StateHandler.lua

local RunService = game:GetService("RunService");
local ReplicatedStorage = game:GetService("ReplicatedStorage");
local Players = game:GetService("Players");

local Remotes = ReplicatedStorage.Remotes;

local StateRemote = Remotes.StateRemote;

local Modules = ReplicatedStorage.Modules;
local Utility = Modules.Utility;

local TablesLibrary = require(Utility.TablesLibrary);
local DefaultStates = require(script.DefaultStates);
local FastSignal = require(Utility.FastSignal);

local StateHandler = {};
StateHandler.Characters = {};

DEAD_CHARACTER_ERROR = "Character isn't alive";
NOT_INITIALIZED_CHARACTER_ERROR = "Character isn't Initialized";
ALREADY_INITIALIZED_CHARACTER_ERROR = "Character has already been Initialized";
STATE_DOESNT_EXIST_ERROR = "State [%s] hasn't been found";
TIMEOUT_WARNING = "[%s]'s state initialization await function has timed out!";

--[[
TODO: When calling a function, if character isn't initialized, make it await until Character has been initialized or it's been time out(10s)
]]

--// PRIVATE
local INIT_TIMEOUT = 10;


local InitializationConnections = {};

local function GetInternalState(CharacterIndex, stateIndex)

end

--// PUBLIC

function StateHandler.Initialize(Character)
    assert(Character, DEAD_CHARACTER_ERROR);
    if StateHandler.Characters[Character] then
        warn(ALREADY_INITIALIZED_CHARACTER_ERROR)
        return;
    end

    StateHandler.Characters[Character] = TablesLibrary.DeepCopyTable(DefaultStates);

    local Data = StateHandler.Characters[Character];

    for StateName, StateData in pairs(Data) do
        Data[StateName].GetPropertyChangedSignal = function(PropertyName : string | nil)
            if Data[StateName].Connection then
                return Data[StateName].Connection;
            end
            Data[StateName].Connection = FastSignal.new();

            return  Data[StateName].Connection;
        end
    end

    if InitializationConnections[Character] then
        InitializationConnections[Character]:Fire();
    end

    return Data;
end

function StateHandler:AwaitInitialization(CharacterIndex : model) : number
    if not StateHandler.Characters[CharacterIndex] then
        task.defer(function()
            task.wait(INIT_TIMEOUT);

            if not StateHandler.Characters[CharacterIndex] then
                warn( TIMEOUT_WARNING:format(CharacterIndex.Name) );
            end
        end)
        if InitializationConnections[CharacterIndex] then
            InitializationConnections[CharacterIndex]:Wait();
        else
            InitializationConnections[CharacterIndex] = FastSignal.new();
            InitializationConnections[CharacterIndex]:Wait();
        end
    end

    InitializationConnections[CharacterIndex] = nil;

    print("Initialized!");

    return 1;
end

function StateHandler:GetPropertyChangedSignal(CharacterIndex : Model, stateIndex : string | number | boolean, PropertyName : string | nil)
    assert(CharacterIndex, DEAD_CHARACTER_ERROR);
    assert(StateHandler.Characters[CharacterIndex], NOT_INITIALIZED_CHARACTER_ERROR);
    assert(StateHandler.Characters[CharacterIndex][stateIndex], STATE_DOESNT_EXIST_ERROR:format(stateIndex));

    return StateHandler.Characters[CharacterIndex][stateIndex].GetPropertyChangedSignal(PropertyName);
end

function StateHandler.Deinitialize(CharacterIndex)
    assert(CharacterIndex, DEAD_CHARACTER_ERROR);
    assert(StateHandler.Characters[CharacterIndex], NOT_INITIALIZED_CHARACTER_ERROR);

    StateHandler.Characters[CharacterIndex] = nil;
end

function StateHandler:GetData(CharacterIndex, stateIndex)
    assert(CharacterIndex, DEAD_CHARACTER_ERROR);

    if not StateHandler.Characters[CharacterIndex] then
        StateHandler:Initialize(CharacterIndex);
    end

    assert(StateHandler.Characters[CharacterIndex][stateIndex], STATE_DOESNT_EXIST_ERROR:format(stateIndex));

    if StateHandler.Characters[CharacterIndex][stateIndex].Duration then

    end

    return StateHandler.Characters[CharacterIndex][stateIndex].Value;
end

function StateHandler:ReturnState(CharacterIndex, stateIndex)
    assert(CharacterIndex, DEAD_CHARACTER_ERROR);
    assert(StateHandler.Characters[CharacterIndex], NOT_INITIALIZED_CHARACTER_ERROR);
    assert(StateHandler.Characters[CharacterIndex][stateIndex], STATE_DOESNT_EXIST_ERROR:format(stateIndex));

    return StateHandler.Characters[CharacterIndex][stateIndex];
end

if RunService:IsClient() then

    function StateHandler:UpdateState(CharacterIndex, stateIndex, stateValue)
        assert(CharacterIndex, DEAD_CHARACTER_ERROR);
        assert(StateHandler.Characters[CharacterIndex], NOT_INITIALIZED_CHARACTER_ERROR);
        assert(StateHandler.Characters[CharacterIndex][stateIndex], STATE_DOESNT_EXIST_ERROR:format(stateIndex));

        if StateHandler.Characters[CharacterIndex][stateIndex].Value == stateValue then return; end

        StateHandler.Characters[CharacterIndex][stateIndex].Value = stateValue;

        if StateHandler.Characters[CharacterIndex][stateIndex].Connection then
            coroutine.wrap(function()
                StateHandler.Characters[CharacterIndex][stateIndex].Connection:Fire(stateValue);
            end)();
        end

        return stateValue;
    end

    return StateHandler;
elseif RunService:IsServer() then

    function StateHandler:UpdateState(CharacterIndex, stateIndex, stateValue, Duration, Priority)
        assert(CharacterIndex, DEAD_CHARACTER_ERROR);
        assert(StateHandler.Characters[CharacterIndex], NOT_INITIALIZED_CHARACTER_ERROR);
        assert(StateHandler.Characters[CharacterIndex][stateIndex], STATE_DOESNT_EXIST_ERROR:format(stateIndex));

        if StateHandler.Characters[CharacterIndex][stateIndex].Value == stateValue then return; end

        local oldStateValue = StateHandler.Characters[CharacterIndex][stateIndex].Value;

        StateHandler.Characters[CharacterIndex][stateIndex].Value = stateValue;

        if Duration and StateHandler.Characters[CharacterIndex][stateIndex].Duration then
            if (StateHandler.Characters[CharacterIndex][stateIndex].Priority > Priority and
                StateHandler.Characters[CharacterIndex][stateIndex].StartTime + StateHandler.Characters[CharacterIndex][stateIndex].Duration < os.clock())
            then
                return;
            end

            local StartTime = os.clock();

            StateHandler.Characters[CharacterIndex][stateIndex].Priority = Priority;
            StateHandler.Characters[CharacterIndex][stateIndex].Duration = Duration;
            StateHandler.Characters[CharacterIndex][stateIndex].StartTime = StartTime;

            task.delay(Duration, function()
                if (StateHandler.Characters[CharacterIndex][stateIndex].StartTime == StartTime and StateHandler.Characters[CharacterIndex][stateIndex].Priority == Priority)
                    or StateHandler.Characters[CharacterIndex][stateIndex].Priority < Priority then

                    StateHandler.Characters[CharacterIndex][stateIndex].Value = oldStateValue;
                end
            end)
        end

        if StateHandler.Characters[CharacterIndex][stateIndex].Connection then
            coroutine.wrap(function()
                StateHandler.Characters[CharacterIndex][stateIndex].Connection:Fire(stateValue);
            end)();
        end

        local Player = Players:GetPlayerFromCharacter(CharacterIndex);

        if Player then
            StateRemote:FireClient(Player, stateIndex, stateValue);
        end

        return stateValue;
    end

    return StateHandler;
end