"""Level parsing utilities for orderbook data."""

import json
import ast
import logging
from typing import List, Any, Tuple


def normalize_levels(levels: Any) -> List[List[float]]:
    """
    Convert string-encoded levels into [[price, size], ...] floats.
    
    Filters out zero/negative sizes. Supports JSON and Python literal formats.
    """
    if not levels or levels == '[]':
        return []

    parsed = _parse_string_to_list(levels)
    if not parsed:
        return []

    pairs: List[List[float]] = []
    for item in parsed:
        price, size = _extract_price_size(item)
        if price is None or size is None:
            continue
        try:
            p, s = float(price), float(size)
            if s > 0:
                pairs.append([p, s])
        except Exception:
            continue

    if not pairs:
        logging.debug("normalize_levels: no valid pairs parsed from input")
    return pairs


def parse_levels_including_zeros(levels: Any) -> List[Tuple[float, float]]:
    """
    Parse levels into (price, size) tuples including zero sizes for deletions.
    
    Similar to normalize_levels but preserves zero sizes (for orderbook deletions).
    """
    if not levels or levels == '[]':
        return []

    parsed = _parse_string_to_list(levels)
    if not parsed:
        return []

    results: List[Tuple[float, float]] = []
    for item in parsed:
        price, size = _extract_price_size(item)
        if price is None or size is None:
            continue
        try:
            p, s = float(price), float(size)
            if s >= 0:
                results.append((p, s))
        except Exception:
            continue

    return results


def _parse_string_to_list(levels: Any) -> List[Any]:
    """Parse string levels to list, trying JSON first then literal_eval."""
    try:
        parsed = json.loads(levels)
    except Exception:
        try:
            parsed = ast.literal_eval(levels)
        except Exception:
            return []
    return parsed if isinstance(parsed, list) else []


def _extract_price_size(item: Any) -> Tuple[Any, Any]:
    """Extract price and size from dict or list/tuple format."""
    if isinstance(item, dict):
        return item.get("price", item.get("p")), item.get("size", item.get("s"))
    elif isinstance(item, (list, tuple)) and len(item) >= 2:
        return item[0], item[1]
    return None, None