require 'couch'
require 'couch/generators/base'

module Couch
  module Generators
    # Receives a name, arguments and the behavior to invoke the generator.
    # It's used as the default entry point for generate and destroy commands.
    def self.invoke(name, args = ARGV, config = {})
      if klass = lookup(name.to_s)
        args << "--help" if args.empty? && klass.arguments.any? { |a| a.required? }
        klass.start(args, config)
      else
        puts "Could not find generator #{name}."
      end
    end

    # Show help message with available generators.
    def self.help(command = 'generate')
      path = File.expand_path("../generators/*/*_generator.rb", __FILE__)
      generators = Dir.glob(path)
      generators.sort!
      generators.map! { |f| File.basename(f) }
      generators.map! { |n| n.sub!(/_generator\.rb$/, '')  }
      longest_name_size = generators.map { |g| g.size }.sort.last
      generators.map! { |g| "%s  # %s" % [g.ljust(longest_name_size), lookup(g).info] }

      puts "Usage: couch #{command} GENERATOR [args] [options]"
      puts
      puts "General options:"
      puts "  -h, [--help]     # Print generators options and usage"
      puts "  -p, [--pretend]  # Run but do not make any changes"
      puts "  -f, [--force]    # Overwrite files that already exist"
      puts "  -s, [--skip]     # Skip files that already exist"
      puts "  -q, [--quiet]    # Supress status output"
      puts
      puts "Please choose a generator below:"
      puts
      puts generators
    end

    protected

    def self.lookup(name)
      # real path
      path = File.expand_path("../generators/#{name}/#{name}_generator.rb", __FILE__)
      # no matches?
      unless File.exists?(path)
        # try to find by prefix
        found = Dir.glob(File.expand_path("../generators/#{name}*/#{name}*_generator.rb", __FILE__))
        if found.size == 1
          path = found.first
          name = File.basename(path).sub(/_generator\.rb$/, '')
        end
      end
      require path
      const_get "#{name.classify}Generator"
    rescue LoadError => e
      raise unless e.message =~ /#{Regexp.escape(path)}$/
    rescue Exception => e
      warn "[WARNING] Could not load generator #{path.inspect}. Error: #{e.message}.\n#{e.backtrace.join("\n")}"
    end
  end
end