require File.dirname(__FILE__) + '/scm/scm'
require File.dirname(__FILE__) + '/scm/git'
require File.dirname(__FILE__) + '/scm/svn'

require 'open-uri'
require 'fileutils'

module Rails
  class TemplateRunner
    attr_reader :behavior, :description, :root

    def initialize(root, template) # :nodoc:
      @root = Dir.pwd + "/" + root

      puts "applying template: #{template}"

      load_template(template)

      puts "#{template} applied."
    end

    def load_template(template)
      begin
        code = open(template).read
        in_root { self.instance_eval(code) }
      rescue LoadError
        raise "The template [#{template}] could not be loaded."
      end
    end

    # Create a new file in the Rails project folder.  Specify the
    # relative path from RAILS_ROOT.  Data is the return value of a block
    # or a data string.
    #
    # ==== Examples
    #
    #     file("lib/fun_party.rb") do
    #       hostname = ask("What is the virtual hostname I should use?")
    #       "vhost.name = #{hostname}"
    #     end
    #
    #     file("config/apach.conf", "your apache config")
    #
    def file(filename, data = nil, &block)
      puts "creating file #{filename}"
      dir, file = [File.dirname(filename), File.basename(filename)]

      inside(dir) do
        File.open(file, "w") do |f|
          if block_given?
            f.write(block.call)
          else
            f.write(data)
          end
        end
      end
    end

    # Install a plugin.  You must provide either a Subversion url or Git url.
    #
    # ==== Examples
    #
    #     plugin 'restful-authentication', :git => 'git://github.com/technoweenie/restful-authentication.git'
    #     plugin 'restful-authentication', :svn => 'svn://svnhub.com/technoweenie/restful-authentication/trunk'
    #
    def plugin(name, options)
      puts "installing plugin #{name}"

      if options[:git] || options[:svn]
        in_root do
          `script/plugin install #{options[:svn] || options[:git]}`
        end
      else
        puts "! no git or svn provided for #{name}.  skipping..."
      end
    end

    # Install a gem into vendor/gems.  You can install a gem in one of three ways:
    #
    #   1. Provide a git repository URL...
    #
    #       gem 'will-paginate', :git => 'git://github.com/mislav/will_paginate.git'
    #
    #   2. Provide a subversion repository URL...
    #
    #       gem 'will-paginate', :svn => 'svn://svnhub.com/mislav/will_paginate/trunk'
    #
    #   3. Provide a gem name and use your system sources to install and unpack it.
    #
    #       gem 'ruby-openid'
    #
    def gem(name, options = {})
      puts "vendoring gem #{name}"
      if options[:git]
        inside("vendor/gems") { Git.clone(options[:git], options[:branch]) }
      elsif options[:svn]
        inside("vendor/gems") { Svn.checkout(options[:svn], options[:branch]) }
      else
        # TODO: Gem dependencies.  Split output on \n, iterate lines looking for Downloaded...
        inside("vendor/gems") do
          # Filename may be different than gem name
          filename = (`gem fetch #{name}`).chomp.gsub(/Downloaded /, '')
          `gem unpack #{filename}.gem`
          File.delete("#{filename}.gem")
        end
      end
    end

    # Run a command in git.
    #
    # ==== Examples
    #
    #     git :init
    #     git :add => "this.file that.rb"
    #     git :add => "onefile.rb", :rm => "badfile.cxx"
    #
    def git(command = {})
      puts "running git #{command}"

      in_root do
        if command.is_a?(Symbol)
          Git.run(command.to_s)
        else
          command.each do |command, options|
            Git.run("#{command} #{options}")
          end
        end
      end
    end

    # Create a new file in the vendor/ directory. Code can be specified
    # in a block or a data string can be given.
    #
    # ==== Examples
    #
    #     vendor("sekrit.rb") do
    #       sekrit_salt = "#{Time.now}--#{3.years.ago}--#{rand}--"
    #       "salt = '#{sekrit_salt}'"
    #     end
    #
    #     vendor("foreign.rb", "# Foreign code is fun")
    #
    def vendor(filename, data = nil, &block)
      puts "vendoring file #{filename}"
      inside("vendor") do |folder|
        File.open("#{folder}/#{filename}", "w") do |f|
          if block_given?
            f.write(block.call)
          else
            f.write(data)
          end
        end
      end
    end

    # Create a new file in the lib/ directory. Code can be specified
    # in a block or a data string can be given.
    #
    # ==== Examples
    #
    #     lib("crypto.rb") do
    #       "crypted_special_value = '#{rand}--#{Time.now}--#{rand(1337)}--'"
    #     end
    #
    #     lib("foreign.rb", "# Foreign code is fun")
    #
    def lib(filename, data = nil)
      puts "add lib file #{filename}"
      inside("lib") do |folder|
        File.open("#{folder}/#{filename}", "w") do |f|
          if block_given?
            f.write(block.call)
          else
            f.write(data)
          end
        end
      end
    end

    # Create a new Rake task in the lib/tasks/application.rake file.
    # Code can be specified  in a block or a data string can be given.
    #
    # ==== Examples
    #
    #     task(:whatever) do
    #       name = ask("What should the task be named?")
    #
    #       "
    #         task :#{name} do
    #           puts 'hi from rake'
    #         end
    #       "
    #     end
    #
    #     task(:go_away, "puts 'be gone!'")
    #
    def task(name, description = nil, &block)
      puts "adding task :#{name}"
      inside("lib/tasks") do |folder|
        File.open("#{folder}/application.rake", "a+") do |f|
          if block_given?
            f.write(block.call)
          else
            f.write(data)
          end
        end
      end
    end

    # Create a new Rakefile with the provided code (either in a block or a string).
    #
    # ==== Examples
    #
    #    rakefile("bootstrap.rake") do
    #      project = ask("What is the UNIX name of your project?")
    #
    #      "namespace :#{project} do
    #         task :bootstrap do
    #           puts "i like boots!"
    #         end
    #       end"
    #   end
    #
    #    rakefile("seed.rake", "puts 'im plantin ur seedz'")
    #
    def rakefile(filename, data = nil, &block)
      puts "adding rakefile #{filename}"
      inside("lib/tasks") do |folder|
        File.open("#{folder}/#{filename}", "w") do |f|
          if block_given?
            f.write(block.call)
          else
            f.write(data)
          end
        end
      end
    end

    # Create a new initializer with the provided code (either in a block or a string).
    #
    # ==== Examples
    #
    #    initializer("globals.rb") do
    #      data = ""
    #
    #      ['MY_WORK', 'ADMINS', 'BEST_COMPANY_EVAR'].each do
    #        data << "#{const} = :entp"
    #      end
    #
    #      data
    #    end
    #
    #    initializer("api.rb", "API_KEY = '123456'")
    #
    def initializer(filename, data = nil, &block)
      puts "adding initializer #{filename}"
      inside("config/initializers") do |folder|
        File.open("#{folder}/#{filename}", "w") do |f|
          if block_given?
            f.write(block.call)
          else
            f.write(data)
          end
        end
      end
    end

    # Generate something using a generator from Rails or a plugin.
    # The second parameter is the argument string that is passed to
    # the generator or an Array that is joined.
    #
    # ==== Example
    #
    #     generate(:authenticated, "user session")
    #
    def generate(what, args = nil)
      puts "generating #{what}"
      args = args.join(" ") if args.class == Array

      in_root { `#{root}/script/generate #{what} #{args}` }
    end

    # Executes a command
    #
    # ==== Example
    # inside('vendor') do
    #   run('ln -s ~/edge rails)
    # end
    def run(command)
      puts "executing #{command} from #{Dir.pwd}"
      `#{command}`
    end

    # Just run the capify command in root
    #
    # ==== Example
    #
    #     capify!
    #
    def capify!
      in_root { `capify .` }
    end

    # Add Rails to /vendor/rails
    #
    # ==== Example
    #
    #     freeze!
    #
    def freeze!(args = {})
      puts "vendoring rails edge"
      in_root { `rake rails:freeze:edge` }
    end

    # Get a user's input
    #
    # ==== Example
    #
    #     answer = ask("Should I freeze the latest Rails?")
    #     freeze! if ask("Should I freeze the latest Rails?") == "yes"
    #
    def ask(string)
      puts string
      gets.strip
    end

    # Make an entry in Rails routing file conifg/routes.rb
    #
    # === Example
    #
    # route "map.root :controller => :welcome"
    #
    def route(routing_code)
      sentinel = 'ActionController::Routing::Routes.draw do |map|'

      in_root do
        gsub_file 'config/routes.rb', /(#{Regexp.escape(sentinel)})/mi do |match|
          "#{match}\n  #{routing_code}\n"
        end
      end
    end

    protected

    # Do something in the root of the Rails application or
    # a provided subfolder; the full path is yielded to the block you provide.
    # The path is set back to the previous path when the method exits.
    def inside(dir = '', &block)
      folder = File.join(root, dir)
      FileUtils.mkdir_p(folder) unless File.exist?(folder)
      FileUtils.cd(folder) { block.arity == 1 ? yield(folder) : yield }
    end

    def in_root
      FileUtils.cd(root) { yield }
    end

    # Helper to test if the user says yes(y)?
    #
    # ==== Example
    #
    #     freeze! if yes?("Should I freeze the latest Rails?")
    #
    def yes?(question)
      answer = ask(question).downcase
      answer == "y" || answer == "yes"
    end

    # Helper to test if the user does NOT say yes(y)?
    #
    # ==== Example
    #
    #     capify! if no?("Will you be using vlad to deploy your application?")
    #
    def no?(question)
      !yes?(question)
    end

    def gsub_file(relative_destination, regexp, *args, &block)
      path = destination_path(relative_destination)
      content = File.read(path).gsub(regexp, *args, &block)
      File.open(path, 'wb') { |file| file.write(content) }
    end

    def destination_path(relative_destination)
      File.join(root, relative_destination)
    end
  end
end