"""Portable, read-only material-code/name lookup for delivery replies."""

from __future__ import annotations

import hashlib
import json
from functools import lru_cache
from pathlib import Path
from typing import Any


MATERIAL_NAME_CACHE_FILE = (
    Path(__file__).resolve().parents[2]
    / "capabilities/am516-delivery-prediction/data/material_names.json"
)


class MaterialNameCacheError(ValueError):
    """A cache error that contains no credentials or raw ERP records."""


def material_names_hash(materials: dict[str, str]) -> str:
    content = json.dumps(materials, ensure_ascii=False, sort_keys=True, separators=(",", ":"))
    return hashlib.sha256(content.encode("utf-8")).hexdigest()


def material_names_from_records(records: list[dict[str, Any]]) -> dict[str, str]:
    if not records:
        raise MaterialNameCacheError("物料查询结果为空，保留原缓存。")
    materials: dict[str, str] = {}
    for row in records:
        code, name = row.get("FNumber"), row.get("FName")
        if not isinstance(code, str) or not code.strip() or not isinstance(name, str) or not name.strip():
            raise MaterialNameCacheError("物料记录缺少有效编码或名称，保留原缓存。")
        code, name = code.strip(), " ".join(name.split())
        if code in materials and materials[code] != name:
            raise MaterialNameCacheError("同一物料编码存在不同名称，需核对后再刷新缓存。")
        materials[code] = name
    return dict(sorted(materials.items()))


def load_material_names(path: Path = MATERIAL_NAME_CACHE_FILE) -> dict[str, str]:
    """Reuse memory until the local file changes; never access ERP."""
    try:
        stat = path.stat()
    except FileNotFoundError as exc:
        raise MaterialNameCacheError("本地物料名称缓存文件缺失") from exc
    except OSError as exc:
        raise MaterialNameCacheError("本地物料名称缓存文件不可读取") from exc
    return _load_material_names(path, (stat.st_mtime_ns, stat.st_size, stat.st_ino))


@lru_cache(maxsize=4)
def _load_material_names(path: Path, version: tuple[int, int, int]) -> dict[str, str]:
    try:
        payload = json.loads(path.read_text(encoding="utf-8"))
    except FileNotFoundError as exc:
        raise MaterialNameCacheError("本地物料名称缓存文件缺失") from exc
    except (OSError, UnicodeError, json.JSONDecodeError) as exc:
        raise MaterialNameCacheError("本地物料名称缓存文件不可读取或格式错误") from exc
    if not isinstance(payload, dict) or payload.get("schema_version") != 1:
        raise MaterialNameCacheError("本地物料名称缓存版本或结构无效")
    materials = payload.get("materials")
    if not isinstance(materials, dict) or not materials:
        raise MaterialNameCacheError("本地物料名称缓存为空或结构无效")
    if any(
        not isinstance(code, str) or not code.strip()
        or not isinstance(name, str) or not name.strip()
        for code, name in materials.items()
    ):
        raise MaterialNameCacheError("本地物料名称缓存包含无效编码或名称")
    if payload.get("material_count") != len(materials) or payload.get("content_sha256") != material_names_hash(materials):
        raise MaterialNameCacheError("本地物料名称缓存计数或完整性校验失败")
    return materials


load_material_names.cache_clear = _load_material_names.cache_clear