This ProBuilder script is designed to identify and draw support lines on a price chart until they are broken by subsequent price action. The code determines potential support levels based on specific candlestick patterns and then visually represents these levels with lines until the price breaks through them.

defparam drawonlastbaronly=true

REM Measure the length of real body, lower shadow, and upper shadow for white and black candles
IF OPEN < CLOSE THEN REM white candle realbody = CLOSE – OPEN lowershadow = OPEN – LOW uppershadow = HIGH – CLOSE ELSIF OPEN > CLOSE THEN REM black candle
realbody = OPEN – CLOSE
lowershadow = CLOSE – LOW
uppershadow = HIGH – OPEN
ENDIF

REM Store support
IF ((lowershadow / realbody) >= 2 AND (realbody/uppershadow) >= 2) AND NOT(OPEN = CLOSE) THEN
$support[i]=low
$bar[i]=barindex
i=i+1
ENDIF

REM check support line
if islastbarupdate and i>1 then
for j = 0 to i-1
checklow = $support[j]
bars = max(1,barindex-$bar[j])
check=0
for z = 1 to bars
if low[z] check=1
break
endif
next
if check=0 then
drawray($bar[j],$support[j],barindex,$support[j]) coloured(0,255,0)
endif
next
endif

RETURN

Explanation of the code:

• Initial Setup: The script starts by setting drawonlastbaronly to true, ensuring that drawing operations are performed only on the last available bar to optimize performance.
• Candlestick Analysis: It measures the real body, lower shadow, and upper shadow of candles. Different calculations are performed based on whether the candle is bullish (white) or bearish (black).
• Support Identification: The script identifies potential support levels by checking if the lower shadow is at least twice the length of the real body and the real body is at least twice the length of the upper shadow, excluding doji candles (where open equals close).
• Storing Support Data: When a potential support is identified, its price level and the corresponding bar index are stored in arrays $support and $bar, respectively.
• Support Line Drawing: On the last update of the bar, the script checks each stored support level to see if it has been broken by any subsequent low prices. If not broken, a green ray (line) is drawn from the bar where the support was identified to the current bar.

This script is useful for traders and analysts who use technical analysis to visually identify and track support levels on price charts.