from typing import Any, Dict, Optional
from server.app.core.node_base import TraceNode, input_port, output_port, param
from server.app.core.node_registry import register_node
import polars as pl
from pathlib import Path
from server.app.core.user_manager import CLOUD_ROOT

@register_node
class CsvLoaderNode(TraceNode):
    """
    简单 CSV 加载器（Polars）
    输入：相对于用户目录或绝对路径的 CSV 文件路径
    输出：Polars DataFrame（DataTable）
    """

    CATEGORY = "IO/Load"
    DISPLAY_NAME = "CSV 加载器"
    DESCRIPTION = "从 CSV 文件加载为 polars.DataFrame（支持用户目录下路径）"
    ICON = "📥"

    @input_port("path", "String", description="CSV 文件路径（相对于用户目录或绝对路径）", required=True)
    @param("sep", "String", default=",", description="分隔符，例如 , 或 \t")
    @output_port("table", "DataTable", description="加载得到的表（polars.DataFrame）")
    def process(self, inputs: Dict[str, Any], context: Optional[Dict] = None) -> Dict[str, Any]:
        file_path = inputs.get("path", ".csv")
        file_path = CLOUD_ROOT / file_path
        
        if not file_path.exists() or not file_path.is_file():
            raise FileNotFoundError(f"CSV 文件未找到: {file_path}")
        
        sep = str(self.get_param("sep", ","))
        # polars will infer dtypes; allow user to override in future
        try:
            if sep.lower() == "\\t":
                sep_char = "\t"
            else:
                sep_char = sep
            df = pl.read_csv(file_path, separator=sep_char)
        except Exception as e:
            raise RuntimeError(f"读取 CSV 失败: {e}")

        return {"table": df}