--[[
	Converts an event into a Promise with an optional predicate
]]

function Promise.fromEvent(event, predicate)
	predicate = predicate or function()
		return true
	end

	return Promise._new(debug.traceback(nil, 2), function(resolve, reject, onCancel)
		local connection
		local shouldDisconnect = false

		local function disconnect()
			connection:Disconnect()
			connection = nil
		end

		-- We use shouldDisconnect because if the callback given to Connect is called before
		-- Connect returns, connection will still be nil. This happens with events that queue up
		-- events when there's nothing connected, such as RemoteEvents

		connection = event:Connect(function(...)
			local callbackValue = predicate(...)

			if callbackValue == true then
				resolve(...)

				if connection then
					disconnect()
				else
					shouldDisconnect = true
				end
			elseif type(callbackValue) ~= "boolean" then
				error("Promise.fromEvent predicate should always return a boolean")
			end
		end)

		if shouldDisconnect and connection then
			return disconnect()
		end

		onCancel(function()
			disconnect()
		end)
	end)
end

return Promise
