import json
import uuid
from typing import Dict, List, Any, Optional, Union
from datetime import datetime
from python_core.kv import kv
from python_core.utils.logger import setup_logger

logger = setup_logger(__name__)

class Db:
    """
    基于KV存储的数据库类
    提供基础的CRUD操作、索引、查询等功能
    """

    def __init__(self, key: str):
        """
        初始化数据库

        Args:
            key: 数据库的唯一标识符，用作KV存储的前缀
        """
        self.kv = kv
        self.key = key
        self.table_prefix = f"db:{key}:table:"
        self.index_prefix = f"db:{key}:index:"
        self.meta_prefix = f"db:{key}:meta:"

        # 初始化数据库元数据
        self._init_metadata()

    def _init_metadata(self):
        """初始化数据库元数据"""
        try:
            meta_key = f"{self.meta_prefix}info"
            existing_meta = self.kv.get(meta_key)

            if not existing_meta:
                # 创建新的数据库元数据
                metadata = {
                    "created_at": datetime.now().isoformat(),
                    "version": "1.0.0",
                    "tables": [],
                    "indexes": {}
                }
                self.kv.set(meta_key, json.dumps(metadata))
                logger.info(f"Initialized new database: {self.key}")
            else:
                logger.info(f"Connected to existing database: {self.key}")

        except Exception as e:
            logger.error(f"Failed to initialize database metadata: {e}")
            raise e

    def _get_metadata(self) -> Dict[str, Any]:
        """获取数据库元数据"""
        try:
            meta_key = f"{self.meta_prefix}info"
            logger.debug(f"Getting metadata with key: {meta_key}")
            meta_str = self.kv.get(meta_key)
            logger.debug(f"Raw metadata string: {meta_str}")
            if meta_str:
                parsed = json.loads(meta_str)
                logger.debug(f"Parsed metadata: {parsed}")
                return parsed
            logger.debug("No metadata found, returning empty dict")
            return {}
        except Exception as e:
            logger.error(f"Failed to get database metadata: {e}")
            import traceback
            traceback.print_exc()
            return {}

    def _update_metadata(self, metadata: Dict[str, Any]):
        """更新数据库元数据"""
        try:
            meta_key = f"{self.meta_prefix}info"
            logger.debug(f"Updating metadata with key: {meta_key}")
            logger.debug(f"Metadata content: {metadata}")
            result = self.kv.set(meta_key, json.dumps(metadata))
            logger.debug(f"Update result: {result}")

            # 添加短暂延迟确保KV同步
            import time
            time.sleep(0.1)

        except Exception as e:
            logger.error(f"Failed to update database metadata: {e}")
            raise e

    def create_table(self, table_name: str, schema: Dict[str, str] = None) -> bool:
        """
        创建表

        Args:
            table_name: 表名
            schema: 表结构定义 (字段名: 类型)

        Returns:
            创建成功返回True
        """
        try:
            metadata = self._get_metadata()

            if table_name in metadata.get("tables", []):
                logger.warning(f"Table '{table_name}' already exists")
                return False

            # 创建表元数据
            table_meta = {
                "name": table_name,
                "created_at": datetime.now().isoformat(),
                "schema": schema or {},
                "record_count": 0,
                "indexes": []
            }

            # 保存表元数据
            table_meta_key = f"{self.meta_prefix}table:{table_name}"
            self.kv.set(table_meta_key, json.dumps(table_meta))

            # 更新数据库元数据
            metadata.setdefault("tables", []).append(table_name)
            self._update_metadata(metadata)

            logger.info(f"Created table: {table_name}")
            return True

        except Exception as e:
            logger.error(f"Failed to create table '{table_name}': {e}")
            raise e

    def drop_table(self, table_name: str) -> bool:
        """
        删除表

        Args:
            table_name: 表名

        Returns:
            删除成功返回True
        """
        try:
            metadata = self._get_metadata()

            if table_name not in metadata.get("tables", []):
                logger.warning(f"Table '{table_name}' does not exist")
                return False

            # 获取表中所有记录的键
            record_keys = self._get_all_record_keys(table_name)

            # 删除所有记录
            if record_keys:
                self.kv.removes(record_keys)

            # 删除表元数据
            table_meta_key = f"{self.meta_prefix}table:{table_name}"
            self.kv.remove(table_meta_key)

            # 删除相关索引
            self._drop_table_indexes(table_name)

            # 更新数据库元数据
            metadata["tables"] = [t for t in metadata.get("tables", []) if t != table_name]
            self._update_metadata(metadata)

            logger.info(f"Dropped table: {table_name}")
            return True

        except Exception as e:
            logger.error(f"Failed to drop table '{table_name}': {e}")
            raise e

    def insert(self, table_name: str, data: Dict[str, Any], record_id: str = None) -> str:
        """
        插入记录

        Args:
            table_name: 表名
            data: 记录数据
            record_id: 记录ID，如果不提供则自动生成

        Returns:
            记录ID
        """
        try:
            if not self._table_exists(table_name):
                raise ValueError(f"Table '{table_name}' does not exist")

            # 生成记录ID
            if not record_id:
                import uuid
                record_id = str(uuid.uuid4())

            # 添加元数据
            record = {
                "id": record_id,
                "data": data,
                "created_at": datetime.now().isoformat(),
                "updated_at": datetime.now().isoformat()
            }

            # 保存记录
            record_key = f"{self.table_prefix}{table_name}:record:{record_id}"
            self.kv.set(record_key, json.dumps(record))

            # 更新表统计
            self._update_table_stats(table_name, record_count_delta=1)

            # 更新索引
            self._update_indexes(table_name, record_id, data)

            logger.debug(f"Inserted record {record_id} into table {table_name}")
            return record_id

        except Exception as e:
            logger.error(f"Failed to insert record into table '{table_name}': {e}")
            raise e

    def get(self, table_name: str, record_id: str) -> Optional[Dict[str, Any]]:
        """
        获取单条记录

        Args:
            table_name: 表名
            record_id: 记录ID

        Returns:
            记录数据，如果不存在返回None
        """
        try:
            if not self._table_exists(table_name):
                raise ValueError(f"Table '{table_name}' does not exist")

            record_key = f"{self.table_prefix}{table_name}:record:{record_id}"
            record_str = self.kv.get(record_key)

            if record_str:
                record = json.loads(record_str)
                return record

            return None

        except Exception as e:
            logger.error(f"Failed to get record {record_id} from table '{table_name}': {e}")
            raise e

    def update(self, table_name: str, record_id: str, data: Dict[str, Any]) -> bool:
        """
        更新记录

        Args:
            table_name: 表名
            record_id: 记录ID
            data: 新的数据

        Returns:
            更新成功返回True
        """
        try:
            if not self._table_exists(table_name):
                raise ValueError(f"Table '{table_name}' does not exist")

            # 获取现有记录
            existing_record = self.get(table_name, record_id)
            if not existing_record:
                logger.warning(f"Record {record_id} not found in table {table_name}")
                return False

            # 更新记录
            updated_record = {
                "id": record_id,
                "data": data,
                "created_at": existing_record.get("created_at"),
                "updated_at": datetime.now().isoformat()
            }

            # 保存更新后的记录
            record_key = f"{self.table_prefix}{table_name}:record:{record_id}"
            self.kv.set(record_key, json.dumps(updated_record))

            # 更新索引
            self._update_indexes(table_name, record_id, data, existing_record.get("data"))

            logger.debug(f"Updated record {record_id} in table {table_name}")
            return True

        except Exception as e:
            logger.error(f"Failed to update record {record_id} in table '{table_name}': {e}")
            raise e

    def delete(self, table_name: str, record_id: str) -> bool:
        """
        删除记录

        Args:
            table_name: 表名
            record_id: 记录ID

        Returns:
            删除成功返回True
        """
        try:
            if not self._table_exists(table_name):
                raise ValueError(f"Table '{table_name}' does not exist")

            # 获取记录以便清理索引
            existing_record = self.get(table_name, record_id)
            if not existing_record:
                logger.warning(f"Record {record_id} not found in table {table_name}")
                return False

            # 删除记录
            record_key = f"{self.table_prefix}{table_name}:record:{record_id}"
            self.kv.remove(record_key)

            # 更新表统计
            self._update_table_stats(table_name, record_count_delta=-1)

            # 清理索引
            self._remove_from_indexes(table_name, record_id, existing_record.get("data"))

            logger.debug(f"Deleted record {record_id} from table {table_name}")
            return True

        except Exception as e:
            logger.error(f"Failed to delete record {record_id} from table '{table_name}': {e}")
            raise e

    def find_all(self, table_name: str, limit: int = 100) -> List[Dict[str, Any]]:
        """
        获取表中所有记录

        Args:
            table_name: 表名
            limit: 最大返回记录数

        Returns:
            记录列表
        """
        try:
            if not self._table_exists(table_name):
                raise ValueError(f"Table '{table_name}' does not exist")

            # 获取所有记录键
            record_keys = self._get_all_record_keys(table_name, limit)

            if not record_keys:
                return []

            # 批量获取记录
            records_data = self.kv.gets(record_keys)
            records = []

            for key, record_str in records_data.items():
                if record_str:
                    try:
                        record = json.loads(record_str)
                        records.append(record)
                    except json.JSONDecodeError:
                        logger.warning(f"Failed to parse record: {key}")

            return records

        except Exception as e:
            logger.error(f"Failed to find all records in table '{table_name}': {e}")
            raise e

    def find_by_field(self, table_name: str, field: str, value: Any, limit: int = 100) -> List[Dict[str, Any]]:
        """
        根据字段值查找记录

        Args:
            table_name: 表名
            field: 字段名
            value: 字段值
            limit: 最大返回记录数

        Returns:
            匹配的记录列表
        """
        try:
            if not self._table_exists(table_name):
                raise ValueError(f"Table '{table_name}' does not exist")

            # 简单的线性搜索（后续可以优化为索引搜索）
            all_records = self.find_all(table_name, limit * 2)  # 获取更多记录以便过滤

            matching_records = []
            for record in all_records:
                if len(matching_records) >= limit:
                    break

                record_data = record.get("data", {})
                if record_data.get(field) == value:
                    matching_records.append(record)

            return matching_records

        except Exception as e:
            logger.error(f"Failed to find records by field in table '{table_name}': {e}")
            raise e

    def count(self, table_name: str) -> int:
        """
        获取表中记录数量

        Args:
            table_name: 表名

        Returns:
            记录数量
        """
        try:
            if not self._table_exists(table_name):
                raise ValueError(f"Table '{table_name}' does not exist")

            table_meta = self._get_table_metadata(table_name)
            return table_meta.get("record_count", 0)

        except Exception as e:
            logger.error(f"Failed to count records in table '{table_name}': {e}")
            raise e

    # 辅助方法
    def _table_exists(self, table_name: str) -> bool:
        """检查表是否存在"""
        metadata = self._get_metadata()
        return table_name in metadata.get("tables", [])

    def _get_table_metadata(self, table_name: str) -> Dict[str, Any]:
        """获取表元数据"""
        table_meta_key = f"{self.meta_prefix}table:{table_name}"
        meta_str = self.kv.get(table_meta_key)
        if meta_str:
            return json.loads(meta_str)
        return {}

    def _update_table_stats(self, table_name: str, record_count_delta: int = 0):
        """更新表统计信息"""
        try:
            table_meta = self._get_table_metadata(table_name)
            table_meta["record_count"] = table_meta.get("record_count", 0) + record_count_delta

            table_meta_key = f"{self.meta_prefix}table:{table_name}"
            self.kv.set(table_meta_key, json.dumps(table_meta))
        except Exception as e:
            logger.error(f"Failed to update table stats for '{table_name}': {e}")

    def _get_all_record_keys(self, table_name: str, limit: int = 1000) -> List[str]:
        """获取表中所有记录的键"""
        try:
            prefix = f"{self.table_prefix}{table_name}:record:"

            # 使用KV的list_keys功能
            result = self.kv.list_keys(prefix=prefix, limit=limit)

            if result and "result" in result:
                keys = []
                for key_info in result["result"]:
                    if isinstance(key_info, dict):
                        keys.append(key_info.get("name"))
                    else:
                        keys.append(str(key_info))
                return keys

            return []

        except Exception as e:
            logger.error(f"Failed to get record keys for table '{table_name}': {e}")
            return []

    def _update_indexes(self, table_name: str, record_id: str, data: Dict[str, Any], old_data: Dict[str, Any] = None):
        """更新索引（简单实现，后续可扩展）"""
        # 这里可以实现索引更新逻辑
        # 目前为简单实现，不做复杂索引
        pass

    def _remove_from_indexes(self, table_name: str, record_id: str, data: Dict[str, Any]):
        """从索引中移除记录"""
        # 这里可以实现索引清理逻辑
        pass

    def _drop_table_indexes(self, table_name: str):
        """删除表的所有索引"""
        # 这里可以实现索引删除逻辑
        pass

    # 实用方法
    def list_tables(self) -> List[str]:
        """列出所有表"""
        metadata = self._get_metadata()
        return metadata.get("tables", [])

    def table_info(self, table_name: str) -> Dict[str, Any]:
        """获取表信息"""
        if not self._table_exists(table_name):
            raise ValueError(f"Table '{table_name}' does not exist")

        return self._get_table_metadata(table_name)

    def database_info(self) -> Dict[str, Any]:
        """获取数据库信息"""
        metadata = self._get_metadata()

        # 添加表的详细信息
        tables_info = {}
        for table_name in metadata.get("tables", []):
            tables_info[table_name] = self._get_table_metadata(table_name)

        return {
            "database_key": self.key,
            "metadata": metadata,
            "tables": tables_info
        }