Re-implement <power>Cost() conditions in clearer way.

diff --git a/conditions/PowerCost.lua b/conditions/PowerCost.lua
index a9b710d..b7f113a 100644
--- a/conditions/PowerCost.lua
+++ b/conditions/PowerCost.lua
@@ -1,6 +1,6 @@
 --[[--------------------------------------------------------------------
     Ovale Spell Priority
-    Copyright (C) 2013 Johnny C. Lam
+    Copyright (C) 2013, 2014 Johnny C. Lam

     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License in the LICENSE
@@ -11,33 +11,74 @@ local _, Ovale = ...

 do
 	local OvaleCondition = Ovale.OvaleCondition
+	local OvaleState = Ovale.OvaleState

-	local API_GetSpellInfo = GetSpellInfo
 	local Compare = OvaleCondition.Compare
+	local state = OvaleState.state

-	--- Get the resource cost of the given spell.
+	-- Return the amount of power of the given power type required to cast the given spell.
+	local function PowerCost(powerType, condition)
+		local spellId, comparator, limit = condition[1], condition[2], condition[3]
+		local value = state:PowerCost(spellId, powerType) or 0
+		return Compare(value, comparator, limit)
+	end
+
+	--- Get the amount of energy required to cast the given spell.
 	-- This returns zero for spells that use either mana or another resource based on stance/specialization, e.g., Monk's Jab.
-	-- @name PowerCost
+	-- @name EnergyCost
 	-- @paramsig number or boolean
 	-- @param id The spell ID.
 	-- @param operator Optional. Comparison operator: less, atMost, equal, atLeast, more.
 	-- @param number Optional. The number to compare against.
-	-- @return The amount of power (energy, focus, rage, etc.).
+	-- @return The amount of energy.
 	-- @return A boolean value for the result of the comparison.
-	-- @see EnergyCost, FocusCost, ManaCost, RageCost
-	-- @usage
-	-- if Energy() > PowerCost(rake) Spell(rake)

-	local function PowerCost(condition)
-		local spellId, comparator, limit = condition[1], condition[2], condition[3]
-		local _, _, _, cost = API_GetSpellInfo(spellId)
-		local value = cost or 0
-		return Compare(value, comparator, limit)
+	local function EnergyCost(condition)
+		return PowerCost("energy", condition)
+	end
+
+	--- Get the amount of focus required to cast the given spell.
+	-- @name FocusCost
+	-- @paramsig number or boolean
+	-- @param id The spell ID.
+	-- @param operator Optional. Comparison operator: less, atMost, equal, atLeast, more.
+	-- @param number Optional. The number to compare against.
+	-- @return The amount of focus.
+	-- @return A boolean value for the result of the comparison.
+
+	local function FocusCost(condition)
+		return PowerCost("focus", condition)
+	end
+
+	--- Get the amount of mana required to cast the given spell.
+	-- This returns zero for spells that use either mana or another resource based on stance/specialization, e.g., Monk's Jab.
+	-- @name ManaCost
+	-- @paramsig number or boolean
+	-- @param id The spell ID.
+	-- @param operator Optional. Comparison operator: less, atMost, equal, atLeast, more.
+	-- @param number Optional. The number to compare against.
+	-- @return The amount of mana.
+	-- @return A boolean value for the result of the comparison.
+
+	local function ManaCost(condition)
+		return PowerCost("mana", condition)
+	end
+
+	--- Get the amount of rage required to cast the given spell.
+	-- @name RageCost
+	-- @paramsig number or boolean
+	-- @param id The spell ID.
+	-- @param operator Optional. Comparison operator: less, atMost, equal, atLeast, more.
+	-- @param number Optional. The number to compare against.
+	-- @return The amount of rage.
+	-- @return A boolean value for the result of the comparison.
+
+	local function RageCost(condition)
+		return PowerCost("rage", condition)
 	end

-	OvaleCondition:RegisterCondition("energycost", true, PowerCost)
-	OvaleCondition:RegisterCondition("focuscost", true, PowerCost)
-	OvaleCondition:RegisterCondition("manacost", true, PowerCost)
-	OvaleCondition:RegisterCondition("powercost", true, PowerCost)
-	OvaleCondition:RegisterCondition("ragecost", true, PowerCost)
+	OvaleCondition:RegisterCondition("energycost", true, EnergyCost)
+	OvaleCondition:RegisterCondition("focuscost", true, FocusCost)
+	OvaleCondition:RegisterCondition("manacost", true, ManaCost)
+	OvaleCondition:RegisterCondition("ragecost", true, RageCost)
 end
\ No newline at end of file