Positive RSI Divergence Detector

//@version=5
indicator(title="Positive RSI Divergence Detector", shorttitle="RSI Div+", overlay=true, max_lines_count=100, max_labels_count=100)

// Inputs
rsiLengthInput = input.int(14, title="RSI Length", minval=1)
pivotLeftInput = input.int(5, title="Pivot Lookback Left", minval=1, tooltip="Number of bars to the left for pivot identification.")
pivotRightInput = input.int(5, title="Pivot Lookback Right", minval=1, tooltip="Number of bars to the right to confirm a pivot. This introduces a delay.")
maxLookbackInput = input.int(60, title="Max Bars Between Pivots", minval=5, tooltip="Maximum number of bars to look back for the first pivot of a divergence.")
minLookbackInput = input.int(3, title="Min Bars Between Pivots", minval=1, tooltip="Minimum number of bars between the two pivots forming a divergence.")

// Calculate RSI
rsiValue = ta.rsi(close, rsiLengthInput)

// Arrays to store historical pivot points (price, RSI value, and bar index)
var priceAtPivotLow = array.new<float>()
var rsiAtPivotLow = array.new<float>()
var barIndexOfPivotLow = array.new<int>()

// --- Pivot Detection ---
// Detect new pivot low. A pivot low is confirmed 'pivotRightInput' bars after it actually occurs.
// ta.pivotlow() returns the price of the pivot if one is found, otherwise na.
// The actual pivot occurred at 'bar_index - pivotRightInput'.
confirmedPivotLowPricePoint = ta.pivotlow(low, pivotLeftInput, pivotRightInput)

if not na(confirmedPivotLowPricePoint)
    // A pivot low was confirmed. The actual low was 'pivotRightInput' bars ago.
    actualPivotBarIndex = bar_index - pivotRightInput
    actualPivotPrice = low[pivotRightInput]    // Price at the actual pivot low bar
    actualPivotRSI = rsiValue[pivotRightInput] // RSI value at the actual pivot low bar

    // Add to our historical pivots if it's a new pivot (not a duplicate of the last one)
    // Corrected logic to prevent "Cannot call `last()` if array is empty" error
    if array.size(barIndexOfPivotLow) == 0
        array.push(priceAtPivotLow, actualPivotPrice)
        array.push(rsiAtPivotLow, actualPivotRSI)
        array.push(barIndexOfPivotLow, actualPivotBarIndex)
    else if array.get(barIndexOfPivotLow, array.size(barIndexOfPivotLow) - 1) != actualPivotBarIndex
        // If array is not empty, check if the new pivot is different from the last one.
        // Using array.get() with last index instead of array.last() for consistency
        array.push(priceAtPivotLow, actualPivotPrice)
        array.push(rsiAtPivotLow, actualPivotRSI)
        array.push(barIndexOfPivotLow, actualPivotBarIndex)

    // Keep arrays from growing excessively by removing very old pivots
    // Pivots older than 'maxLookbackInput' plus some buffer are unlikely to be used.
    if array.size(barIndexOfPivotLow) > 0 and (bar_index - array.get(barIndexOfPivotLow, 0) > maxLookbackInput + pivotLeftInput + pivotRightInput + 20)
        array.shift(priceAtPivotLow)
        array.shift(rsiAtPivotLow)
        array.shift(barIndexOfPivotLow)

// --- Divergence Detection ---
isBullishDivergenceFound = false
var pivot1_bar = 0
var pivot2_bar = 0 // Bar indices for the two lows of the divergence
var pivot1_price = 0.0
var pivot2_price = 0.0
// float pivot1_rsi = na, pivot2_rsi = na // Not strictly needed for alert message text if using bar indices/time

if array.size(barIndexOfPivotLow) >= 2
    // The latest confirmed pivot is "Pivot 2" (the more recent low)
    p2_array_idx = array.size(barIndexOfPivotLow) - 1
    pivot2_bar := array.get(barIndexOfPivotLow, p2_array_idx) // Re-assignment to already declared var, so := is ok
    pivot2_price := array.get(priceAtPivotLow, p2_array_idx)   // Re-assignment to already declared var, so := is ok
    p2_rsi = array.get(rsiAtPivotLow, p2_array_idx)      // New declaration in scope, use =

    // Iterate through previous pivots ("Pivot 1" candidates - the earlier low)
    // We start from the second to last pivot and go backwards.
    for i = array.size(barIndexOfPivotLow) - 2 to 0
        p1_bar_candidate = array.get(barIndexOfPivotLow, i)
        p1_price_candidate = array.get(priceAtPivotLow, i)
        p1_rsi_candidate = array.get(rsiAtPivotLow, i)

        // Check if Pivot 1 is within the lookback period relative to Pivot 2
        if (pivot2_bar - p1_bar_candidate <= maxLookbackInput) and (pivot2_bar - p1_bar_candidate >= minLookbackInput)
            // Bullish Divergence Condition:
            // Price: Lower Low (Pivot 2 price < Pivot 1 price)
            // RSI: Higher Low (Pivot 2 RSI > Pivot 1 RSI)
            if pivot2_price < p1_price_candidate and p2_rsi > p1_rsi_candidate
                isBullishDivergenceFound := true // Re-assignment to already declared var
                // Store the details of the pivots forming this specific divergence
                pivot1_bar := p1_bar_candidate   // Re-assignment
                pivot1_price := p1_price_candidate // Re-assignment
                // pivot1_rsi := p1_rsi_candidate // Stored if needed for other plots
                // pivot2_price and pivot2_bar are already set

                // Found a valid divergence, no need to check older Pivot 1 candidates for this Pivot 2.
                // The loop naturally finds the P1 closest to P2 first (if multiple P1s could form a divergence with P2).
                break
        else if (pivot2_bar - p1_bar_candidate > maxLookbackInput)
            // Optimization: If this Pivot 1 candidate is too old, any earlier ones will also be too old.
            break

// --- Alerting and Plotting ---
var lastAlertedPivot2Bar = 0 // Tracks the bar index of the last Pivot 2 that triggered an alert/label
triggerVisualsAndAlert = false

if isBullishDivergenceFound
    if pivot2_bar != lastAlertedPivot2Bar // Ensure we only act once for each confirmed Pivot 2 of a divergence
        triggerVisualsAndAlert := true // Re-assignment
        lastAlertedPivot2Bar := pivot2_bar // Re-assignment

        // Draw a line on the price chart connecting the two lows of the divergence
        line.new(x1=pivot1_bar, y1=pivot1_price,
                 x2=pivot2_bar, y2=pivot2_price,
                 color=color.new(color.blue, 0), width=2, style=line.style_solid)

        // Optional: Draw a line on the RSI chart (requires RSI to be plotted in the same pane or a separate pane by this script)
        // For now, this script assumes you might have a separate RSI indicator.
        // If plotting RSI here: plot(rsiValue, "RSI", color.purple)
        // line.new(x1=pivot1_bar, y1=array.get(rsiAtPivotLow, /*index of p1*/),
        //          x2=pivot2_bar, y2=array.get(rsiAtPivotLow, /*index of p2*/),
        //          color=color.new(color.blue, 50), width=1, style=line.style_dashed)
        // Finding exact array indices for p1_rsi for line drawing needs care if array is shifted.
        // Simpler to just use p1_rsi_candidate and p2_rsi from the detection loop if that line is desired.

        // Add a label below the second low (Pivot 2) of the divergence
        label.new(x=pivot2_bar, y=pivot2_price, text="RSI Div+",
                  xloc=xloc.bar_index, yloc=yloc.belowbar,
                  color=color.new(color.green, 75), textcolor=color.white,
                  style=label.style_label_up, size=size.small,
                  tooltip="Positive RSI Divergence\n" +
                          "Low 1 (Bar: " + str.tostring(pivot1_bar) + "): " + str.tostring(pivot1_price, format.mintick) + "\n" +
                          "Low 2 (Bar: " + str.tostring(pivot2_bar) + "): " + str.tostring(pivot2_price, format.mintick))


// Alert Condition: Triggers when a new divergence is confirmed
alertcondition(triggerVisualsAndAlert,
               title="Positive RSI Divergence",
               message="{{ticker}} ({{interval}}): Positive RSI Divergence detected! Check chart for details.")

// For visual confirmation of RSI, you can add the standard RSI indicator to your chart separately.
// Or, to plot RSI in a separate pane with this script:
// 1. Change `overlay=true` to `overlay=false` in the `indicator()` line.
// 2. Uncomment the following line:
// plot(rsiValue, title="RSI", color=color.new(color.purple, 0))