require "ostruct"
require "fileutils"
require "erb"
require "json"
require "pathname"
require "pry"

class Registry
  PATH = Pathname.new(File.expand_path("../../registry.json", __FILE__))
  def initialize
    @data = JSON.load(File.open(Registry::PATH))
  end
  attr_accessor :data
  def save
    f = File.open(Registry::PATH, "w+")
    f.puts JSON.pretty_generate(@data)
    f.close
  end
end

def atomic_write(path, content)
  dir = File.dirname(path)
  unless Dir.exist?(dir)
    FileUtils.mkdir_p(dir)
  end
  temp_path = path.to_s + ".tmp"
  File.open(temp_path, 'w+') do |f|
    f.write(content)
  end

  FileUtils.mv(temp_path, path)
end

def sh(cmd, *args)
  puts "$ #{cmd} "+ args.map {|a| "'#{a}'" }.join(" ")
  system(cmd, *args)
end

def die(msg)
  $stderr.puts(msg)
  exit(1)
end

def try(hash, *args)
  result = hash
  args.each do |arg|
    if result.respond_to?(:[]) && result[arg]
      result = result[arg]
    else
      return nil
    end
  end
  result
end

class TemplateContext < OpenStruct
  def get_binding
    binding
  end
end

class Template
  def initialize(path)
    @erb = ERB.new(File.read(path), nil, '-')
  end
  def render(params={})
    @erb.result(TemplateContext.new(params).get_binding)
  end
end

class CommandTemplate
  def initialize(command)
    @erb = ERB.new(command, nil, '-')
  end
  def execute(params={})
    args = params.dup
    args.each do |k,v|
      args[k] = Shellwords.escape(v)
    end
    cmd = @erb.result(TemplateContext.new(args).get_binding)
    sh(cmd)
  end
end