local BASE_HEIGHT = 80

local PAIR_FLAGS = {
	["no-attack"] = "no-attack",
	["no-attack-ubered"] = "no-attack-ubered",
}

local waitingPairBots = {
	Carriers = {},
	Carried = {},
}

local function canAttack(flag)
	return flag ~= PAIR_FLAGS["no-attack"] and flag ~= PAIR_FLAGS["no-attack-ubered"]
end

function PairBots(carrier, carried, pairFlag)
	local height = BASE_HEIGHT * carrier.m_flModelScale

	local carrierCallbacks = {}
	local carrierTimer

	local noTeleportForThisTick = 0

	local lastOrigin
	local function teleport()
		if not IsValid(carrier) then
			-- prevents carried briefly disappearing after carrier death

			if not lastOrigin then
				return
			end

			if not IsValid(carried) or not carried:IsAlive() then
				return
			end

			carried:SetAbsOrigin(lastOrigin + Vector(0, 0, height))

			return
		end

		local origin = carrier:GetAbsOrigin()

		if noTeleportForThisTick <= 0 then
			carried:SetAbsOrigin(origin + Vector(0, 0, height))
		else
			noTeleportForThisTick = noTeleportForThisTick - 1
		end

		lastOrigin = origin
	end

	local exitedSpawn = false

	local died = false
	timer.Simple(1, function()
		if died then
			return
		end

		carrierTimer = timer.Create(0, function()
			teleport()

			if pairFlag ~= PAIR_FLAGS["no-attack-ubered"] then
				if not carrier:InCond(TF_COND_INVULNERABLE_HIDE_UNLESS_DAMAGED) then
					carried:RemoveCond(TF_COND_INVULNERABLE_HIDE_UNLESS_DAMAGED)

					-- (royal): when bot exits spawn, we make the carrier bot land on the ground for 1 frame so that its TFBot thinks it's out of spawn & can now attack
					if not exitedSpawn then
						exitedSpawn = true

						noTeleportForThisTick = 1
						carried:SetAbsOrigin(carrier:GetAbsOrigin())
					end
				end
			end
		end, 0)
	end)

	teleport()

	local function endPairLogic()
		for _, id in pairs(carrierCallbacks) do
			carrier:RemoveCallback(id)
		end

		if carrierTimer then
			timer.Stop(carrierTimer)
		end

		died = true
	end

	carrierCallbacks.died = carrier:AddCallback(ON_DEATH, function()
		carried:RemoveCond(TF_COND_INVULNERABLE_HIDE_UNLESS_DAMAGED)

		if not canAttack(pairFlag) then
			timer.Simple(2, function()
				carried:SetAttributeValue("no_attack", nil)
			end)
		end

		endPairLogic()

		if not lastOrigin then
			return
		end

		-- suspend in place to prevent source jank from teleporting it back to spawn
		local iterated = 1
		for _ = 0, 1, 0.1 do
			timer.Simple(0.07 * iterated, function()
				carried:SetAbsOrigin(lastOrigin)
			end)

			iterated = iterated + 1
		end
	end)
	carrierCallbacks.spawn = carrier:AddCallback(ON_SPAWN, function()
		endPairLogic()
	end)
end

local function waveInit(wave)
	waitingPairBots = {
		Carriers = {},
		Carried = {},
	}
end

if OnWaveInitFuncs then
	table.insert(OnWaveInitFuncs, waveInit)
else
	function OnWaveInit(wave)
		waveInit(wave)
	end
end

local function waveSpawnBot(bot, wave, tags)
	for _, tag in pairs(tags) do
		local split = {}

		for k, _ in string.gmatch(tag, "([^_]+)") do
			table.insert(split, k)
		end

		if split[1]:lower() == "pair" then
			local pairName = split[2]
			local pairPlacement = split[3]:lower()
			local flag = split[4] and split[4]:lower()

			local waitTable
			local otherWaitTable

			if pairPlacement == "carried" then
				waitTable = waitingPairBots.Carried
				otherWaitTable = waitingPairBots.Carriers

				if not canAttack(flag) then
					timer.Simple(1, function()
						bot:SetAttributeValue("no_attack", 1)
					end)
				end

				if flag == PAIR_FLAGS["no-attack-ubered"] then
					bot:AddCond(TF_COND_INVULNERABLE_HIDE_UNLESS_DAMAGED)
				end
			elseif pairPlacement == "carrier" then
				waitTable = waitingPairBots.Carriers
				otherWaitTable = waitingPairBots.Carried
			else
				print("invalid carrier placement tag")
			end

			if not waitTable[pairName] then
				waitTable[pairName] = {}
			end

			table.insert(waitTable[pairName], bot)
			if otherWaitTable[pairName] and otherWaitTable[pairName][1] then
				PairBots(waitingPairBots.Carriers[pairName][1], waitingPairBots.Carried[pairName][1], flag)

				waitingPairBots.Carriers[pairName] = nil
				waitingPairBots.Carried[pairName] = nil
			end
		end
	end
end

if OnWaveSpawnBotFuncs then
	table.insert(OnWaveSpawnBotFuncs, waveSpawnBot)
else
	function OnWaveSpawnBot(wave)
		waveSpawnBot(wave)
	end
end