function FindStartingItem(id)
	if not id then return end

	local t

	local num = tonumber(id)
	if num then
		t = GAMEMODE.Items[num]
	else
		for i, tab in pairs(GAMEMODE.Items) do
			if tab.Signature == id then
				t = tab
				break
			end
		end
	end

	if t and t.WorthShop then return t end
end

function FindItem(id)
	if not id then return end

	local t

	local num = tonumber(id)
	if num then
		t = GAMEMODE.Items[num]
	else
		for i, tab in pairs(GAMEMODE.Items) do
			if tab.Signature == id then
				t = tab
				break
			end
		end
	end

	return t
end

function TrueVisible(posa, posb, filter)
	local filt = ents.FindByClass("projectile_*")
	filt = table.Add(filt, player.GetAll())
	if filter then
		filt[#filt + 1] = filter
	end

	return not util.TraceLine({start = posa, endpos = posb, filter = filt, mask = MASK_SHOT}).Hit
end

function TrueVisibleFilters(posa, posb, ...)
	local filt = ents.FindByClass("projectile_*")
	filt = table.Add(filt, player.GetAll())
	if ... ~= nil then
		for k, v in pairs({...}) do
			filt[#filt + 1] = v
		end
	end

	return not util.TraceLine({start = posa, endpos = posb, filter = filt, mask = MASK_SHOT}).Hit
end

MASK_SHOT_OPAQUE = bit.bor(MASK_SHOT, CONTENTS_OPAQUE)
-- Literally if photon particles can reach point b from point a.
function LightVisible(posa, posb, ...)
	local filter = {}
	if ... ~= nil then
		for k, v in pairs({...}) do
			filter[#filter + 1] = v
		end
	end

	return not util.TraceLine({start = posa, endpos = posb, mask = MASK_SHOT_OPAQUE, filter}).Hit
end

function WorldVisible(posa, posb)
	return not util.TraceLine({start = posa, endpos = posb, mask = MASK_SOLID_BRUSHONLY}).Hit
end

function ValidFunction(ent, funcname, ...)
	if ent and ent:IsValid() and ent[funcname] then
		return ent[funcname](ent, ...)
	end
end

function CosineInterpolation(y1, y2, mu)
	local mu2 = (1 - math.cos(mu * math.pi)) / 2
	return y1 * (1 - mu2) + y2 * mu2
end

function string.AndSeparate(list)
	local length = #list
	if length <= 0 then return "" end
	if length == 1 then return list[1] end
	if length == 2 then return list[1].." and "..list[2] end

	return table.concat(list, ", ", 1, length - 1)..", and "..list[length]
end

function util.SkewedDistance(a, b, skew)
	if a.z > b.z then
		return math.sqrt((b.x - a.x) ^ 2 + (b.y - a.y) ^ 2 + ((a.z - b.z) * skew) ^ 2)
	end

	return a:Distance(b)
end

function util.Blood(pos, amount, dir, force, noprediction)
	local effectdata = EffectData()
		effectdata:SetOrigin(pos)
		effectdata:SetMagnitude(amount)
		effectdata:SetNormal(dir)
		effectdata:SetScale(math.max(128, force))
	util.Effect("bloodstream", effectdata, nil, noprediction)
end

-- I had to make this since the default function checks visibility vs. the entitiy's center and not the nearest position.
function util.BlastDamageEx(inflictor, attacker, epicenter, radius, damage, damagetype)
	local filter = inflictor
	for _, ent in pairs(ents.FindInSphere(epicenter, radius)) do
		local nearest = ent:NearestPoint(epicenter)
		if TrueVisibleFilters(epicenter, nearest, inflictor, ent) then
			ent:TakeSpecialDamage(((radius - nearest:Distance(epicenter)) / radius) * damage, damagetype, attacker, inflictor, nearest)
		end
	end
end

function util.BlastDamage2(inflictor, attacker, epicenter, radius, damage)
	util.BlastDamageEx(inflictor, attacker, epicenter, radius, damage, DMG_BLAST)
end

function util.PoisonBlastDamage(inflictor, attacker, epicenter, radius, damage, noreduce)
	local filter = inflictor
	for _, ent in pairs(ents.FindInSphere(epicenter, radius)) do
		local nearest = ent:NearestPoint(epicenter)
		if TrueVisibleFilters(epicenter, nearest, inflictor, ent) then
			ent:PoisonDamage(((radius - nearest:Distance(epicenter)) / radius) * damage, attacker, inflictor, nil, noreduce)
		end
	end
end

function util.ToMinutesSeconds(seconds)
	local minutes = math.floor(seconds / 60)
	seconds = seconds - minutes * 60

    return string.format("%02d:%02d", minutes, math.floor(seconds))
end

function util.ToMinutesSecondsMilliseconds(seconds)
	local minutes = math.floor(seconds / 60)
	seconds = seconds - minutes * 60

	local milliseconds = math.floor(seconds % 1 * 100)

    return string.format("%02d:%02d.%02d", minutes, math.floor(seconds), milliseconds)
end

function util.RemoveAll(class)
	for _, ent in pairs(ents.FindByClass(class)) do
		ent:Remove()
	end
end

local function TooNear(spawn, tab, dist)
	local spawnpos = spawn:GetPos()
	for _, ent in pairs(tab) do
		if ent:GetPos():Distance(spawnpos) <= dist then
			return true
		end
	end

	return false
end
function team.GetSpawnPointGrouped(teamid, dist)
	dist = dist or 200

	local tab = {}
	local spawns = team.GetSpawnPoint(teamid)

	for _, spawn in pairs(spawns) do
		if not TooNear(spawn, tab, dist) then
			table.insert(tab, spawn)
		end
	end

	return tab
end

function AccessorFuncDT(tab, membername, type, id)
	local emeta = FindMetaTable("Entity")
	local setter = emeta["SetDT"..type]
	local getter = emeta["GetDT"..type]

	tab["Set"..membername] = function(me, val)
		setter(me, id, val)
	end

	tab["Get"..membername] = function(me)
		return getter(me, id)
	end
end

function team.GetValidSpawnPoint(teamid)
	local t = {}

	local spawns = team.GetSpawnPoint(teamid)
	if spawns then
		for _, ent in pairs(spawns) do
			if ent:IsValid() then
				t[#t + 1] = ent
			end
		end
	end

	return t
end

function timer.SimpleEx(delay, action, ...)
	if ... == nil then
		timer.Simple(delay, action)
	else
		local a, b, c, d, e, f, g, h, i, j, k = ...
		timer.Simple(delay, function() action(a, b, c, d, e, f, g, h, i, j, k) end)
	end
end

function timer.CreateEx(timername, delay, repeats, action, ...)
	if ... == nil then
		timer.Create(timername, delay, repeats, action)
	else
		local a, b, c, d, e, f, g, h, i, j, k = ...
		timer.Create(timername, delay, repeats, function() action(a, b, c, d, e, f, g, h, i, j, k) end)
	end
end

function ents.CreateLimited(class, limit)
	if #ents.FindByClass(class) >= (limit or 200) then return NULL end

	return ents.Create(class)
end

function tonumbersafe(a)
	local n = tonumber(a)

	if n then
		if n == 0 or n < 0 or n > 0 then
			return n
		end

		-- NaN!
		return 0
	end

	return nil
end