import asyncio
import atexit
import json
import os
import re
import socket
import unittest
from collections.abc import AsyncGenerator, Iterable
from datetime import datetime, timezone
from pathlib import Path
from typing import (
    Any,
    Dict,
    List,
    Optional,
    Set,
    Tuple,
    Union,
)
from uuid import uuid4

import aiohttp
import aiosqlite
from aiohttp import web


class AsyncDataSet:
    """
    Distributed AsyncDataSet with client-server model over Unix sockets.

    Parameters:
    - file: Path to the SQLite database file
    - socket_path: Path to Unix socket for inter-process communication (default: "ads.sock")
    - max_concurrent_queries: Maximum concurrent database operations (default: 1)
      Set to 1 to prevent "database is locked" errors with SQLite
    """

    _KV_TABLE = "__kv_store"
    _DEFAULT_COLUMNS = {
        "uid": "TEXT PRIMARY KEY",
        "created_at": "TEXT",
        "updated_at": "TEXT",
        "deleted_at": "TEXT",
    }

    def __init__(
        self, file: str, socket_path: str = "ads.sock", max_concurrent_queries: int = 1
    ):
        self._file = file
        self._socket_path = socket_path
        self._table_columns_cache: Dict[str, Set[str]] = {}
        self._is_server = None  # None means not initialized yet
        self._server = None
        self._runner = None
        self._client_session = None
        self._initialized = False
        self._init_lock = None  # Will be created when needed
        self._max_concurrent_queries = max_concurrent_queries
        self._db_semaphore = None  # Will be created when needed
        self._db_connection = None  # Persistent database connection

    async def _ensure_initialized(self):
        """Ensure the instance is initialized as server or client."""
        if self._initialized:
            return

        # Create lock if needed (first time in async context)
        if self._init_lock is None:
            self._init_lock = asyncio.Lock()

        async with self._init_lock:
            if self._initialized:
                return

            await self._initialize()

            # Create semaphore for database operations (server only)
            if self._is_server:
                self._db_semaphore = asyncio.Semaphore(self._max_concurrent_queries)

            self._initialized = True

    async def _initialize(self):
        """Initialize as server or client."""
        try:
            # Try to create Unix socket
            if os.path.exists(self._socket_path):
                # Check if socket is active
                sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
                try:
                    sock.connect(self._socket_path)
                    sock.close()
                    # Socket is active, we're a client
                    self._is_server = False
                    await self._setup_client()
                except (ConnectionRefusedError, FileNotFoundError):
                    # Socket file exists but not active, remove and become server
                    os.unlink(self._socket_path)
                    self._is_server = True
                    await self._setup_server()
            else:
                # No socket file, become server
                self._is_server = True
                await self._setup_server()
        except Exception:
            # Fallback to client mode
            self._is_server = False
            await self._setup_client()

        # Establish persistent database connection
        self._db_connection = await aiosqlite.connect(self._file)

    async def _setup_server(self):
        """Setup aiohttp server."""
        app = web.Application()

        # Add routes for all methods
        app.router.add_post("/insert", self._handle_insert)
        app.router.add_post("/update", self._handle_update)
        app.router.add_post("/delete", self._handle_delete)
        app.router.add_post("/upsert", self._handle_upsert)
        app.router.add_post("/get", self._handle_get)
        app.router.add_post("/find", self._handle_find)
        app.router.add_post("/count", self._handle_count)
        app.router.add_post("/exists", self._handle_exists)
        app.router.add_post("/kv_set", self._handle_kv_set)
        app.router.add_post("/kv_get", self._handle_kv_get)
        app.router.add_post("/execute_raw", self._handle_execute_raw)
        app.router.add_post("/query_raw", self._handle_query_raw)
        app.router.add_post("/query_one", self._handle_query_one)
        app.router.add_post("/create_table", self._handle_create_table)
        app.router.add_post("/insert_unique", self._handle_insert_unique)
        app.router.add_post("/aggregate", self._handle_aggregate)

        self._runner = web.AppRunner(app)
        await self._runner.setup()
        self._server = web.UnixSite(self._runner, self._socket_path)
        await self._server.start()

        # Register cleanup
        def cleanup():
            if os.path.exists(self._socket_path):
                os.unlink(self._socket_path)

        atexit.register(cleanup)

    async def _setup_client(self):
        """Setup aiohttp client."""
        connector = aiohttp.UnixConnector(path=self._socket_path)
        self._client_session = aiohttp.ClientSession(connector=connector)

    async def _make_request(self, endpoint: str, data: Dict[str, Any]) -> Any:
        """Make HTTP request to server."""
        if not self._client_session:
            await self._setup_client()

        url = f"http://localhost/{endpoint}"
        async with self._client_session.post(url, json=data) as resp:
            result = await resp.json()
            if result.get("error"):
                raise Exception(result["error"])
            return result.get("result")

    # Server handlers
    async def _handle_insert(self, request):
        data = await request.json()
        try:
            result = await self._server_insert(
                data["table"], data["args"], data.get("return_id", False)
            )
            return web.json_response({"result": result})
        except Exception as e:
            return web.json_response({"error": str(e)}, status=500)

    async def _handle_update(self, request):
        data = await request.json()
        try:
            result = await self._server_update(
                data["table"], data["args"], data.get("where")
            )
            return web.json_response({"result": result})
        except Exception as e:
            return web.json_response({"error": str(e)}, status=500)

    async def _handle_delete(self, request):
        data = await request.json()
        try:
            result = await self._server_delete(data["table"], data.get("where"))
            return web.json_response({"result": result})
        except Exception as e:
            return web.json_response({"error": str(e)}, status=500)

    async def _handle_upsert(self, request):
        data = await request.json()
        try:
            result = await self._server_upsert(
                data["table"], data["args"], data.get("where")
            )
            return web.json_response({"result": result})
        except Exception as e:
            return web.json_response({"error": str(e)}, status=500)

    async def _handle_get(self, request):
        data = await request.json()
        try:
            result = await self._server_get(data["table"], data.get("where"))
            return web.json_response({"result": result})
        except Exception as e:
            return web.json_response({"error": str(e)}, status=500)

    async def _handle_find(self, request):
        data = await request.json()
        try:
            result = await self._server_find(
                data["table"],
                data.get("where"),
                limit=data.get("limit", 0),
                offset=data.get("offset", 0),
                order_by=data.get("order_by"),
            )
            return web.json_response({"result": result})
        except Exception as e:
            return web.json_response({"error": str(e)}, status=500)

    async def _handle_count(self, request):
        data = await request.json()
        try:
            result = await self._server_count(data["table"], data.get("where"))
            return web.json_response({"result": result})
        except Exception as e:
            return web.json_response({"error": str(e)}, status=500)

    async def _handle_exists(self, request):
        data = await request.json()
        try:
            result = await self._server_exists(data["table"], data["where"])
            return web.json_response({"result": result})
        except Exception as e:
            return web.json_response({"error": str(e)}, status=500)

    async def _handle_kv_set(self, request):
        data = await request.json()
        try:
            await self._server_kv_set(
                data["key"], data["value"], table=data.get("table")
            )
            return web.json_response({"result": None})
        except Exception as e:
            return web.json_response({"error": str(e)}, status=500)

    async def _handle_kv_get(self, request):
        data = await request.json()
        try:
            result = await self._server_kv_get(
                data["key"], default=data.get("default"), table=data.get("table")
            )
            return web.json_response({"result": result})
        except Exception as e:
            return web.json_response({"error": str(e)}, status=500)

    async def _handle_execute_raw(self, request):
        data = await request.json()
        try:
            result = await self._server_execute_raw(
                data["sql"],
                tuple(data.get("params", [])) if data.get("params") else None,
            )
            return web.json_response(
                {"result": result.rowcount if hasattr(result, "rowcount") else None}
            )
        except Exception as e:
            return web.json_response({"error": str(e)}, status=500)

    async def _handle_query_raw(self, request):
        data = await request.json()
        try:
            result = await self._server_query_raw(
                data["sql"],
                tuple(data.get("params", [])) if data.get("params") else None,
            )
            return web.json_response({"result": result})
        except Exception as e:
            return web.json_response({"error": str(e)}, status=500)

    async def _handle_query_one(self, request):
        data = await request.json()
        try:
            result = await self._server_query_one(
                data["sql"],
                tuple(data.get("params", [])) if data.get("params") else None,
            )
            return web.json_response({"result": result})
        except Exception as e:
            return web.json_response({"error": str(e)}, status=500)

    async def _handle_create_table(self, request):
        data = await request.json()
        try:
            await self._server_create_table(
                data["table"], data["schema"], data.get("constraints")
            )
            return web.json_response({"result": None})
        except Exception as e:
            return web.json_response({"error": str(e)}, status=500)

    async def _handle_insert_unique(self, request):
        data = await request.json()
        try:
            result = await self._server_insert_unique(
                data["table"], data["args"], data["unique_fields"]
            )
            return web.json_response({"result": result})
        except Exception as e:
            return web.json_response({"error": str(e)}, status=500)

    async def _handle_aggregate(self, request):
        data = await request.json()
        try:
            result = await self._server_aggregate(
                data["table"],
                data["function"],
                data.get("column", "*"),
                data.get("where"),
            )
            return web.json_response({"result": result})
        except Exception as e:
            return web.json_response({"error": str(e)}, status=500)

    # Public methods that delegate to server or client
    async def insert(
        self, table: str, args: Dict[str, Any], return_id: bool = False
    ) -> Union[str, int]:
        await self._ensure_initialized()
        if self._is_server:
            return await self._server_insert(table, args, return_id)
        else:
            return await self._make_request(
                "insert", {"table": table, "args": args, "return_id": return_id}
            )

    async def update(
        self, table: str, args: Dict[str, Any], where: Optional[Dict[str, Any]] = None
    ) -> int:
        await self._ensure_initialized()
        if self._is_server:
            return await self._server_update(table, args, where)
        else:
            return await self._make_request(
                "update", {"table": table, "args": args, "where": where}
            )

    async def delete(self, table: str, where: Optional[Dict[str, Any]] = None) -> int:
        await self._ensure_initialized()
        if self._is_server:
            return await self._server_delete(table, where)
        else:
            return await self._make_request("delete", {"table": table, "where": where})

    async def upsert(
        self, table: str, args: Dict[str, Any], where: Optional[Dict[str, Any]] = None
    ) -> str | None:
        await self._ensure_initialized()
        if self._is_server:
            return await self._server_upsert(table, args, where)
        else:
            return await self._make_request(
                "upsert", {"table": table, "args": args, "where": where}
            )

    async def get(
        self, table: str, where: Optional[Dict[str, Any]] = None
    ) -> Optional[Dict[str, Any]]:
        await self._ensure_initialized()
        if self._is_server:
            return await self._server_get(table, where)
        else:
            return await self._make_request("get", {"table": table, "where": where})

    async def find(
        self,
        table: str,
        where: Optional[Dict[str, Any]] = None,
        *,
        limit: int = 0,
        offset: int = 0,
        order_by: Optional[str] = None,
    ) -> List[Dict[str, Any]]:
        await self._ensure_initialized()
        if self._is_server:
            return await self._server_find(
                table, where, limit=limit, offset=offset, order_by=order_by
            )
        else:
            return await self._make_request(
                "find",
                {
                    "table": table,
                    "where": where,
                    "limit": limit,
                    "offset": offset,
                    "order_by": order_by,
                },
            )

    async def count(self, table: str, where: Optional[Dict[str, Any]] = None) -> int:
        await self._ensure_initialized()
        if self._is_server:
            return await self._server_count(table, where)
        else:
            return await self._make_request("count", {"table": table, "where": where})

    async def exists(self, table: str, where: Dict[str, Any]) -> bool:
        await self._ensure_initialized()
        if self._is_server:
            return await self._server_exists(table, where)
        else:
            return await self._make_request("exists", {"table": table, "where": where})

    async def kv_set(self, key: str, value: Any, *, table: str | None = None) -> None:
        await self._ensure_initialized()
        if self._is_server:
            return await self._server_kv_set(key, value, table=table)
        else:
            return await self._make_request(
                "kv_set", {"key": key, "value": value, "table": table}
            )

    async def kv_get(
        self, key: str, *, default: Any = None, table: str | None = None
    ) -> Any:
        await self._ensure_initialized()
        if self._is_server:
            return await self._server_kv_get(key, default=default, table=table)
        else:
            return await self._make_request(
                "kv_get", {"key": key, "default": default, "table": table}
            )

    async def execute_raw(self, sql: str, params: Optional[Tuple] = None) -> Any:
        await self._ensure_initialized()
        if self._is_server:
            return await self._server_execute_raw(sql, params)
        else:
            return await self._make_request(
                "execute_raw", {"sql": sql, "params": list(params) if params else None}
            )

    async def query_raw(
        self, sql: str, params: Optional[Tuple] = None
    ) -> List[Dict[str, Any]]:
        await self._ensure_initialized()
        if self._is_server:
            return await self._server_query_raw(sql, params)
        else:
            return await self._make_request(
                "query_raw", {"sql": sql, "params": list(params) if params else None}
            )

    async def query_one(
        self, sql: str, params: Optional[Tuple] = None
    ) -> Optional[Dict[str, Any]]:
        await self._ensure_initialized()
        if self._is_server:
            return await self._server_query_one(sql, params)
        else:
            return await self._make_request(
                "query_one", {"sql": sql, "params": list(params) if params else None}
            )

    async def create_table(
        self,
        table: str,
        schema: Dict[str, str],
        constraints: Optional[List[str]] = None,
    ):
        await self._ensure_initialized()
        if self._is_server:
            return await self._server_create_table(table, schema, constraints)
        else:
            return await self._make_request(
                "create_table",
                {"table": table, "schema": schema, "constraints": constraints},
            )

    async def insert_unique(
        self, table: str, args: Dict[str, Any], unique_fields: List[str]
    ) -> Union[str, None]:
        await self._ensure_initialized()
        if self._is_server:
            return await self._server_insert_unique(table, args, unique_fields)
        else:
            return await self._make_request(
                "insert_unique",
                {"table": table, "args": args, "unique_fields": unique_fields},
            )

    async def aggregate(
        self,
        table: str,
        function: str,
        column: str = "*",
        where: Optional[Dict[str, Any]] = None,
    ) -> Any:
        await self._ensure_initialized()
        if self._is_server:
            return await self._server_aggregate(table, function, column, where)
        else:
            return await self._make_request(
                "aggregate",
                {
                    "table": table,
                    "function": function,
                    "column": column,
                    "where": where,
                },
            )

    async def transaction(self):
        """Context manager for transactions."""
        await self._ensure_initialized()
        if self._is_server:
            return TransactionContext(self._db_connection, self._db_semaphore)
        else:
            raise NotImplementedError("Transactions not supported in client mode")

    # Server implementation methods (original logic)
    @staticmethod
    def _utc_iso() -> str:
        return (
            datetime.now(timezone.utc)
            .replace(microsecond=0)
            .isoformat()
            .replace("+00:00", "Z")
        )

    @staticmethod
    def _py_to_sqlite_type(value: Any) -> str:
        if value is None:
            return "TEXT"
        if isinstance(value, bool):
            return "INTEGER"
        if isinstance(value, int):
            return "INTEGER"
        if isinstance(value, float):
            return "REAL"
        if isinstance(value, (bytes, bytearray, memoryview)):
            return "BLOB"
        return "TEXT"

    async def _get_table_columns(self, table: str) -> Set[str]:
        """Get actual columns that exist in the table."""
        if table in self._table_columns_cache:
            return self._table_columns_cache[table]

        columns = set()
        try:
            async with self._db_semaphore:
                async with self._db_connection.execute(
                    f"PRAGMA table_info({table})"
                ) as cursor:
                    async for row in cursor:
                        columns.add(row[1])  # Column name is at index 1
            self._table_columns_cache[table] = columns
        except:
            pass
        return columns

    async def _invalidate_column_cache(self, table: str):
        """Invalidate column cache for a table."""
        if table in self._table_columns_cache:
            del self._table_columns_cache[table]

    async def _ensure_column(self, table: str, name: str, value: Any) -> None:
        col_type = self._py_to_sqlite_type(value)
        try:
            async with self._db_semaphore:
                await self._db_connection.execute(
                    f"ALTER TABLE {table} ADD COLUMN `{name}` {col_type}"
                )
                await self._db_connection.commit()
            await self._invalidate_column_cache(table)
        except aiosqlite.OperationalError as e:
            if "duplicate column name" in str(e).lower():
                pass  # Column already exists
            else:
                raise

    async def _ensure_table(self, table: str, col_sources: Dict[str, Any]) -> None:
        # Always include default columns
        cols = self._DEFAULT_COLUMNS.copy()

        # Add columns from col_sources
        for key, val in col_sources.items():
            if key not in cols:
                cols[key] = self._py_to_sqlite_type(val)

        columns_sql = ", ".join(f"`{k}` {t}" for k, t in cols.items())
        async with self._db_semaphore:
            await self._db_connection.execute(
                f"CREATE TABLE IF NOT EXISTS {table} ({columns_sql})"
            )
            await self._db_connection.commit()
        await self._invalidate_column_cache(table)

    async def _table_exists(self, table: str) -> bool:
        """Check if a table exists."""
        async with self._db_semaphore:
            async with self._db_connection.execute(
                "SELECT name FROM sqlite_master WHERE type='table' AND name=?", (table,)
            ) as cursor:
                return await cursor.fetchone() is not None

    _RE_NO_COLUMN = re.compile(r"(?:no such column:|has no column named) (\w+)")
    _RE_NO_TABLE = re.compile(r"no such table: (\w+)")

    @classmethod
    def _missing_column_from_error(
        cls, err: aiosqlite.OperationalError
    ) -> Optional[str]:
        m = cls._RE_NO_COLUMN.search(str(err))
        return m.group(1) if m else None

    @classmethod
    def _missing_table_from_error(
        cls, err: aiosqlite.OperationalError
    ) -> Optional[str]:
        m = cls._RE_NO_TABLE.search(str(err))
        return m.group(1) if m else None

    async def _safe_execute(
        self,
        table: str,
        sql: str,
        params: Iterable[Any],
        col_sources: Dict[str, Any],
        max_retries: int = 10,
    ) -> aiosqlite.Cursor:
        retries = 0
        while retries < max_retries:
            try:
                async with self._db_semaphore:
                    cursor = await self._db_connection.execute(sql, params)
                    await self._db_connection.commit()
                    return cursor
            except aiosqlite.OperationalError as err:
                retries += 1
                err_str = str(err).lower()

                # Handle missing column
                col = self._missing_column_from_error(err)
                if col:
                    if col in col_sources:
                        await self._ensure_column(table, col, col_sources[col])
                    else:
                        # Column not in sources, ensure it with NULL/TEXT type
                        await self._ensure_column(table, col, None)
                    continue

                # Handle missing table
                tbl = self._missing_table_from_error(err)
                if tbl:
                    await self._ensure_table(tbl, col_sources)
                    continue

                # Handle other column-related errors
                if "has no column named" in err_str:
                    # Extract column name differently
                    match = re.search(r"table \w+ has no column named (\w+)", err_str)
                    if match:
                        col_name = match.group(1)
                        if col_name in col_sources:
                            await self._ensure_column(
                                table, col_name, col_sources[col_name]
                            )
                        else:
                            await self._ensure_column(table, col_name, None)
                        continue

                raise
        raise Exception(f"Max retries ({max_retries}) exceeded")

    async def _filter_existing_columns(
        self, table: str, data: Dict[str, Any]
    ) -> Dict[str, Any]:
        """Filter data to only include columns that exist in the table."""
        if not await self._table_exists(table):
            return data

        existing_columns = await self._get_table_columns(table)
        if not existing_columns:
            return data

        return {k: v for k, v in data.items() if k in existing_columns}

    async def _safe_query(
        self,
        table: str,
        sql: str,
        params: Iterable[Any],
        col_sources: Dict[str, Any],
    ) -> AsyncGenerator[Dict[str, Any], None]:
        # Check if table exists first
        if not await self._table_exists(table):
            return

        max_retries = 10
        retries = 0

        while retries < max_retries:
            try:
                async with self._db_semaphore:
                    self._db_connection.row_factory = aiosqlite.Row
                    async with self._db_connection.execute(sql, params) as cursor:
                        # Fetch all rows while holding the semaphore
                        rows = await cursor.fetchall()

                # Yield rows after releasing the semaphore
                for row in rows:
                    yield dict(row)
                return
            except aiosqlite.OperationalError as err:
                retries += 1
                err_str = str(err).lower()

                # Handle missing table
                tbl = self._missing_table_from_error(err)
                if tbl:
                    # For queries, if table doesn't exist, just return empty
                    return

                # Handle missing column in WHERE clause or SELECT
                if "no such column" in err_str:
                    # For queries with missing columns, return empty
                    return

                raise

    @staticmethod
    def _build_where(where: Optional[Dict[str, Any]]) -> tuple[str, List[Any]]:
        if not where:
            return "", []
        clauses, vals = zip(*[(f"`{k}` = ?", v) for k, v in where.items()])
        return " WHERE " + " AND ".join(clauses), list(vals)

    async def _server_insert(
        self, table: str, args: Dict[str, Any], return_id: bool = False
    ) -> Union[str, int]:
        """Insert a record. If return_id=True, returns auto-incremented ID instead of UUID."""
        uid = str(uuid4())
        now = self._utc_iso()
        record = {
            "uid": uid,
            "created_at": now,
            "updated_at": now,
            "deleted_at": None,
            **args,
        }

        # Ensure table exists with all needed columns
        await self._ensure_table(table, record)

        # Handle auto-increment ID if requested
        if return_id and "id" not in args:
            # Ensure id column exists
            async with self._db_semaphore:
                # Add id column if it doesn't exist
                try:
                    await self._db_connection.execute(
                        f"ALTER TABLE {table} ADD COLUMN id INTEGER PRIMARY KEY AUTOINCREMENT"
                    )
                    await self._db_connection.commit()
                except aiosqlite.OperationalError as e:
                    if "duplicate column name" not in str(e).lower():
                        # Try without autoincrement constraint
                        try:
                            await self._db_connection.execute(
                                f"ALTER TABLE {table} ADD COLUMN id INTEGER"
                            )
                            await self._db_connection.commit()
                        except:
                            pass

            await self._invalidate_column_cache(table)

            # Insert and get lastrowid
            cols = "`" + "`, `".join(record.keys()) + "`"
            qs = ", ".join(["?"] * len(record))
            sql = f"INSERT INTO {table} ({cols}) VALUES ({qs})"
            cursor = await self._safe_execute(table, sql, list(record.values()), record)
            return cursor.lastrowid

        cols = "`" + "`, `".join(record) + "`"
        qs = ", ".join(["?"] * len(record))
        sql = f"INSERT INTO {table} ({cols}) VALUES ({qs})"
        await self._safe_execute(table, sql, list(record.values()), record)
        return uid

    async def _server_update(
        self,
        table: str,
        args: Dict[str, Any],
        where: Optional[Dict[str, Any]] = None,
    ) -> int:
        if not args:
            return 0

        # Check if table exists
        if not await self._table_exists(table):
            return 0

        args["updated_at"] = self._utc_iso()

        # Ensure all columns exist
        all_cols = {**args, **(where or {})}
        await self._ensure_table(table, all_cols)
        for col, val in all_cols.items():
            await self._ensure_column(table, col, val)

        set_clause = ", ".join(f"`{k}` = ?" for k in args)
        where_clause, where_params = self._build_where(where)
        sql = f"UPDATE {table} SET {set_clause}{where_clause}"
        params = list(args.values()) + where_params
        cur = await self._safe_execute(table, sql, params, all_cols)
        return cur.rowcount

    async def _server_delete(
        self, table: str, where: Optional[Dict[str, Any]] = None
    ) -> int:
        # Check if table exists
        if not await self._table_exists(table):
            return 0

        where_clause, where_params = self._build_where(where)
        sql = f"DELETE FROM {table}{where_clause}"
        cur = await self._safe_execute(table, sql, where_params, where or {})
        return cur.rowcount

    async def _server_upsert(
        self,
        table: str,
        args: Dict[str, Any],
        where: Optional[Dict[str, Any]] = None,
    ) -> str | None:
        if not args:
            raise ValueError("Nothing to update. Empty dict given.")
        args["updated_at"] = self._utc_iso()
        affected = await self._server_update(table, args, where)
        if affected:
            rec = await self._server_get(table, where)
            return rec.get("uid") if rec else None
        merged = {**(where or {}), **args}
        return await self._server_insert(table, merged)

    async def _server_get(
        self, table: str, where: Optional[Dict[str, Any]] = None
    ) -> Optional[Dict[str, Any]]:
        where_clause, where_params = self._build_where(where)
        sql = f"SELECT * FROM {table}{where_clause} LIMIT 1"
        async for row in self._safe_query(table, sql, where_params, where or {}):
            return row
        return None

    async def _server_find(
        self,
        table: str,
        where: Optional[Dict[str, Any]] = None,
        *,
        limit: int = 0,
        offset: int = 0,
        order_by: Optional[str] = None,
    ) -> List[Dict[str, Any]]:
        """Find records with optional ordering."""
        where_clause, where_params = self._build_where(where)
        order_clause = f" ORDER BY {order_by}" if order_by else ""
        extra = (f" LIMIT {limit}" if limit else "") + (
            f" OFFSET {offset}" if offset else ""
        )
        sql = f"SELECT * FROM {table}{where_clause}{order_clause}{extra}"
        return [
            row async for row in self._safe_query(table, sql, where_params, where or {})
        ]

    async def _server_count(
        self, table: str, where: Optional[Dict[str, Any]] = None
    ) -> int:
        # Check if table exists
        if not await self._table_exists(table):
            return 0

        where_clause, where_params = self._build_where(where)
        sql = f"SELECT COUNT(*) FROM {table}{where_clause}"
        gen = self._safe_query(table, sql, where_params, where or {})
        async for row in gen:
            return next(iter(row.values()), 0)
        return 0

    async def _server_exists(self, table: str, where: Dict[str, Any]) -> bool:
        return (await self._server_count(table, where)) > 0

    async def _server_kv_set(
        self,
        key: str,
        value: Any,
        *,
        table: str | None = None,
    ) -> None:
        tbl = table or self._KV_TABLE
        json_val = json.dumps(value, default=str)
        await self._server_upsert(tbl, {"value": json_val}, {"key": key})

    async def _server_kv_get(
        self,
        key: str,
        *,
        default: Any = None,
        table: str | None = None,
    ) -> Any:
        tbl = table or self._KV_TABLE
        row = await self._server_get(tbl, {"key": key})
        if not row:
            return default
        try:
            return json.loads(row["value"])
        except Exception:
            return default

    async def _server_execute_raw(
        self, sql: str, params: Optional[Tuple] = None
    ) -> Any:
        """Execute raw SQL for complex queries like JOINs."""
        async with self._db_semaphore:
            cursor = await self._db_connection.execute(sql, params or ())
            await self._db_connection.commit()
            return cursor

    async def _server_query_raw(
        self, sql: str, params: Optional[Tuple] = None
    ) -> List[Dict[str, Any]]:
        """Execute raw SQL query and return results as list of dicts."""
        try:
            async with self._db_semaphore:
                self._db_connection.row_factory = aiosqlite.Row
                async with self._db_connection.execute(sql, params or ()) as cursor:
                    return [dict(row) async for row in cursor]
        except aiosqlite.OperationalError:
            # Return empty list if query fails
            return []

    async def _server_query_one(
        self, sql: str, params: Optional[Tuple] = None
    ) -> Optional[Dict[str, Any]]:
        """Execute raw SQL query and return single result."""
        results = await self._server_query_raw(sql + " LIMIT 1", params)
        return results[0] if results else None

    async def _server_create_table(
        self,
        table: str,
        schema: Dict[str, str],
        constraints: Optional[List[str]] = None,
    ):
        """Create table with custom schema and constraints. Always includes default columns."""
        # Merge default columns with custom schema
        full_schema = self._DEFAULT_COLUMNS.copy()
        full_schema.update(schema)

        columns = [f"`{col}` {dtype}" for col, dtype in full_schema.items()]
        if constraints:
            columns.extend(constraints)
        columns_sql = ", ".join(columns)

        async with self._db_semaphore:
            await self._db_connection.execute(
                f"CREATE TABLE IF NOT EXISTS {table} ({columns_sql})"
            )
            await self._db_connection.commit()
        await self._invalidate_column_cache(table)

    async def _server_insert_unique(
        self, table: str, args: Dict[str, Any], unique_fields: List[str]
    ) -> Union[str, None]:
        """Insert with unique constraint handling. Returns uid on success, None if duplicate."""
        try:
            return await self._server_insert(table, args)
        except aiosqlite.IntegrityError as e:
            if "UNIQUE" in str(e):
                return None
            raise

    async def _server_aggregate(
        self,
        table: str,
        function: str,
        column: str = "*",
        where: Optional[Dict[str, Any]] = None,
    ) -> Any:
        """Perform aggregate functions like SUM, AVG, MAX, MIN."""
        # Check if table exists
        if not await self._table_exists(table):
            return None

        where_clause, where_params = self._build_where(where)
        sql = f"SELECT {function}({column}) as result FROM {table}{where_clause}"
        result = await self._server_query_one(sql, tuple(where_params))
        return result["result"] if result else None

    async def close(self):
        """Close the connection or server."""
        if not self._initialized:
            return

        if self._client_session:
            await self._client_session.close()
        if self._runner:
            await self._runner.cleanup()
        if os.path.exists(self._socket_path) and self._is_server:
            os.unlink(self._socket_path)
        if self._db_connection:
            await self._db_connection.close()


class TransactionContext:
    """Context manager for database transactions."""

    def __init__(
        self, db_connection: aiosqlite.Connection, semaphore: asyncio.Semaphore = None
    ):
        self.db_connection = db_connection
        self.semaphore = semaphore

    async def __aenter__(self):
        if self.semaphore:
            await self.semaphore.acquire()
        try:
            await self.db_connection.execute("BEGIN")
            return self.db_connection
        except:
            if self.semaphore:
                self.semaphore.release()
            raise

    async def __aexit__(self, exc_type, exc_val, exc_tb):
        try:
            if exc_type is None:
                await self.db_connection.commit()
            else:
                await self.db_connection.rollback()
        finally:
            if self.semaphore:
                self.semaphore.release()


# Test cases remain the same but with additional tests for new functionality
class TestAsyncDataSet(unittest.IsolatedAsyncioTestCase):

    async def asyncSetUp(self):
        self.db_path = Path("temp_test.db")
        if self.db_path.exists():
            self.db_path.unlink()
        self.connector = AsyncDataSet(str(self.db_path), max_concurrent_queries=1)

    async def asyncTearDown(self):
        await self.connector.close()
        if self.db_path.exists():
            self.db_path.unlink()

    async def test_insert_and_get(self):
        await self.connector.insert("people", {"name": "John Doe", "age": 30})
        rec = await self.connector.get("people", {"name": "John Doe"})
        self.assertIsNotNone(rec)
        self.assertEqual(rec["name"], "John Doe")

    async def test_get_nonexistent(self):
        result = await self.connector.get("people", {"name": "Jane Doe"})
        self.assertIsNone(result)

    async def test_update(self):
        await self.connector.insert("people", {"name": "John Doe", "age": 30})
        await self.connector.update("people", {"age": 31}, {"name": "John Doe"})
        rec = await self.connector.get("people", {"name": "John Doe"})
        self.assertEqual(rec["age"], 31)

    async def test_order_by(self):
        await self.connector.insert("people", {"name": "Alice", "age": 25})
        await self.connector.insert("people", {"name": "Bob", "age": 30})
        await self.connector.insert("people", {"name": "Charlie", "age": 20})

        results = await self.connector.find("people", order_by="age ASC")
        self.assertEqual(results[0]["name"], "Charlie")
        self.assertEqual(results[-1]["name"], "Bob")

    async def test_raw_query(self):
        await self.connector.insert("people", {"name": "John", "age": 30})
        await self.connector.insert("people", {"name": "Jane", "age": 25})

        results = await self.connector.query_raw(
            "SELECT * FROM people WHERE age > ?", (26,)
        )
        self.assertEqual(len(results), 1)
        self.assertEqual(results[0]["name"], "John")

    async def test_aggregate(self):
        await self.connector.insert("people", {"name": "John", "age": 30})
        await self.connector.insert("people", {"name": "Jane", "age": 25})
        await self.connector.insert("people", {"name": "Bob", "age": 35})

        avg_age = await self.connector.aggregate("people", "AVG", "age")
        self.assertEqual(avg_age, 30)

        max_age = await self.connector.aggregate("people", "MAX", "age")
        self.assertEqual(max_age, 35)

    async def test_insert_with_auto_id(self):
        # Test auto-increment ID functionality
        id1 = await self.connector.insert("posts", {"title": "First"}, return_id=True)
        id2 = await self.connector.insert("posts", {"title": "Second"}, return_id=True)
        self.assertEqual(id2, id1 + 1)

    async def test_transaction(self):
        await self.connector._ensure_initialized()
        if self.connector._is_server:
            async with self.connector.transaction() as conn:
                await conn.execute(
                    "INSERT INTO people (uid, name, age, created_at, updated_at) VALUES (?, ?, ?, ?, ?)",
                    ("test-uid", "John", 30, "2024-01-01", "2024-01-01"),
                )
                # Transaction will be committed

            rec = await self.connector.get("people", {"name": "John"})
            self.assertIsNotNone(rec)

    async def test_create_custom_table(self):
        schema = {
            "id": "INTEGER PRIMARY KEY AUTOINCREMENT",
            "username": "TEXT NOT NULL",
            "email": "TEXT NOT NULL",
            "score": "INTEGER DEFAULT 0",
        }
        constraints = ["UNIQUE(username)", "UNIQUE(email)"]

        await self.connector.create_table("users", schema, constraints)

        # Test that table was created with constraints
        result = await self.connector.insert_unique(
            "users",
            {"username": "john", "email": "john@example.com"},
            ["username", "email"],
        )
        self.assertIsNotNone(result)

        # Test duplicate insert
        result = await self.connector.insert_unique(
            "users",
            {"username": "john", "email": "different@example.com"},
            ["username", "email"],
        )
        self.assertIsNone(result)

    async def test_missing_table_operations(self):
        # Test operations on non-existent tables
        self.assertEqual(await self.connector.count("nonexistent"), 0)
        self.assertEqual(await self.connector.find("nonexistent"), [])
        self.assertIsNone(await self.connector.get("nonexistent"))
        self.assertFalse(await self.connector.exists("nonexistent", {"id": 1}))
        self.assertEqual(await self.connector.delete("nonexistent"), 0)
        self.assertEqual(
            await self.connector.update("nonexistent", {"name": "test"}), 0
        )

    async def test_auto_column_creation(self):
        # Insert with new columns that don't exist yet
        await self.connector.insert(
            "dynamic", {"col1": "value1", "col2": 42, "col3": 3.14}
        )

        # Add more columns in next insert
        await self.connector.insert(
            "dynamic", {"col1": "value2", "col4": True, "col5": None}
        )

        # All records should be retrievable
        records = await self.connector.find("dynamic")
        self.assertEqual(len(records), 2)


if __name__ == "__main__":
    unittest.main()