Add basic trend to individual month results ("+50% from last month") …

…lots of todos here

lib/weed/stats.rb

@@ -45,10 +45,15 @@ def self.find_by_day(date, conditions)
     end
   end
 
-  def self.by_month(year, month, conditions)
+  def self.by_month(year, month, conditions, flags = [])
     # nil bucket_id means ANY bucket_id, but that's only relevant on creating cached records
     cached_conditions = { :bucket_id => nil }.merge(conditions)
-    Weed::CachedStats.with_scope(:find => {:conditions => cached_conditions }) do
+    if flags && flags == :trend || flags.include?(:trend)
+      this_month = Date.new year, month, 1
+      previous_month = this_month - 2 # go back a day
+      previous = by_month(previous_month.year, previous_month.month, conditions)
+    end
+    result = Weed::CachedStats.with_scope(:find => {:conditions => cached_conditions }) do
       unless cached = Weed::CachedStats.first(:conditions => ['period = ? AND year = ? AND month = ?', 'month', year, month])
         days = Weed::CachedStats.count(:conditions => ['period = ? AND year = ? AND month = ?', 'day', year, month])
         today = Date.today
@@ -68,6 +73,13 @@ def self.by_month(year, month, conditions)
         cached.counter 
       end
     end
+    if flags && flags == :trend || flags.include?(:trend)
+      delta = result - previous
+      [result, previous, "#{(delta * 100 / previous)}%"]
+      # todo: store this in the CachedStats model so we don't have to calc it each time
+    else
+      result
+    end
   end
 
   def self.by_year(year, conditions)

test/stats_test.rb

@@ -57,6 +57,36 @@ class StatsTest < ActiveSupport::TestCase
     assert_equal 0, Weed::CachedStats.sum('counter', :conditions => { :year => date.year, :period => "year", :bucket_id => 13 })
   end
 
+  context "with trends" do
+    it "gives a trend" do
+      date = Date.new(2010, 1, 4)
+      2.times { Weed::Stats.hit!({ :bucket_id => 15, :cdate => date - 40}) }
+      2.times { Weed::Stats.hit!({ :bucket_id => 15, :cdate => date - 20}) }
+      2.times { Weed::Stats.hit!({ :bucket_id => 15, :cdate => date }) }
+
+      stats = Weed::Stats.by_month date.year, date.month, { :bucket_id => 15 }, :trend
+      assert_equal [2, 2, '0%'], stats
+    end
+
+    it "shows a rising trend" do
+      date = Date.new(2010, 1, 4)
+      2.times { Weed::Stats.hit!({ :bucket_id => 125, :cdate => date - 20}) }
+      3.times { Weed::Stats.hit!({ :bucket_id => 125, :cdate => date }) }
+
+      stats = Weed::Stats.by_month date.year, date.month, { :bucket_id => 125 }, :trend
+      assert_equal [3, 2, '50%'], stats
+    end
+
+    it "shows a falling trend" do
+      date = Date.new(2010, 1, 4)
+      4.times { Weed::Stats.hit!({ :bucket_id => 135, :cdate => date - 20}) }
+      2.times { Weed::Stats.hit!({ :bucket_id => 135, :cdate => date }) }
+
+      stats = Weed::Stats.by_month date.year, date.month, { :bucket_id => 135 }, :trend
+      assert_equal [2, 4, '-50%'], stats
+    end
+  end
+
   # this is slow as fuck
   # it "calculates total results" do
   #   # provide a range of year data

weed.rb

@@ -59,7 +59,6 @@ class Application < Sinatra::Base
       end
       { "state" => "success", "imported" => counter }.to_json
     end
-
 
     # todo: auth