"""Central capability resolution and FastAPI enforcement dependencies."""

from __future__ import annotations

import os
from typing import Any, Callable

from fastapi import Depends, HTTPException

from rights_registry import load_grants_for_roles
from services.audit import log_audit
from tenant_context import TenantContext, get_tenant_context, require_tenant_context

CAPABILITY_ENFORCE_ENV = "CAPABILITY_ENFORCE"


def capability_enforcement_mode() -> str:
    raw = os.getenv(CAPABILITY_ENFORCE_ENV, "probe").strip().lower()
    return "enforce" if raw in ("1", "true", "enforce", "yes") else "probe"


def resolve_capabilities(*, portal_role: str, tenant_role: str | None) -> frozenset[str]:
    return frozenset(load_grants_for_roles(portal_role=portal_role, tenant_role=tenant_role))


def has_capability(ctx: TenantContext, capability_key: str) -> bool:
    return capability_key in ctx.capabilities


def check_capability(ctx: TenantContext, capability_key: str) -> dict[str, Any]:
    allowed = has_capability(ctx, capability_key)
    return {
        "capability_key": capability_key,
        "allowed": allowed,
        "reason": None if allowed else "missing_grant",
    }


def require_capability(capability_key: str) -> Callable[..., TenantContext]:
    """FastAPI dependency — blocks in enforce mode, probes in probe mode."""

    def _dependency(ctx: TenantContext = Depends(require_tenant_context)) -> TenantContext:
        return _enforce_capability(ctx, capability_key)

    return _dependency


def require_capability_ctx(capability_key: str) -> Callable[..., TenantContext]:
    """Like require_capability but allows portal context without active tenant."""

    def _dependency(ctx: TenantContext = Depends(get_tenant_context)) -> TenantContext:
        return _enforce_capability(ctx, capability_key)

    return _dependency


def _enforce_capability(ctx: TenantContext, capability_key: str) -> TenantContext:
    result = check_capability(ctx, capability_key)
    if result["allowed"]:
        return ctx

    log_audit(
        "capability.denied",
        user_id=ctx.user_id,
        tenant_id=ctx.tenant_id,
        details={
            "capability_key": capability_key,
            "mode": capability_enforcement_mode(),
            "portal_role": ctx.portal_role,
            "tenant_role": ctx.tenant_role,
        },
    )

    if capability_enforcement_mode() == "enforce":
        raise HTTPException(
            status_code=403,
            detail=f"Capability fehlt: {capability_key}",
        )
    return ctx