"""Technical indicators."""

from errors import InsufficientDataError, UnsupportedIndicatorError


def _closes(candles: list) -> list[float]:
    return [float(c[4]) for c in candles]


def _ema_series(values: list[float], period: int) -> list[float]:
    if len(values) < period:
        raise InsufficientDataError(f"EMA({period}) requires at least {period} candles, got {len(values)}")
    k = 2 / (period + 1)
    ema_vals = [sum(values[:period]) / period]
    for v in values[period:]:
        ema_vals.append(v * k + ema_vals[-1] * (1 - k))
    return ema_vals


def ema(candles: list, period: int = 20) -> float:
    return round(_ema_series(_closes(candles), period)[-1], 6)


def rsi(candles: list, period: int = 14) -> float:
    closes = _closes(candles)
    if len(closes) < period + 1:
        raise InsufficientDataError(f"RSI({period}) requires at least {period + 1} candles, got {len(closes)}")
    deltas = [closes[i] - closes[i - 1] for i in range(1, len(closes))]
    gains = [max(d, 0.0) for d in deltas]
    losses = [abs(min(d, 0.0)) for d in deltas]
    avg_gain = sum(gains[:period]) / period
    avg_loss = sum(losses[:period]) / period
    for i in range(period, len(deltas)):
        avg_gain = (avg_gain * (period - 1) + gains[i]) / period
        avg_loss = (avg_loss * (period - 1) + losses[i]) / period
    if avg_loss == 0:
        return 100.0
    rs = avg_gain / avg_loss
    return round(100 - (100 / (1 + rs)), 2)


def macd(candles: list, fast_period: int = 12, slow_period: int = 26, signal_period: int = 9) -> dict:
    closes = _closes(candles)
    if len(closes) < slow_period + signal_period:
        raise InsufficientDataError("MACD requires more candles")
    fast_ema = _ema_series(closes, fast_period)
    slow_ema = _ema_series(closes, slow_period)
    offset = len(fast_ema) - len(slow_ema)
    macd_line = [fast_ema[i + offset] - slow_ema[i] for i in range(len(slow_ema))]
    signal_line = _ema_series(macd_line, signal_period)
    macd_val = round(macd_line[-1], 6)
    signal_val = round(signal_line[-1], 6)
    return {"macd": macd_val, "signal": signal_val, "histogram": round(macd_val - signal_val, 6)}


def sma(candles: list, period: int = 20) -> float:
    closes = _closes(candles)
    if len(closes) < period:
        raise InsufficientDataError(f"SMA({period}) requires at least {period} candles, got {len(closes)}")
    return round(sum(closes[-period:]) / period, 6)


def compute_indicator(candles: list, indicator: str, params: dict) -> dict:
    ind = indicator.lower()
    if ind == "rsi":
        value = rsi(candles, period=int(params.get("period", 14)))
    elif ind == "ema":
        value = ema(candles, period=int(params.get("period", 20)))
    elif ind == "macd":
        value = macd(candles, fast_period=int(params.get("fast_period", 12)), slow_period=int(params.get("slow_period", 26)), signal_period=int(params.get("signal_period", 9)))
    elif ind == "sma":
        value = sma(candles, period=int(params.get("period", 20)))
    else:
        raise UnsupportedIndicatorError(f"Unsupported indicator: {indicator}")
    return {"indicator": ind, "value": value}