkdir_p!(Path.dirname(file_path))
              end

              # Copy the uploaded file from the temporary directory
              File.copy!(upload_path, file_path)

              updated_full_pack = put_in(full_pack, ["files", shortcode], filename)

              {:ok, updated_full_pack}
            else
              _ -> {:error, conn |> put_status(:bad_request) |> text("\"file\" not provided")}
            end
          else
            {:error,
             conn
             |> put_status(:conflict)
             |> text("An emoji with the \"#{shortcode}\" shortcode already exists")}
          end

        "remove" ->
          if Map.has_key?(full_pack["files"], shortcode) do
            {emoji_file_path, updated_full_pack} = pop_in(full_pack, ["files", shortcode])

            emoji_file_path = Path.join(pack_dir, emoji_file_path)

            # Delete the emoji file
            File.rm!(emoji_file_path)

            # If the old directory has no more files, remove it
            if String.contains?(emoji_file_path, "/") do
              dir = Path.dirname(emoji_file_path)

              if Enum.empty?(File.ls!(dir)) do
                File.rmdir!(dir)
              end
            end

            {:ok, updated_full_pack}
          else
            {:error,
             conn |> put_status(:bad_request) |> text("Emoji \"#{shortcode}\" does not exist")}
          end

        "update" ->
          if Map.has_key?(full_pack["files"], shortcode) do
            with %{"new_shortcode" => new_shortcode, "new_filename" => new_filename} <- params do
              # First, remove the old shortcode, saving the old path
              {old_emoji_file_path, updated_full_pack} = pop_in(full_pack, ["files", shortcode])
              old_emoji_file_path = Path.join(pack_dir, old_emoji_file_path)
              new_emoji_file_path = Path.join(pack_dir, new_filename)

              # If the name contains directories, create them
              if String.contains?(new_emoji_file_path, "/") do
                File.mkdir_p!(Path.dirname(new_emoji_file_path))
              end

              # Move/Rename the old filename to a new filename
              # These are probably on the same filesystem, so just rename should work
              :ok = File.rename(old_emoji_file_path, new_emoji_file_path)

              # If the old directory has no more files, remove it
              if String.contains?(old_emoji_file_path, "/") do
                dir = Path.dirname(old_emoji_file_path)

                if Enum.empty?(File.ls!(dir)) do
                  File.rmdir!(dir)
                end
              end

              # Then, put in the new shortcode with the new path
              updated_full_pack =
                put_in(updated_full_pack, ["files", new_shortcode], new_filename)

              {:ok, updated_full_pack}
            else
              _ ->
                {:error,
                 conn
                 |> put_status(:bad_request)
                 |> text("new_shortcode or new_file were not specified")}
            end
          else
            {:error,
             conn |> put_status(:bad_request) |> text("Emoji \"#{shortcode}\" does not exist")}
          end

        _ ->
          {:error, conn |> put_status(:bad_request) |> text("Unknown action: #{action}")}
      end

    case res do
      {:ok, updated_full_pack} ->
        # Write the emoji pack file
        File.write!(pack_file_p, Jason.encode!(updated_full_pack, pretty: true))

        # Return the modified file list
        conn |> json(updated_full_pack["files"])

      {:error, e} ->
        e
    end
  end
end