Starting to fill in tournament ranking bits

rails/map-mash/app/controllers/mashes_controller.rb

@@ -8,7 +8,7 @@ class MashesController < ApplicationController
   alias_method :show, :redirect_to_new
 
   def new
-    @map_a, @map_b = Map.rand(2)
+    @map_a, @map_b = Map.pair
 
     @mash = Mash.new(
       :requester => request.remote_ip,

rails/map-mash/app/models/map.rb

@@ -6,8 +6,39 @@ class Map < ActiveRecord::Base
     self.find_or_initialize_by_name(city_name).save!
   end
 
-  def self.rand(count = 2)
-    self.find(:all, :order => 'RANDOM()', :limit => count)
+  def self.pair
+    if Mash.count == 0
+      self.all(:order => 'RANDOM()', :limit => count)
+    else
+      first_conditions = <<-SQL
+      NOT EXISTS (
+          SELECT * FROM `mashes`
+          WHERE `winner` = `maps`.`id`
+      )
+      SQL
+      second_conditions = <<-SQL
+      `maps`.`id` != :first_id
+          AND (
+              SELECT COUNT(*) FROM `mashes`
+              WHERE `winner` = :first_id
+          ) = (
+              SELECT COUNT(*) FROM `mashes`
+              WHERE `winner` = `maps`.`id`
+          )
+      SQL
+
+      first = self.all(
+          :order => 'RANDOM()',
+          :limit => 1,
+          :conditions => [first_conditions]
+      ).first
+      second = self.all(
+          :order => 'RANDOM()',
+          :limit => 1,
+          :conditions => [second_conditions, {:first_id => first.id}]
+      ).first
+      [first, second]
+    end
   end
 
   def self.import(csv_filename)
@@ -22,4 +53,24 @@ class Map < ActiveRecord::Base
       end
     end
   end
+
+  def >(other)
+    self.points > other.points
+  end
+
+  def <(other)
+    self.points < other.points
+  end
+
+  def ==(other)
+    self.points == other.points
+  end
+
+  def rounds
+    Mash.count(:conditions => ['map_a = :id OR map_b = :id', {:id => self.id}])
+  end
+
+  def points
+    Mash.count(:conditions => ['winner = ?', self.id])
+  end
 end