require 'open3'

module Rails
  module Upgrading
    class ApplicationChecker
      def initialize
        @issues = []
        
        raise NotInRailsAppError unless in_rails_app?
      end
      
      def in_rails_app?
        File.exist?("config/environment.rb")
      end
      
      # Run all the check methods
      def run
        the_methods = (self.public_methods - Object.methods) - ["run", "initialize"]
        
        the_methods.each {|m| send m }
      end
      
      # Check for deprecated ActiveRecord calls
      def check_ar_methods
        files = []
        ["find(:all", "find(:first", ":conditions =>", ":joins =>"].each do |v|
          lines = grep_for(v, "app/")
          files += extract_filenames(lines) || []
        end
        
        unless files.empty?
          alert(
            "Soon-to-be-deprecated ActiveRecord calls", 
            "Methods such as find(:all), find(:first), finds with conditions, and the :joins option will soon be deprecated.",
            "http://m.onkey.org/2010/1/22/active-record-query-interface",
            files
          )
        end

        lines = grep_for("named_scope", "app/models/")
        files = extract_filenames(lines)
        
        if files
          alert(
            "named_scope is now just scope", 
            "The named_scope method has been renamed to just scope.",
            "http://github.com/rails/rails/commit/d60bb0a9e4be2ac0a9de9a69041a4ddc2e0cc914",
            files
          )
        end
      end
      
      # Check for deprecated router syntax
      def check_routes
        lines = ["map.", "ActionController::Routing::Routes", ".resources"].map do |v|
          grep_for(v, "config/routes.rb").empty? ? nil : true
        end.compact
        
        unless lines.empty?
          alert(
            "Old router API", 
            "The router API has totally changed.",
            "http://yehudakatz.com/2009/12/26/the-rails-3-router-rack-it-up/",
            "config/routes.rb"
          )
        end
      end
      
      # Check for old (pre-application.rb) environment.rb file
      def check_environment
        unless File.exist?("config/application.rb")
          alert(
            "New file needed: config/application.rb", 
            "You need to add a config/application.rb.",
            "http://omgbloglol.com/post/353978923/the-path-to-rails-3-approaching-the-upgrade",
            "config/application.rb"
          )
        end
        
        lines = grep_for("config.", "config/environment.rb")
        
        unless lines.empty?
          alert(
            "Old environment.rb", 
            "environment.rb doesn't do what it used to; you'll need to move some of that into application.rb.",
            "http://omgbloglol.com/post/353978923/the-path-to-rails-3-approaching-the-upgrade",
            "config/environment.rb"
          )
        end
      end
      
      # Check for old-style config.gem calls
      def check_gems
        lines = grep_for("config.gem ", "config/*.rb")
        files = extract_filenames(lines)
        
        if files
          alert(
            "Old gem bundling (config.gems)", 
            "The old way of bundling is gone now.  You need a Gemfile for bundler.",
            "http://omgbloglol.com/post/353978923/the-path-to-rails-3-approaching-the-upgrade",
            files
          )
        end
      end
      
      # Checks for old mailer syntax in both mailer classes and those
      # classes utilizing the mailers
      def check_mailers
        lines = grep_for("deliver_", "app/models/ #{base_path}app/controllers/ #{base_path}app/observers/")
        files = extract_filenames(lines)
        
        if files
          alert(
            "Deprecated ActionMailer API", 
            "You're using the old ActionMailer API to send e-mails in a controller, model, or observer.",
            "http://lindsaar.net/2010/1/26/new-actionmailer-api-in-rails-3",
            files
          )
        end
        
        files = []
        ["recipients ", "attachment ", "subject ", "from "].each do |v|
          lines = grep_for(v, "app/models/")
          files += extract_filenames(lines) || []
        end
        
        unless files.empty?
          alert(
            "Old ActionMailer class API", 
            "You're using the old API in a mailer class.",
            "http://lindsaar.net/2010/1/26/new-actionmailer-api-in-rails-3",
            files
          )
        end
      end
      
      # Checks for old-style generators
      def check_generators
        generators = Dir.glob(base_path + "vendor/plugins/**/generators/**/")
        
        unless generators.empty?
          files = generators.map do |g|
                    grep_for("def manifest", g).empty? ? g : nil
                  end.compact
        
          if files
            alert(
              "Old Rails generator API", 
              "A plugin in the app is using the old generator API (a new one may be available at http://github.com/trydionel/rails3-generators).",
              "http://blog.plataformatec.com.br/2010/01/discovering-rails-3-generators/",
              files
            )
          end
        end
      end
      
      # Checks a list of known broken plugins and gems
      def check_plugins
        # This list is off the wiki; will need to be updated often, esp. since RSpec is working on it
        bad_plugins = ["rspec", "rspec-rails", "hoptoad", "authlogic", "nifty-generators",
           "restful_authentication", "searchlogic", "cucumber", "cucumber-rails", "devise",
           "inherited_resources"]
        
        bad_plugins = bad_plugins.map do |p| 
                        p if File.exist?("#{base_path}vendor/plugins/#{p}") || !Dir.glob("#{base_path}vendor/gems/#{p}-*").empty?
                      end.compact

        unless bad_plugins.empty?
          alert(
            "Known broken plugins", 
            "At least one plugin in your app is broken (according to the wiki).  Most of project maintainers are rapidly working towards compatability, but do be aware you may encounter issues.",
            "http://wiki.rubyonrails.org/rails/version3/plugins_and_gems",
            bad_plugins
          )
        end
      end
      
    private
      # Find a string in a set of files; calls +find_with_grep+ and +find_with_rak+
      # depending on platform.
      #
      # TODO: Figure out if this works on Windows.
      def grep_for(text, where = "./")
        # If they're on Windows, they probably don't have grep.
        @probably_has_grep ||= (Config::CONFIG['host_os'].downcase =~ /mswin|windows|mingw/).nil?

        if @probably_has_grep
          find_with_grep(text, base_path + where)
        else
          find_with_rak(text, base_path + where)
        end
      end
      
      # Sets a base path for finding files; mostly for testing
      def base_path
        Dir.pwd + "/"
      end
      
      # Use the grep utility to find a string in a set of files
      def find_with_grep(text, where)
        value = ""
      
        Open3.popen3("grep -r '#{text}' #{where}") do |stdin, stdout, stderr|
          value = stdout.read
        end
      
        value
      end
      
      # Use the rak gem to grep the files (not yet implemented)
      def find_with_rak(text, where)
        value = ""

        Open3.popen3("rak --nogroup -l '#{Regexp.escape(text)}' #{where}") do |stdin, stdout, stderr|
          value = stdout.read
        end
      
        value
      end
      
      # Extract the filenames from the grep output
      def extract_filenames(output)
        if @probably_has_grep
          extract_filenames_from_grep(output)
        else
          extract_filenames_from_rak(output)
        end
      end
      
      def extract_filenames_from_grep(output)
        return nil if output.empty?
        
        # I hate rescue nil as much as the next guy but I have a reason here at least...
        fnames = output.split("\n").map do |fn| 
          fn.match(/^(.+?):/)[1] rescue nil
        end.compact
        
        fnames.uniq
      end
      
      def extract_filenames_from_rak(output)
        return nil if output.empty?
        
        output.split("\n").uniq
      end
      
      # Terminal colors, borrowed from Thor
      CLEAR      = "\e[0m"
      BOLD       = "\e[1m"
      RED        = "\e[31m"
      YELLOW     = "\e[33m"
      CYAN       = "\e[36m"
      WHITE      = "\e[37m"
      
      # Show an upgrade alert to the user
      def alert(title, text, more_info_url, culprits)
        if Config::CONFIG['host_os'].downcase =~ /mswin|windows|mingw/
          basic_alert(title, text, more_info_url, culprits)
        else
          color_alert(title, text, more_info_url, culprits)
        end
      end
      
      # Show an upgrade alert to the user.  If we're on Windows, we can't
      # use terminal colors, hence this method.
      def basic_alert(title, text, more_info_url, culprits)
        puts "** " + title
        puts text
        puts "More information: #{more_info_url}"
        puts
        puts "The culprits: "
        culprits.each do |c|
          puts "\t- #{c}"
        end
        puts
      end
      
      # Show a colorful alert to the user
      def color_alert(title, text, more_info_url, culprits)
        puts "#{RED}#{BOLD}#{title}#{CLEAR}"
        puts "#{WHITE}#{text}"
        puts "#{BOLD}More information:#{CLEAR} #{CYAN}#{more_info_url}"
        puts
        puts "#{WHITE}The culprits: "
        culprits.each do |c|
          puts "#{YELLOW}\t- #{c}"
        end
      ensure
        puts "#{CLEAR}"
      end
    end
  end
end