data_loader.py

import os
import pandas as pd

def load_data(input_path):
    if not os.path.exists(input_path):
        raise FileNotFoundError(f"{input_path} not found")

    # Single file
    if os.path.isfile(input_path):
        df = pd.read_csv(input_path)
        return df, {"single_case": df}

    # Folder
    elif os.path.isdir(input_path):
        all_files = [
            os.path.join(input_path, f)
            for f in os.listdir(input_path)
            if f.endswith(".csv")
        ]

        if not all_files:
            raise ValueError("No CSV files found in directory")

        df_list = []
        individual_dfs = {}

        for file in all_files:
            temp_df = pd.read_csv(file)

            case_name = os.path.splitext(os.path.basename(file))[0]

            if "case_name" not in temp_df.columns:
                temp_df["case_name"] = case_name

            df_list.append(temp_df)
            individual_dfs[case_name] = temp_df

        combined_df = pd.concat(df_list, ignore_index=True)

        return combined_df, individual_dfs

    else:
        raise ValueError("Invalid input path")