diff --git a/app/models/submission.rb b/app/models/submission.rb
new file mode 100644
--- /dev/null
+++ b/app/models/submission.rb
@@ -0,0 +1,64 @@
+class Submission < ActiveRecord::Base
+
+  belongs_to :language
+  belongs_to :problem
+
+  def self.find_by_user_and_problem(user_id, problem_id)
+    subcount = count(:conditions => "user_id = #{user_id} AND problem_id = #{problem_id}")
+    if subcount != 0
+      last_sub = find(:first, 
+		      :conditions => {:user_id => user_id,
+			:problem_id => problem_id},
+		      :order => 'submitted_at DESC')
+    else
+      last_sub = nil
+    end
+    return subcount, last_sub
+  end
+
+  def self.find_last_by_problem(problem_id)
+    # need to put in SQL command, maybe there's a better way
+    Submission.find_by_sql("SELECT * FROM submissions " +
+			   "WHERE id = " +
+			   "(SELECT MAX(id) FROM submissions AS subs " +
+			   "WHERE subs.user_id = submissions.user_id AND " +
+                           "problem_id = " + problem_id.to_s + " " +
+			   "GROUP BY user_id)")
+  end
+
+  def self.find_option_in_source(option, source)
+    i = 0
+    source.each_line do |s|
+      if s =~ option
+	words = s.split
+	return words[1]
+      end
+      i = i + 1
+      if i==10
+	return nil
+      end
+    end
+    return nil
+  end
+
+  def self.find_language_in_source(source)
+    langopt = find_option_in_source(/^LANG:/,source)
+    if language = Language.find_by_name(langopt)
+      return language
+    elsif language = Language.find_by_pretty_name(langopt)
+      return language
+    else
+      return nil
+    end
+  end
+
+  def self.find_problem_in_source(source)
+    prob_opt = find_option_in_source(/^TASK:/,source)
+    if problem = Problem.find_by_name(prob_opt)
+      return problem
+    else
+      return nil
+    end
+  end
+
+end