// Licensed under the Apache License, Version 2.0
// © mihakralj
//@version=6
indicator("Intraday Momentum Index (IMI)", "IMI", overlay=false)

//@function Calculates IMI using intraday price ranges (open vs close)
//@param period Number of bars used in the calculation
//@returns IMI value (0-100)
//@optimized Uses circular buffer for O(1) per-bar complexity
imi(simple int period) =>
    if period <= 0
        runtime.error("Period must be greater than 0")
    float gain = 0.0
    float loss = 0.0
    if close > open
        gain := close - open
    else if close < open
        loss := open - close
    var array<float> gain_buffer = array.new_float(period, 0.0)
    var array<float> loss_buffer = array.new_float(period, 0.0)
    var int idx = 0
    var float gain_sum = 0.0
    var float loss_sum = 0.0
    gain_sum -= array.get(gain_buffer, idx)
    loss_sum -= array.get(loss_buffer, idx)
    array.set(gain_buffer, idx, gain)
    array.set(loss_buffer, idx, loss)
    gain_sum += gain
    loss_sum += loss
    idx := (idx + 1) % period
    float total = gain_sum + loss_sum
    float imi_value = total != 0.0 ? 100.0 * gain_sum / total : 50.0
    imi_value

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

// Inputs
i_period = input.int(14, "Period", minval=1, tooltip="Number of bars used in the calculation")

// Calculate IMI
imi_value = imi(i_period)

// Plot
plot(imi_value, "IMI", color=color.yellow, linewidth=2)