--	DependencyLoader
--	

--	TODO: disable bootstrap if we load successfully?

--	TODO: implement a feature to disable unneeded libraries when a parent 
--	is disabled?

local addonName, addonTable = ...


local DependencyLoader = LibStub("AceAddon-3.0"):NewAddon(addonName, "AceHook-3.0", "AceEvent-3.0")
_G[addonName] = DependencyLoader

addonTable.interface = DependencyLoader

local classes = addonTable.classes


local LibPrint = LibStub("LibPrint-1.0")
local LibScriptLink = LibStub("LibScriptLink-1.0")

DependencyLoader.printStream = LibPrint:NewStream("DependencyLoader", "DpLdr", print)
DependencyLoader.debugStream = LibPrint:NewStream("DependencyLoader", "DpLdr", "mcm")

DependencyLoader.queuedEnables = {}		--	addons queued to be enabled after PLAYER_LOGIN


function DependencyLoader:Print(...)
	self.printStream:Print(...)
end


function DependencyLoader:Debug(...)
	self.debugStream:Print(...)
end


function DependencyLoader:OnInitialize()
	self:Debug("Initializing", addonName)
	self:Enable()
end


function DependencyLoader:OnEnable()
	--	this may get called early so don't rely on 
	--	it as an indicator for PLAYER_LOGIN
	
	self:RegisterEvent("PLAYER_LOGIN")
	
	self:RawHook("LoadAddOn", true)
	self:RawHook("EnableAddOn", true)
	
	self:PrepareAllAddons()
	
	self:Print("Enabled", addonName)
end


function DependencyLoader:PLAYER_LOGIN(...)
	self:Debug(...)
	
	self:ProcessEnableQueue()
end


function DependencyLoader:OnDisable()
	self:Print("Disabled", addonName)
end


--	Does not consider user settings or addon errata.
function DependencyLoader:IsForceLoadAvailable()
	if IsLoggedIn() then
		return false
	else
		return true
	end
end


function DependencyLoader:IsForceLoadAllowed()
	--	TODO: check user settings
	return true
end


function DependencyLoader:CanForceLoad()
	return self:IsForceLoadAvailable() and self:IsForceLoadAllowed()
end


--	Enables any dependencies needed by the addons 
--	that have already been enabled
function DependencyLoader:PrepareAllAddons()
	local requestReload = false
	
	for i=1, GetNumAddOns() do
		local addon = classes.Addon:Get(i)
		
		--	TODO: what if an addon was loaded but its deps were then disabled?
		if addon:IsEnabled() and not addon:IsLoaded() then
			self:EnableAddOn(addon:GetName())
		end
	end
	
	--[[
	if requestReload then
		local message = LibScriptLink:NewLink(ReloadUI) .. " to reload your UI."
		self:Print(message)
	end
	]]
end


--	FIXME: use pcall in EnableAddOn and LoadAddOn, so that if my part errors,  
--	it can still use the unhooked version

function DependencyLoader:EnableAddOn(...)
	local id = ...
	
	self:Debug("EnableAddOn", ...)
	
	--	even though we know EnableAddOn can cause force-loading before PLAYER_LOGIN, 
	--	DO NOT attempt to "fix" it: another addon that -does- know about 
	--	the different behavior might call our hook.
	
	if classes.Addon:Exists(id) then
		local addon = classes.Addon:Get(id)
		local tree = classes.Tree:Get(addon)
		
		local requestReload = false
		
		if self:CanForceLoad() then
			--	NOTE: if we can force-load, then will enabling LoD addons cause them to load too?
			--	A: no, they will still wait for LoadAddOn
			
			--	Can the addon be loaded on demand if force-loading is 
			--	allowed for its dependencies
			--	if so, enable all deps and force-load if nec.
			--		deps will get enabled if all parents are lod, force-loaded
			--		if any parent can't be loaded on demand
			--	else
			--	if the addon is not loadable on demand but the tree can be
			--	force-loaded, then force-load it all
			--		deps will all get loaded since req. for root to load
			--	else
			--	if it can be loaded with a reloadui then prepare after login
			--	else
			--	it can't be loaded, maybe tell the user
			
			if tree:CanForceLoad() then
				if addon:CanLoD() then
					tree:PrepareForLoD()
				else
					tree:ForceLoad()
				end
			elseif tree:CanLoad() then
				tree:PrepareForLoad()
				requestReload = true
			else
				--	TODO: tell user
			end
			
			
			--[[
			if tree:CanLoDWithForce() then
				tree:PrepareForLoD()
			elseif tree:CanForceLoad() then
				tree:ForceLoad()
			elseif tree:CanLoad() then
				tree:PrepareForLoad()
				requestReload = true
			else
				--	TODO: tell user
			end
			]]
		else
			--	if it can be loaded on demand (deps are loaded or LoD) then
			--	prepare it (enable all deps)
			--	else
			--	if it can be loaded (and isn't already) then
			--		if force loading is available, we have to wait, then enable everything
			--		else
			--		prepare for reload (TODO: move this check and similar to PLAYER_LOGOUT)
			--	else
			--	can't be loaded, maybe tell the user
			
			if tree:CanLoD() then
				tree:PrepareForLoad()
				--	don't actually intend to reload, just enable everything
			elseif tree:CanLoad() then
				tree:PrepareForLoad()
				requestReload = true
			else
				--	TODO: tell user
			end
		end
		
		if requestReload then
			self:RequestReload()
		end
	end
	
	--	propogate the call even if it doesn't exist or deps are unavailable
	return self.hooks.EnableAddOn(...)
end



---	Prepares the addon tree rooted at the specified addon
function DependencyLoader:LoadAddOn(...)
	local id = ...
	
	self:Debug("LoadAddOn", ...)
	
	if classes.Addon:Exists(id) then
		local addon = classes.Addon:Get(id)
		local tree = classes.Tree:Get(addon)
		
		if tree:CanLoD() then
			tree:PrepareForLoD()
		elseif tree:CanLoad() then
			tree:PrepareForReload()
		end
	end
		
	--	call even if it can't be loaded so regular returns appear
	return self.hooks.LoadAddOn(...)
end


function DependencyLoader:RequestReload()
	--	TODO: this should only run once
end


function DependencyLoader:QueueEnable(name)
	self.queuedEnables[name] = true
end


function DependencyLoader:RawEnableAddOn(...)
	return self.hooks.EnableAddOn(...)
end


function DependencyLoader:RawLoadAddOn(...)
	return self.hooks.LoadAddOn(...)
end


function DependencyLoader:ProcessEnableQueue()
	for addon in pairs(self.queuedEnables) do
		self:RawEnableAddOn(addon)
		self.queuedEnables[addon] = nil
	end
end