require 'criterion'
require 'restrictions'
module Criteria

  # Represents a query constructed out of #Criterion objects.
  # Query is itself a criterion and thus exposes all restriction helper methods
  class Query < CriterionContainer
    attr_accessor :limit
    attr_accessor :offset
    attr_reader :model_class
    
    # Construct a new query for the given _model_class_
    def initialize(model_class)
      super()
      @model_class = model_class
      @join_aliases = {}
      @join_aliases[model_class.table_name] = model_class.table_name
      yield self if block_given?
    end
    
    # builds the correct join alias for association includes
    # the table name is determined by reflecting on the parent model classes' attributes
    # if this is the first time this table is used in the query, user the table name as the alias
    # for subsequent uses, uses <pluralized_attribute_name>_<table_name>[_index] where index is only used if the same association is used more than once (see ActiveRecord::Associations::Base)
    def join_alias(reflection, model_class, parent_model_class)
      table_name = model_class.table_name
      new_alias = table_name
      if @join_aliases[table_name]
        new_alias = "#{reflection.pluralize}_#{parent_model_class.table_name}"
        if @join_aliases[table_name].include? new_alias
          new_alias += '1'
          while @join_aliases[table_name].include? new_alias
            new_alias = new_alias.succ
          end
        end
      end
      (@join_aliases[table_name] ||= []) << new_alias
      return new_alias
    end
    
    # execute the finder query.
    def find(options={})
      @model_class.send('find', :all, build_query(options))
    end
    
    def query
      self
    end
    
    # returns the table prefix for this model
    def prefix
      @model_class.name.pluralize.underscore
    end
    
    private
    
    # builds the AR query conditions, parameters and includes
    def build_query(options={})
      conditions = build_conditions
      includes = joins
      query_params = options
      query_params[:conditions] = conditions if conditions && !conditions.empty?
      query_params[:include] = includes if includes && !includes.empty?
      p query_params if $DEBUG
      query_params
    end
    
    def build_conditions
      con = condition
      nil unless con
      par = params
      ([con].concat par).compact
    end
    
  end

end