build a manual "integrator" with R shiny,plotly,javascript -- 3

Hello. I am looking for someone with knowledge of javascript, Rshiny and plotly to build a manual integrator. Signal are plotted on subplots one under the other in plotly. Below each signal there is a straight line with limits that correspond to the integration edges of the signal. I want the user to be able to drag these data points interactively in plotly and then update the shaded area between the signal curve and the 2 selected data points.