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lua/pac3/libraries/urlobj/cache.lua

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+--[[
+| This file was obtained through the combined efforts
+| of Madbluntz & Plymouth Antiquarian Society.
+|
+| Credits: lifestorm, Gregory Wayne Rossel JR.,
+| 	Maloy, DrPepper10 @ RIP, Atle!
+|
+| Visit for more: https://plymouth.thetwilightzone.ru/
+--]]
+
+local crypto = include("pac3/libraries/urlobj/crypto.lua")
+
+local CACHE = {}
+
+local function CreateCache(cacheId)
+	local cache = {}
+	setmetatable(cache, { __index = CACHE })
+
+	cache:Initialize(cacheId)
+
+	return cache
+end
+
+function CACHE:Initialize(cacheId)
+	self.Version = 3 -- Update this if the crypto library changes
+
+	self.Path    = "pac3_cache/" .. string.lower(cacheId)
+
+	file.CreateDir(self.Path)
+end
+
+function CACHE:AddItem(itemId, data)
+	local hash = self:GetItemIdHash(itemId)
+	local path = self.Path .. "/" .. hash .. ".txt"
+	local key  = self:GetItemIdEncryptionKey(itemId)
+
+	-- Version
+	local f = file.Open(path, "wb", "DATA")
+	if not f then return end
+	f:WriteLong(self.Version)
+
+	-- Header
+	local compressedItemId = util.Compress(itemId)
+	local entryItemId = crypto.EncryptString(compressedItemId, key)
+	f:WriteLong(#entryItemId)
+	f:Write(entryItemId, #entryItemId)
+
+	-- Data
+	local compressedData = util.Compress(data)
+	data = crypto.EncryptString(compressedData, key)
+	f:WriteLong(#data)
+	f:Write(data, #data)
+
+	f:Close()
+end
+
+function CACHE:Clear()
+	for _, fileName in ipairs(file.Find(self.Path .. "/*", "DATA")) do
+		file.Delete(self.Path .. "/" .. fileName)
+	end
+end
+
+function CACHE:ClearBefore(time)
+	for _, fileName in ipairs(file.Find(self.Path .. "/*", "DATA")) do
+		if file.Time(self.Path .. "/" .. fileName, "DATA") < time then
+			file.Delete(self.Path .. "/" .. fileName)
+		end
+	end
+end
+
+function CACHE:ContainsItem(itemId)
+	return self:GetItem(itemId) ~= nil
+end
+
+function CACHE:GetItem(itemId)
+	local hash = self:GetItemIdHash(itemId)
+	local path = self.Path .. "/" .. hash .. ".txt"
+
+	if not file.Exists(path, "DATA") then return nil end
+
+	local f = file.Open(path, "rb", "DATA")
+	if not f then return nil end
+
+	local key = self:GetItemIdEncryptionKey(itemId)
+
+	-- Version
+	local version = f:ReadLong()
+	if version ~= self.Version then
+		f:Close()
+		return nil
+	end
+
+	-- Header
+	local entryItemIdLength = f:ReadLong()
+	local entryItemId = crypto.DecryptString(f:Read(entryItemIdLength), key)
+	entryItemId = util.Decompress(entryItemId)
+
+	if itemId ~= entryItemId then
+		f:Close()
+		return nil
+	end
+
+	-- Data
+	local dataLength = f:ReadLong()
+	local data       = f:Read(dataLength, key)
+
+	f:Close()
+
+	data = crypto.DecryptString(data, key)
+	data = util.Decompress(data)
+
+	return data
+end
+
+function CACHE:GetItemIdEncryptionKey(itemId)
+	return crypto.GenerateKey(string.reverse(itemId))
+end
+
+function CACHE:GetItemIdHash(itemId)
+	return string.format("%08x", tonumber(util.CRC(itemId)))
+end
+
+return CreateCache