require 'erb'
require 'fileutils'

module GemStone
  
  VERSION = '0.2'
  
  class MissingOption < Exception; end

  class CLI

    def self.ask_options
      options = {}
      while options.empty? do
        puts "Hi, I'll need some data about your next ruby gem, please answer all questions"
        questions = [
                      [:name        , 'gem name?'], 
                      [:author      , 'gem author?'], 
                      [:email       , 'author email?'], 
                      [:summary     , 'gem summary? (be brief)'], 
                      [:description , 'gem description? (not so brief)'], 
                      [:homepage    , 'gem homepage URL?'], 
                      [:executable  , 'will the gem include an executable? (y/n)'] 
                    ]

        questions.each do |option, question|
          puts question
          options[option] = gets.chomp
        end
        options[:executable] = options[:executable].downcase.include?('y')
      
        begin
          OptionsValidator.validate!(options)
        rescue MissingOption => e
          puts "Please answer all questions."
          options = {}
        end
      end
      options
    end
    
  end
  
  class OptionsValidator
    
    REQUIRED_OPTIONS = [:name, :author, :email, :description, :summary, :homepage, :executable]
    
    def self.validate!(options)
      REQUIRED_OPTIONS.each do |option|
        raise MissingOption, "'#{option}' option required" unless present?(options[option])
      end
    end

    def self.present?(value)
      !value.nil? && !value.to_s.strip.empty?
    end
    
  end
  
  class Generator
  
    def initialize(options = nil)
      cli_mode = options.nil?
      options ||= CLI.ask_options
      @options = options
      OptionsValidator.validate!(@options)
      @options[:gem_file_name] = underscore(@options[:name])
      @options[:gem_class_name] = classify(@options[:name])
      @options[:gem_path] ||= "./#{options[:gem_file_name]}"
      %w{ README.md Changelog.md Gemfile RakeFile LICENSE test/test_helper.rb }.each{ |path| render_file path }
      render_file 'sample.gemspec', "#{@options[:gem_file_name]}.gemspec"
      render_file 'test/sample_test.rb', "test/#{@options[:gem_file_name]}_test.rb"
      render_file 'lib/sample.rb', "lib/#{@options[:gem_file_name]}.rb"
      if @options[:executable]
        render_file('bin/sample', "bin/#{@options[:gem_file_name]}")
        exec_path = result_path "bin/#{@options[:gem_file_name]}"
        `chmod +x #{exec_path}`
      end
      puts "Your gem is ready at #{@options[:gem_path]}, start coding!" if cli_mode
    end
  
    # 'My gem' => 'my_gem'
    def underscore(gem_name)
      gem_name.strip.downcase.gsub(' ', '_')
    end
  
    # 'My gem' => 'MyGem'
    def classify(gem_name)
      gem_name.strip.split.map{ |word| word.capitalize}.join.gsub(' ', '')
    end
    
    def render_file(path, result_file_path = path)
      source_path = File.join 'template', path
      result_file_path = result_path(result_file_path)
      FileUtils.mkdir_p File.dirname(result_file_path)
      result = ERB.new(File.read(source_path)).result(binding)
      File.open(result_file_path, 'w') {|f| f.write(result) }
    end
  
    def result_path(source_path)
      File.join @options[:gem_path], source_path
    end
  
  end
  
end