module BetterAr
  module FinderMethods
    # Breaks down the hash to do a {ActiveRecord::Relation} query
    #
    # example:
    #  User.all(:age => 10, :limit! => 2, :offset! => 3, :order! => :name)
    #
    # is the same as:
    #  User.where(:age => 10).limit(2).offset(3).order(:name)
    #
    # if the key :conditions is present it will fall back to legacy
    #
    # any key with the '!' at the end will be assumed to be a sql operator. The key should match either an {ActiveRecord::Relation} instance method or an ARel predicate.
    #
    # Implicit joins are supported.
    # example:
    #  User.all(:records => {:name => 'test'})
    #
    # is the same as:
    #  User.joins(:records).where(:records => {:name => 'test'})
    #
    # @param [Hash]
    #   Optional
    # @return [ActiveRecord::Relation]
    def all(opts = {})
      if opts.is_a?(Hash)
        if opts.empty?
          super()
        elsif opts.key?(:conditions)
          super(opts)
        else
          relation = clone
          relation = better_ar_apply_sql_clauses(relation, opts)
          relation = better_ar_apply_associations(relation, opts)
          relation.where(opts)
        end
      else
        relation = clone
        relation.where(opts)
      end
    end

    # Forces a limit of 1 on the collection
    #
    # example:
    #  User.first(:age => 10, :name => 'Brian')
    #
    # is the same as:
    #  User.where(:age => 10, :name => 'Brian').limit(1).first
    #
    # if the key :conditions is present it will fall back to legacy
    #
    # @param [Hash]
    #   Optional follows same convention as {#all}
    # @return [ActiveRecord::Base]
    def first(opts = {})
      if opts.empty?
        super()
      elsif opts.key?(:conditions)
        super(opts)
      else
        all(opts.merge(:limit! => 1)).first
      end
    end

    private

    def better_ar_apply_sql_clauses(relation, opts = {})
      opts.keys.select { |key| key.to_s =~ /!$/ }.each do |clause|
        if value = opts.delete(clause)
          relation = relation.send(clause.to_s.sub('!',''), value)
        end
      end

      relation
    end

    def better_ar_apply_associations(relation, opts = {})
      reflect_on_all_associations.select do |association|
        !association.options[:polymorphic] &&
          better_ar_join_keys(opts).include?(association.table_name.to_sym)
      end.each do |association|
        relation = relation.joins(association.name)
      end

      relation
    end

    def better_ar_join_keys(opts = {})
      opts.keys.select { |key| !opts[key].kind_of?(ActiveRecord::Base) }
    end

  end
end

ActiveRecord::Relation.send(:include, BetterAr::FinderMethods)