import os
from pathlib import Path
from typing import List, Optional
import pandas as pd
import pyarrow.parquet as pq
from config import PARQUET_ROOT


def list_model_types() -> List[str]:
    """返回 PARQUET_ROOT 下所有机型文件夹名称。"""
    return [p.name for p in PARQUET_ROOT.iterdir() if p.is_dir()]


def list_turbines(model_name: str) -> List[dict]:
    """
    返回某机型下所有风机信息列表。
    每条记录: {model_name, farm_name, turbine_name, path}
    """
    records = []
    model_root = PARQUET_ROOT / model_name
    if not model_root.exists():
        return records
    for farm_dir in model_root.iterdir():
        if not farm_dir.is_dir():
            continue
        for pq_file in farm_dir.glob("*.parquet"):
            if pq_file.name.startswith("._"):
                continue
            records.append({
                "model_name":   model_name,
                "farm_name":    farm_dir.name,
                "turbine_name": pq_file.stem,
                "path":         pq_file,
            })
    return records


def load_turbine(
    path: Path,
    required_cols: List[str],
    optional_cols: Optional[List[str]] = None,
) -> Optional[pd.DataFrame]:
    """
    读取单台风机 parquet 文件，带测点缺失容错。

    - required_cols: 任意一列缺失则跳过该文件，返回 None
    - optional_cols: 存在则读取，不存在则忽略
    - 返回仅包含实际存在列的 DataFrame，已对 required_cols 做 dropna
    """
    try:
        pq_file = pq.ParquetFile(path)
        schema_names = set(pq_file.schema.names)
    except Exception as e:
        print(f"[WARN] 无法读取 schema {path.name}: {e}")
        return None

    missing_required = [c for c in required_cols if c not in schema_names]
    if missing_required:
        print(f"[SKIP] {path.name} 缺少必要测点: {missing_required}")
        return None

    cols_to_read = list(required_cols)
    if optional_cols:
        cols_to_read += [c for c in optional_cols if c in schema_names]

    try:
        df = pq_file.read(columns=cols_to_read).to_pandas()
    except Exception as e:
        print(f"[WARN] 读取数据失败 {path.name}: {e}")
        return None

    # 转换数值类型，跳过时间戳列，过滤必要列的空值
    numeric_cols = [c for c in cols_to_read if c != "data_time"]
    for col in numeric_cols:
        df[col] = pd.to_numeric(df[col], errors='coerce')
    df = df.dropna(subset=required_cols)

    if df.empty:
        print(f"[SKIP] {path.name} 必要测点全为空值")
        return None

    return df


def load_model_type(
    model_name: str,
    required_cols: List[str],
    optional_cols: Optional[List[str]] = None,
) -> pd.DataFrame:
    """
    聚合某机型下所有风机数据为一个 DataFrame（用于训练）。
    自动附加 farm_name / turbine_name 列便于溯源。
    """
    frames = []
    for rec in list_turbines(model_name):
        df = load_turbine(rec["path"], required_cols, optional_cols)
        if df is None:
            continue
        df = df.copy()
        df["farm_name"]    = rec["farm_name"]
        df["turbine_name"] = rec["turbine_name"]
        frames.append(df)

    if not frames:
        print(f"[WARN] 机型 {model_name} 无有效数据（所需列: {required_cols}）")
        return pd.DataFrame()

    result = pd.concat(frames, ignore_index=True)
    print(f"[INFO] 机型 {model_name} 加载完成，共 {len(result)} 行，{len(frames)} 台风机")
    return result