"""Label utilities for CodeBERT multi-label classification."""

from __future__ import annotations

from pathlib import Path
from typing import Dict, List, Sequence, Union

import numpy as np
import yaml

CONFIG_PATH = (
    Path(__file__).resolve().parent.parent / "config" / "codebert_labels.yaml"
)


def load_codebert_labels(config_path: Path = CONFIG_PATH) -> List[str]:
    with open(config_path) as f:
        data = yaml.safe_load(f)
    return list(data["labels"])


def load_alias_map(config_path: Path = CONFIG_PATH) -> Dict[str, List[str]]:
    with open(config_path) as f:
        data = yaml.safe_load(f)
    return {k: list(v) for k, v in data["alias_map"].items()}


def label_to_multihot(
    error_labels: Union[str, Sequence[str]],
    label_list: List[str] | None = None,
    alias_map: Dict[str, List[str]] | None = None,
) -> np.ndarray:
    """
    Convert error label(s) to multi-hot vector.

    Accepts:
      - comma-separated string: "JOIN_ERROR,AGGREGATION_ERROR"
      - list of label strings
      - single dataset label_name (resolved via alias_map)
    """
    labels = label_list or load_codebert_labels()
    aliases = alias_map or load_alias_map()
    index = {name: i for i, name in enumerate(labels)}
    vec = np.zeros(len(labels), dtype=np.float32)

    if isinstance(error_labels, str):
        raw = [s.strip() for s in error_labels.split(",") if s.strip()]
        if len(raw) == 1 and raw[0] in aliases:
            raw = aliases[raw[0]]
        elif len(raw) == 1 and raw[0] in index:
            raw = [raw[0]]
        elif len(raw) == 1 and raw[0] not in index:
            mapped = aliases.get(raw[0], [])
            raw = mapped
    else:
        raw = list(error_labels)
        expanded: List[str] = []
        for item in raw:
            if item in aliases:
                expanded.extend(aliases[item])
            elif item in index:
                expanded.append(item)
        raw = expanded

    for name in raw:
        if name not in index:
            raise ValueError(f"Unknown label '{name}'. Expected one of {labels}")
        vec[index[name]] = 1.0

    if vec.sum() == 0:
        raise ValueError(f"No valid labels found in {error_labels}")
    return vec


def multihot_to_label_names(
    vec: np.ndarray,
    label_list: List[str] | None = None,
    threshold: float = 0.5,
) -> List[str]:
    labels = label_list or load_codebert_labels()
    indices = np.where(vec >= threshold)[0]
    return [labels[i] for i in indices]