require 'optparse'

module Plist4r
  module Mixlib
    # <tt></tt>
    #   Author:: Adam Jacob (<adam@opscode.com>)
    #   Copyright:: Copyright (c) 2008 Opscode, Inc.
    #   License:: Apache License, Version 2.0
    #   
    #   Licensed under the Apache License, Version 2.0 (the "License");
    #   you may not use this file except in compliance with the License.
    #   You may obtain a copy of the License at
    #   
    #       http://www.apache.org/licenses/LICENSE-2.0
    #   
    #   Unless required by applicable law or agreed to in writing, software
    #   distributed under the License is distributed on an "AS IS" BASIS,
    #   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    #   See the License for the specific language governing permissions and
    #   limitations under the License.
    #
    module CLI
      module ClassMethods       
        # Add a command line option.
        #
        # === Parameters
        # name<Symbol>:: The name of the option to add
        # args<Hash>:: A hash of arguments for the option, specifying how it should be parsed.
        # === Returns
        # true:: Always returns true.
        def option(name, args)
          @options ||= {}
          raise(ArgumentError, "Option name must be a symbol") unless name.kind_of?(Symbol)
          @options[name.to_sym] = args
        end
      
        # Get the hash of current options.
        #
        # === Returns
        # @options<Hash>:: The current options hash.
        def options
          @options ||= {}
          @options
        end
      
        # Set the current options hash
        #
        # === Parameters
        # val<Hash>:: The hash to set the options to
        #
        # === Returns
        # @options<Hash>:: The current options hash.
        def options=(val)
          raise(ArgumentError, "Options must recieve a hash") unless val.kind_of?(Hash)
          @options = val
        end
      
        # Change the banner.  Defaults to:
        #   Usage: #{0} (options)
        #
        # === Parameters
        # bstring<String>:: The string to set the banner to
        # 
        # === Returns
        # @banner<String>:: The current banner
        def banner(bstring=nil)
          if bstring
            @banner = bstring
          else
            @banner ||= "Usage: #{$0} (options)"
            @banner
          end
        end
      end
    
      attr_accessor :options, :config, :banner, :opt_parser
    
      # Create a new Mixlib::CLI class.  If you override this, make sure you call super!
      #
      # === Parameters
      # *args<Array>:: The array of arguments passed to the initializer
      #
      # === Returns
      # object<Mixlib::Config>:: Returns an instance of whatever you wanted :)
      def initialize(*args)
        @options = Hash.new
        @config  = Hash.new
      
        # Set the banner
        @banner  = self.class.banner
      
        # Dupe the class options for this instance
        klass_options = self.class.options
        klass_options.keys.inject(@options) { |memo, key| memo[key] = klass_options[key].dup; memo }
      
        # Set the default configuration values for this instance
        @options.each do |config_key, config_opts|
          config_opts[:on] ||= :on
          config_opts[:boolean] ||= false
          config_opts[:required] ||= false
          config_opts[:proc] ||= nil
          config_opts[:show_options] ||= false
          config_opts[:exit] ||= nil
        
          if config_opts.has_key?(:default)
            @config[config_key] = config_opts[:default]
          end
        end
      
        super(*args)
      end
    
      # Parses an array, by default ARGV, for command line options (as configured at 
      # the class level).
      # === Parameters
      # argv<Array>:: The array of arguments to parse; defaults to ARGV
      #
      # === Returns
      # argv<Array>:: Returns any un-parsed elements.
      def parse_options(argv=ARGV)
        argv = argv.dup
        @opt_parser = OptionParser.new do |opts|  
          # Set the banner
          opts.banner = banner        
        
          # Create new options
          options.sort { |a, b| a[0].to_s <=> b[0].to_s }.each do |opt_key, opt_val|          
            opt_args = build_option_arguments(opt_val)
          
            opt_method = case opt_val[:on]
              when :on
                :on
              when :tail
                :on_tail
              when :head
                :on_head
              else
                raise ArgumentError, "You must pass :on, :tail, or :head to :on"
              end
                      
            parse_block = case opt_val[:boolean]
              when true
                Proc.new() do
                  config[opt_key] = (opt_val[:proc] && opt_val[:proc].call(true)) || true
                  puts opts if opt_val[:show_options]
                  exit opt_val[:exit] if opt_val[:exit]
                end
              when false
                Proc.new() do |c|
                  config[opt_key] = (opt_val[:proc] && opt_val[:proc].call(c)) || c
                  puts opts if opt_val[:show_options]
                  exit opt_val[:exit] if opt_val[:exit]
                end
              end
                    
            full_opt = [ opt_method ]
            opt_args.inject(full_opt) { |memo, arg| memo << arg; memo }
            full_opt << parse_block
            opts.send(*full_opt)
          end
        end
        @opt_parser.parse!(argv)
      
        # Deal with any required values
        options.each do |opt_key, opt_value|
          if opt_value[:required] && ! config[opt_key]
            reqarg = opt_value[:short] || opt_value[:long]
            puts "You must supply #{reqarg}!"
            puts @opt_parser
            exit 2
          end
        end
      
        argv
      end
    
      def build_option_arguments(opt_setting)      
        arguments = Array.new
      
        arguments << opt_setting[:short] if opt_setting.has_key?(:short)
        arguments << opt_setting[:long] if opt_setting.has_key?(:long)
      
        if opt_setting.has_key?(:description)
          description = opt_setting[:description]
          description << " (required)" if opt_setting[:required]
          arguments << description
        end
          
        arguments
      end
    
      def self.included(receiver)
        receiver.extend(Mixlib::CLI::ClassMethods)
      end
    
    end
  end
end