defmodule Nomad.RemoteDeploy do
  alias Nomad.{DeploymentScript, UpstartScript, NginxScript, RemoteSetupScript}

  @moduledoc """
  Transfers the production release to the remote host and sets up the 
  host's environment, the application and the remote NGINX Web Server.
  """
  
  @doc """
  Deploys the production release to the remote host.
  """
  def run do 
    system_user = "whoami"
                  |> System.cmd([]) 
                  |> Tuple.to_list 
                  |> List.first 
                  |> String.split("\n") 
                  |> List.first

    {_, 0} =
    if Mix.Shell.IO.yes? "Do you want to setup the remote host?" do
      :ok = build_remote_setup_script
      {_, 0} = transfer_remote_setup_script system_user
      execute_remote_setup_script
    end

    :ok    = build_deployment_script
    :ok    = build_upstart_script
    :ok    = build_nginx_script
    {_, 0} = deploy_to_remote_host system_user
    {_, 0} = transfer_deployment_script system_user
    {_, 0} = transfer_upstart_script system_user
    {_, 0} = transfer_nginx_script system_user
    {_, 0} = execute_remote_deployment_script
    :ok    = local_cleanup
    remote_cleanup
  end

  defp deploy_to_remote_host(system_user) do
    System.cmd "scp", [
                       "-i", "/home/#{system_user}/.ssh/#{Application.get_env(:nomad, :ssh_key)}.pub", 
                       "rel/#{System.get_env("APP_NAME")}/releases/0.0.1/"
                       <> "#{System.get_env("APP_NAME")}.tar.gz", 
                       "#{System.get_env("USERNAME")}@#{System.get_env("HOST")}:/root"
                      ]                       
  end

  defp transfer_deployment_script(system_user) do 
    Mix.Shell.IO.info "Going to transfer the after deployment script."
    System.cmd "scp", [
                       "-i", "/home/#{system_user}/.ssh/#{Application.get_env(:nomad, :ssh_key)}.pub", 
                       "after_deploy.sh", 
                       "#{System.get_env("USERNAME")}@#{System.get_env("HOST")}:/root"
                      ]
  end

  defp transfer_upstart_script(system_user) do
    Mix.Shell.IO.info "Going to transfer the Upstart script."
    System.cmd "scp", [
                       "-i", "/home/#{system_user}/.ssh/#{Application.get_env(:nomad, :ssh_key)}.pub", 
                       "#{System.get_env("APP_NAME")}.conf", 
                       "#{System.get_env("USERNAME")}@#{System.get_env("HOST")}:/etc/init"
                      ]    
  end

  defp transfer_nginx_script(system_user) do
    Mix.Shell.IO.info "Going to transfer the NGINX script."
    System.cmd "scp", [
                       "-i", "/home/#{system_user}/.ssh/#{Application.get_env(:nomad, :ssh_key)}.pub", 
                       "#{System.get_env("APP_NAME")}", 
                       "#{System.get_env("USERNAME")}@#{System.get_env("HOST")}:/etc/nginx/sites-available"
                      ]    
  end

  defp transfer_remote_setup_script(system_user) do 
    Mix.Shell.IO.info "Going to transfer the remote setup script."
    System.cmd "scp", [
                       "-i", "/home/#{system_user}/.ssh/#{Application.get_env(:nomad, :ssh_key)}.pub", 
                       "remote_setup.sh", 
                       "#{System.get_env("USERNAME")}@#{System.get_env("HOST")}:/root"
                      ]      
  end  

  defp execute_remote_setup_script do 
    Mix.Shell.IO.info "Going to run the remote setup script."                                             
    System.cmd "ssh", ["#{System.get_env("USERNAME")}@#{System.get_env("HOST")}", 
                       "chmod o+rx remote_setup.sh;" 
                       <> "./remote_setup.sh"
                      ]    
  end

  defp execute_remote_deployment_script do
    Mix.Shell.IO.info "Going to run the remote script."                                             
    System.cmd "ssh", ["#{System.get_env("USERNAME")}@#{System.get_env("HOST")}", 
                       "chmod o+rx after_deploy.sh;" 
                       <> "./after_deploy.sh"
                      ]
  end

  defp build_deployment_script do
    DeploymentScript.build_script
  end

  defp build_remote_setup_script do 
    RemoteSetupScript.build_script
  end

  defp build_upstart_script do 
    UpstartScript.build_script
  end

  defp build_nginx_script do 
    NginxScript.build_script
  end

  defp local_cleanup do 
    Mix.Shell.IO.info "Cleaning up local dir."
    {_, 0} = System.cmd "rm", ["-rf", "rel"]
    :ok    = DeploymentScript.delete_script
    :ok    = UpstartScript.delete_script
    :ok    = RemoteSetupScript.delete_script
  end

  defp remote_cleanup do 
    Mix.Shell.IO.info "Cleaning up remote dir."
    System.cmd "ssh", ["#{System.get_env("USERNAME")}@#{System.get_env("HOST")}",
                       "rm -rf after_deploy.sh #{System.get_env("APP_NAME")}.tar.gz"
                      ]
  end  
end