"""Audit log service — centralized logging for all operations."""
from typing import Optional, List, Dict, Any
from sqlalchemy import select, func
from sqlalchemy.ext.asyncio import AsyncSession

from app.models.audit_log import AuditLog


class AuditLogService:
    @staticmethod
    async def log(
        db: AsyncSession,
        user_id: int,
        action: str,
        target_type: str,
        target_id: Optional[int] = None,
        detail: Optional[str] = None,
        ip_address: Optional[str] = None,
    ) -> AuditLog:
        """Create an audit log entry."""
        entry = AuditLog(
            user_id=user_id,
            action=action,
            target_type=target_type,
            target_id=target_id,
            detail=detail[:500] if detail else None,
            ip_address=ip_address,
        )
        db.add(entry)
        # Don't commit — let the caller's transaction handle it
        await db.flush()
        return entry

    @staticmethod
    async def list_logs(
        db: AsyncSession,
        page: int = 1,
        page_size: int = 20,
        user_id: Optional[int] = None,
        action: Optional[str] = None,
        target_type: Optional[str] = None,
    ) -> Dict[str, Any]:
        """List audit logs with pagination and filters."""
        stmt = select(AuditLog)

        if user_id:
            stmt = stmt.where(AuditLog.user_id == user_id)
        if action:
            stmt = stmt.where(AuditLog.action == action)
        if target_type:
            stmt = stmt.where(AuditLog.target_type == target_type)

        total_stmt = select(func.count()).select_from(stmt.subquery())
        total = (await db.execute(total_stmt)).scalar()

        stmt = stmt.order_by(AuditLog.created_at.desc())
        stmt = stmt.offset((page - 1) * page_size).limit(page_size)
        result = await db.execute(stmt)
        logs = result.scalars().all()

        return {
            "total": total,
            "page": page,
            "page_size": page_size,
            "items": [
                {
                    "id": log.id,
                    "user_id": log.user_id,
                    "action": log.action,
                    "target_type": log.target_type,
                    "target_id": log.target_id,
                    "detail": log.detail,
                    "ip_address": log.ip_address,
                    "created_at": log.created_at.isoformat() if log.created_at else None,
                }
                for log in logs
            ],
        }