local function buildJoint(parentAttachment, partForJointAttachment)
    local jointName = parentAttachment.Name:gsub("RigAttachment", "")
    local motor = partForJointAttachment.Parent:FindFirstChild(jointName)
    if not motor then
        motor = Instance.new("Motor6D")
    end
	motor.Name = jointName

    motor.Part0 = parentAttachment.Parent
    motor.Part1 = partForJointAttachment.Parent

	motor.C0 = parentAttachment.CFrame
    motor.C1 = partForJointAttachment.CFrame

    motor.Parent = partForJointAttachment.Parent
end

function buildRigFromAttachments(last, part)
	for _, attachment in pairs(part:GetChildren()) do
		if attachment:IsA("Attachment") and string.find(attachment.Name, "RigAttachment") then
			for _, sibling in pairs(part.Parent:GetChildren()) do
				if sibling ~= part and sibling ~= last then
					local matchingAttachment = sibling:FindFirstChild(attachment.Name)
					if matchingAttachment then
						buildJoint(attachment, matchingAttachment)
						buildRigFromAttachments(part, matchingAttachment.Parent)
					end
				end
			end
		end
	end
end

local function getOldCharacterMesh(character, newCharacterMesh)
    for _, obj in pairs(character:GetChildren()) do
        if obj:IsA("CharacterMesh") and obj.BodyPart == newCharacterMesh.BodyPart then
            return obj
        end
    end
    return nil
end

function applyBodyPart(character, r15Folder)
    local humanoid = character:FindFirstChild("Humanoid")
    if humanoid.RigType == Enum.HumanoidRigType.R15 then
        for _, part in pairs(r15Folder:GetChildren()) do
            local oldPart = character:FindFirstChild(part.Name)
            part:Clone().Parent = character
            oldPart.Name = ""
            oldPart:Destroy()
        end
        -- Rebuild the rig
        -- Note: if applying many body parts at once it is more efficient to call this after applying them all
        buildRigFromAttachments(nil, character.HumanoidRootPart)
    else
        for _, characterMesh in pairs(r15Folder:GetChildren()) do
            local oldCharacterMesh = getOldCharacterMesh(character, characterMesh)
            if oldCharacterMesh then
                oldCharacterMesh:Destroy()
            end
            characterMesh.Parent = character
        end
    end
end