local LocalPlayer = game:GetService("Players").LocalPlayer
local RunService = game:GetService("RunService")
local UserInputService = game:GetService("UserInputService")
local Camera = workspace.CurrentCamera
local Mouse = LocalPlayer:GetMouse()
local target, offset
local antiGravity = 196.2

function getAngles(origin, aimPos, aimVelocity, speed)
    local tolerance = 1e-5
    local aimVector = CFrame.lookAt(origin, aimPos).LookVector
    local cosAngle = aimVector:Dot(aimVelocity.Unit)
    local v = speed
    local g = workspace.Gravity - antiGravity
    local initialGuess = (aimPos - origin).Magnitude / (speed - (aimVelocity.Magnitude * cosAngle))
    
    if initialGuess < 0 or initialGuess ~= initialGuess then
        return nil
    end
    
    local d = aimPos - origin
    
    local t = initialGuess
	for _ = 1, 100 do
		local rt = math.sqrt((d.X + aimVelocity.X * t)^2 + (d.Z + aimVelocity.Z * t)^2)
		local st = math.sqrt(v^4 - g * (g * rt^2 + 2 * (d.Y + aimVelocity.Y * t) * v^2))

        if st < 0 then
            return nil
		end

		local thetat = math.atan((v^2 - st) / (g * rt))
		local ft = (rt / (v * math.cos(thetat))) - t
        
        if math.abs(ft) <= tolerance then
            local displacement = (aimPos + (aimVelocity * t)) - origin
            local horizontalAngle = math.atan2(displacement.X, displacement.Z)
            local verticalAngle = thetat
            local xzDisplacement = rt
            return horizontalAngle + math.rad(180), verticalAngle, xzDisplacement, t
        end
		
		local rPrime = ((d.X + aimVelocity.X * t) * aimVelocity.X + (d.Z + aimVelocity.Z * t) * aimVelocity.Z) / rt
		local sPrime = (-g * (g * rt * rPrime + aimVelocity.Y * v^2)) / st
		local thetaPrime = (-sPrime * rt - (v^2 - st) * rPrime) / (g * rt^3 + (v^2 - st)^2)
		local cost, sint = math.cos(thetat), math.sin(thetat)
		local dft = ((rPrime / (v * cost)) + (rt * sint * thetaPrime) / (v * cost^2)) - 1
        if dft == nil or dft == 0 then
            break
        end
        
        t = t - ft / dft
    end
end

local function changeBulletGravity(input, _gameProcessed)
    if input.KeyCode == Enum.KeyCode.Two then
        antiGravity = 163.5
        return
    end
    if input.KeyCode == Enum.KeyCode.Three then
        antiGravity = 196.2
        return
    end
end

local function setTarget(input, _gameProcessed)
    if input.UserInputType ~= Enum.UserInputType.MouseButton3 then
        return
    end

    if not (target and offset) then
        if not (Mouse.Target and Mouse.Hit) then
            return
        end
        target = Mouse.Target
        offset = target.Position - Mouse.Hit.Position
    else
        target = nil
        offset = nil
    end
end

local function aimTarget()
    if not (target and target.Parent) then return end

    local origin = LocalPlayer.Character.HumanoidRootPart.Position
    local horizontalAngle, verticalAngle, dist = getAngles(origin, target.Position - offset, target.Velocity, 800)
    if not dist then return end

    local direction = CFrame.fromOrientation(verticalAngle, horizontalAngle, 0).LookVector * dist
    local pos, _ = Camera:WorldToViewportPoint(origin + direction)
    local loc = UserInputService:GetMouseLocation()
    mousemoverel(pos.X - loc.X, pos.Y - loc.Y)
end

RunService:BindToRenderStep('AimAt', Enum.RenderPriority.Camera.Value + 1, aimTarget)
UserInputService.InputBegan:Connect(changeBulletGravity)
UserInputService.InputBegan:Connect(setTarget)