"""
合并指定目录下所有表头一致的 CSV 文件为一个 CSV。
"""

from __future__ import annotations

import argparse
from pathlib import Path

import pandas as pd

_PROJECT_ROOT = Path(__file__).resolve().parent
DEFAULT_INPUT_DIR = _PROJECT_ROOT / '/Users/onesvmwhoops/Documents/no scratch spray for cats'
DEFAULT_OUTPUT_PATH = _PROJECT_ROOT / "merged_reviews.csv"


def merge_csv_directory(
    input_dir: str | Path,
    output_path: str | Path,
    *,
    pattern: str = "*.csv",
    recursive: bool = False,
) -> pd.DataFrame:
    """
    读取目录内所有匹配的 CSV（表头须一致），纵向合并后写入 output_path。

    :param input_dir: 含多个 CSV 的目录
    :param output_path: 合并结果输出路径
    :param pattern: 文件名 glob，默认 *.csv
    :param recursive: 是否包含子目录中的 CSV
    :return: 合并后的 DataFrame
    """
    input_dir = Path(input_dir).resolve()
    output_path = Path(output_path).resolve()

    if not input_dir.is_dir():
        raise NotADirectoryError(f"目录不存在: {input_dir}")

    globber = input_dir.rglob if recursive else input_dir.glob
    csv_files = sorted(
        p for p in globber(pattern) if p.is_file() and p.resolve() != output_path
    )

    if not csv_files:
        raise FileNotFoundError(f"未在 {input_dir} 找到匹配 {pattern!r} 的 CSV 文件")

    frames: list[pd.DataFrame] = []
    expected_columns: list[str] | None = None

    for path in csv_files:
        df = pd.read_csv(path, dtype=str, keep_default_na=False)
        if expected_columns is None:
            expected_columns = list(df.columns)
        elif list(df.columns) != expected_columns:
            raise ValueError(
                f"表头不一致: {path.name}\n"
                f"  期望: {expected_columns}\n"
                f"  实际: {list(df.columns)}"
            )
        frames.append(df)

    merged = pd.concat(frames, ignore_index=True)
    output_path.parent.mkdir(parents=True, exist_ok=True)
    merged.to_csv(output_path, index=False, encoding="utf-8-sig")

    print(f"已合并 {len(csv_files)} 个文件，共 {len(merged)} 行 -> {output_path}")
    for path in csv_files:
        print(f"  - {path.name}")

    return merged


def main() -> None:
    parser = argparse.ArgumentParser(description="合并目录内表头相同的 CSV 文件")
    parser.add_argument(
        "-i",
        "--input",
        type=Path,
        default=DEFAULT_INPUT_DIR,
        metavar="DIR",
        help=f"输入目录（默认: {DEFAULT_INPUT_DIR}）",
    )
    parser.add_argument(
        "-o",
        "--output",
        type=Path,
        default=DEFAULT_OUTPUT_PATH,
        metavar="FILE",
        help=f"输出 CSV 路径（默认: {DEFAULT_OUTPUT_PATH}）",
    )
    parser.add_argument(
        "-r",
        "--recursive",
        action="store_true",
        help="是否递归搜索子目录",
    )
    args = parser.parse_args()

    merge_csv_directory(args.input, args.output, recursive=args.recursive)


if __name__ == "__main__":
    main()