// Licensed under the Apache License, Version 2.0
// © mihakralj
//@version=6
indicator("Trade Volume Index (TVI)", "TVI", overlay=false)

//@function Calculates Trade Volume Index
//@param price Price series for tick direction analysis
//@param vol Volume series for weighting
//@param min_tick Minimum price movement to register direction change
//@returns Trade Volume Index value
//@optimized for performance and dirty data
tvi(series float price, simple float min_tick, series float vol=volume) =>
    float p = nz(price, close), float v = nz(vol, 0.0)
    float pp = nz(p[1], p)
    float price_change = p - pp
    var int direction = 1
    var float tvi_sum = 0.0
    direction := price_change > min_tick ? 1 : price_change < -min_tick ? 0 : direction
    tvi_sum += direction == 1 ? v : -v
    tvi_sum

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

// Inputs
i_price_source = input.source(close, "Price Field", tooltip="Open, High, Low or Closing price")
i_min_tick = input.float(0.125, "Min. Move", minval=0.0001, tooltip="Minimum price change to register direction")

// Calculation
tvi_value = tvi(i_price_source, i_min_tick)

// Plot
plot(tvi_value, "TVI", color=color.yellow, linewidth=2)