"""Costruzione del record di metadati a partire da un file nativo Creo."""

from __future__ import annotations

import hashlib
import os
import re
from collections import defaultdict
from datetime import datetime, timezone

from . import params, ugc

SCHEMA_VERSION = 1
METHOD = "ugc_native_reader"

#: Prefissi dei parametri generati da Creo (impostazioni lamiera, materiale di
#: sistema, ...). Restano nell'output ma marcati come "system", per non
#: annegare i parametri aziendali nel rumore.
SYSTEM_PREFIXES = ("PTC_", "SMT_", "PRO_", "__")

#: Nome file Creo con numero di versione: "9258400201.prt.12".
_NAME_RE = re.compile(r"^(?P<stem>.+?)\.(?P<ext>prt|asm|drw|frm|lay)(?:\.(?P<ver>\d+))?$", re.I)


def split_filename(filename: str) -> tuple[str, str, int | None]:
    """"9258400201.prt.12" -> ("9258400201", "prt", 12)."""
    match = _NAME_RE.match(filename)
    if not match:
        stem, _, ext = filename.rpartition(".")
        return (stem or filename), ext.lower(), None
    version = match.group("ver")
    return match.group("stem"), match.group("ext").lower(), int(version) if version else None


def _confidence(values: set, occurrences: int, sections: set) -> float:
    if len(values) > 1:
        return 0.40
    if len(sections) >= 2:
        return 0.99
    if occurrences >= 2:
        return 0.95
    return 0.80


def _aggregate(occurrences: list) -> dict:
    """Raggruppa le comparse per nome e assegna stato e confidenza."""
    grouped = defaultdict(list)
    for occurrence in occurrences:
        grouped[occurrence.name].append(occurrence)

    result = {}
    for name, group in grouped.items():
        kind = group[0].kind
        sections = {o.section for o in group if o.section}
        # Solo i parametri del modello compaiono nella tabella estesa; quelli
        # che vivono unicamente nella copia neutra appartengono alle feature
        # (fori, lavorazioni), non al modello.
        owner = "model" if any(o.form == "extended" for o in group) else "feature"

        entry = {
            "type": kind,
            "owner": owner,
            "scope": "system" if name.startswith(SYSTEM_PREFIXES) else "user",
            "occurrences": len(group),
            "sections": sorted(sections),
        }

        if kind == "real":
            raws = sorted({o.raw.hex() for o in group if o.raw})
            expressions = sorted({o.expression for o in group if o.expression})
            entry.update(
                value=None,
                status="encoded_not_decoded",
                confidence=None,
                raw=raws[0] if len(raws) == 1 else raws,
            )
            if expressions:
                # Il valore non e' costante: lo produce una relazione.
                entry["driven_by"] = expressions[0] if len(expressions) == 1 else expressions
        else:
            values = {o.value for o in group}
            entry["confidence"] = _confidence(values, len(group), sections)
            if len(values) == 1:
                entry.update(value=group[0].value, status="found")
            else:
                entry.update(
                    value=None,
                    status="conflict",
                    candidates=sorted(values),
                )
        result[name] = entry

    return dict(sorted(result.items()))


def extract(path: str, expected: "list[str] | None" = None) -> dict:
    """Estrae i metadati da un singolo file. Solleva ugc.NotACreoFile se il
    file non e' un nativo Creo riconoscibile."""
    with open(path, "rb") as handle:
        data = handle.read()

    container = ugc.parse(data)
    occurrences = params.iter_occurrences(data)
    for occurrence in occurrences:
        occurrence.section = container.section_at(occurrence.offset)

    filename = os.path.basename(path)
    stem, ext, version = split_filename(filename)

    parameters = _aggregate(occurrences)

    # I disegni non contengono la tabella parametri del modello: segnalarne
    # l'assenza come "parametro mancante" sarebbe fuorviante.
    holds_parameters = container.base_kind in ("PART", "ASSEMBLY")
    if holds_parameters:
        for name in expected or []:
            parameters.setdefault(
                name, {"value": None, "status": "parameter_not_present", "type": None}
            )

    return {
        "schema_version": SCHEMA_VERSION,
        "source_file": os.path.abspath(path),
        "file": {
            "name": filename,
            "size": len(data),
            "sha256": hashlib.sha256(data).hexdigest(),
            "modified": datetime.fromtimestamp(
                os.path.getmtime(path), timezone.utc
            ).isoformat(),
            "creo_version_number": version,
        },
        "model": {
            "name": container.common_name.rsplit(".", 1)[0] or stem,
            "file_name": container.common_name or f"{stem}.{ext}",
            "kind": container.base_kind,
            "subtype": container.subtype,
            "creo_version": container.creo_version,
            "banner": container.banner,
        },
        "extraction": {
            "method": METHOD,
            "extracted_at": datetime.now(timezone.utc).isoformat(timespec="seconds"),
            "sections": len(container.sections),
            "parameters_found": len(occurrences),
            "holds_model_parameters": holds_parameters,
        },
        "parameters": parameters,
    }


def latest_versions(paths: "list[str]") -> "list[str]":
    """Tra piu' versioni dello stesso modello tiene solo la piu' recente."""
    best: dict = {}
    for path in paths:
        stem, ext, version = split_filename(os.path.basename(path))
        key = (os.path.dirname(os.path.abspath(path)), stem, ext)
        current = best.get(key)
        if current is None or (version or -1) > (current[0] or -1):
            best[key] = (version, path)
    return sorted(path for _, path in best.values())