drag and drop - jQuery plugin for building formulas by dragging and dropping -

i want provide back-end application customers, can set-up rules dragging , dropping, processed on page call.

this how should work: there basic elements of customer can build if blocks, e.g.

<request_url> contains <term_xyz>

<agent> equals 'chrome'

and on. i'm looking jquery plug-in provide easy drag , drop solution concatenating these block formula using boolean operators, like

((condition_1 or condition_2) , condition_3) or (condition_3 , condition_4)

with formula can trigger operations, in end there instruction like

if <formula> <do_something>

which allows customers build absolutely flexible instructions.

my question now: is there ready-to-use jquery plugin can used build formula via drag , drop based on conditions?

note: know how handle , code functionality in application process these instructions, need formula round brackets , boolean operators front-end. and know of jquerys "droppable" , "sortable", that's last option me build on own these.

i once needed script build compley and/or rules , used jquery query builder.

it doesn't support drag&drop default has a plugin (that never used).

at least take starting point , expand fit needs.

hope helps.