"""
db_client.py — single shared, hardened Supabase client.

All runtime modules import `supabase` from here instead of each calling
create_client() themselves. Two reasons:

1. HTTP/1.1 instead of HTTP/2. The default PostgREST httpx client uses HTTP/2,
   and Supabase's edge intermittently sends a graceful GOAWAY to recycle the
   connection. httpx then raises on the pooled connection:
       httpx.RemoteProtocolError: <ConnectionTerminated error_code:NO_ERROR>
   which surfaced as random 500s ("I seem to have lost my train of thought").
   Forcing http2=False removes that whole error class.

2. One connection pool instead of ~10 (every module used to build its own
   client), with sane timeouts and short keep-alive so idle connections are
   dropped before the server closes them.

db_execute() wraps a query with a small retry for the residual transient
disconnect that HTTP/1.1 keep-alive can still hit.
"""
import time
import httpx
from supabase import create_client
from supabase.lib.client_options import ClientOptions
from config import SUPABASE_URL, SUPABASE_SERVICE_KEY

# CRITICAL: PostgREST and Storage must NOT share one httpx.Client.
# supabase-py passes a single ClientOptions.httpx_client to BOTH the postgrest and
# storage sub-clients. The storage client SETS base_url=".../storage/v1/" on that
# shared client the first time it is used. With a shared client, every DB query
# AFTER a storage op (e.g. the db5 FAISS archive that runs on every turn) was sent
# to the storage endpoint -> Fastify "Route ... not found" 404 storm on tables
# that exist. Reproduced and verified locally. Fix: a separate httpx client for
# storage so it cannot corrupt postgrest's base_url.
# http2=False avoids the original HTTP/2 GOAWAY RemoteProtocolError.
def _make_httpx() -> httpx.Client:
    return httpx.Client(
        http2=False,
        timeout=httpx.Timeout(30.0, connect=10.0),
        limits=httpx.Limits(
            max_keepalive_connections=10,
            max_connections=40,
            keepalive_expiry=15.0,
        ),
    )

_httpx_client = _make_httpx()          # postgrest (+ auth + functions)
_storage_httpx_client = _make_httpx()  # storage ONLY — isolated

try:
    import supabase as _supabase_pkg
    _SUPABASE_VERSION = getattr(_supabase_pkg, "__version__", "unknown")
except Exception:
    _SUPABASE_VERSION = "unknown"

try:
    supabase = create_client(
        SUPABASE_URL,
        SUPABASE_SERVICE_KEY,
        options=ClientOptions(httpx_client=_httpx_client),
    )
    # Re-bind the storage sub-client to its OWN httpx client so storage ops can't
    # overwrite postgrest's base_url (see comment above).
    try:
        supabase._storage = supabase._init_storage_client(
            storage_url=supabase.storage_url,
            headers=supabase.options.headers,
            storage_client_timeout=supabase.options.storage_client_timeout,
            http_client=_storage_httpx_client,
        )
        print(f"[db_client] supabase-py {_SUPABASE_VERSION}: HTTP/1.1 client ACTIVE, storage isolated")
    except Exception as _e:
        print(f"[db_client] WARNING: could not isolate storage client ({_e}); "
              "storage ops may corrupt postgrest base_url")
        print(f"[db_client] supabase-py {_SUPABASE_VERSION}: HTTP/1.1 client ACTIVE")
except TypeError:
    # Older supabase-py (<2.15) has no httpx_client option. Don't crash the app —
    # fall back to the default client (HTTP/2, the RemoteProtocolError risk returns).
    # Bump the supabase pin in requirements.txt to restore the hardened client.
    print(f"WARNING: supabase-py {_SUPABASE_VERSION} too old for httpx_client; "
          "using default HTTP/2 client. Pin supabase>=2.15 to restore HTTP/1.1.")
    supabase = create_client(SUPABASE_URL, SUPABASE_SERVICE_KEY)

# Transient transport errors worth retrying (stale keep-alive, brief network blips).
_RETRYABLE = (httpx.RemoteProtocolError, httpx.ConnectError, httpx.ReadError, httpx.WriteError)

try:
    from postgrest.exceptions import APIError
except Exception:  # pragma: no cover - import shape varies across versions
    APIError = None


def _is_transient_schema_cache_error(e) -> bool:
    """PostgREST briefly returns 404 'Route ... not found' / PGRST205 'schema cache'
    while it reloads its schema (e.g. after DDL). The table exists; the request just
    raced the cache reload. These are safe to retry; genuine 4xx (constraint, bad
    column) are not.
    """
    if APIError is None or not isinstance(e, APIError):
        return False
    code = str(getattr(e, "code", "") or "")
    msg = (str(getattr(e, "message", "") or "") + " " + str(getattr(e, "details", "") or "")).lower()
    return code in ("404", "PGRST205") or "schema cache" in msg or "not found" in msg


def db_execute(query, retries: int = 2):
    """Execute a postgrest/supabase query builder, retrying transient transport
    errors and transient PostgREST schema-cache misses.

    Usage: db_execute(supabase.table("x").select("*").eq("id", uid))
    """
    last = None
    for attempt in range(retries + 1):
        try:
            return query.execute()
        except _RETRYABLE as e:
            last = e
            if attempt < retries:
                time.sleep(0.3 * (attempt + 1))
                continue
            raise
        except Exception as e:
            if _is_transient_schema_cache_error(e) and attempt < retries:
                last = e
                time.sleep(0.5 * (attempt + 1))
                continue
            raise
    raise last  # pragma: no cover