MobSpawner

local rs = game:GetService("ReplicatedStorage")
local mobs = rs:WaitForChild("Mobs")

local mobSpawners = workspace:WaitForChild("MobSpawns")

local rand = Random.new()

local ps = game:GetService("PhysicsService")

local mobsCG = "Mobs"
local charsCG = "Characters"

ps:RegisterCollisionGroup(mobsCG)
ps:RegisterCollisionGroup(charsCG)

ps:CollisionGroupSetCollidable(mobsCG, charsCG, false)

local respawnTime = 3
local maxDistanceCanMoveFromSpawn = 15


function calculateRandomPosition(originPosition:Vector3)

    local randomOffset = rand:NextNumber(5, maxDistanceCanMoveFromSpawn)
    local randomX = rand:NextNumber(0, randomOffset)
    local randomZ = math.sqrt(randomOffset^2 - randomX^2)

    local newPosition = originPosition + Vector3.new(randomX, 0, randomZ)

    return newPosition
end


function handleSpawner(spawner:Part)

    local typeOfMob = spawner.Name

    if mobs:FindFirstChild(typeOfMob) then

        local spawnerCF = spawner.CFrame

        local newMob = mobs[typeOfMob]:Clone()

        for _, descendant in pairs(newMob:GetDescendants()) do
            if descendant:IsA("BasePart") then
                descendant.CollisionGroup = mobsCG
            end
        end

        local mobConfig = newMob:WaitForChild("Configuration")

        local mobAnims = newMob:WaitForChild("Animations")
        local animTracks = nil

        local mobHumanoid = newMob:WaitForChild("Humanoid")
        local mobRoot = newMob:WaitForChild("HumanoidRootPart")

        local mobHealthBar = rs:WaitForChild("HealthBar"):WaitForChild("HealthBarGui"):Clone()
        mobHealthBar.StudsOffset = Vector3.new(0, newMob:GetExtentsSize().Y * 0.6, 0)
        mobHealthBar.Enabled = false
        mobHealthBar.Parent = newMob.HumanoidRootPart

        mobHumanoid.DisplayDistanceType = Enum.HumanoidDisplayDistanceType.None
        mobHumanoid.HealthDisplayType = Enum.HumanoidHealthDisplayType.AlwaysOff

        mobHumanoid.MaxHealth = 1000000
        mobHumanoid.Health = 1000000

        mobHumanoid.WalkSpeed = mobConfig:WaitForChild("WalkSpeed").Value

        mobHumanoid.HealthChanged:Connect(function(newHealth)

            local damageDealt = mobHumanoid.MaxHealth - newHealth

            mobConfig:WaitForChild("CurrentHealth").Value -= damageDealt

            mobHumanoid.Health = mobHumanoid.MaxHealth
        end)


        while true do

            mobConfig:WaitForChild("CurrentHealth").Value = mobConfig:WaitForChild("MaxHealth").Value

            newMob.Parent = workspace
            mobRoot.CFrame = spawnerCF

            if not animTracks then
                animTracks = {}

                for _, anim in pairs(mobAnims:GetChildren()) do

                    local newTrack = mobHumanoid:WaitForChild("Animator"):LoadAnimation(anim)
                    animTracks[anim.Name] = newTrack
                end
            end

            local lastAttacked = 0

            local goalRandomPosition = nil

            while true do

                if (mobConfig:WaitForChild("CurrentHealth").Value ~= mobConfig:WaitForChild("MaxHealth").Value) then

                    mobHealthBar.MobName.Text = newMob.Name
                    mobHealthBar.BarBackground.Health.Text = mobConfig.CurrentHealth.Value .. "/" .. mobConfig.MaxHealth.Value
                    mobHealthBar.BarBackground.Bar.Size = UDim2.new(mobConfig.CurrentHealth.Value / mobConfig.MaxHealth.Value, 0, 1, 0)

                    mobHealthBar.Enabled = true

                else
                    mobHealthBar.Enabled = false
                end

                if (not animTracks.Idle.IsPlaying) then
                    animTracks.Idle:Play()
                end

                local v = mobRoot.AssemblyLinearVelocity * Vector3.new(1, 0, 1)

                if (v.Magnitude > 0.1) and (not animTracks.Walk.IsPlaying) then
                    animTracks.Walk:AdjustSpeed(mobHumanoid.WalkSpeed / 8)
                    animTracks.Walk:Play()

                elseif (v.Magnitude <= 0.1) and (animTracks.Walk.IsPlaying) then
                    animTracks.Walk:Stop()
                end

                local players = game:GetService("Players"):GetPlayers()
                local closestCharacterInRange = nil

                for _, player in pairs(players) do

                    local character = player.Character
                    if (character) and (character:FindFirstChild("Humanoid")) and (character.Humanoid.Health > 0) then

                        for _, descendant in pairs(character:GetDescendants()) do
                            if descendant:IsA("BasePart") then
                                descendant.CollisionGroup = charsCG
                            end
                        end

                        local mobPos = mobRoot.Position
                        local charPos = character.HumanoidRootPart.Position

                        local raycastParams = RaycastParams.new()
                        raycastParams.FilterDescendantsInstances = {newMob, character}
                        local lineOfSight = not workspace:Raycast(mobPos, charPos, raycastParams)

                        local distanceFrom = (mobPos - charPos).Magnitude
                        local maxDistanceAllowed = mobConfig:WaitForChild("DetectionRange").Value

                        if (lineOfSight) and (distanceFrom <= maxDistanceAllowed) then

                            if (not closestCharacterInRange) then
                                closestCharacterInRange = {character, distanceFrom}
                            elseif (distanceFrom < closestCharacterInRange[2]) then
                                closestCharacterInRange = {character, distanceFrom}
                            end
                        end
                    end
                end


                if (closestCharacterInRange) then
                    mobHumanoid:MoveTo(closestCharacterInRange[1].HumanoidRootPart.Position)

                    local attackCooldown = mobConfig:WaitForChild("AttackCooldown").Value

                    local canAttack = (tick() - lastAttacked) >= attackCooldown
                    if (canAttack) then

                        local attackRange = mobConfig:WaitForChild("AttackRange").Value
                        local inAttackRange = (closestCharacterInRange[2]) <= attackRange

                        if (inAttackRange) then
                            mobRoot:WaitForChild("AttackSound"):Play()

                            local raycastParams = RaycastParams.new()
                            raycastParams.FilterDescendantsInstances = {newMob}

                            local raycast = workspace:Raycast(mobRoot.Position, mobRoot.CFrame.LookVector * mobConfig.AttackRange.Value, raycastParams)

                            local targetHumanoid = raycast and (raycast.Instance.Parent:FindFirstChild("Humanoid") or raycast.Instance.Parent.Parent:FindFirstChild("Humanoid"))
                            if (targetHumanoid) and (game.Players:GetPlayerFromCharacter(targetHumanoid.Parent))  then

                                task.spawn(function()
                                    task.wait(0.4)
                                    targetHumanoid:TakeDamage(mobConfig:WaitForChild("Damage").Value)
                                end)
                            end

                            animTracks.Attack:Play()

                            mobRoot.AssemblyLinearVelocity = mobRoot.CFrame.LookVector * Vector3.new(60, 0, 60) + mobRoot.CFrame.UpVector * 6

                            lastAttacked = tick()
                        end
                    end

                else

                    local originPosition = spawnerCF.Position

                    if (goalRandomPosition) and (typeof(goalRandomPosition) == "Vector3") then
                        mobHumanoid:MoveTo(goalRandomPosition)

                        if ((goalRandomPosition - mobRoot.Position).Magnitude <= 5) or (mobRoot.AssemblyLinearVelocity.Magnitude < 0.1) then
                            goalRandomPosition = nil
                        end

                    elseif (goalRandomPosition) then

                        if ((tick() - goalRandomPosition[1]) >= goalRandomPosition[2]) then
                            goalRandomPosition = nil
                        end

                    else

                        local moveToNewSpot = rand:NextNumber()

                        if (moveToNewSpot > 0.5) then
                            goalRandomPosition = calculateRandomPosition(originPosition)

                        else
                            goalRandomPosition = {tick(), rand:NextNumber(1, 5)}
                        end
                    end
                end


                if (mobConfig.CurrentHealth.Value <= 0) then
                    break
                end

                task.wait(0.05)
            end

            newMob.Parent = game:GetService("ServerStorage")

            task.wait(respawnTime)
        end


    else
        warn("Mob of type\n" .. typeOfMob .. "\n was not found. Make sure you spelled the name properly for the spawner part.")
    end
end


for _, spawner in pairs(mobSpawners:GetChildren()) do
    task.spawn(handleSpawner, spawner)
end

mobSpawners.ChildAdded:Connect(function(child)
    task.spawn(handleSpawner, child)
end)