Stochastic RSI

// This source code is subject to the terms of the Mozilla Public License 2.0 at https://mozilla.org/MPL/2.0/
// © claygrace74

//@version=6
indicator("Stochastic RSI", shorttitle="StochRSI", format=format.percent, overlay=false)

// ==================== Settings ====================
var stoch_group = "Stochastic RSI Settings"
int periodK = input.int(14, "Stochastic %K Length", minval=1, group=stoch_group)
int smoothK = input.int(3, "%K Smoothing", minval=1, group=stoch_group)
int smoothD = input.int(3, "%D Smoothing", minval=1, group=stoch_group)

var disp_group = "Display Settings"
int rsiob   = input.int(80, "Overbought Level", minval=50, maxval=100, group=disp_group)
int rsios   = input.int(20, "Oversold Level", minval=0, maxval=50, group=disp_group)
bool i_showDiv     = input.bool(true, "Show K-D Divergence Histogram", group=disp_group)
bool i_showSignals = input.bool(true, "Show K/D Cross Signals", group=disp_group)
bool i_showZoneFill = input.bool(true, "Show OB/OS Zone Fills", group=disp_group)

// ==================================================================================
// SMMA Helper
// ==================================================================================
smma(src, length) =>
    sma = ta.sma(src, length)
    smma = 0.0
    smma := na(smma[1]) ? sma : (smma[1] * (length - 1) + src) / length
    smma

// ==================================================================================
// Stochastic RSI Calculation
// ==================================================================================
k = smma(ta.stoch(close, high, low, periodK), smoothK)
d = smma(k, smoothD)
divergence = (math.round(k) - math.round(d)) + 50

// Signals
bullCross = ta.crossover(k, d) and d < rsios
bearCross = ta.crossunder(k, d) and d > rsiob
obEntry   = ta.crossover(k, rsiob)
osEntry   = ta.crossunder(k, rsios)
obExit    = ta.crossunder(k, rsiob)
osExit    = ta.crossover(k, rsios)

// 4-color divergence histogram
divGrowBull  = divergence >= 50 and divergence > divergence[1]
divShrinkBull = divergence >= 50 and divergence <= divergence[1]
divGrowBear  = divergence < 50 and divergence < divergence[1]
divShrinkBear = divergence < 50 and divergence >= divergence[1]
divColor = divGrowBull ? color.rgb(0, 200, 80) : divShrinkBull ? color.rgb(0, 120, 50) : divGrowBear ? color.rgb(200, 30, 30) : color.rgb(120, 40, 40)

// K line color gradient
kColor = color.from_gradient(k, 10, 90, color.green, color.red)

// ==================================================================================
// Grid Layout
// ==================================================================================
h100 = hline(100, "100", color=color.new(color.gray, 80))
hOB  = hline(rsiob, "Overbought", color=color.new(color.red, 50))
hMid = hline(50, "Midline", color=color.new(color.gray, 60))
hOS  = hline(rsios, "Oversold", color=color.new(color.green, 50))
h0   = hline(0, "0", color=color.new(color.gray, 80))

// Zone fills
fill(hOB, h100, color=i_showZoneFill ? color.new(color.red, 90) : color(na), title="OB Zone")
fill(h0, hOS,   color=i_showZoneFill ? color.new(color.green, 90) : color(na), title="OS Zone")

// ==================================================================================
// Plots
// ==================================================================================
plot(i_showDiv ? divergence : na, title='K-D Divergence', linewidth=2, style=plot.style_columns, color=divColor, histbase=50)
plot(k, title='%K', linewidth=2, style=plot.style_line, color=kColor)
plot(d, title='%D', linewidth=2, style=plot.style_line, color=color.rgb(255, 174, 0))

// Cross signals
plotshape(i_showSignals and bullCross, style=shape.triangleup,   location=location.bottom, color=color.green, text="Buy",  textcolor=color.green, size=size.tiny, title="Bull K/D Cross")
plotshape(i_showSignals and bearCross, style=shape.triangledown, location=location.top,    color=color.red,   text="Sell", textcolor=color.red,   size=size.tiny, title="Bear K/D Cross")
plotshape(i_showSignals and osExit,    style=shape.circle, location=location.bottom, color=color.new(color.green, 30), size=size.tiny, title="OS Exit")
plotshape(i_showSignals and obExit,    style=shape.circle, location=location.top,    color=color.new(color.red, 30),   size=size.tiny, title="OB Exit")

// ==================================================================================
// Alert Conditions
// ==================================================================================
alertcondition(bullCross,  "Bullish K/D Cross",    "K crossed above D in oversold zone")
alertcondition(bearCross,  "Bearish K/D Cross",    "K crossed below D in overbought zone")
alertcondition(obEntry,    "Entered Overbought",   "StochRSI K entered overbought territory")
alertcondition(osEntry,    "Entered Oversold",     "StochRSI K entered oversold territory")
alertcondition(osExit,     "Exited Oversold",      "StochRSI K crossed back above oversold")
alertcondition(obExit,     "Exited Overbought",    "StochRSI K crossed back below overbought")