module Trigga
  module ParamFu
    def self.included(base)
      base.extend(AllMethods)
      base.send(:include, AllMethods)
    end
    
    module AllMethods
      def require_obj_or_id(opts, key)
        obj_or_id(opts,key)
        raise ArgumentError.new("#{key} or #{key_with_id(key)} are required") unless opts[key_with_id(key)]
        opts
      end
      
      def require_param(opts, *keys)
        keys.to_a.each do |k|
          raise ArgumentError.new("#{k} is required") unless opts[k]
        end
        opts
      end

      def obj_or_id(opts, key)
        opts[key_with_id(key)] ||= opts[key].id if opts[key]
      end
      
      def key_with_id(key)
        (key.to_s + '_id').to_sym
      end
      
      def require_one_of( opts, *keys )
        present = (opts.keys & keys)
        raise ArgumentError.new( "at least one of the arguments #{keys.inspect} is required" ) if present.empty?
        return present
      end
      
      def id_or_name_condition(table, val)
        condition = {:where => nil, :values=>nil}
        unless val.to_s.empty?
          unless val.to_s.match(/[^0-9]/)
            condition[:where] = "#{table}.id = ?"
            condition[:values] = val.to_i
          else
            condition[:where] = "#{table}.name LIKE ?"
            condition[:values] = "#{'%' + val.gsub(/\s*\(\d+\)/,"")  + '%'}"
          end
        end
        condition
      end
      
      
      # fallback when we don't have ActiveSupport's pluralize method available
      def to_plural(s)
        (s.match(/[aeiou]$/i) ? s + 's' : s + 'es' )
      end
      
      # Give this a hash per model in the format:
      # Model class => { param_name => { :operator=>(db operator - defaults to '='), 
      # =>                              :field_name=>(field_name in the database - defaults to param_name) 
      # =>                            }
      # =>             }
      # and it will return an ActiveRecord finder :conditions clause using any params which are present in the given :params
      # e.g. if you have params = { :created_date_from=>'2011-10-09 00:01:02', :status=>'A', :click_url=>'items.html' }
      # then calling:
      # 
      # params_to_conditions( :params=>params, :models=>{
      #  Click => {:click_url=>{ :operator=>"like", :field_name=>'request_path' }, 
      #            :status => {},
      #            :http_referer=>{:operator=>'like'},
      #            :created_date_from => {:operator=> ">=", :field_name=>'timestamp'}
      #            }
      # })
      #
      #
      # will generate:
      #
      # [ 'clicks.request_path like (?) AND clicks.status = ? AND clicks.created_date_from >= ?', '%items.html%', 'A', '2011-10-09 00:01:02' ]
      #
      # It will ignore any criteria given which are NOT in the given :params hash
      #
      def params_to_conditions( opts={} )
        require_param(opts, :params, :models) 
        
        conds = { :where=>[], :values=>[] }

        opts[:models].each { |model_class, field_defs|
          parsed_model_conditions = model_conditions( opts[:params], model_class, field_defs )
          conds[:where]  += parsed_model_conditions[:where]
          conds[:values] += parsed_model_conditions[:values]
        }
       
        [ conds[:where].join(" AND ") ] + conds[:values]
      end
      
      def model_conditions( opts, model_class, field_defs )
        h = {:where=>[], :values=>[]}
        field_defs.each{ |field_name, definition|
          parsed_field_def = parse_field_definition( opts, model_class, field_name, definition )
          h[:where] += parsed_field_def[:where]
          h[:values] += parsed_field_def[:values]
        }
        h
      end
      
      def parse_field_definition( opts, model_class, param_name, definition )
        c = {:where=>[], :values=>[]}
        if opts[param_name]
          c[:where] << "( #{model_class.table_name}.#{definition[:field_name] || param_name.to_s} #{definition[:operator] || '='} (?) )" 
          c[:values] << opts[param_name] 
        end
        c
      end
    end
  end
end