lifetrack/apps/api/app/modules/health/foods.py

"""Food referential: local `food_items` cache first, Open Food Facts proxy next.

Rules from docs/research/nutrition-sources.md §4.3:
- every OFF call goes through the backend (never the browser);
- mandatory custom User-Agent `AppName/Version (ContactEmail)`;
- each fetched product is cached in `food_items` so it is never fetched twice;
- OFF unreachable must degrade gracefully (French 503 only when nothing local).

Tests inject an `httpx.MockTransport` through `set_http_transport` — the suite
never touches the network.
"""

from decimal import Decimal
from typing import Any

import httpx
from sqlalchemy import func, or_, select
from sqlalchemy.orm import Session

from app.core.errors import AppError
from app.modules.health.models import FoodItem
from app.modules.health.schemas import FoodSearchItem, FoodSearchResponse

OFF_SEARCH_URL = "https://search.openfoodfacts.org/search"
OFF_PRODUCT_URL = "https://world.openfoodfacts.org/api/v2/product/{barcode}.json"
OFF_USER_AGENT = "LifeTrack/1.0 (meejayproduction@gmail.com)"
OFF_TIMEOUT_S = 5.0
OFF_SOURCE = "off"

OFF_FIELDS = (
    "code,product_name,product_name_fr,brands,quantity,serving_size,"
    "serving_quantity,nutriments"
)

_TRANSPORT: httpx.BaseTransport | None = None


class ServiceUnavailableError(AppError):
    status_code, code = 503, "service_unavailable"


def set_http_transport(transport: httpx.BaseTransport | None) -> None:
    """Test seam: inject an httpx transport (MockTransport) for OFF calls."""
    global _TRANSPORT
    _TRANSPORT = transport


def _client() -> httpx.Client:
    return httpx.Client(
        timeout=OFF_TIMEOUT_S,
        headers={"User-Agent": OFF_USER_AGENT},
        transport=_TRANSPORT,
    )


def _num(value: Any) -> Decimal | None:
    if value is None or value == "":
        return None
    try:
        return Decimal(str(float(value)))
    except (TypeError, ValueError, ArithmeticError):
        return None


def _text(value: Any) -> str:
    """OFF fields are user-contributed: a field documented as a string sometimes
    arrives as a list (multi-value) or a number. Coerce anything to a clean string."""
    if value is None:
        return ""
    if isinstance(value, (list, tuple)):
        value = value[0] if value else ""
    return str(value).strip()


def _kcal_100g(nutriments: dict[str, Any]) -> Decimal | None:
    """kcal per 100 g, recomputed from kJ when the kcal field is missing."""
    kcal = _num(nutriments.get("energy-kcal_100g"))
    if kcal is not None:
        return kcal
    kj = _num(nutriments.get("energy_100g")) or _num(nutriments.get("energy-kj_100g"))
    if kj is None:
        return None
    return Decimal(str(round(float(kj) / 4.184, 1)))


def normalize_off_product(product: dict[str, Any]) -> dict[str, Any] | None:
    """Map one OFF product payload to `food_items` columns (per 100 g)."""
    name = _text(product.get("product_name_fr")) or _text(product.get("product_name"))
    if not name:
        return None
    nutriments = product.get("nutriments")
    if not isinstance(nutriments, dict):
        nutriments = {}
    return {
        "source": OFF_SOURCE,
        "source_id": _text(product.get("code")) or None,
        "name": name[:200],
        "brand": _text(product.get("brands")).split(",")[0].strip()[:100] or None,
        "energy_kcal_100g": _kcal_100g(nutriments),
        "protein_g_100g": _num(nutriments.get("proteins_100g")),
        "carbs_g_100g": _num(nutriments.get("carbohydrates_100g")),
        "sugar_g_100g": _num(nutriments.get("sugars_100g")),
        "fat_g_100g": _num(nutriments.get("fat_100g")),
        "sat_fat_g_100g": _num(nutriments.get("saturated-fat_100g")),
        "fiber_g_100g": _num(nutriments.get("fiber_100g")),
        "salt_g_100g": _num(nutriments.get("salt_100g")),
        "serving_size_g": _num(product.get("serving_quantity")),
        "raw": product,
    }


def cache_product(db: Session, data: dict[str, Any]) -> FoodItem:
    """Upsert one product into the local cache, keyed by (source, source_id)."""
    item: FoodItem | None = None
    if data["source_id"]:
        item = db.scalar(
            select(FoodItem).where(
                FoodItem.source == data["source"],
                FoodItem.source_id == data["source_id"],
            )
        )
    if item is None:
        item = FoodItem(source=data["source"], source_id=data["source_id"])
        db.add(item)
    for key, value in data.items():
        if key not in {"source", "source_id"}:
            setattr(item, key, value)
    return item


def search_local(db: Session, query: str, limit: int) -> list[FoodItem]:
    pattern = f"%{query.lower()}%"
    stmt = (
        select(FoodItem)
        .where(
            or_(
                func.lower(FoodItem.name).like(pattern),
                func.lower(func.coalesce(FoodItem.brand, "")).like(pattern),
            )
        )
        .order_by(FoodItem.name.asc())
        .limit(limit)
    )
    return list(db.scalars(stmt).all())


def fetch_off_search(query: str, limit: int) -> list[dict[str, Any]]:
    """Full-text search on Open Food Facts (Search-a-licious)."""
    with _client() as client:
        response = client.get(
            OFF_SEARCH_URL,
            params={"q": query, "langs": "fr", "page_size": limit},
        )
        response.raise_for_status()
        payload = response.json()
    hits = payload.get("hits")
    if hits is None:
        hits = payload.get("products") or []
    return [hit for hit in hits if isinstance(hit, dict)]


def fetch_off_product(barcode: str) -> dict[str, Any] | None:
    with _client() as client:
        response = client.get(
            OFF_PRODUCT_URL.format(barcode=barcode), params={"fields": OFF_FIELDS}
        )
        response.raise_for_status()
        payload = response.json()
    if payload.get("status") in (0, "failure"):
        return None
    return payload.get("product")


def search_foods(db: Session, query: str, limit: int = 20) -> FoodSearchResponse:
    """Local cache first, then Open Food Facts; caches every OFF hit."""
    query = query.strip()
    if len(query) < 2:
        raise AppError("Saisissez au moins 2 caractères pour rechercher un aliment.")
    local = search_local(db, query, limit)
    items = [FoodSearchItem.model_validate(row) for row in local]
    if len(items) >= limit:
        return FoodSearchResponse(query=query, items=items, origin="cache")

    known = {(row.source, row.source_id) for row in local}
    try:
        hits = fetch_off_search(query, limit - len(items))
    except (httpx.HTTPError, ValueError) as exc:
        if items:
            return FoodSearchResponse(query=query, items=items, origin="cache")
        raise ServiceUnavailableError(
            "La base Open Food Facts est momentanément injoignable. "
            "Réessayez plus tard ou saisissez l'aliment manuellement."
        ) from exc

    for hit in hits:
        data = normalize_off_product(hit)
        if data is None or (data["source"], data["source_id"]) in known:
            continue
        known.add((data["source"], data["source_id"]))
        cached = cache_product(db, data)
        items.append(FoodSearchItem.model_validate(cached))
    db.commit()
    return FoodSearchResponse(query=query, items=items[:limit], origin="cache+off")


def food_by_barcode(db: Session, barcode: str) -> FoodSearchItem:
    """Cache lookup, then OFF product endpoint."""
    barcode = barcode.strip()
    cached = db.scalar(
        select(FoodItem).where(
            FoodItem.source == OFF_SOURCE, FoodItem.source_id == barcode
        )
    )
    if cached is not None:
        return FoodSearchItem.model_validate(cached)
    try:
        product = fetch_off_product(barcode)
    except (httpx.HTTPError, ValueError) as exc:
        raise ServiceUnavailableError(
            "La base Open Food Facts est momentanément injoignable. "
            "Réessayez plus tard ou saisissez l'aliment manuellement."
        ) from exc
    data = normalize_off_product(product or {})
    if data is None:
        from app.core.errors import NotFoundError

        raise NotFoundError("Aucun produit ne correspond à ce code-barres.")
    item = cache_product(db, data)
    db.commit()
    db.refresh(item)
    return FoodSearchItem.model_validate(item)