functions = {}
clients = {}
spring = {}

renderRate = 120

--// Spring Class Setup
do
    local e = 2.7182818284590452353602875 -- euler's number

    function spring.new(position, velocity, target)
        local self = setmetatable({}, {__index = spring})

        self.position = position
        self.velocity = velocity
        self.target = target
        self.k = 1
        self.d = 1 -- friction constant

        return self
    end

    function spring:update()
        local x = self.target - self.position
        local f = x * self.k
        self.velocity = (self.velocity * (1 - self.d)) + f
        self.position = self.position + self.velocity
    end
end


-- // Modules
local chain = require(game.ReplicatedStorage.FABRIK)
--
local Character = script.Parent
local RightShoulderBase0, RightShoulderBase1 = Character.RightUpperArm.RightShoulder.C0, Character.RightUpperArm.RightShoulder.C1
local LeftShoulderBase0, LeftShoulderBase1 = Character.LeftUpperArm.LeftShoulder.C0, Character.LeftUpperArm.LeftShoulder.C1

local ElbowBase0, ElbowBase1 = Character.RightLowerArm.RightElbow.C0, Character.RightLowerArm.RightElbow.C1



Character.RightUpperArm.RightShoulder.C0 = RightShoulderBase0 --* CFrame.Angles(math.rad(45),0,0)
Character.RightUpperArm.RightShoulder.C1 = RightShoulderBase1

Character.RightLowerArm.RightElbow.C0 = ElbowBase0 --* CFrame.Angles(math.rad(-45),0,0)
Character.RightLowerArm.RightElbow.C1 = ElbowBase1


character = {}

local function projectVector(a, b)
    return a - a:Dot(b.unit)*b
end

local function vectorToAngle(v0,v1,plane)
    v0,v1 = projectVector(v0.unit, plane), projectVector(v1.unit, plane)
    local angle = math.acos(v0:Dot(v1))
    local cross = v0:Cross(v1)
    if plane:Dot(cross) < 0 then
        angle = -angle
    end
    return angle
end

local rightArm = chain.new({
        Vector3.new(0,0,0), --Shoulder
        Vector3.new(0,-0.9,0), --Elbow
        Vector3.new(0,-2,0) --Grip
    },
        Vector3.new(0,-2,0)
)

local leftArm = chain.new({
        Vector3.new(0,0,0), --Shoulder
        Vector3.new(0,-0.9,0), --Elbow
        Vector3.new(0,-2,0) --Grip
    },
        Vector3.new(0,-2,0)
    )


wait(2)
local completed = false
local lastUpdate = 0
local part = Instance.new("Part",game.Workspace)
part.Size = Vector3.new(.2,.2,.2)
part.Anchored = true
local parts = {}


game:GetService('RunService').RenderStepped:connect(function()
    if tick() > lastUpdate + 1/renderRate then
        lastUpdate = tick()
        local ShoulderCF = CFrame.new(Character.UpperTorso.RightShoulderRigAttachment.WorldPosition, Character.UpperTorso.RightShoulderRigAttachment.WorldPosition + Character.UpperTorso.CFrame.lookVector)
        local LeftShoulderCF = CFrame.new(Character.UpperTorso.LeftShoulderRigAttachment.WorldPosition, Character.UpperTorso.LeftShoulderRigAttachment.WorldPosition + Character.UpperTorso.CFrame.lookVector)
        local target = ShoulderCF:toObjectSpace(Character:FindFirstChild('Weapon').CFrame).p
        rightArm.target = target
        leftArm.target = LeftShoulderCF:toObjectSpace(Character:FindFirstChild('Weapon').CFrame * CFrame.new(0,0,-.8)).p   --+Right/-Left, +Up/-Down, +Back/-Forward
        rightArm:solve()
        leftArm:solve()
        --part.CFrame = ShoulderCF * CFrame.new(rightArm.joints[3])
        --// Right Arm
        local Vectors = {
            ShoulderBase    = Vector3.new(0,-1,0),
            ShoulderFace    = Vector3.new(0,0,-1),
            ShoulderToElbow = (rightArm.joints[2] - rightArm.joints[1]).unit,

            ElbowBase       = (rightArm.joints[2] - rightArm.joints[1]).unit,
            --ElbowFace     =
            ElbowToGrip     = (rightArm.joints[3] - rightArm.joints[2]).unit
        }

        local Normals = {
            Right           = Vector3.FromNormalId(Enum.NormalId.Right),
            Up              = Vector3.FromNormalId(Enum.NormalId.Top),
            Front           = Vector3.FromNormalId(Enum.NormalId.Front),
        }
        local RightShoulderX = vectorToAngle(Vectors.ShoulderBase, Vectors.ShoulderToElbow, Normals.Front)
        local RightShoulderY = vectorToAngle(Vectors.ShoulderFace, Vectors.ShoulderToElbow, Normals.Up)

        local RightElbowX    = vectorToAngle(Vectors.ElbowBase, Vectors.ElbowToGrip, Normals.Front)
        local RightElbowY    = vectorToAngle(Vectors.ShoulderFace, Vectors.ElbowToGrip, Normals.Up)
        print(math.deg(RightElbowX),math.deg(RightShoulderY))
        Character.RightUpperArm.RightShoulder.C0 = RightShoulderBase0 * CFrame.Angles(RightShoulderX, RightElbowY, -RightShoulderY) --ShoulderZ, ShoulderX), 1/20)
        Character.RightLowerArm.RightElbow.C0 = ElbowBase0 * CFrame.Angles(RightElbowX,0,0)
        for i,v in ipairs(parts) do
            v:Destroy()
        end
        for i,v in ipairs(rightArm.joints) do
            local part = Instance.new("Part",game.Workspace)
            part.Size = Vector3.new(.2,.2,.2)
            part.Anchored = true
            part.CFrame = ShoulderCF * CFrame.new(v)
            part.CanCollide = false
            table.insert(parts,part)
        end
        --Character.RightLowerArm.RightElbow.C0 = ElbowBase0 * CFrame.Angles(RightElbowX,0,0)
    --
    --  --// Left Arm
    --  local LeftShoulderX = vectorToAngle((Vector3.new(0,-1,0) - leftArm.joints[1]).unit, (leftArm.joints[2] - leftArm.joints[1]).unit)
    --  local LeftShoulderY = vectorToAngle((Vector3.new(1,0,0) - leftArm.joints[1]).unit, (leftArm.joints[2] - leftArm.joints[1]).unit)
    --
    --  local LeftElbowX = vectorToAngle((leftArm.joints[2] - leftArm.joints[1]).unit, (leftArm.joints[3] - leftArm.joints[2]).unit)
    --  local LeftElbowY = vectorToAngle((Vector3.new(-1,0,0)).unit, (leftArm.joints[2] - leftArm.joints[1]).unit)
    --  print(math.deg(LeftElbowY))
    --  Character.LeftUpperArm.LeftShoulder.C0 = LeftShoulderBase0 * CFrame.Angles(LeftShoulderX, LeftShoulderY, LeftElbowY) --ShoulderZ, ShoulderX), 1/20)
    --  Character.LeftLowerArm.LeftElbow.C0 = ElbowBase0 * CFrame.Angles(LeftElbowX,0,0)
    else
        print("Didn't render")
    end
end)