import os
from collections import defaultdict
import numpy as np
import random


def fix_seed(seed):
    random.seed(seed)
    np.random.seed(seed)

def collect_video_paths(base_path):
    """
    Traverses the base_path directory, collecting video file paths
    organized by class folder names.
    
    Args:
        base_path (str): The root directory containing class subfolders.

    Returns:
        dict: A dictionary mapping each class name to a list of video file paths.
    """
    video_dict = defaultdict(list)
    
    if not os.path.exists(base_path):
        raise FileNotFoundError(f"Directory not found: {base_path}")
    
    for class_name in os.listdir(base_path):
        class_dir = os.path.join(base_path, class_name)
        if os.path.isdir(class_dir):
            for video_file in os.listdir(class_dir):
                video_path = os.path.join(class_dir, video_file)
                video_dict[class_name].append(video_path)
    
    return video_dict


def separate_by_class(video_dict):
    """
    Reorganizes video_dict into a nested dictionary:
    {
        class_name: {
            video_key: [list of video paths]
        }
    }
    where video_key is derived from the filename (e.g., 'abc_001.mp4' → 'abc')
    """
    all_class_dict = defaultdict(lambda: defaultdict(list))

    for video_class, videos in video_dict.items():
        for v in videos:
            video_name = os.path.basename(v)

            split_video_name = video_name.split("_")
            len_split = len(split_video_name)
            video_key = "_".join(split_video_name[:min(len_split, 4) - 1])

            all_class_dict[video_class][video_key].append(v)

    sorted_class_dict = {}
    for cls in sorted(all_class_dict.keys(), key=str):
        inner_dict = all_class_dict[cls]
        sorted_inner_dict = dict(sorted(inner_dict.items(), key=lambda x: str(x[0])))
        sorted_class_dict[cls] = sorted_inner_dict


    return sorted_class_dict


def get_train_val_test(video_list_class, split_configuration=[0.9, 0.05, 0.05]):

    train_val_test_dict = defaultdict(dict)

    for video_class, video_keys in video_list_class.items():
        # Shuffle video keys
        tmp_video_key = list(video_keys)
        random.shuffle(tmp_video_key)

        n_total = len(tmp_video_key)
        n_train = round(split_configuration[0] * n_total)
        n_val = round(split_configuration[1] * n_total)

        # Make sure all samples are used, including remainder
        n_test = n_total - n_train - n_val

        # Split the shuffled list
        train = tmp_video_key[:n_train]
        val = tmp_video_key[n_train:n_train + n_val]
        test = tmp_video_key[n_train + n_val:n_train + n_val + n_test]

        train_val_test_dict[video_class] = {
            "train": train,
            "val": val,
            "test": test
        }

    return train_val_test_dict

def collect_videos(out_data, full_video_dict, train_list, val_list, test_list):
        for video_class, splits in out_data.items():
            for split_name, video_keys in splits.items():
                for video_key in video_keys:
                    video_paths = full_video_dict[video_class][video_key]
                    if split_name == "train":
                        train_list.extend(video_paths)
                    elif split_name == "val":
                        val_list.extend(video_paths)
                    elif split_name == "test":
                        test_list.extend(video_paths)
        
def write_txt(file_path, video_list):
    with open(file_path, "w") as f:
        for path in video_list:
            video_name = ".".join(os.path.basename(path).split(".")[:-1])
            f.write(f"{video_name}\n")


def _print_inspect(video_list_class):
    for video_class, values in video_list_class.items():
        print(f"### {video_class} ### with total {len(values)}")
        for video_key in values:
            print(video_key, len(values[video_key]))

if __name__ == "__main__":
    fix_seed(11293)
    nas_path = "/mnt/nas192"
    train_path = os.path.join(
        nas_path,
        "Research_materials/PIA_clip_dataset/CLIP4Clip_format/PIA_clip_outdoor_v2/original_train_set_processed"
    )
    val_test_path = os.path.join(
        nas_path,
        "Research_materials/PIA_clip_dataset/CLIP4Clip_format/PIA_clip_outdoor_v2/original_val_test_set_processed"
    )

    video_list_train = collect_video_paths(train_path)
    video_list_class_train = separate_by_class(video_list_train)
    video_list_val_test = collect_video_paths(val_test_path)
    video_list_class_val_test = separate_by_class(video_list_val_test)


    
    split_configuration = {
        "video_list_class_train": [0.94, 0.03, 0.03],
        "video_list_class_val_test": [0.9, 0.05, 0.05]
    }

    out_train = get_train_val_test(video_list_class_train, split_configuration["video_list_class_train"])
    out_val_test = get_train_val_test(video_list_class_val_test, split_configuration["video_list_class_val_test"])

    train_list = []
    val_list = []
    test_list = []

    collect_videos(out_train, video_list_class_train, train_list, val_list, test_list)
    print(f"Length Train {len(train_list)} {len(val_list)} {len(test_list)}")
    collect_videos(out_val_test, video_list_class_val_test, train_list, val_list, test_list)
    print(f"Length Train Val Test {len(train_list)} {len(val_list)} {len(test_list)}")
    
    # txt_out_dir = "./"
    # write_txt(os.path.join(txt_out_dir, "train_list.txt"), train_list)
    # write_txt(os.path.join(txt_out_dir, "val_list.txt"), val_list)
    # write_txt(os.path.join(txt_out_dir, "test_list.txt"), test_list)

    # print("Saved train.txt, val.txt, and test.txt in ./splits")