defmodule Mix.Tasks.Firmware do
  use Mix.Task
  import Mix.Nerves.Utils
  alias Mix.Nerves.Preflight

  @shortdoc "Build a firmware bundle"

  @moduledoc """
  Build a firmware image for the selected target platform.

  This task builds the project, combines the generated OTP release with
  a Nerves system image, and creates a `.fw` file that may be written
  to an SDCard or sent to a device.

  ## Command line options

    * `--verbose` - produce detailed output about release assembly

  ## Environment variables

    * `NERVES_SYSTEM`    - may be set to a local directory to specify the Nerves
      system image that is used

    * `NERVES_TOOLCHAIN` - may be set to a local directory to specify the
      Nerves toolchain (C/C++ crosscompiler) that is used
  """

  @switches [verbose: :boolean]

  @impl true
  def run(args) do
    Preflight.check!()
    debug_info("Nerves Firmware Assembler")

    {opts, _, _} = OptionParser.parse(args, switches: @switches)

    system_path = check_nerves_system_is_set!()

    check_nerves_toolchain_is_set!()

    # Check for required files
    if use_distillery?() do
      rel_config =
        File.cwd!()
        |> Path.join("rel/config.exs")

      if !File.exists?(rel_config) do
        Mix.raise("""
          You are missing a release config file. Run  nerves.release.init task first
        """)
      end
    else
      vm_args =
        File.cwd!()
        |> Path.join("rel/vm.args.eex")

      if !File.exists?(vm_args) do
        Mix.raise("""
          rel/vm.args needs to be moved to rel/vm.args.eex
        """)
      end
    end

    # By this point, paths have already been loaded.
    # We just want to ensure any custom systems are compiled
    # via the precompile checks
    Mix.Task.run("nerves.precompile", ["--no-loadpaths"])
    Mix.Task.run("compile", [])

    Mix.Nerves.IO.shell_info("Building OTP Release...")

    if use_distillery?() do
      clean_distillery_release(opts)
      build_distillery_release(opts)
    else
      build_release()
    end

    build_firmware(system_path)
  end

  @doc false
  def result({_, 0}), do: nil

  def result({result, _}),
    do:
      Mix.raise("""
      Nerves encountered an error. #{inspect(result)}
      """)

  defp clean_distillery_release(opts) do
    verbosity = if opts[:verbose], do: "--verbose", else: "--silent"

    try do
      Mix.Task.run("distillery.release.clean", [verbosity, "--implode", "--no-confirm"])
    catch
      :exit, _ -> :noop
    end
  end

  defp build_release() do
    Mix.Task.run("release", [])
  end

  defp build_distillery_release(opts) do
    verbosity = if opts[:verbose], do: "--verbose", else: "--quiet"
    Mix.Task.run("distillery.release", [verbosity, "--no-tar"])
  end

  defp build_firmware(system_path) do
    config = Mix.Project.config()
    otp_app = config[:app]

    compiler_check()
    firmware_config = Application.get_env(:nerves, :firmware)

    rootfs_priorities =
      Nerves.Env.package(:nerves_system_br)
      |> rootfs_priorities()

    rel2fw_path = Path.join(system_path, "scripts/rel2fw.sh")
    cmd = "bash"
    args = [rel2fw_path]

    if firmware_config[:rootfs_additions] do
      Mix.shell().error(
        "The :rootfs_additions configuration option has been deprecated. Please use :rootfs_overlay instead."
      )
    end

    build_rootfs_overlay = Path.join([Mix.Project.build_path(), "nerves", "rootfs_overlay"])
    File.mkdir_p(build_rootfs_overlay)

    write_erlinit_config(build_rootfs_overlay)

    project_rootfs_overlay =
      case firmware_config[:rootfs_overlay] || firmware_config[:rootfs_additions] do
        nil ->
          []

        overlays when is_list(overlays) ->
          overlays

        overlay ->
          [Path.expand(overlay)]
      end

    rootfs_overlays =
      [build_rootfs_overlay | project_rootfs_overlay]
      |> Enum.map(&["-a", &1])
      |> List.flatten()

    fwup_conf =
      case firmware_config[:fwup_conf] do
        nil -> []
        fwup_conf -> ["-c", Path.join(File.cwd!(), fwup_conf)]
      end

    fw = ["-f", Nerves.Env.firmware_path(config)]
    release_path = Path.join(Mix.Project.build_path(), "rel/#{otp_app}")
    output = [release_path]
    args = args ++ fwup_conf ++ rootfs_overlays ++ fw ++ rootfs_priorities ++ output
    env = standard_fwup_variables(config)

    set_provisioning(firmware_config[:provisioning])

    config
    |> Nerves.Env.images_path()
    |> File.mkdir_p()

    shell(cmd, args, env: env)
    |> result
  end

  defp standard_fwup_variables(config) do
    # Assuming the fwup.conf file respects these variable like the official
    # systems do, this will set the .fw metadata to what's in the mix.exs.
    [
      {"NERVES_FW_VERSION", config[:version]},
      {"NERVES_FW_PRODUCT", config[:name] || to_string(config[:app])},
      {"NERVES_FW_DESCRIPTION", config[:description]},
      {"NERVES_FW_AUTHOR", config[:author]}
    ]
  end

  # Need to check min version for nerves_system_br to check if passing the
  # rootfs priorities option is supported. This was added in the 1.7.1 release
  # https://github.com/nerves-project/nerves_system_br/releases/tag/v1.7.1
  defp rootfs_priorities(%Nerves.Package{app: :nerves_system_br, version: vsn}) do
    case Version.compare(vsn, "1.7.1") do
      r when r in [:gt, :eq] ->
        rootfs_priorities_file =
          Path.join([Mix.Project.build_path(), "nerves", "rootfs.priorities"])

        if File.exists?(rootfs_priorities_file) do
          ["-p", rootfs_priorities_file]
        else
          []
        end

      _ ->
        []
    end
  end

  defp rootfs_priorities(_), do: []

  defp compiler_check() do
    with {:ok, otpc} <- module_compiler_version(:code),
         {:ok, otp_requirement} <- Version.parse_requirement("~> #{otpc.major}.#{otpc.minor}"),
         {:ok, elixirc} <- module_compiler_version(Kernel) do
      unless Version.match?(elixirc, otp_requirement) do
        Mix.raise("""
        The Erlang compiler that compiled Elixir is older than the compiler
        used to compile OTP.

        Elixir: #{elixirc.major}.#{elixirc.minor}.#{elixirc.patch}
        OTP:    #{otpc.major}.#{otpc.minor}.#{otpc.patch}

        Please use a version of Elixir that was compiled using the same major
        version of OTP.

        For example:

        If your target is running OTP 22, you should use a version of Elixir
        that was compiled using OTP 22.

        If you're using asdf to manage Elixir versions, run:

        asdf install elixir #{System.version()}-otp-#{system_otp_release()}
        asdf global elixir #{System.version()}-otp-#{system_otp_release()}
        """)
      end
    else
      error ->
        Mix.raise("""
        Nerves was unable to verify the Erlang compiler version.
        Error: #{error}
        """)
    end
  end

  def module_compiler_version(mod) do
    with {:file, path} <- :code.is_loaded(mod),
         {:ok, {_, [compile_info: compile_info]}} <- :beam_lib.chunks(path, [:compile_info]),
         {:ok, vsn} <- Keyword.fetch(compile_info, :version),
         vsn <- to_string(vsn) do
      parse_version(vsn)
    end
  end

  def system_otp_release do
    :erlang.system_info(:otp_release)
    |> to_string()
  end

  defp write_erlinit_config(build_overlay) do
    with user_opts <- Application.get_env(:nerves, :erlinit, []),
         {:ok, system_config_file} <- Nerves.Erlinit.system_config_file(Nerves.Env.system()),
         {:ok, system_config_file} <- File.read(system_config_file),
         system_opts <- Nerves.Erlinit.decode_config(system_config_file),
         erlinit_opts <- Nerves.Erlinit.merge_opts(system_opts, user_opts),
         erlinit_config <- Nerves.Erlinit.encode_config(erlinit_opts) do
      erlinit_config_file = Path.join(build_overlay, "etc/erlinit.config")

      Path.dirname(erlinit_config_file)
      |> File.mkdir_p()

      header = erlinit_config_header(user_opts)

      File.write(erlinit_config_file, header <> erlinit_config)
      {:ok, erlinit_config_file}
    else
      {:error, :no_config} ->
        Nerves.Utils.Shell.warn("There was no system erlinit.config found")
        :noop

      _e ->
        :noop
    end
  end

  def erlinit_config_header(opts) do
    """
    # Generated from rootfs_overlay/etc/erlinit.config
    """ <>
      if opts != [] do
        """
        # with overrides from the application config
        """
      else
        """
        """
      end
  end
end