-- ServerScriptService/Server/Services/DataService.luau (ProfileStore)
local Players = game:GetService("Players")
local ServerScriptService = game:GetService("ServerScriptService")

local ProfileStore = require(ServerScriptService.ServerPackages.ProfileStore)

local TEMPLATE = {
	version = 1,
	coins = 0,
	inventory = {} :: { [string]: number },
}
type PlayerData = typeof(TEMPLATE)

local PlayerStore = ProfileStore.New("PlayerData", TEMPLATE)
local profiles: { [Player]: typeof(PlayerStore:StartSessionAsync("")) } = {}

local function onPlayerAdded(player: Player)
	local profile = PlayerStore:StartSessionAsync(`User_{player.UserId}`, {
		Cancel = function()
			return player.Parent ~= Players -- stop waiting if the player left
		end,
	})
	if profile == nil then
		player:Kick("Could not load your data. Please rejoin.")
		return
	end
	profile:AddUserId(player.UserId) -- GDPR / right-to-be-forgotten linkage
	profile:Reconcile() -- fill in fields added to TEMPLATE since this profile was created
	profile.OnSessionEnd:Connect(function()
		profiles[player] = nil
		player:Kick("Your data was loaded on another server. Please rejoin.")
	end)
	if player.Parent == Players then
		profiles[player] = profile
	else
		profile:EndSession() -- left while loading
	end
end

for _, player in Players:GetPlayers() do
	task.spawn(onPlayerAdded, player)
end
Players.PlayerAdded:Connect(onPlayerAdded)
Players.PlayerRemoving:Connect(function(player)
	local profile = profiles[player]
	if profile then
		profile:EndSession() -- saves and releases the lock
	end
end)

local DataService = {}
function DataService.get(player: Player): PlayerData?
	local profile = profiles[player]
	return profile and profile.Data
end
return DataService

--!strict
type Data = { [string]: any }

local MIGRATIONS: { (Data) -> () } = {
	[1] = function(data) -- v1 -> v2: "gold" renamed to "coins"
		data.coins = data.gold or 0
		data.gold = nil
	end,
	[2] = function(data) -- v2 -> v3: inventory list -> counts
		local counts: { [string]: number } = {}
		for _, itemId in data.inventory or {} do
			counts[itemId] = (counts[itemId] or 0) + 1
		end
		data.inventory = counts
	end,
}
local CURRENT_VERSION = #MIGRATIONS + 1

local function migrate(data: Data): Data
	local version = data.version or 1
	while version < CURRENT_VERSION do
		MIGRATIONS[version](data)
		version += 1
	end
	data.version = CURRENT_VERSION
	return data
end

print(migrate({ gold = 5, inventory = { "Sword", "Sword" } }))