"""Label blending utilities for CTA experiments."""

from typing import Union, List


# Predefined blend configurations
BLEND_CONFIGS = {
    'equal': [0.25, 0.25, 0.25, 0.25],
    'zscore_heavy': [0.5, 0.2, 0.15, 0.15],
    'rolling_heavy': [0.1, 0.1, 0.3, 0.5],
    'cs_heavy': [0.2, 0.5, 0.15, 0.15],
    'short_term': [0.1, 0.1, 0.4, 0.4],
    'long_term': [0.4, 0.2, 0.2, 0.2],
}

DEFAULT_BLEND = [0.2, 0.1, 0.3, 0.4]  # [zscore, cs_zscore, roll20, roll60]


def get_blend_weights(weights: Union[str, List[float], None]) -> List[float]:
    """Resolve blend weights from string name or list.

    Args:
        weights: Config name, list of 4 floats, or None for default

    Returns:
        List of 4 weights summing to 1.0
    """
    if weights is None:
        return DEFAULT_BLEND

    if isinstance(weights, str):
        if weights not in BLEND_CONFIGS:
            raise ValueError(f"Unknown blend config: {weights}. "
                           f"Available: {list(BLEND_CONFIGS.keys())}")
        return BLEND_CONFIGS[weights]

    if isinstance(weights, (list, tuple)):
        if len(weights) != 4:
            raise ValueError(f"Blend weights must have 4 values, got {len(weights)}")
        if abs(sum(weights) - 1.0) > 1e-6:
            raise ValueError(f"Blend weights must sum to 1.0, got {sum(weights)}")
        return list(weights)

    raise ValueError(f"Invalid blend weights type: {type(weights)}")


def describe_blend_config(weights: Union[str, List[float]]) -> str:
    """Get human-readable description of blend config.

    Args:
        weights: Config name or list of weights

    Returns:
        Description string
    """
    names = ['zscore', 'cs_zscore', 'rolling_20', 'rolling_60']

    if isinstance(weights, str):
        w = get_blend_weights(weights)
        return f"{weights}: {dict(zip(names, w))}"

    w = weights
    return f"custom: {dict(zip(names, w))}"