--[[
    The existance of this source file is to allow WIM to run in its own
    AnimationSystem.lua environment. Until WoW 3.1 is released, this will be
    needed to avoid taint issues with the Vehicle Unit Frame (VUF). Since the
    VUF uses the same system, if WIM has an animation executing the same time
    VUF does, it causes VUF to be tainted and blocked. A poor design on
    Blizzard's part. Trust me, I don't want un-needed code packaged in WIM either.
]]

--[[	animTable = {	--Note that only consistent data should be in here. These tables are meant to be shared across "sessions" of animations. Put changing data in the frame.
	totalTime = number,		--Time to complete the animation in seconds.
	updateFunc = function,		--The function called to do the actual change. Takes self, elapsed fraction. Usually frame.SetPoint, frame.SetAlpha, ect.
	getPosFunc = function,		--The function returning the data being passed into updateFunc. For example. might return .18 if updateFunc is frame.SetAlpha.
--]]

-- imports
local WIM = WIM;
local _G = _G;
local table = table;
local type = type;
local pairs = pairs;

-- set namespace
setfenv(1, WIM);

local AnimatingFrames = {};

local AnimUpdateFrame = _G.CreateFrame("Frame");

local function Animation_UpdateFrame(self, animElapsed, animTable)
	local totalTime = animTable.totalTime
	if ( animElapsed and (animElapsed < totalTime)) then	--Should be animating
		local elapsedFraction = self.animReverse and (1-animElapsed/totalTime) or (animElapsed/totalTime);
		animTable.updateFunc(self, animTable.getPosFunc(self, elapsedFraction));
	else	--Just finished animating
		animTable.updateFunc(self, animTable.getPosFunc(self, self.animReverse and 0 or 1));
		self.animating = false;
		
		AnimatingFrames[self][animTable.updateFunc] = 0;	--We use 0 instead of nil'ing out because we don't want to mess with 'next' (used in pairs)
		
		if ( self.animPostFunc ) then
			self.animPostFunc(self);
		end

	end
end

local totalElapsed = 0;
local function Animation_OnUpdate(self, elapsed)
	totalElapsed = totalElapsed + elapsed;
	local isAnyFrameAnimating = false;
	for frame, frameTable in pairs(AnimatingFrames) do
		for frameTable, animTable in pairs(frameTable) do
			if ( animTable ~= 0 ) then
				Animation_UpdateFrame(frame, totalElapsed - frame.animStartTime, animTable);
				isAnyFrameAnimating = true;
			end
		end
	end
	if ( not isAnyFrameAnimating ) then
		table.wipe(AnimatingFrames);
		AnimUpdateFrame:SetScript("OnUpdate", nil);
	end
end

-- WIM API
function SetUpAnimation(frame, animTable, postFunc, reverse)
	if ( type(animTable.updateFunc) == "string" ) then
		animTable.updateFunc = frame[animTable.updateFunc];
	end
	if ( not AnimatingFrames[frame] ) then
		AnimatingFrames[frame] = {};
	end
	
	AnimatingFrames[frame][animTable.updateFunc] = animTable;
	
	frame.animStartTime = totalElapsed;
	frame.animReverse = reverse;	
	frame.animPostFunc = postFunc;
	frame.animating = true;
	
	animTable.updateFunc(frame, animTable.getPosFunc(frame, frame.animReverse and 1 or 0));
	
	AnimUpdateFrame:SetScript("OnUpdate", Animation_OnUpdate);
end