from app.bars.models import Bar


def sma(values: list[float], period: int) -> list[float | None]:
    if period <= 0:
        raise ValueError("period must be positive")
    output: list[float | None] = [None] * len(values)
    total = 0.0
    for index, value in enumerate(values):
        total += value
        if index >= period:
            total -= values[index - period]
        if index >= period - 1:
            output[index] = total / period
    return output


def ema(values: list[float], period: int) -> list[float | None]:
    if period <= 0:
        raise ValueError("period must be positive")
    output: list[float | None] = [None] * len(values)
    if len(values) < period:
        return output
    value = sum(values[:period]) / period
    output[period - 1] = value
    multiplier = 2 / (period + 1)
    for index in range(period, len(values)):
        value = (values[index] - value) * multiplier + value
        output[index] = value
    return output


def atr(bars: list[Bar], period: int = 14) -> list[float | None]:
    if period <= 0:
        raise ValueError("period must be positive")
    ranges: list[float] = []
    for index, bar in enumerate(bars):
        previous_close = bars[index - 1].c if index else bar.c
        ranges.append(max(bar.h - bar.l, abs(bar.h - previous_close), abs(bar.l - previous_close)))
    return sma(ranges, period)