loreal-utilisation-dept/backend/app/services/airtable_fetch.py

"""Airtable fetch helpers.

Decisions:
- Paginated with pageSize=100; we follow the `offset` cursor.
- 429 → sleep 30s then retry once (Airtable docs). Any subsequent 429 raises.
- Field normalisation lives here so routers/handlers stay schema-pure.
- Date filtering for bookings uses filterByFormula on Start/End Date — we
  fetch bookings that overlap the requested window (start <= to AND end >= from).
"""

from __future__ import annotations

import asyncio
import logging
from datetime import date
from typing import Any, AsyncIterator
from urllib.parse import urlencode

import httpx

from app.config import settings
from app.deps.airtable import airtable_client


logger = logging.getLogger(__name__)


# ----------------------------------------------------------------------
# Low-level pagination
# ----------------------------------------------------------------------

async def _paginate(
    table: str,
    params: dict[str, Any] | None = None,
    *,
    max_retries_429: int = 1,
) -> AsyncIterator[dict[str, Any]]:
    """Async iterator yielding individual Airtable records."""
    client = airtable_client.client
    base_params: dict[str, Any] = {"pageSize": 100}
    if params:
        base_params.update(params)

    offset: str | None = None
    while True:
        q = dict(base_params)
        if offset:
            q["offset"] = offset

        # urlencode here so list values (filterByFormula doesn't use lists,
        # but fields[] would) are serialised consistently.
        url = f"/{table}?{urlencode(q, doseq=True)}"

        retries_left = max_retries_429
        while True:
            resp = await client.get(url)
            if resp.status_code == 429 and retries_left > 0:
                logger.warning("Airtable 429 on %s — sleeping 30s before retry", table)
                await asyncio.sleep(30)
                retries_left -= 1
                continue
            resp.raise_for_status()
            break

        payload = resp.json()
        for rec in payload.get("records", []):
            yield rec
        offset = payload.get("offset")
        if not offset:
            return


# ----------------------------------------------------------------------
# Field normalisation
# ----------------------------------------------------------------------

def _to_bool(v: Any) -> bool:
    if isinstance(v, bool):
        return v
    if v is None:
        return False
    if isinstance(v, str):
        return v.strip().lower() in {"true", "yes", "1", "checked"}
    return bool(v)


def _to_float(v: Any, default: float = 0.0) -> float:
    if v is None or v == "":
        return default
    try:
        return float(v)
    except (TypeError, ValueError):
        return default


def _to_date(v: Any) -> date | None:
    if not v:
        return None
    if isinstance(v, date):
        return v
    try:
        # Airtable returns ISO date strings.
        return date.fromisoformat(str(v)[:10])
    except ValueError:
        return None


def _as_list(v: Any) -> list[str]:
    if v is None:
        return []
    if isinstance(v, list):
        return [str(x) for x in v]
    return [str(v)]


def _flatten(v: Any) -> str | None:
    # Airtable returns linked-record and lookup fields as lists, even when
    # the cardinality is 1 — e.g. "Resource Name" on Booking Resource comes
    # back as ["Aadesh Khale"]. Callers downstream (merge service, frontend
    # types) expect scalars; flatten here at the boundary.
    if v is None:
        return None
    if isinstance(v, list):
        return str(v[0]).strip() if v and v[0] is not None else None
    s = str(v).strip()
    return s or None


def normalise_resource(rec: dict[str, Any]) -> dict[str, Any]:
    f = rec.get("fields", {})
    # Roles may be a multi-select array, a single linked record name, or a string.
    roles_raw = f.get("Roles") or f.get("Role") or []
    return {
        "recordId": rec.get("id"),
        "name": f.get("Name") or f.get("Resource Name") or "",
        "email": f.get("Email") or None,
        "department": f.get("Department") or None,
        "roles": _as_list(roles_raw),
        "inactive": _to_bool(f.get("Inactive")),
        "availHoursPerWeek": _to_float(
            f.get("Availability Hour (per week)")
            or f.get("Availability Hours (per week)")
            or f.get("Available Hours")
            or 0
        ),
        "startDate": _to_date(f.get("Start Date")),
        "endDate": _to_date(f.get("End Date")),
        "employmentType": f.get("Employment Type") or f.get("FTE / Freelancer") or None,
        "country": f.get("Country") or None,
    }


def normalise_booking(rec: dict[str, Any]) -> dict[str, Any]:
    f = rec.get("fields", {})
    # Every linked/lookup field on Booking Resource comes back as a list from
    # Airtable — flatten at the boundary so downstream consumers get scalars.
    return {
        "id": rec.get("id"),
        "task": _flatten(f.get("Task") or f.get("Task Description")),
        "startDate": _to_date(f.get("Start Date")),
        "endDate": _to_date(f.get("End Date")),
        "resourceName": _flatten(
            f.get("Resource Name (from Resource)")
            or f.get("Resource Name")
            or f.get("Resource")
        ),
        "projectNumber": _flatten(
            f.get("Project Number (from Master)")
            or f.get("Project Number")
            or f.get("Project No.")
        ),
        "projectName": _flatten(
            f.get("Project Name (from Master)")
            or f.get("Project Name")
            or f.get("Project Title")
        ),
        "department": _flatten(
            f.get("Department (from Resource Name)")
            or f.get("Department")
        ),
        "division": _flatten(f.get("Division")),
        "hoursSelection": _as_list(f.get("Hours Selection") or f.get("Days") or []),
        "totalHoursBooked": _to_float(
            f.get("Total Hours Booked") or f.get("Total Hours") or 0
        ),
        "bookingStatus": _flatten(f.get("Booking Status") or f.get("Status")),
        "placeholder": _to_bool(f.get("Placeholder")),
    }


# ----------------------------------------------------------------------
# Public fetchers
# ----------------------------------------------------------------------

async def fetch_resources(*, include_inactive: bool = False) -> list[dict[str, Any]]:
    params: dict[str, Any] = {}
    if not include_inactive:
        # Airtable formula — only resources not marked inactive.
        params["filterByFormula"] = "NOT({Inactive})"
    out: list[dict[str, Any]] = []
    async for rec in _paginate(settings.AIRTABLE_TABLE_RESOURCES, params):
        out.append(normalise_resource(rec))
    return out


def _date_filter(from_: date | None, to: date | None) -> str | None:
    """Build a filterByFormula that picks bookings overlapping [from_, to]."""
    if not from_ and not to:
        return None
    clauses: list[str] = []
    if to is not None:
        # Start <= to  →  IS_BEFORE({Start Date}, to+1) for safety.
        clauses.append(f"IS_BEFORE({{Start Date}}, '{to.isoformat()}')")
    if from_ is not None:
        clauses.append(f"IS_AFTER({{End Date}}, '{from_.isoformat()}')")
    if len(clauses) == 1:
        return clauses[0]
    return f"AND({', '.join(clauses)})"


def _escape_formula_literal(s: str) -> str:
    """Escape a value for safe embedding inside a single-quoted Airtable
    formula literal. Single quotes are the only escape we need; Airtable
    treats backslashes literally inside string literals, so we use
    `\\'` to terminate-and-resume the quoted string semantics expected
    by formula engines."""
    return s.replace("\\", "\\\\").replace("'", "\\'")


def _multi_value_or(field: str, raw: str) -> str | None:
    """Build an OR(...) clause matching `field` against each comma-
    separated value in `raw`. Returns None if no non-empty values."""
    parts = [v.strip() for v in raw.split(",")]
    parts = [p for p in parts if p]
    if not parts:
        return None
    pieces = [f"{{{field}}}='{_escape_formula_literal(v)}'" for v in parts]
    if len(pieces) == 1:
        return pieces[0]
    return f"OR({', '.join(pieces)})"


def _bookings_filter(
    from_: date | None,
    to: date | None,
    department: str | None,
    name: str | None,
) -> str | None:
    """Combine date overlap + optional department/name filters into a
    single AND(...) filterByFormula. Department matches against the
    flattened lookup field `Department (from Resource Name)`; name
    against `Resource Name (from Resource)`."""
    clauses: list[str] = []
    date_clause = _date_filter(from_, to)
    if date_clause:
        clauses.append(date_clause)
    if department:
        dep_clause = _multi_value_or("Department (from Resource Name)", department)
        if dep_clause:
            clauses.append(dep_clause)
    if name:
        name_clause = _multi_value_or("Resource Name (from Resource)", name)
        if name_clause:
            clauses.append(name_clause)
    if not clauses:
        return None
    if len(clauses) == 1:
        return clauses[0]
    return f"AND({', '.join(clauses)})"


async def fetch_bookings(
    *,
    from_: date | None = None,
    to: date | None = None,
    department: str | None = None,
    name: str | None = None,
) -> list[dict[str, Any]]:
    params: dict[str, Any] = {}
    formula = _bookings_filter(from_, to, department, name)
    if formula:
        params["filterByFormula"] = formula
    out: list[dict[str, Any]] = []
    async for rec in _paginate(settings.AIRTABLE_TABLE_BOOKINGS, params):
        out.append(normalise_booking(rec))
    return out