"""
Request-weiter Mandanten-Kontext (ACCESS_LAYER_AND_GOVERNANCE_PLAN.md, Stufe B).

Zielt auf einheitliche Auflösung aus Session + Header X-Active-Club-Id + Profilfeld active_club_id.
Router können Depends(get_tenant_context) nutzen oder resolve_tenant_context mit bereits geladenen Mitgliedschaften (ein DB-Block).
"""
from __future__ import annotations

from dataclasses import dataclass
from typing import Any, Dict, List, Optional

from fastapi import Depends, Header, HTTPException

from auth import require_auth, require_auth_flexible
from club_tenancy import is_platform_admin, memberships_with_roles
from db import get_db, get_cursor


def _club_exists(cur, club_id: int) -> bool:
    cur.execute("SELECT 1 FROM clubs WHERE id = %s", (club_id,))
    return cur.fetchone() is not None


def parse_active_club_header(raw: Optional[str]) -> Optional[int]:
    """Parst X-Active-Club-Id; leer → None. Ungültig → HTTP 400."""
    if raw is None:
        return None
    s = str(raw).strip()
    if not s:
        return None
    try:
        v = int(s)
    except ValueError:
        raise HTTPException(status_code=400, detail="X-Active-Club-Id ungültig")
    if v < 1:
        raise HTTPException(status_code=400, detail="X-Active-Club-Id ungültig")
    return v


def library_content_visibility_sql(
    *,
    alias: str,
    profile_id: int,
    role: str,
    effective_club_id: Optional[int],
) -> tuple[str, List[Any]]:
    """
    WHERE-Baustein für Bibliothekslisten (Übungen, Vorlagen, Rahmenprogramme):
    official, eigene private, club nur im aktiven Vereinskontext (effective_club_id).
    Plattform-Admin: keine Einschränkung (TRUE).
    Ohne effective_club_id: kein club-Zweig (nur official + private).
    """
    if is_platform_admin(role):
        return "TRUE", []

    parts: List[str] = [
        f"{alias}.visibility = 'official'",
        f"({alias}.visibility = 'private' AND {alias}.created_by = %s)",
    ]
    params: List[Any] = [profile_id]

    if effective_club_id is not None:
        parts.append(
            f"""(
                {alias}.visibility = 'club'
                AND {alias}.club_id IS NOT NULL
                AND {alias}.club_id = %s
                AND EXISTS (
                    SELECT 1 FROM club_members cm
                    WHERE cm.profile_id = %s AND cm.club_id = {alias}.club_id AND cm.status = 'active'
                )
            )"""
        )
        params.extend([effective_club_id, profile_id])

    return "(" + " OR ".join(parts) + ")", params


@dataclass
class TenantContext:
    profile_id: int
    global_role: str
    # Header > gespeichertes Profil > Fallback; Plattform-Admin ohne Header: Profil-Verein wenn existent
    effective_club_id: Optional[int]
    club_ids: frozenset[int]
    memberships: List[Dict[str, Any]]


def resolve_tenant_context(
    cur,
    *,
    profile_id: int,
    global_role: str,
    header_raw: Optional[str],
    memberships: Optional[List[Dict[str, Any]]] = None,
    stored_active_club_id: Optional[int] = None,
    invalid_header_policy: str = "reject",
) -> TenantContext:
    """
    Mitgliedschaften: wenn nicht übergeben, wird aus der DB geladen (aktive Mitgliedschaften).

    Auflösung effective_club_id:
    - Plattform-Admin: Header setzt beliebigen existierenden Verein; ohne Header → gespeichertes
      active_club_id falls der Verein existiert, sonst None.
    - Sonst: gültiger Header zwingend Mitgliedschaft — bei ``reject`` sonst 403, bei ``ignore`` wie ohne Header.
      Ohne gültigen Header: gespeichertes active_club_id wenn Mitglied; sonst einziger Verein;
      bei mehreren ohne gültige Vorgabe → min(club_ids) (Fallback).
    """
    role_lc = (global_role or "").lower()
    header_cid = parse_active_club_header(header_raw)

    if memberships is None:
        memberships = memberships_with_roles(cur, profile_id, active_only=True)

    club_ids = frozenset(int(r["id"]) for r in memberships if r.get("id") is not None)

    if is_platform_admin(role_lc):
        if header_cid is not None:
            if not _club_exists(cur, header_cid):
                raise HTTPException(status_code=400, detail="Verein nicht gefunden")
            effective = header_cid
        elif (
            stored_active_club_id is not None
            and _club_exists(cur, stored_active_club_id)
        ):
            effective = stored_active_club_id
        else:
            effective = None
        return TenantContext(
            profile_id=profile_id,
            global_role=role_lc,
            effective_club_id=effective,
            club_ids=club_ids,
            memberships=memberships,
        )

    chosen_header = header_cid
    if chosen_header is not None and chosen_header not in club_ids:
        if invalid_header_policy == "reject":
            raise HTTPException(
                status_code=403,
                detail="Keine Mitgliedschaft im gewählten Verein",
            )
        chosen_header = None

    if chosen_header is not None:
        effective = chosen_header
    elif stored_active_club_id is not None and stored_active_club_id in club_ids:
        effective = stored_active_club_id
    elif len(club_ids) == 1:
        effective = next(iter(club_ids))
    elif len(club_ids) == 0:
        effective = None
    else:
        effective = min(club_ids)

    return TenantContext(
        profile_id=profile_id,
        global_role=role_lc,
        effective_club_id=effective,
        club_ids=club_ids,
        memberships=memberships,
    )


def get_tenant_context(
    session: dict = Depends(require_auth),
    x_active_club_id: Optional[str] = Header(default=None, alias="X-Active-Club-Id"),
) -> TenantContext:
    """FastAPI-Dependency: öffnet eine DB-Verbindung und liefert TenantContext."""
    pid = int(session["profile_id"])
    role = session.get("role") or ""
    stored: Optional[int] = None
    with get_db() as conn:
        cur = get_cursor(conn)
        cur.execute("SELECT active_club_id FROM profiles WHERE id = %s", (pid,))
        row = cur.fetchone()
        if row is not None:
            ac = row.get("active_club_id")
            if ac is not None:
                stored = int(ac)
        return resolve_tenant_context(
            cur,
            profile_id=pid,
            global_role=role,
            header_raw=x_active_club_id,
            memberships=None,
            stored_active_club_id=stored,
        )


def get_tenant_context_flexible(
    session: dict = Depends(require_auth_flexible),
    x_active_club_id: Optional[str] = Header(default=None, alias="X-Active-Club-Id"),
) -> TenantContext:
    """
    Wie get_tenant_context, aber Auth per Header oder Query ?ssetoken (für <img>/<video> ohne Custom-Header).
    """
    pid = int(session["profile_id"])
    role = session.get("role") or ""
    stored: Optional[int] = None
    with get_db() as conn:
        cur = get_cursor(conn)
        cur.execute("SELECT active_club_id FROM profiles WHERE id = %s", (pid,))
        row = cur.fetchone()
        if row is not None:
            ac = row.get("active_club_id")
            if ac is not None:
                stored = int(ac)
        return resolve_tenant_context(
            cur,
            profile_id=pid,
            global_role=role,
            header_raw=x_active_club_id,
            memberships=None,
            stored_active_club_id=stored,
        )


def tenant_context_from_session_only(
    cur,
    session: dict,
    header_raw: Optional[str],
    *,
    memberships: Optional[List[Dict[str, Any]]] = None,
    stored_active_club_id: Optional[int] = None,
    invalid_header_policy: str = "reject",
) -> TenantContext:
    """Variante ohne FastAPI (Tests / gemeinsamer Cursor mit anderen Queries)."""
    pid = int(session["profile_id"])
    role = session.get("role") or ""
    return resolve_tenant_context(
        cur,
        profile_id=pid,
        global_role=role,
        header_raw=header_raw,
        memberships=memberships,
        stored_active_club_id=stored_active_club_id,
        invalid_header_policy=invalid_header_policy,
    )