// Licensed under the Apache License, Version 2.0
// © mihakralj
//@version=6
indicator("Volume Rate of Change (VROC)", "VROC", overlay=false)

//@function Calculates Volume Rate of Change
//@param vol Volume series for rate of change calculation
//@param period Number of periods for comparison
//@param calc_type Calculation type: true for percentage, false for point change
//@returns Volume Rate of Change value
//@optimized for performance and dirty data
vroc(simple int period, simple bool calc_type, series float vol = volume) =>
    float current_volume = vol
    float historical_volume = vol[period]
    if na(current_volume) or na(historical_volume)
        na
    else if calc_type
        historical_volume != 0.0 ? ((current_volume - historical_volume) / historical_volume) * 100.0 : na
    else
        current_volume - historical_volume

// ---------- Main loop ----------

// Inputs
i_period = input.int(12, "Period", minval=1, tooltip="Number of periods for comparison")
i_calc_type = input.string("Point", "Calculation Type", options=["Point", "Percent"], tooltip="Point or Percent calculation")

// Calculation
is_percent = i_calc_type == "Percent"
vroc_value = vroc(i_period, is_percent)

// Plot
plot(vroc_value, "VROC", color=color.yellow, linewidth=2)