"""
Talkgroup name resolution.

C2 owns the `systems` collection, and a system's config carries the full
talkgroup table — id and human name for every channel the node scans. The edge
node only knows the name when OP25 happened to have it in the loaded tags file,
so `tgid_name` on a call_start, and the `talkgroup_name` form field on /upload,
are both frequently empty for a talkgroup C2 can name perfectly well.

This resolver is the single place that closes that gap. `mqtt_handler` had its
own copy of the lookup on the call_start path, so calls got a name written to
their document while the /upload path — the one that drives transcription,
correlation and, critically, the incident *title* — kept whatever empty string
the node sent. The result was 84 of 100 incidents named "Ems — TGID 9048"
instead of "Ems — Ossining Police Dispatch" (server-26#34).

Order of preference: whatever the caller was given, then the call document
(written at call_start), then the system config. Returns None when nothing
knows the name, so callers keep their existing "TGID {id}" fallback.
"""

from typing import Optional

from app.internal import firestore as fstore
from app.internal.logger import logger


async def name_from_system(system_id: Optional[str], talkgroup_id: Optional[int]) -> Optional[str]:
    """Look a talkgroup's name up in its system's config. None if unknown."""
    if not system_id or talkgroup_id is None:
        return None
    try:
        tgid_int = int(talkgroup_id)
    except (TypeError, ValueError):
        return None

    system_doc = await fstore.doc_get_cached("systems", system_id)
    if not system_doc:
        return None

    for tg in system_doc.get("config", {}).get("talkgroups", []):
        try:
            if int(tg.get("id", -1)) == tgid_int:
                return tg.get("name") or None
        except (TypeError, ValueError):
            continue
    return None


async def resolve(
    system_id: Optional[str],
    talkgroup_id: Optional[int],
    hint: Optional[str] = None,
    call_doc: Optional[dict] = None,
) -> Optional[str]:
    """
    Best available human name for a talkgroup.

    `hint` is whatever the caller already had (OP25 metadata, a form field).
    `call_doc` is an already-fetched call document, if the caller has one —
    passing it avoids a second read.
    """
    if hint:
        return hint

    if call_doc:
        from_doc = call_doc.get("talkgroup_name")
        if from_doc:
            return from_doc

    resolved = await name_from_system(system_id, talkgroup_id)
    if resolved:
        logger.info(
            f"Resolved talkgroup name from system config: "
            f"TGID {talkgroup_id} → {resolved!r}"
        )
    return resolved