"""Bulk permission service — mass share/unshare operations for entity permissions.

Provides efficient batch operations for sharing multiple entities at once
with the same principal and permission level.
"""

from __future__ import annotations

import logging
import uuid
from datetime import datetime, UTC
from typing import Any

from sqlalchemy import and_, or_, select
from sqlalchemy.ext.asyncio import AsyncSession

from app.models.entity_permission import EntityPermission
from app.models.group import UserGroup
from app.models.user import User, UserTenant

logger = logging.getLogger(__name__)

_PERM_RANK = {"none": 0, "read": 1, "write": 2, "admin": 3, "delete": 4, "owner": 5}


def _rank(level: str) -> int:
    return _PERM_RANK.get(level, 0)


async def bulk_share(
    db: AsyncSession,
    tenant_id: uuid.UUID,
    entity_type: str,
    entity_ids: list[str],
    principal_type: str,
    principal_id: str,
    level: str,
    created_by: uuid.UUID | None = None,
) -> dict[str, Any]:
    """Share multiple entities with a principal at a given permission level.

    Args:
        db: Database session
        tenant_id: Tenant UUID
        entity_type: Type of entity (e.g. 'contact', 'document')
        entity_ids: List of entity UUID strings
        principal_type: 'user', 'group', or 'role'
        principal_id: UUID string of the principal
        level: Permission level ('read', 'write', 'admin', 'delete')
        created_by: User UUID who initiated the bulk share

    Returns:
        Dict with counts of created, updated, skipped, and errors
    """
    principal_uuid = uuid.UUID(principal_id)
    entity_uuids = [uuid.UUID(eid) for eid in entity_ids]

    created_count = 0
    updated_count = 0
    skipped_count = 0
    errors: list[dict] = []

    for entity_uuid in entity_uuids:
        try:
            # Check for existing permission
            existing_q = await db.execute(
                select(EntityPermission)
                .where(EntityPermission.entity_type == entity_type)
                .where(EntityPermission.entity_id == entity_uuid)
                .where(EntityPermission.principal_type == principal_type)
                .where(EntityPermission.principal_id == principal_uuid)
                .where(EntityPermission.tenant_id == tenant_id)
            )
            existing = existing_q.scalar_one_or_none()

            if existing:
                # Update if new level is higher
                if _rank(level) > _rank(existing.permission_level):
                    existing.permission_level = level
                    updated_count += 1
                else:
                    skipped_count += 1
            else:
                perm = EntityPermission(
                    tenant_id=tenant_id,
                    entity_type=entity_type,
                    entity_id=entity_uuid,
                    principal_type=principal_type,
                    principal_id=principal_uuid,
                    permission_level=level,
                    created_by=created_by,
                )
                db.add(perm)
                created_count += 1

        except Exception as e:
            errors.append({
                "entity_id": str(entity_uuid),
                "error": str(e),
            })
            logger.warning("Bulk share error for %s/%s: %s", entity_type, entity_uuid, e)

    await db.commit()

    return {
        "created": created_count,
        "updated": updated_count,
        "skipped": skipped_count,
        "errors": errors,
        "total": len(entity_ids),
    }


async def bulk_unshare(
    db: AsyncSession,
    tenant_id: uuid.UUID,
    entity_type: str,
    entity_ids: list[str],
    principal_type: str,
    principal_id: str,
) -> dict[str, Any]:
    """Remove permissions for a principal from multiple entities."""
    principal_uuid = uuid.UUID(principal_id)
    entity_uuids = [uuid.UUID(eid) for eid in entity_ids]

    deleted_count = 0
    errors: list[dict] = []

    for entity_uuid in entity_uuids:
        try:
            result = await db.execute(
                select(EntityPermission)
                .where(EntityPermission.entity_type == entity_type)
                .where(EntityPermission.entity_id == entity_uuid)
                .where(EntityPermission.principal_type == principal_type)
                .where(EntityPermission.principal_id == principal_uuid)
                .where(EntityPermission.tenant_id == tenant_id)
            )
            perm = result.scalar_one_or_none()
            if perm:
                await db.delete(perm)
                deleted_count += 1
        except Exception as e:
            errors.append({
                "entity_id": str(entity_uuid),
                "error": str(e),
            })

    await db.commit()

    return {
        "deleted": deleted_count,
        "errors": errors,
        "total": len(entity_ids),
    }