dotenv

#!/usr/bin/env ruby

class Dotenv
  ALLOWED_ENVS = %w(production test development staging preview qa xingbox dev prod).freeze
  QUOTES = ["\"", "'"]
  COMMAND_REGEXP = /\$\((.+)\)/

  attr_reader :argv, :env, :loaded_vars

  def initialize(argv, env)
    @argv = argv
    @env = env
    @loaded_vars = {}
  end

  def run
    load_dotenv(file)
    load_dotenv(env_file)
    load_dotenv('.env.local')
    load_dotenv(local_env_file)
    add_loaded_environment_variables

    if command != ''
      exec command
    else
      puts 'dotenv: exec needs a command to run'
    end
  end

  def command
    if file_passed?
      if exec_arg?(2)
        args_from(3)
      else
        args_from(2)
      end
    elsif env_passed?
      if exec_arg?(1)
        args_from(2)
      else
        args_from(1)
      end
    else
      if exec_arg?(0)
        args_from(1)
      else
        args_from(0)
      end
    end
  end

  def file
    file_passed? ? argv[1] : '.env'
  end

  def current_env
    return argv[0] if env_passed?

    env['RAILS_ENV'] || env['ENV'] || 'development'
  end

  def env_file
    ".env.#{current_env}"
  end

  def local_env_file
    "#{env_file}.local"
  end

  def add_loaded_environment_variables
    loaded_vars.each { |key, value| env[key] = value }
  end

  def file_passed?
   argv[0] == '-f'
  end

  def env_passed?
    ALLOWED_ENVS.include?(argv[0])
  end

  def args_from(index)
    argv[index..-1].join(' ')
  end

  def exec_arg?(index)
    argv[index] == 'exec'
  end

  def load_dotenv(file)
    return unless file
    return unless File.exists?(file)

    text = File.read(file)

    text.lines.each do |line|
      line = line.gsub("\n", '').gsub('export ', '')

      next if line.length.zero? || line[0] == '#'

      key, value = line.split('=')
      value ||= ''

      strip_quotes!(value)
      substitute_commands(value)

      loaded_vars[key] = value || ''
    end
  end

  def strip_quotes!(value)
    strip_quote!(value, 0)
    strip_quote!(value, -1)
  end

  def strip_quote!(value, position)
    value[position] = '' if QUOTES.include?(value[position])
  end

  def substitute_commands(value)
    commands = value.scan(COMMAND_REGEXP).flatten

    commands.each do |command|
      key = "$(#{command})"
      result = `#{command}`.gsub("\n", '')
      value.gsub!(key, result)
    end
  end
end

Dotenv.new(ARGV, ENV).run