# indie:lang_version = 5
from indie import indicator, MainContext, param, plot, color, MutSeriesF, Var
from indie.algorithms import Ema, Highest
from indie.drawings import LabelAbs, AbsolutePosition
from math import isnan

@indicator('BBP Alert', overlay_main_pane=False)
@param.int('length', default=13, min=1, title='EMA Length')
@param.int('lookback', default=20, min=1, title='Peak Lookback Period')
@param.bool('show_alerts', default=True, title='Show Alert Markers')
@param.bool('show_threshold', default=True, title='Show 50% Threshold Line')
@plot.line('bbp', color=color.BLUE, title='Bull Bear Power')
@plot.line('threshold', color=color.RED, title='50% Threshold')
@plot.marker('alert', color=color.RED, size=7)
class Main(MainContext):
    def __init__(self, length, lookback, show_alerts, show_threshold):
        self._alert_triggered: bool = False  # Track if alert already triggered for current cycle
        
    def calc(self, length, lookback, show_alerts, show_threshold):
        # Calculate Bull Bear Power
        ema_close = Ema.new(self.close, length)
        bear_power = self.low[0] - ema_close[0]
        bull_power = self.high[0] - ema_close[0]
        bbp = bull_power + bear_power
        
        # Store BBP in a series for peak tracking
        bbp_series = MutSeriesF.new(bbp)
        
        # Find the recent peak over lookback period
        recent_peak = Highest.new(bbp_series, lookback)[0]
        
        # Calculate 50% threshold
        threshold_50pct = recent_peak * 0.5
        
        # Check alert condition: current BBP < 50% of recent peak
        alert_condition = False
        if not isnan(recent_peak) and not isnan(bbp) and recent_peak > 0:
            if bbp < threshold_50pct and not self._alert_triggered:
                alert_condition = True
                self._alert_triggered = True
        
        # Reset alert flag when BBP recovers above 75% of peak (hysteresis to avoid spam)
        if not isnan(recent_peak) and not isnan(bbp) and recent_peak > 0:
            if bbp > recent_peak * 0.75:
                self._alert_triggered = False
        
        # Prepare return values
        bbp_value = bbp
        threshold_value = threshold_50pct if show_threshold and not isnan(threshold_50pct) else 0.0
        alert_marker = bbp if (alert_condition and show_alerts) else 0.0
        
        # Draw alert label when condition is met
        if alert_condition and show_alerts:
            pos = AbsolutePosition(time=self.time[0], price=bbp)
            label = LabelAbs('ALERT: Bull Power Weakened', pos, 
                           font_size=12, text_color=color.WHITE, bg_color=color.RED)
            self.chart.draw(label)
        
        return bbp_value, threshold_value, alert_marker