--[[
	The server side lazy loader for pac3 costumes
	PAC3 outfits are not downloaded until they are needed, we can keep the inital download to join the server pretty small this way.
	The downside is that the game might lag a little when someone wears something that is rare/new and everyone has to download it.

	Console Commands:
		artery_reload_pacs
			The server will cache PAC's so it dosen't need to read form disk every time. If you're live editing pac's on the server, and are wondering why your changes aren't showing, use this command. There is no command to clear client cache, because applying a pac also sends a hash of the pac to the client, and the client re-downloads if the hashes are different.


	Functions:
		entity:ApplyPac(String costume)	::	nil
			Find the file /data/pacs/<costume>.pac (on the server) and tell clients to apply it to ent. This will automatically download the pac to any clients nessessary.

		entity:RemovePac(String costume) :: nil
			Remove the pac from the entity.

		entity:GetPacs()	::	table
			Retreives a list of the pacs an entity is wearing, as strings

	Network Strings:
		"artery_getworldpacs",
		"artery_giveworldpacs",
		"artery_applypac",
		"artery_removepac",
		"artery_requestpac",
		"artery_downloadpac"
]]

local p3 = {}

local nwstrings = {
	"artery_getworldpacs",
	"artery_giveworldpacs",
	"artery_applypac",
	"artery_removepac",
	"artery_requestpac",
	"artery_downloadpac"
}
for _,v in pairs(nwstrings) do
	util.AddNetworkString(v)
end

--If the server has pac installed, restrict player's from putting on their own pacs
hook.Add("PrePACConfigApply", "stoppacs", function(ply, outfit_data)
	if not ply:IsAdmin() then
		return false, "You don't have permission to do that!"
		end
end)

local pacsources = {
	["data/artery/pacs/"] = "GAME"
}
function p3.AddPacSource(filepath,from)
	pacsources[filepath] = from
end

--When the server starts, get all the pacs and calculate their hashes so we can index them quickly without haveing to read from disk each time.
local pachashes = {}
local function loadhashes()
	for path,part in pairs(pacsources) do
		local files,_ = file.Find(path.."*",part)
		for _,v in ipairs(files) do
			local filepath = string.format("%s%s",path,v)
			local filetext = file.Read(filepath,part)
			local filehash = util.CRC(filetext)
			pachashes[string.StripExtension(v)] = tonumber(filehash)
		end
	end
end
loadhashes()
concommand.Add("artery_reload_pac_hashes",loadhashes)
concommand.Add("artery_print_pac_hashes",function(ply,cmd,args)
	PrintTable(pachashes)
end)

local appliedpacs = {}

function p3.ApplyPac(what, name)
	print("Applying pac", name, "to",what)
	assert(pachashes[name],string.format("Tried to apply pac %s which didn't have a hash. Pac hashes are:%s",name,table.ToString(pachashes,"pachashes",true)))
	appliedpacs[what] = appliedpacs[what] or {}
	appliedpacs[what][name] = pachashes[name]
	net.Start("artery_applypac")
	net.WriteEntity(what)
	net.WriteString(name)
	--If this pac is from an addon that was loaded after this file was, we may need to reload hashes.
	if not pachashes[name] then
		loadhashes()
	end
	net.WriteUInt(pachashes[name],32)
	net.Broadcast()
end

function p3.RemovePac(what, name)
	print("Removeing pac",what,"from",name)
	assert(appliedpacs[what][name],"Attempted to remove a pac that an entity is not wearing!")
	appliedpacs[what][name] = nil
	if #appliedpacs[what] == 0 then
		appliedpacs[what] = nil
	end
	net.Start("artery_removepac")
	net.WriteEntity(what)
	net.WriteString(name)
	net.WriteUInt(pachashes[name],32)
	net.Broadcast()
end

function p3.GetPacs(what)
	return appliedpacs[what] or {}
end

--If a player joins the server, tell them all about the pacs that are applied
net.Receive("artery_getworldpacs",function(ln,ply)
	net.Start("artery_giveworldpacs")
	net.WriteTable(appliedpacs)
	net.Send(ply)
end)

local max_pacs_in_cache = 10
local pacs_in_cache = 0
local pac_cache = {}

--Load something from our cache
local function cacheload(key)
	--If it's already in the cache, just update the time it was last used and return the pac.
	if pac_cache[key] ~= nil then
		print("Pac was already in the cache.")
		pac_cache[key].time = CurTime()
		if pac_cache[key].pac == nil then
			PrintTable(pac_cache)
			error("Pac was loaded, but the txt was nil!")
		end
		return pac_cache[key].pac
	end

	--Otherwise, we need to load it.
	local pacpath = string.format("data/artery/pacs/%s.txt",key)
	local pacfile = file.Read(pacpath,"GAME")
	print("Pac was not in cache, reloading, pac txt is",pacfile)

	--If we haven't reached max cache yet, just put it in
	if pacs_in_cache < max_pacs_in_cache then
		pac_cache[key] = {
			["pac"] = pacfile,
			["time"] = CurTime()
		}
		pacs_in_cache = pacs_in_cache + 1
		return pacfile
	else
		--We have max pac's, delete the oldest one, and put the new one in.
		local oldest,oldstr = CurTime(),""
		for k,v in pairs(pac_cache) do
			if v.time < oldest then
				oldest = v.time
				oldstr = k
			end
		end
		pac_cache[oldstr] = nil
		pac_cache[key] = {
			["pac"] = pacfile,
			["time"] = CurTime()
		}
		return pacfile
	end
end

net.Receive("artery_requestpac",function(ln,ply)
	local pac_name = net.ReadString()

	--Double check that we're not executing a directory traversal attack https://www.owasp.org/index.php/Path_Traversal
	if string.find(pac_name,"..",1,true) then
		Report(string.format("Directory traversal attack attempted by %s:%s using artery_requestpac string %q",ply:Nick(),ply:SteamID64(),pac_name))
	end

	local pac_txt = cacheload(pac_name)

	assert(pac_name,"Pac's name was nil!")
	assert(pac_txt, "Pac's txt was nil (from the cache)")

	net.Start("artery_downloadpac")
	net.WriteString(pac_name)
	net.WriteString(pac_txt)
	net.WriteUInt(pachashes[pac_name],32)
	net.Send(ply)

end)

--Does all the things needed to edit pac's live
concommand.Add("artery_reload_pacs",function()
	pac_cache = {}
	pacs_in_cache = 0
	loadhashes()
end)

return p3