"""Shared label constants and helpers used across the labeling pipeline."""

from __future__ import annotations

# ---------------------------------------------------------------------------
# Fine-grained labels (13 classes) — used by new models
# ---------------------------------------------------------------------------
CELL_LABELS = [
    "value", "aggregation", "header", "metadata", "comment", "empty", "junk",
    "col_header_1", "col_header_2", "col_header_3",
    "row_header_1", "row_header_2", "row_header_3",
]
LABEL2IDX = {label: i for i, label in enumerate(CELL_LABELS)}
NUM_CLASSES = len(CELL_LABELS)

MAX_HEADER_LEVEL = 3

# ---------------------------------------------------------------------------
# Coarse labels (9 classes) — legacy models and backward-compatible evaluation
# ---------------------------------------------------------------------------
COARSE_LABELS = [
    "value",
    "col_header", "row_header",
    "aggregation", "header", "metadata", "comment", "empty", "junk",
]
COARSE_LABEL2IDX = {label: i for i, label in enumerate(COARSE_LABELS)}
NUM_COARSE_CLASSES = len(COARSE_LABELS)

# Map each fine-grained index to the corresponding coarse index
fine_to_coarse_idx: dict[int, int] = {}
for _fine_idx, _fine_label in enumerate(CELL_LABELS):
    _coarse_label = (
        "col_header" if _fine_label.startswith("col_header_") else
        "row_header" if _fine_label.startswith("row_header_") else
        _fine_label
    )
    fine_to_coarse_idx[_fine_idx] = COARSE_LABEL2IDX[_coarse_label]

# ---------------------------------------------------------------------------
# Convenience sets
# ---------------------------------------------------------------------------
VALUE_LABELS = {"value", "aggregation"}
DATA_LABELS = {"value", "aggregation"}
KNOWN_FLAT_LABELS = {"value", "aggregation", "header", "metadata", "comment", "empty", "junk"}


# ---------------------------------------------------------------------------
# Predicates
# ---------------------------------------------------------------------------
def is_row_header(label: str | None) -> bool:
    return label is not None and label.startswith("row_header_")


def is_col_header(label: str | None) -> bool:
    return label is not None and label.startswith("col_header_")


def header_level(label: str) -> int:
    return int(label.rsplit("_", 1)[1])


def clamp_header_level(label: str, max_level: int = MAX_HEADER_LEVEL) -> str:
    """Clamp header level to *max_level*.  e.g. col_header_8 -> col_header_3."""
    if is_col_header(label):
        lvl = min(header_level(label), max_level)
        return f"col_header_{lvl}"
    if is_row_header(label):
        lvl = min(header_level(label), max_level)
        return f"row_header_{lvl}"
    return label


def is_header(label: str | None) -> bool:
    return label == "header"


def normalize_label(label: str | None) -> str:
    """Collapse row_header_N -> row_header, col_header_N -> col_header.

    Also maps legacy/orphan labels to their current equivalents.
    """
    if label is None:
        return "unlabeled"
    if label == "column_group":
        return "metadata"
    if label == "attribute":
        return "value"
    if is_row_header(label):
        return "row_header"
    if is_col_header(label):
        return "col_header"
    return label


def is_known_label(label: str | None) -> bool:
    """Check if label is a recognized cell label (handles any header level)."""
    if label is None:
        return False
    clamped = clamp_header_level(label)
    if clamped in LABEL2IDX:
        return True
    normalized = normalize_label(label)
    return normalized in LABEL2IDX or normalized in COARSE_LABEL2IDX


def is_fine_grained_label(label: str | None) -> bool:
    """Return True if *label* is one of the 13 fine-grained class names."""
    return label is not None and label in LABEL2IDX


def is_comment(label: str | None) -> bool:
    return label == "comment"


def is_junk(label: str | None) -> bool:
    return label == "junk"


def is_data_label(label: str | None) -> bool:
    """Return True for any label that represents labeled content (not unlabeled)."""
    if label in KNOWN_FLAT_LABELS:
        return True
    if is_col_header(label) or is_row_header(label):
        return True
    return False