"""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
from app.models.guest_user import GuestUser

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_guest(
    request: Request,
    redis: aioredis.Redis = Depends(get_redis_dep),
) -> dict[str, Any]:
    """Get the current guest user from guest session cookie.

    Returns session data dict with guest_user_id, tenant_id, email, name.
    Used for guest-specific endpoints (guest login, guest contacts).
    """
    session_id = request.cookies.get("guest_session")
    if not session_id:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail={"detail": "Not authenticated", "code": "not_authenticated"},
        )

    import json

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

    session_data = json.loads(raw)

    # Extend TTL on each request (sliding session)
    await redis.expire(f"guest_session:{session_id}", 1800)

    return session_data


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
    await refresh_session_ttl(redis, session_id)

    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 role (legacy + new permission system).

    Legacy role string 'admin' is deprecated — log a warning when used.
    New system uses is_system_admin or *:* permission.
    """
    if current_user.get("is_system_admin"):
        return current_user

    # Legacy role string fallback — deprecated
    if current_user.get("role") == "admin":
        logger.warning(
            "Legacy role string 'admin' used for user=%s — deprecated, "
            "migrate to is_system_admin or *:* permission",
            current_user.get("user_id"),
        )
        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 (admin, editor, or custom role with write perms).

    Legacy role strings 'admin'/'editor' are deprecated — log a warning when used.
    New system checks specific module:write permissions instead of broad wildcards.
    """
    if current_user.get("is_system_admin"):
        return current_user

    # Legacy role string fallback — deprecated
    role = current_user.get("role", "viewer")
    if role in ("admin", "editor"):
        logger.warning(
            "Legacy role string '%s' used for user=%s in require_write — deprecated, "
            "migrate to specific module:write permissions",
            role, current_user.get("user_id"),
        )
        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.

    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]:
        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 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() -> 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",
                    },
                )
            # Per-tenant activation check with Redis cache
            from app.core.redis import get_redis
            from app.core.db import async_session_maker
            from sqlalchemy import text
            import json

            redis = get_redis()
            # Get tenant_id from current session context
            async with async_session_maker() as db:
                result = await db.execute(
                    text("SELECT current_setting('app.current_tenant_id', true)::uuid")
                )
                tenant_id = result.scalar()

            if tenant_id is not None and 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
                async with async_session_maker() as db:
                    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]
                        # Cache the result (60s TTL)
                        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)
                        await redis.setex(cache_key, 60, json.dumps(True))
            else:
                # No Redis or no tenant_id — fallback to DB query without cache
                async with async_session_maker() as db:
                    result = await db.execute(
                        text("""
                            SELECT is_active FROM tenant_plugin_activation
                            WHERE plugin_name = :name
                            AND tenant_id = current_setting('app.current_tenant_id', true)::uuid
                        """),
                        {"name": plugin_name},
                    )
                    row = result.first()
                    if row is not None and not row[0]:
                        raise HTTPException(
                            status_code=status.HTTP_403_FORBIDDEN,
                            detail={
                                "detail": f"Plugin '{plugin_name}' is not active for this tenant",
                                "code": "plugin_inactive_tenant",
                            },
                        )
        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