"""Technical indicators and metadata for the crypto MCP."""

from collections import OrderedDict
from math import sqrt

from errors import InsufficientDataError, UnsupportedIndicatorError


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


def _highs(candles: list) -> list[float]:
    return [float(c[2]) for c in candles]


def _lows(candles: list) -> list[float]:
    return [float(c[3]) for c in candles]


def _volumes(candles: list) -> list[float]:
    return [float(c[5]) 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 atr(candles: list, period: int = 14) -> float:
    highs = _highs(candles)
    lows = _lows(candles)
    closes = _closes(candles)
    if len(closes) < period + 1:
        raise InsufficientDataError(f"ATR({period}) requires at least {period + 1} candles, got {len(closes)}")
    true_ranges = []
    for i in range(1, len(candles)):
        high = highs[i]
        low = lows[i]
        prev_close = closes[i - 1]
        tr = max(high - low, abs(high - prev_close), abs(low - prev_close))
        true_ranges.append(tr)
    first_atr = sum(true_ranges[:period]) / period
    atr_val = first_atr
    for tr in true_ranges[period:]:
        atr_val = ((atr_val * (period - 1)) + tr) / period
    return round(atr_val, 6)


def bollinger_bands(candles: list, period: int = 20, multiplier: float = 2.0) -> dict:
    closes = _closes(candles)
    if len(closes) < period:
        raise InsufficientDataError(f"Bollinger Bands require at least {period} candles, got {len(closes)}")
    window = closes[-period:]
    middle = sum(window) / period
    variance = sum((price - middle) ** 2 for price in window) / period
    std_dev = sqrt(variance)
    upper = middle + multiplier * std_dev
    lower = middle - multiplier * std_dev
    return {"middle": round(middle, 6), "upper": round(upper, 6), "lower": round(lower, 6)}


def vwap(candles: list, period: int | None = None) -> float:
    if period is not None and period <= 0:
        raise InsufficientDataError("VWAP period must be positive")
    subset = candles[-period:] if period is not None else candles
    if len(subset) < 1:
        raise InsufficientDataError("VWAP requires at least 1 candle")
    volumes = _volumes(subset)
    if sum(volumes) == 0:
        raise InsufficientDataError("VWAP requires non-zero volume")
    typical_prices = [((float(c[2]) + float(c[3]) + float(c[4])) / 3) for c in subset]
    pv = sum(tp * vol for tp, vol in zip(typical_prices, volumes))
    total_vol = sum(volumes)
    return round(pv / total_vol, 6)


def _rsi_handler(candles: list, params: dict):
    return rsi(candles, period=int(params.get("period", 14)))


def _ema_handler(candles: list, params: dict):
    return ema(candles, period=int(params.get("period", 20)))


def _macd_handler(candles: list, params: dict):
    return 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)),
    )


def _sma_handler(candles: list, params: dict):
    return sma(candles, period=int(params.get("period", 20)))


def _atr_handler(candles: list, params: dict):
    return atr(candles, period=int(params.get("period", 14)))


def _bollinger_handler(candles: list, params: dict):
    return bollinger_bands(
        candles,
        period=int(params.get("period", 20)),
        multiplier=float(params.get("multiplier", 2.0)),
    )


def _vwap_handler(candles: list, params: dict):
    period = params.get("period")
    if period is not None:
        period = int(period)
    return vwap(candles, period=period)


SUPPORTED_INDICATORS = OrderedDict(
    {
        "rsi": {
            "description": "Relative Strength Index (RSI) — momentum oscillator (0-100) derived from closing price gains/losses; higher values indicate stronger upward pressure.",
            "handler": _rsi_handler,
            "params": {"period": {"type": "integer", "default": 14, "min": 2}},
            "value_type": "number",
        },
        "ema": {
            "description": "Exponential Moving Average (EMA) — weighted moving average emphasizing recent closes to highlight near-term direction.",
            "handler": _ema_handler,
            "params": {"period": {"type": "integer", "default": 20, "min": 2}},
            "value_type": "number",
        },
        "sma": {
            "description": "Simple Moving Average (SMA) — unweighted rolling average of closes, useful for longer-term baselines (e.g., 200-period trend).",
            "handler": _sma_handler,
            "params": {"period": {"type": "integer", "default": 20, "min": 2}},
            "value_type": "number",
        },
        "macd": {
            "description": "Moving Average Convergence Divergence (MACD) — returns MACD, signal, and histogram values for spotting momentum shifts between fast/slow EMAs.",
            "handler": _macd_handler,
            "params": {
                "fast_period": {"type": "integer", "default": 12, "min": 2},
                "slow_period": {"type": "integer", "default": 26, "min": 3},
                "signal_period": {"type": "integer", "default": 9, "min": 2},
            },
            "value_type": "object",
        },
        "atr": {
            "description": "Average True Range (ATR) — classic volatility gauge derived from true range; higher values imply wider expected movement.",
            "handler": _atr_handler,
            "params": {"period": {"type": "integer", "default": 14, "min": 2}},
            "value_type": "number",
        },
        "bollinger": {
            "description": "Bollinger Bands — middle SMA with upper/lower bands offset by standard deviations; helpful for squeeze/mean-reversion checks.",
            "handler": _bollinger_handler,
            "params": {
                "period": {"type": "integer", "default": 20, "min": 2},
                "multiplier": {"type": "number", "default": 2.0, "min": 0.5},
            },
            "value_type": "object",
        },
        "vwap": {
            "description": "Volume Weighted Average Price (VWAP) — rolling average price weighted by traded volume; useful as an intraday fair-value anchor.",
            "handler": _vwap_handler,
            "params": {"period": {"type": "integer", "default": None, "nullable": True}},
            "value_type": "number",
        },
    }
)


def get_supported_indicators() -> list[dict]:
    entries: list[dict] = []
    for name, meta in SUPPORTED_INDICATORS.items():
        entries.append(
            {
                "name": name,
                "description": meta["description"],
                "params": meta["params"],
                "value_type": meta.get("value_type", "number"),
            }
        )
    return entries


def compute_indicator(candles: list, indicator: str, params: dict) -> dict:
    ind = indicator.lower()
    if ind not in SUPPORTED_INDICATORS:
        raise UnsupportedIndicatorError(f"Unsupported indicator: {indicator}")
    handler = SUPPORTED_INDICATORS[ind]["handler"]
    value = handler(candles, params)
    return {"indicator": ind, "value": value}