"""FastAPI dependencies: auth, db, tenant context, RBAC."""

from __future__ import annotations

import logging
import uuid
from typing import Any

import redis.asyncio as aioredis
from fastapi import Depends, HTTPException, Request, status
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.config import get_settings
from app.core.auth import get_redis, get_session_data, refresh_session_ttl
from app.core.db import get_db, set_tenant_context, set_user_context
logger = logging.getLogger(__name__)

# Known write-permission modules — used by require_write() to check
# specific permissions instead of broad wildcards like *:write
_WRITE_PERMISSIONS = [
    "contacts:write",
    "contacts:create",
    "users:write",
    "roles:write",
    "audit:write",
    "attachments:write",
    "workflows:write",
    "sequences:write",
    "addresses:write",
    "taxes:write",
    "currencies:write",
    "notifications:write",
    "import_export:write",
    "user_preferences:write",
]


async def get_redis_dep() -> aioredis.Redis:
    """FastAPI dependency for Redis client."""
    return get_redis()


async def get_current_user(
    request: Request,
    db: AsyncSession = Depends(get_db),
    redis: aioredis.Redis = Depends(get_redis_dep),
) -> dict[str, Any]:
    """Get the current authenticated user from session cookie.

    Returns session data dict with user_id, tenant_id, email, name, role,
    and resolved permissions from Redis cache.
    """
    settings = get_settings()

    session_id = request.cookies.get(settings.session_cookie_name)
    if not session_id:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail={"detail": "Not authenticated", "code": "not_authenticated"},
        )

    session_data = await get_session_data(redis, session_id)
    if session_data is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail={"detail": "Session expired or invalid", "code": "session_invalid"},
        )

    # Sliding session: extend TTL on each authenticated request
    # Best-effort during Redis outage — session still valid from DB fallback
    try:
        await refresh_session_ttl(redis, session_id)
    except Exception:
        logger.debug("refresh_session_ttl failed (Redis may be down) — continuing")

    if not session_data.get("is_active", True):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail={"detail": "User account deactivated", "code": "user_inactive"},
        )

    # Set RLS tenant context
    tenant_id = uuid.UUID(session_data["tenant_id"])
    await set_tenant_context(db, tenant_id)

    # Set RLS user context for row-level security
    user_id = uuid.UUID(session_data["user_id"])
    from app.models.group import UserGroup
    groups_q = await db.execute(
        select(UserGroup.group_id)
        .where(UserGroup.user_id == user_id)
        .where(UserGroup.tenant_id == tenant_id)
    )
    group_ids = [row[0] for row in groups_q]
    is_admin = session_data.get("is_system_admin", False)
    await set_user_context(db, user_id, group_ids, is_admin)

    # Check membership status (P1.7: suspended membership should not be usable)
    from app.models.user import UserTenant
    membership_q = await db.execute(
        select(UserTenant.status)
        .where(UserTenant.user_id == user_id)
        .where(UserTenant.tenant_id == tenant_id)
    )
    membership_status = membership_q.scalar_one_or_none()
    if membership_status is not None and membership_status != "active":
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail={"detail": f"Mitgliedschaft ist {membership_status}, Zugriff verweigert", "code": "membership_suspended"},
        )

    # Load resolved permissions from cache (or DB on miss)
    from app.core.permissions import get_cached_permissions

    user_id = uuid.UUID(session_data["user_id"])
    resolved = await get_cached_permissions(db, redis, user_id, tenant_id)
    session_data["permissions"] = resolved.get("permissions", [])
    session_data["denied_permissions"] = resolved.get("denied", [])
    session_data["field_permissions"] = resolved.get("field_permissions", {})
    session_data["is_system_admin"] = resolved.get("is_system_admin", False)

    return session_data


async def get_current_user_bearer(
    request: Request,
    db: AsyncSession = Depends(get_db),
) -> dict[str, Any]:
    """Get the current user from a Bearer API token.

    Alternative to session-based auth for programmatic access (MCP, API clients).
    Returns the same dict shape as get_current_user.
    """
    auth_header = request.headers.get("Authorization", "")
    if not auth_header.startswith("Bearer "):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail={"detail": "Bearer token required", "code": "not_authenticated"},
        )

    token = auth_header[7:]  # Strip "Bearer "
    from app.core.api_token import verify_api_token

    user_data = await verify_api_token(db, token)
    if user_data is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail={"detail": "Invalid or expired token", "code": "token_invalid"},
        )

    # Set RLS tenant context
    tenant_id = uuid.UUID(user_data["tenant_id"])
    await set_tenant_context(db, tenant_id)

    # Set RLS user context
    user_id = uuid.UUID(user_data["user_id"])
    from app.models.group import UserGroup
    groups_q = await db.execute(
        select(UserGroup.group_id)
        .where(UserGroup.user_id == user_id)
        .where(UserGroup.tenant_id == tenant_id)
    )
    group_ids = [row[0] for row in groups_q]
    is_admin = user_data.get("is_system_admin", False)
    await set_user_context(db, user_id, group_ids, is_admin)

    # Load resolved permissions
    from app.core.permissions import get_cached_permissions
    redis = get_redis()
    resolved = await get_cached_permissions(db, redis, user_id, tenant_id)
    user_data["permissions"] = resolved.get("permissions", [])
    user_data["denied_permissions"] = resolved.get("denied", [])
    user_data["field_permissions"] = resolved.get("field_permissions", {})
    user_data["is_system_admin"] = resolved.get("is_system_admin", False)

    return user_data


async def get_current_user_or_bearer(
    request: Request,
    db: AsyncSession = Depends(get_db),
    redis: aioredis.Redis = Depends(get_redis_dep),
) -> dict[str, Any]:
    """Get current user from session cookie OR Bearer token.

    Tries session auth first, falls back to Bearer token.
    Used by MCP routes that accept both auth methods.
    """
    auth_header = request.headers.get("Authorization", "")
    if auth_header.startswith("Bearer "):
        return await get_current_user_bearer(request, db)
    return await get_current_user(request, db, redis)


async def require_admin(
    current_user: dict[str, Any] = Depends(get_current_user),
) -> dict[str, Any]:
    """Require admin access via is_system_admin or *:* permission.

    ⚠️ Legacy Role Bypass entfernt — alle Admins müssen echte role_id haben
    Legacy role string 'admin' no longer grants access. Users must have
    is_system_admin=True or *:* permission through the RBAC system.
    """
    if current_user.get("is_system_admin"):
        return current_user

    # New permission system check
    from app.core.permissions import check_permission

    if check_permission(current_user, "*:*"):
        return current_user

    raise HTTPException(
        status_code=status.HTTP_403_FORBIDDEN,
        detail={"detail": "Admin access required", "code": "forbidden"},
    )


async def require_write(
    current_user: dict[str, Any] = Depends(get_current_user),
) -> dict[str, Any]:
    """Require write permission via is_system_admin or specific module:write permissions.

    ⚠️ Legacy Role Bypass entfernt — alle Admins müssen echte role_id haben
    Legacy role strings 'admin'/'editor' no longer grant write access. Users must
    have is_system_admin=True or specific module:write permissions through RBAC.
    """
    if current_user.get("is_system_admin"):
        return current_user

    # Check via permission system for specific write permissions
    from app.core.permissions import check_permission

    for perm in _WRITE_PERMISSIONS:
        if check_permission(current_user, perm):
            return current_user

    raise HTTPException(
        status_code=status.HTTP_403_FORBIDDEN,
        detail={"detail": "Write access required", "code": "forbidden"},
    )


def require_permission(permission: str):
    """FastAPI dependency factory: require a specific permission.

    Enforces API token scopes (Problem 2 fix): when the request is authenticated
    via a Bearer API token, ``_token_scopes`` is set on the user context. The
    required permission must be present in the scopes (wildcard match supported).
    Session-auth requests (no ``_token_scopes``) use the normal permission check.

    Usage:
        @router.get("/contacts", dependencies=[Depends(require_permission("contacts:read"))])
    """
    async def _check(
        current_user: dict[str, Any] = Depends(get_current_user),
    ) -> dict[str, Any]:
        # API token scope enforcement (Problem 2 fix)
        token_scopes = current_user.get("_token_scopes")
        if token_scopes is not None:
            from app.core.permissions import _permission_matches_any
            if not _permission_matches_any(set(token_scopes), permission):
                raise HTTPException(
                    status_code=status.HTTP_403_FORBIDDEN,
                    detail={
                        "detail": f"Token scope '{permission}' required",
                        "code": "insufficient_scope",
                    },
                )
            return current_user

        if current_user.get("is_system_admin"):
            return current_user
        from app.core.permissions import check_permission

        if check_permission(current_user, permission):
            return current_user
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail={
                "detail": f"Permission '{permission}' required",
                "code": "forbidden",
            },
        )

    return _check


def require_field_access(module: str, field: str, default: str = "read"):
    """FastAPI dependency factory: require field-level access.

    Usage:
        @router.get("/contacts/{id}", dependencies=[Depends(require_field_access("contacts", "annual_revenue"))])
    """
    async def _check(
        current_user: dict[str, Any] = Depends(get_current_user),
    ) -> dict[str, Any]:
        if current_user.get("is_system_admin"):
            return current_user
        from app.core.permissions import check_field_access

        access = check_field_access(current_user, module, field, default)
        if access == "hidden":
            raise HTTPException(
                status_code=status.HTTP_403_FORBIDDEN,
                detail={
                    "detail": f"Field '{field}' is hidden",
                    "code": "field_hidden",
                },
            )
        return current_user

    return _check


async def get_tenant_id(
    current_user: dict[str, Any] = Depends(get_current_user),
) -> uuid.UUID:
    """Extract tenant_id from current user session."""
    return uuid.UUID(current_user["tenant_id"])


async def get_current_user_id(
    current_user: dict[str, Any] = Depends(get_current_user),
) -> uuid.UUID:
    """Extract user_id from current user session."""
    return uuid.UUID(current_user["user_id"])


def require_active_plugin(plugin_name: str):
    """FastAPI dependency factory: require that a plugin is active.

    Checks both global activation (permission registry) and per-tenant
    activation (tenant_plugin_activation table).

    Uses the current_user dependency to get tenant_id — does NOT guess
    the tenant from a new DB session via current_setting().

    Uses Redis cache for per-tenant check to avoid DB query on every request.
    Cache key: plugin-activation:{tenant_id}:{plugin_name}
    TTL: 60 seconds. Invalidated on activate/deactivate.

    Returns 403 if the plugin is not active.
    Fails closed (503) on errors.
    """
    async def _check(
        db: AsyncSession = Depends(get_db),
    ) -> None:
        from app.core.permission_registry import get_permission_registry
        try:
            registry = get_permission_registry()
            if not registry.is_plugin_active(plugin_name):
                raise HTTPException(
                    status_code=status.HTTP_403_FORBIDDEN,
                    detail={
                        "detail": f"Plugin '{plugin_name}' is not active",
                        "code": "plugin_inactive",
                    },
                )
            # Get tenant_id from existing db session (NOT a new session)
            # The tenant context is set by middleware/get_current_user on this same session
            from sqlalchemy import text as sa_text

            result = await db.execute(
                sa_text("SELECT current_setting('app.current_tenant_id', true)::uuid")
            )
            tenant_id = result.scalar()

            if tenant_id is None:
                # No tenant context — plugin is active by default (backward compatible)
                return

            # Per-tenant activation check with Redis cache
            from app.core.redis import get_redis
            from sqlalchemy import text
            import json

            redis = get_redis()
            if redis is not None:
                cache_key = f"plugin-activation:{tenant_id}:{plugin_name}"
                cached = await redis.get(cache_key)
                if cached is not None:
                    is_active = json.loads(cached)
                    if not is_active:
                        raise HTTPException(
                            status_code=status.HTTP_403_FORBIDDEN,
                            detail={
                                "detail": f"Plugin '{plugin_name}' is not active for this tenant",
                                "code": "plugin_inactive_tenant",
                            },
                        )
                    return  # Cache hit — plugin is active for this tenant

            # Cache miss — query DB using the existing db session (tenant context already set)
            result = await db.execute(
                text("""
                    SELECT is_active FROM tenant_plugin_activation
                    WHERE plugin_name = :name
                    AND tenant_id = :tid
                """),
                {"name": plugin_name, "tid": tenant_id},
            )
            row = result.first()
            if row is not None:
                is_active = row[0]
                if redis is not None:
                    await redis.setex(cache_key, 60, json.dumps(is_active))
                if not is_active:
                    raise HTTPException(
                        status_code=status.HTTP_403_FORBIDDEN,
                        detail={
                            "detail": f"Plugin '{plugin_name}' is not active for this tenant",
                            "code": "plugin_inactive_tenant",
                        },
                    )
            else:
                # No entry = default active (backward compatible)
                if redis is not None:
                    await redis.setex(cache_key, 60, json.dumps(True))
        except HTTPException:
            raise
        except Exception as exc:
            # Fail-closed: if registry check fails, deny access (P1.2 fix)
            logger.error("Plugin activation check failed for '%s': %s", plugin_name, exc)
            raise HTTPException(
                status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
                detail={"detail": f"Plugin activation check failed", "code": "plugin_check_error"},
            )

    return _check