Smooth Slow RSI
// This source code is subject to the terms of the Mozilla Public License 2.0 at https://mozilla.org/MPL/2.0/
// © peacefulLizard50262

//@version=5
indicator("Smooth Slow RSI")
rsi(src, len) =>
    rsi = ta.rsi(src, len)
    f = -math.pow(math.abs(math.abs(rsi - 50) - 50), 1 + math.pow(len / 14, 0.618) - 1) / math.pow(50, math.pow(len / 14, 0.618) - 1) + 50
    rsia = if rsi > 50
        f + 50
    else
        -f + 50
    rsia

rsi_len = input.int(140, "RSI Length", group = "RSI") 
smoothing = input.int(20, "Smoothing Length", group = "RSI")

rsi = rsi(ta.hma(close, smoothing), rsi_len)

ma(source, length, type) =>
    switch type
        "SMA" => ta.sma(source, length)
        "Bollinger Bands" => ta.sma(source, length)
        "EMA" => ta.ema(source, length)
        "SMMA (RMA)" => ta.rma(source, length)
        "WMA" => ta.wma(source, length)
        "VWMA" => ta.vwma(source, length)
maEnable = input.bool(false, "Enable MA", group="MA Settings")
maTypeInput = input.string("SMA", title="MA Type", options=["SMA", "Bollinger Bands", "EMA", "SMMA (RMA)", "WMA", "VWMA"], group="MA Settings")
maLengthInput = input.int(14, title="MA Length", group="MA Settings")
bbMultInput = input.float(2.0, minval=0.001, maxval=50, title="BB StdDev", group="MA Settings")

rsiMA = maEnable ? ma(rsi, maLengthInput, maTypeInput) : na
isBB = maTypeInput == "Bollinger Bands"

plot(rsi, "RSI", color=#7E57C2)
plot(rsiMA, "RSI-based MA", color=color.yellow)
rsiUpperBand = hline(70, "RSI Upper Band", color=#787B86)
hline(50, "RSI Middle Band", color=color.new(#787B86, 50))
rsiLowerBand = hline(30, "RSI Lower Band", color=#787B86)
fill(rsiUpperBand, rsiLowerBand, color=color.rgb(126, 87, 194, 90), title="RSI Background Fill")
bbUpperBand = plot(isBB ? rsiMA + ta.stdev(rsi, maLengthInput) * bbMultInput : na, title = "Upper Bollinger Band", color=color.green)
bbLowerBand = plot(isBB ? rsiMA - ta.stdev(rsi, maLengthInput) * bbMultInput : na, title = "Lower Bollinger Band", color=color.green)
fill(bbUpperBand, bbLowerBand, color= isBB ? color.new(color.green, 90) : na, title="Bollinger Bands Background Fill")
