local Bobbing = {}
Bobbing.__index = Bobbing

Bobbing.LeanMultiplier = 1.5
Bobbing.TurnAlpha = .05
Bobbing.SwayMultiplier = 1.7

type Euler = CFrame
type AnimationsMap = {[string]: (tick: number, dt: number) -> Euler}

local Animations: AnimationsMap = {}

local Storage = game:GetService("ReplicatedStorage")
local UIS     = game:GetService("UserInputService")
local Algebra = require(Storage:WaitForChild("AlgebraEasings"))

local CN = CFrame.new
local ANG = CFrame.Angles

local CameraLean = CN()

function Bobbing.constructor(HumanoidRootPart: BasePart, CurrentCamera: Camera, Humanoid: Humanoid)
    return setmetatable({
        HumanoidRootPart = HumanoidRootPart,
        CurrentCamera = CurrentCamera,
        Humanoid = Humanoid
    }, Bobbing)
end

function Animations.Idle(t, dt)
    return ANG(
        math.rad(math.sin(t)/350),
        math.rad(math.sin(t)/150),
        math.rad(-math.cos(t)/50)
    )
end

function Animations.Walk(t, dt)
    return ANG(0,0,0)
end

function Bobbing:Frame(dt: number)
    local Root = self.HumanoidRootPart
    local Camera = self.CurrentCamera
    local Humanoid = self.Humanoid

    local CameraCF = Camera.CFrame
    local Magnitude = Root:GetVelocityAtPosition(Root.Position).Magnitude
    local CurrentAnimation = Animations[Magnitude>1 and "Walk" or "Idle"](tick(), dt)

    --Lean the camera based on looking and moving direction(s)
    local MouseDelta = UIS:GetMouseDelta()
    local LeanDegree = -CameraCF.RightVector:Dot(Humanoid.MoveDirection)*Bobbing.LeanMultiplier
    local LeanMult = math.max(-Bobbing.SwayMultiplier, math.min(LeanDegree-MouseDelta.X, Bobbing.SwayMultiplier))
    CameraLean = CameraLean:Lerp(ANG(0, 0, math.rad(LeanMult)), Bobbing.TurnAlpha)

    Camera.CFrame *= CurrentAnimation*CameraLean
end

return Bobbing