"""Deterministic thickness band from free-text thickness_in (METADATA-15 / QUALITY-95).

The owner enters thickness in 1/8-inch steps on capture. The Woo attribute is a
synced band term. We map thickness_in into the first half-open band [low, high)
that contains it, derived only from the live synced term names/slugs — never a
hardcoded Woo term id.

Round-up semantics: bands are half-open on the upper bound, so a value that sits
on a shared boundary (e.g. 1.0 in) belongs to the band that *starts* at that
value (1"–1 1/2"), not the band that ends there (3/4"–1").
"""

from __future__ import annotations

import re
from typing import Any, Iterable, Optional

# Mixed number / fraction / decimal inch token, optional trailing quote.
_INCH_RE = re.compile(
    r"(?P<a>\d+)\s+(?P<n>\d+)\s*/\s*(?P<d>\d+)"  # 1 1/2
    r"|(?P<n2>\d+)\s*/\s*(?P<d2>\d+)"  # 1/2
    r"|(?P<dec>\d+(?:\.\d+)?)",  # 1 or 1.5
    re.IGNORECASE,
)
_QTR_RANGE_RE = re.compile(r"^(\d+)-(\d+)qtr$", re.IGNORECASE)
_QTR_MIN_RE = re.compile(r"^(\d+)qtr$", re.IGNORECASE)


def parse_inch_token(text: str) -> Optional[float]:
    """Parse one inch token like '1 1/2', '3/4', '2', or 2-with-quote → float inches."""
    t = (text or "").strip().rstrip("\"'").strip()
    if not t:
        return None
    m = _INCH_RE.fullmatch(t) or _INCH_RE.search(t)
    if not m:
        return None
    if m.group("a") is not None:
        return float(m.group("a")) + float(m.group("n")) / float(m.group("d"))
    if m.group("n2") is not None:
        return float(m.group("n2")) / float(m.group("d2"))
    if m.group("dec") is not None:
        return float(m.group("dec"))
    return None


def _bounds_from_name(name: str) -> Optional[tuple[float, float]]:
    """Return half-open [low, high) inches from a Woo thickness term name."""
    raw = (name or "").strip()
    low_s = raw.lower()
    if not raw:
        return None

    # Under X / less than X / < X
    m = re.match(r"^(?:under|below|less than|<)\s*(.+)$", low_s, re.IGNORECASE)
    if m:
        hi = parse_inch_token(m.group(1))
        if hi is not None:
            return (0.0, hi)

    # Over X / above X / > X / X+
    m = re.match(r"^(?:over|above|greater than|>)\s*(.+)$", low_s, re.IGNORECASE)
    if m:
        lo = parse_inch_token(m.group(1))
        if lo is not None:
            return (lo, float("inf"))
    m = re.match(r"^(.+?)\+\s*$", raw)
    if m:
        lo = parse_inch_token(m.group(1))
        if lo is not None:
            return (lo, float("inf"))

    # Range: "A - B" / "A–B" / "A- B" (quotes optional on either side)
    parts = re.split(r"\s*[-–—]\s*", raw, maxsplit=1)
    if len(parts) == 2:
        lo = parse_inch_token(parts[0])
        hi = parse_inch_token(parts[1])
        if lo is not None and hi is not None and hi > lo:
            return (lo, hi)

    # Single value band treated as [v, v+epsilon) — rare
    only = parse_inch_token(raw)
    if only is not None:
        return (only, only + 1e-9)
    return None


def _bounds_from_slug(slug: str) -> Optional[tuple[float, float]]:
    """Fallback: quarter-inch slugs like '4-6qtr', '12qtr', 'xthin'."""
    s = (slug or "").strip().lower()
    if not s:
        return None
    if s in {"xthin", "under", "thin"}:
        return (0.0, 0.5)
    m = _QTR_RANGE_RE.match(s)
    if m:
        lo = int(m.group(1)) * 0.25
        hi = int(m.group(2)) * 0.25
        if hi > lo:
            return (lo, hi)
    m = _QTR_MIN_RE.match(s)
    if m:
        lo = int(m.group(1)) * 0.25
        return (lo, float("inf"))
    return None


def term_bounds(term: dict[str, Any]) -> Optional[tuple[float, float]]:
    """Bounds for one synced thickness term; name first, slug fallback."""
    return _bounds_from_name(str(term.get("name") or "")) or _bounds_from_slug(
        str(term.get("slug") or "")
    )


def resolve_thickness_band_id(
    thickness_in: float | int | None,
    terms: Iterable[dict[str, Any]],
) -> Optional[int]:
    """Pick the synced thickness term id for thickness_in, or None if unknown.

    terms: iterable of {id, name, slug?} from the live Woo thickness attribute.
    """
    if thickness_in is None:
        return None
    try:
        t = float(thickness_in)
    except (TypeError, ValueError):
        return None
    if t < 0:
        return None

    scored: list[tuple[float, float, int]] = []  # (low, high, id)
    for term in terms:
        b = term_bounds(term)
        if b is None:
            continue
        tid = term.get("id")
        if tid is None:
            continue
        lo, hi = b
        scored.append((lo, hi, int(tid)))

    if not scored:
        return None

    # Prefer the tightest band that contains t under half-open [low, high).
    matches = [(hi - lo, lo, hi, tid) for lo, hi, tid in scored if lo <= t < hi]
    if matches:
        matches.sort()  # tightest span first
        return matches[0][3]

    # If nothing matched (gaps in taxonomy), pick nearest band by lower edge.
    scored.sort(key=lambda x: x[0])
    for lo, hi, tid in scored:
        if t < hi:
            return tid
    return scored[-1][2]


def load_thickness_terms(conn) -> list[dict[str, Any]]:
    """Live Thickness attribute terms from the synced Woo cache."""
    row = conn.execute(
        "SELECT id FROM woo_attributes WHERE lower(name)=? OR lower(slug)=?",
        ("thickness", "thickness"),
    ).fetchone()
    if row is None:
        # Case-insensitive name variants ("Thickness", "pa_thk" style slugs stay open)
        row = conn.execute(
            "SELECT id FROM woo_attributes WHERE lower(name) LIKE '%thickness%'"
        ).fetchone()
    if row is None:
        return []
    attr_id = row[0]
    rows = conn.execute(
        "SELECT id, name, slug FROM woo_attribute_terms WHERE attribute_id=? ORDER BY id",
        (attr_id,),
    ).fetchall()
    return [{"id": r[0], "name": r[1], "slug": r[2]} for r in rows]