local RunService = game:GetService("RunService")
local Workspace = game:GetService("Workspace")
local Players = game:GetService("Players")

-- 🛑 Place ID Verification
if game.PlaceId ~= 18626211593 then
    warn("This script only runs in the verified place ID.")
    return
end

-- Delay start
task.wait(3)

-- Folder detection (accept singular or plural)
local function getFolder(name)
    return Workspace:FindFirstChild(name)
end

local npcFolder = getFolder("NPC") or getFolder("NPCs")
local entityFolder = getFolder("Entity") or getFolder("Entities")

local folders = {}
if npcFolder then table.insert(folders, {folder = npcFolder, type = "npc"}) end
if entityFolder then table.insert(folders, {folder = entityFolder, type = "entity"}) end

-- Tracking tables
local highlights = {}
local lastPositions = {}
local hostiles = {} -- active hostile NPCs
local hostileMemory = {} -- saved hostile records for session
local pulseTimers = {} -- timers for non-hostile NPC pulsing

-- 30Hz loop control
local interval = 1 / 30
local lastUpdate = 0

local localPlayer = Players.LocalPlayer
local function getChar()
    return localPlayer and localPlayer.Character or nil
end

-- Helper: build full path to NPC
local function getFullPath(obj)
    local path = {}
    local current = obj
    while current and current.Parent do
        table.insert(path, 1, current.Name)
        current = current.Parent
        if current == Workspace then break end
    end
    return table.concat(path, ".")
end

-- Save NPC as hostile in session memory
local function saveToSessionMemory(model)
    local path = getFullPath(model)
    local name = model.Name
    local id = path .. ":" .. name
    if not hostileMemory[id] then
        hostileMemory[id] = {
            name = name,
            path = path,
            time = os.time()
        }
        print("⚠ Hostile saved:", name, "at", path)
    end
end

-- Billboard for hostile NPCs
local function createBillboard(model)
    if model:FindFirstChild("HostileBillboard") then return end
    local billboard = Instance.new("BillboardGui")
    billboard.Name = "HostileBillboard"
    billboard.Adornee = model:FindFirstChild("HumanoidRootPart")
    billboard.AlwaysOnTop = true
    billboard.Size = UDim2.new(0, 100, 0, 30)
    billboard.StudsOffset = Vector3.new(0, 4, 0)
    billboard.MaxDistance = 100
    billboard.Parent = model

    local textLabel = Instance.new("TextLabel", billboard)
    textLabel.Size = UDim2.new(1, 0, 1, 0)
    textLabel.BackgroundTransparency = 1
    textLabel.Text = ">HOSTILE<"
    textLabel.TextColor3 = Color3.fromRGB(255, 0, 0)
    textLabel.Font = Enum.Font.Nunito
    textLabel.TextScaled = true
end

-- Apply initial highlight
local function applyHighlight(model, folderType)
    if highlights[model] then return end
    local hrp = model:FindFirstChild("HumanoidRootPart")
    if hrp then
        local hl = Instance.new("Highlight")
        hl.Adornee = model
        if folderType == "npc" then
            -- Initially green
            hl.FillColor = Color3.fromRGB(0, 255, 0)
        elseif folderType == "entity" then
            hl.FillColor = Color3.fromRGB(0, 100, 255) -- blue
        end
        hl.OutlineColor = Color3.fromRGB(255, 255, 255)
        hl.Parent = model
        highlights[model] = hl

        model.AncestryChanged:Connect(function(_, parent)
            if not parent and highlights[model] then
                highlights[model]:Destroy()
                highlights[model] = nil
                lastPositions[model] = nil
                hostiles[model] = nil
                pulseTimers[model] = nil
            end
        end)
    end
end

-- Cleanup destroyed NPCs/entities
local function cleanupInvalid()
    for model, hl in pairs(highlights) do
        if not model.Parent then
            if hl then hl:Destroy() end
            highlights[model] = nil
            lastPositions[model] = nil
            hostiles[model] = nil
            pulseTimers[model] = nil
        end
    end
end

-- Pulse highlight for non-hostile NPCs
local function pulseNonHostiles()
    for model, hl in pairs(highlights) do
        if model.Parent and not hostiles[model] and npcFolder and (model:IsDescendantOf(npcFolder) or (npcFolder and npcFolder.Name == "NPCs")) then
            if pulseTimers[model] == nil then
                pulseTimers[model] = os.clock()
            end
            local elapsed = os.clock() - pulseTimers[model]
            if elapsed >= 120 then -- every 2 minutes
                task.spawn(function()
                    local originalColor = hl.FillColor
                    hl.FillColor = Color3.fromRGB(0, 255, 0)
                    task.wait(3)
                    hl.FillColor = originalColor
                end)
                pulseTimers[model] = os.clock()
            end
        end
    end
end

-- Distance-based visibility for entities
local function updateEntityVisibility()
    local char = getChar()
    local hrp = char and char:FindFirstChild("HumanoidRootPart")
    if not hrp then return end

    for model, hl in pairs(highlights) do
        if model.Parent and hl.FillColor == Color3.fromRGB(0, 100, 255) then
            local entHrp = model:FindFirstChild("HumanoidRootPart")
            if entHrp then
                local dist = (entHrp.Position - hrp.Position).Magnitude
                hl.Enabled = (dist >= 300 and dist <= 800)
            end
        end
    end
end

-- Main loop
RunService.Heartbeat:Connect(function(dt)
    lastUpdate += dt
    if lastUpdate >= interval then
        for _, entry in ipairs(folders) do
            for _, model in ipairs(entry.folder:GetChildren()) do
                if model:IsA("Model") and model:FindFirstChild("HumanoidRootPart") then
                    applyHighlight(model, entry.type)

                    if entry.type == "npc" then
                        local hrp = model.HumanoidRootPart
                        local lastPos = lastPositions[model]
                        local currentPos = hrp.Position
                        local id = getFullPath(model) .. ":" .. model.Name

                        if hostiles[model] or hostileMemory[id] then
                            highlights[model].FillColor = Color3.fromRGB(255, 0, 0)
                            hostiles[model] = true
                            createBillboard(model)
                            saveToSessionMemory(model)
                        else
                            if lastPos and (currentPos - lastPos).Magnitude > 0.05 then
                                highlights[model].FillColor = Color3.fromRGB(255, 0, 0)
                                hostiles[model] = true
                                createBillboard(model)
                                saveToSessionMemory(model)
                            else
                                highlights[model].FillColor = Color3.fromRGB(0, 255, 0)
                            end
                        end
                        lastPositions[model] = currentPos
                    end
                end
            end
        end

        pulseNonHostiles()
        updateEntityVisibility()
        cleanupInvalid()
        lastUpdate = 0
    end
end)