defmodule Mix.Tasks.LambdaRelease do
  @moduledoc """
  Create zip file for AWS Lamdba with custom runtime.
  Use this command under Docker image `amazonlinux:2017.03.1.20170812`
  `erintheblack/elixir-lambda-builder:20200112.01` is prepared to build.

  ### How to build
  ```
  $ docker run -d -it --name elx erintheblack/elixir-lambda-builder:20200112.01
  $ docker cp ${project} elx:/tmp
  $ docker exec elx /bin/bash -c "cd /tmp/${project}; mix deps.get; mix lambda_release"
  $ docker cp elx:/tmp/${app_name}.zip .
  ```
  """

  use Mix.Task

  @bootstrap """
#!/bin/sh

set -euo pipefail
export HOME=/
RESPONSE=$(bin/app eval "$(echo "$_HANDLER").start()")
"""

  @doc """
  Create zip file for AWS Lamdba with custom runtime.
  """
  @impl Mix.Task
  def run(_args) do
    app_name = Mix.Project.config |> Keyword.get(:app) |> to_string
    Mix.env(:prod)
    Mix.Shell.cmd("rm -f -R ./_build/prod/*", &IO.puts/1)
    Mix.Task.run("release")
    File.write("./_build/prod/rel/#{app_name}/bootstrap", @bootstrap)
    Mix.Shell.cmd("mv ./_build/prod/rel/#{app_name}/bin/#{app_name} ./_build/prod/rel/#{app_name}/bin/app", &IO.puts/1)
    Mix.Shell.cmd("rm -f ./_build/prod/rel/#{app_name}/bin/#{app_name}.bat", &IO.puts/1)
    Mix.Shell.cmd("chmod +x ./_build/prod/rel/#{app_name}/bin/app", &IO.puts/1)
    Mix.Shell.cmd("chmod +x ./_build/prod/rel/#{app_name}/releases/*/elixir", &IO.puts/1)
    Mix.Shell.cmd("chmod +x ./_build/prod/rel/#{app_name}/erts-*/bin/erl", &IO.puts/1)
    Mix.Shell.cmd("chmod +x ./_build/prod/rel/#{app_name}/bootstrap", &IO.puts/1)
    Mix.Shell.cmd("cd ./_build/prod/rel/#{app_name}; zip #{app_name} -r -q *", &IO.puts/1)
    Mix.Shell.cmd("mv -f ./_build/prod/rel/#{app_name}/#{app_name}.zip ../", &IO.puts/1)
    Mix.Shell.cmd("mv ./_build/prod/rel/#{app_name}/bin/app ./_build/prod/rel/#{app_name}/bin/#{app_name}", &IO.puts/1)
  end
end