--[=[
	@class RagdollCollisionUtils
]=]

local require = require(script.Parent.loader).load(script)

local EnumUtils = require("EnumUtils")
local RxBrioUtils = require("RxBrioUtils")
local RxR15Utils = require("RxR15Utils")
local Maid = require("Maid")

local RagdollCollisionUtils = {}

local R15_NO_COLLIDES = {
	{"LowerTorso", "LeftUpperArm"},
	{"LeftUpperArm", "LeftHand"},

	{"LowerTorso", "RightUpperArm"},
	{"RightUpperArm", "RightHand"},

	{"LeftUpperLeg", "RightUpperLeg"},

	{"UpperTorso", "RightUpperLeg"},
	{"RightUpperLeg", "RightFoot"},

	{"UpperTorso", "LeftUpperLeg"},
	{"LeftUpperLeg", "LeftFoot"},

	-- Support weird R15 rigs
	{"UpperTorso", "LeftLowerLeg"},
	{"UpperTorso", "RightLowerLeg"},
	{"LowerTorso", "LeftLowerLeg"},
	{"LowerTorso", "RightLowerLeg"},

	{"UpperTorso", "LeftLowerArm"},
	{"UpperTorso", "RightLowerArm"},

	{"Head", "LeftUpperArm"},
	{"Head", "RightUpperArm"},

	-- Basically every other part
	{"HumanoidRootPart", "LeftUpperArm"},
	{"HumanoidRootPart", "RightUpperArm"},
	{"HumanoidRootPart", "LeftLowerArm"},
	{"HumanoidRootPart", "RightLowerArm"},
	{"HumanoidRootPart", "LeftLowerLeg"},
	{"HumanoidRootPart", "RightLowerLeg"},
	{"HumanoidRootPart", "LeftUpperLeg"},
	{"HumanoidRootPart", "RightUpperLeg"},
	{"HumanoidRootPart", "Head"},
	{"HumanoidRootPart", "LeftFoot"},
	{"HumanoidRootPart", "RightFoot"},
	{"HumanoidRootPart", "LeftHand"},
	{"HumanoidRootPart", "RightHand"},
	{"HumanoidRootPart", "UpperTorso"},
	{"HumanoidRootPart", "LowerTorso"},
}

local R15_PARTS = {
	"LeftUpperArm";
	"RightUpperArm";
	"LeftLowerArm";
	"RightLowerArm";
	"LeftLowerLeg";
	"RightLowerLeg";
	"LeftUpperLeg";
	"RightUpperLeg";
	"Head";
	"LeftFoot";
	"RightFoot";
	"LeftHand";
	"RightHand";
	"UpperTorso";
	"LowerTorso";
}

local R6_NO_COLLIDES = {
	{"Left Leg", "Right Leg"},
	{"Head", "Right Arm"},
	{"Head", "Left Arm"},

	{"HumanoidRootPart", "Head"},
	{"HumanoidRootPart", "Right Leg"},
	{"HumanoidRootPart", "Right Arm"},
	{"HumanoidRootPart", "Left Leg"},
	{"HumanoidRootPart", "Left Arm"},
}

function RagdollCollisionUtils.getCollisionData(rigType: Enum.HumanoidRigType)
	if rigType == Enum.HumanoidRigType.R15 then
		return R15_NO_COLLIDES
	elseif rigType == Enum.HumanoidRigType.R6 then
		return R6_NO_COLLIDES
	else
		error(string.format("[RagdollCollisionUtils] - Unknown rigType %q", tostring(rigType)))
	end
end

function RagdollCollisionUtils.preventCollisionAmongOthers(character: Model, part: BasePart)
	local topMaid = Maid.new()

	for _, partName in R15_PARTS do
		topMaid:GiveTask(RxR15Utils.observeCharacterPartBrio(character, partName):Subscribe(function(brio)
			if brio:IsDead() then
				return
			end

			local maid = brio:ToMaid()
			local foundPart = brio:GetValue()

			local noCollide = Instance.new("NoCollisionConstraint")
			noCollide.Name = "RagdollNoCollisionConstraint_Animating"
			noCollide.Part0 = part
			noCollide.Part1 = foundPart
			noCollide.Parent = part
			maid:GiveTask(noCollide)
		end))
	end

	return topMaid
end

function RagdollCollisionUtils.ensureNoCollides(character: Model, rigType: Enum.HumanoidRigType)
	assert(typeof(character) == "Instance" and character:IsA("Model"), "Bad character")
	assert(EnumUtils.isOfType(Enum.HumanoidRigType, rigType), "Bad rigType")

	local topMaid = Maid.new()

	for _, data in RagdollCollisionUtils.getCollisionData(rigType) do
		local part0Name, part1Name = unpack(data)

		local observable = RxBrioUtils.flatCombineLatest({
			part0 = RxR15Utils.observeCharacterPartBrio(character, part0Name);
			part1 = RxR15Utils.observeCharacterPartBrio(character, part1Name);
		})

		topMaid:GiveTask(observable:Subscribe(function(state)
			if state.part0 and state.part1 then
				local maid = Maid.new()

				local noCollide = Instance.new("NoCollisionConstraint")
				noCollide.Name = "RagdollNoCollisionConstraint"
				noCollide.Part0 = state.part0
				noCollide.Part1 = state.part1
				noCollide.Parent = state.part1
				maid:GiveTask(noCollide)

				topMaid[data] = maid
			else
				topMaid[data] = nil
			end
		end))
	end

	return topMaid
end


return RagdollCollisionUtils