# app/catalog.py
from __future__ import annotations
import json
import os
import re
from typing import Dict, Any, List, Optional, Tuple

# In-memory singleton
_CATALOG: Optional[Dict[str, Any]] = None

def _norm(s: str) -> str:
    """lightweight normalization for fuzzy-ish equality"""
    return re.sub(r"\s+", " ", (s or "").strip().lower())

def get_catalog_path() -> str:
    """
    Resolve catalog path in this order:
      1) ENV CAFE_CATALOG_PATH
      2) repo-relative data/menu_catalog.json (current default)
    """
    env_path = os.getenv("CAFE_CATALOG_PATH")
    if env_path:
        return env_path
    here = os.path.dirname(os.path.abspath(__file__))
    root = os.path.dirname(here)
    return os.path.join(root, "data", "menu_catalog.json")

def _load_from_disk(path: str) -> Dict[str, Any]:
    if not os.path.exists(path):
        raise FileNotFoundError(
            f"Catalog not found at {path}. "
            "Set CAFE_CATALOG_PATH in your .env or place data/menu_catalog.json."
        )
    with open(path, "r", encoding="utf-8") as f:
        try:
            data = json.load(f)
        except json.JSONDecodeError as e:
            raise ValueError(f"Catalog JSON invalid at {path}: {e}") from e
    # quick shape checks (non-fatal, but helpful)
    if not isinstance(data, dict) or "items" not in data or "schema" not in data:
        raise ValueError("Catalog must contain top-level keys: 'items' and 'schema'.")
    if not isinstance(data["items"], list):
        raise ValueError("'items' must be a list.")
    if not isinstance(data["schema"], dict):
        raise ValueError("'schema' must be a dict.")
    return data

def load_catalog(force_reload: bool = False) -> Dict[str, Any]:
    global _CATALOG
    if _CATALOG is not None and not force_reload:
        return _CATALOG
    path = get_catalog_path()
    _CATALOG = _load_from_disk(path)
    return _CATALOG

def find_item_by_name(name: str) -> Optional[Dict[str, Any]]:
    c = load_catalog()
    q = _norm(name)
    if not q:
        return None
    for it in c["items"]:
        nm = _norm(it.get("name", ""))
        if q == nm or q in nm:
            return it
        # optional alias list support: ["alias1", "alias2"]
        for alias in it.get("aliases", []) or []:
            if q == _norm(alias) or q in _norm(alias):
                return it
    return None

def find_item_by_sku(sku: str) -> Optional[Dict[str, Any]]:
    c = load_catalog()
    target = (sku or "").strip()
    if not target:
        return None
    for it in c["items"]:
        if str(it.get("sku", "")).strip() == target:
            return it
    return None

def required_fields_for_category(category: str) -> List[str]:
    c = load_catalog()
    schema = c["schema"].get(category) or {}
    rf = schema.get("required_fields") or []
    return list(rf)

def optional_fields_for_category(category: str) -> List[str]:
    c = load_catalog()
    schema = c["schema"].get(category) or {}
    of = schema.get("optional_fields") or []
    return list(of)

def _resolve_item(order_item: Dict[str, Any]) -> Optional[Dict[str, Any]]:
    it: Optional[Dict[str, Any]] = None
    if order_item.get("sku"):
        it = find_item_by_sku(str(order_item["sku"]))
    if not it and order_item.get("name"):
        it = find_item_by_name(str(order_item["name"]))
    return it

def compute_missing_fields(order_item: Dict[str, Any]) -> List[str]:
    """
    order_item example:
      {"name": "Margherita Pizza", "qty": 2, "size": "large", ...}
    Uses catalog schema to see which fields are missing.
    """
    it = _resolve_item(order_item)
    if not it:
        return ["name"]  # we don’t even know the item yet

    category = it["category"]
    req = set(required_fields_for_category(category))

    present = set(k for k in order_item.keys() if k in req or k in {"qty", "name", "sku"})

    # qty normalization: consider qty present if >= 1
    if "qty" in req:
        try:
            q = int(order_item.get("qty", 0))
        except Exception:
            q = 0
        if q >= 1:
            present.add("qty")
        # else leave "qty" missing
    else:
        # even if qty isn't required, count it as present if provided
        if order_item.get("qty") is not None:
            present.add("qty")

    missing = [f for f in req if f not in present]
    return missing

def friendly_requirements_prompt(order_item: Dict[str, Any]) -> str:
    it = _resolve_item(order_item)
    if not it:
        return "Which item would you like to order?"

    category = it["category"]
    req = required_fields_for_category(category)
    opt = optional_fields_for_category(category)

    parts: List[str] = []
    opt_txt = f" Optional: {', '.join(opt)}." if opt else ""
    if req:
        parts.append(f"I need {', '.join(req)} for {it['name']}.{opt_txt}")
    else:
        parts.append(f"Please specify quantity for {it['name']}.{opt_txt}")

    # Also list choices for required options (e.g., size choices)
    opts = it.get("options") or {}
    choice_bits: List[str] = []
    for k, spec in opts.items():
        if spec.get("required"):
            choices = spec.get("choices") or []
            if choices:
                choice_bits.append(f"{k}: {', '.join(choices)}")
    if choice_bits:
        parts.append("Choices → " + " | ".join(choice_bits))

    return " ".join(parts)