require "digest/md5"
require "railsless-deploy"
require "multi_json"

def remote_file_exists?(full_path)
  'true' ==  capture("if [ -e #{full_path} ]; then echo 'true'; fi").strip
end

def remote_file_content_same_as?(full_path, content)
  Digest::MD5.hexdigest(content) == capture("md5sum #{full_path} | awk '{ print $1 }'").strip
end

def remote_file_differs?(full_path, content)
  exists = remote_file_exists?(full_path)
  !exists || exists && !remote_file_content_same_as?(full_path, content)
end

Capistrano::Configuration.instance(:must_exist).load do |configuration|
  before "deploy", "deploy:create_release_dir"
  before "deploy", "node:check_upstart_config"
  after "deploy:update", "node:install_packages", "node:restart"
  after "deploy:rollback", "node:restart"

  package_json = MultiJson.load(File.open("package.json").read) rescue {}

  _cset :application, package_json["name"] 
  _cset :app_command, package_json["main"] || "index.js"
  _cset :app_environment, ""

  _cset :node_binary, "/usr/bin/node"
  _cset :node_env, "production"
  _cset :node_user, "deploy"

  _cset(:upstart_job_name) { "#{application}-#{node_env}" }
  _cset(:upstart_file_path) { "/etc/init/#{upstart_job_name}.conf" }
  _cset(:upstart_file_contents) {
<<EOD
#!upstart
description "#{application} node app"
author      "capistrano"

start on runlevel [2345]
stop on shutdown

respawn
respawn limit 99 5

script
    cd #{current_path} && exec sudo -u #{node_user} NODE_ENV=#{node_env} #{app_environment} #{node_binary} #{current_path}/#{app_command} 2>> #{shared_path}/#{node_env}.err.log 1>> #{shared_path}/#{node_env}.out.log
end script
EOD
  }


  namespace :node do
    desc "Check required packages and install if packages are not installed"
    task :install_packages do
      run "mkdir -p #{shared_path}/node_modules"
      run "cp #{release_path}/package.json #{shared_path}"
      run "cp #{release_path}/npm-shrinkwrap.json #{shared_path}"
      run "cd #{shared_path} && npm install #{(node_env == 'production') ? '--production' : ''} --loglevel warn"
      run "ln -s #{shared_path}/node_modules #{release_path}/node_modules"
    end

    task :check_upstart_config do
      create_upstart_config if remote_file_differs?(upstart_file_path, upstart_file_contents)
    end

    desc "Create upstart script for this node app"
    task :create_upstart_config do
      temp_config_file_path = "#{shared_path}/#{application}.conf"

      # Generate and upload the upstart script
      put upstart_file_contents, temp_config_file_path

      # Copy the script into place and make executable
      sudo "cp #{temp_config_file_path} #{upstart_file_path}"
    end

    desc "Start the node application"
    task :start do
      sudo "start #{upstart_job_name}"
    end

    desc "Stop the node application"
    task :stop do
      sudo "stop #{upstart_job_name}"
    end

    desc "Restart the node application"
    task :restart do
      sudo "stop #{upstart_job_name}; true"
      sudo "start #{upstart_job_name}"
    end
  end

  namespace :deploy do
    task :create_release_dir, :except => {:no_release => true} do
      mkdir_releases = "mkdir -p #{fetch :releases_path}"
      mkdir_commands = ["log", "pids"].map {|dir| "mkdir -p #{shared_path}/#{dir}"}
      run mkdir_commands.unshift(mkdir_releases).join(" && ")
    end
  end
end